SISTEMA CONTROL MIX · 2015. 1. 16. · Jr. Bajada Balta 169, Oficina 702 – Miraflores - Lima 18...

Jr. Bajada Balta 169, Oficina 702 – Miraflores - Lima 18 Teléfonos : 2430414, Celular : 998133533, e-mail : [email protected] Rev.02

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SISTEMA CONTROL MIX

EXPEDIENTE TÉCNICO

2015


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SISTEMA CONTROL MIX

EXPEDIENTE TÉCNICO

1. DESCRIPCIÓN GENERAL

A. El Sistema Control Mix está constituido por un círculo de calidad de 6 etapas para garantizar : 1) el muestreo, 2) moldeo, 3) transporte a laboratorio, 4) curado, 5) ensayo en compresión y 6) remisión de resultados de ensayos en cumplimiento de las normas estándar aplicables.

B. Las normas estándar en su última versión bajo las cuales se ha configurado el

Sistema Control Mix son : ! ASTM C31/C31M-12 "Standard Practice for Making and Curing Concrete

Test Specimens in the Field". ! ASTM C39/C39M-12a "Standard Test Method for Compressive Strength of

Cylindrical Concrete Specimens". ! ASTM C172/C172M-10 "Standard Practice for Sampling Freshly Mixed

Concrete". ! ASTM C470/C470M-09 "Standard Specification for Molds for Forming

Concrete Test Cylinders Vertically". ! ASTM C511-09 "Standard Specification for Mixing Rooms, Moist Cabinets,

Moist Rooms, and Water Storage Tanks Used in the Testing of Hydraulic Cements and Concretes".

! ASTM C1231/1231M-12 "Standard Practice for Use of Unbonded Caps in Determination of Compressive Strength of Hardened Concrete Cylinders"

C. Las normas peruanas NTP están basadas en las normas ASTM detalladas, sin

embargo, se ha decidido emplear la fuente original dado que corresponden a las versiones revisadas y actualizadas regularmente, y nuestra Norma E 060-2009 define su empleo en vez de las Normas NTP para el caso particular del muestreo y ensayo de concreto. (Acápites 5.6.3.1 y 5.6.3.2)

2. DETALLES TÉCNICOS DEL SISTEMA CONTROL MIX 2.1 ETAPA 1 : MUESTREO DEL CONCRETO FRESCO EN OBRA

A. El muestreo del concreto en obra en conformidad con el Sistema Control Mix es ejecutado por personal designado por el cliente, previa capacitación, evaluación y certificación a cargo de especialistas de Control Mix Express (CME).

B. En el Anexo I se adjuntan los documentos que habilitan al suscrito y a la Ing.

Mercedes Neyra como instructores certificados por ASTM International para la capacitación en las Normas ASTM incluidas en el Código ACI-318 y al Técnico Richard Lino con Certificación del American Concrete Institute como Técnico para Control de Concreto Grado I, responsable de las capacitaciones prácticas del personal en obra.


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C. La capacitación que imparte CME está basada en el Programa de Certificación para

Técnicos de Control de Concreto Grado I del American Concrete Institute - ACI, en los aspectos de muestreo, moldeo de testigos en campo, determinación del asentamiento (slump) y medición de temperatura del concreto fresco conforme a las Normas ASTM aplicables.

D. Al personal que aprueba la evaluación teórica y práctica que considera el Programa

de Capacitación se le asigna un código de certificación, siendo el único personal reconocido por el Sistema Control Mix como habilitado para el muestreo y moldeo de los testigos en obra, no recibiéndose ningún testigo que no haya sido muestreado y moldeado por dicho personal calificado, en cumplimiento de las Normas ASTM C31. En el Anexo I se adjunta un ejemplo de Certificado.

2.2 ETAPA 2 : MOLDEO DE TESTIGOS DE CONCRETO

A. Luego de ser efectuado el muestreo del concreto fresco, por parte del personal certificado del cliente, en la oportunidad y frecuencia que éste considere conveniente según la norma ASTM C 31, este personal procede al moldeo de los testigos cilíndricos.

B. El Sistema Control Mix considera el suministro y empleo de módulos para testigos

constituidos por una caja de madera para protección y traslado de testigos de diseño original de CME, 6 moldes cilíndricos plásticos de 4" de diámetro x 8"de altura, varilla compactadora, martillo de goma y regla enrasadora previstos por la norma ASTM C31.

C. Los moldes plásticos han sido fabricados para CME cumpliendo los requisitos y

tolerancias de la Norma ASTM C470 y constan adicionalmente de una tapa también de plástico de ajuste hermético, para garantizar el mantenimiento de la humedad del testigo luego de moldeado y enrasado.

D. Efectuado el moldeo de los testigos en condición estándar controlada, el personal

certificado coloca cuidadosamente los moldes con tapa dentro de la caja de madera, que tiene la doble función de proteger los testigos de golpes o maltratos durante las 48 horas previas a su traslado al laboratorio y proveer aislamiento térmico para asegurar que los testigos se mantengan dentro del rango de temperatura de 16ºC a 27ºC, o curado inicial a ser garantizado en el periodo indicado, en cumplimiento de ASTM C31 para que no se afecte la resistencia a 28 días.

E. El personal responsable del moldeo de los testigos tiene a su cargo la generación de

la orden de servicio para CME con todos los detalles relativos al tipo de concreto, procedencia, fechas de ensayo, etc. que deberán figurar en el certificado de ensayos correspondiente y que adjuntará a cada módulo de testigos, incluyéndose en el Anexo II el formato correspondiente.

2.3 ETAPA 3 : TRANSPORTE DE MÓDULOS CON TESTIGOS AL LABORATORIO

A. El transporte al laboratorio es efectuado por personal técnico de CME en unidades móviles con anaqueles especialmente acondicionados para el traslado de los módulos de madera con los testigos, a fin de garantizar que no sufran golpes ni daños.


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B. En conformidad con ASTM C31, el transporte se efectúa no antes de 8 horas de

producido el fraguado final del concreto, ni después de 48 horas de haberse moldeado los testigos, no debiendo durar el traslado más de 4 horas.

2.4 ETAPA 4 : CURADO EN CONDICIONES CONTROLADAS

A. Los testigos son trasladados al Laboratorio de CME en Villa El Salvador donde se ingresa y registra cada módulo con su orden de servicio correspondiente en la base de datos del software original patentado que forma parte del Sistema Control Mix.

B. El software registra también la ubicación matricial única que tendrán los testigos en

los anaqueles de las cámaras de curado, emitiendo etiquetas con códigos de barras para su identificación.

C. Los testigos se desmoldan y de inmediato se le colocan sus etiquetas de

identificación, colocándose en grupos de 3 en cajas plásticas de diseño especial numeradas, para su almacenaje ordenado en los anaqueles de los cuartos de curado.

D. Se cuenta con cajas numeradas de color rojo donde se depositan los testigos a

ensayarse a edad temprana (normalmente a 7 días o la edad que requiera el cliente ) y también con cajas de color azul para almacenar los testigos a probarse a 28 días o mayor edad si lo requiere el cliente, de tal forma de eliminar cualquier posibilidad de confusión en almacenaje e identificación de los testigos.

E. En un periodo máximo de 30 minutos luego de ser desmoldados, etiquetados y

colocados en sus cajas plásticas, los testigos se trasladan a su ubicación programada en las cámaras de curado.

F. Las cámaras de curado cumplen con los requisitos de la Norma ASTM C511 y

cuentan con un sistema de circuito cerrado de aspersores aéreos de neblina y un tanque de agua con bomba recirculante y control de temperatura para garantizar el mantenimiento de la humedad superficial permanente y la temperatura en el rango de 21ºC a 25ºC previsto en ASTM C31.

2.5 ETAPA 5 : ENSAYO EN COMPRESIÓN DE LOS TESTIGOS

A. El software del Sistema Control Mix emite diariamente un reporte de los testigos programados para ser ensayados en la fecha, con su ubicación matricial en las cámaras de curado, a fin de que sean trasladados al laboratorio de ensayos.

B. Los testigos se trasladan en sus cajas de curado al laboratorio de ensayos para

mantener su condición de humedad hasta el momento de ser probados.

C. Se cuenta con dos prensas británicas Marca JV Tech, Nº de Serie 0481313 y Nº Serie 0431138, digitales, totalmente automatizadas, controladas por el software del Sistema Control Mix y con certificados de calibración vigentes emitidos por la empresa Celda EIRL, empleando celda de calibración trazable al NIST (United States National Institute of Standards & Technology) en conformidad con la Norma ASTM E74-06, adjuntándose una copia de los certificados en el Anexo III.


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D. Como elemento de distribución de carga en el ensayo de compresión se emplean

cabezales de acero y pads de neopreno en conformidad con la Norma ASTM C1231.

E. Luego de colocado el testigo en su posición de ensayo en la prensa, se procede a escanear el código de barras para su reconocimiento por el software, y la comprobación de que procede el ensayo programado, con lo que el técnico autoriza a través de la computadora el inicio de la prueba que se efectúa automáticamente sin intervención de ningún personal, con la velocidad de carga programada previamente dentro del rango de 0.20 Mpa/seg a 0.30 Mpa/seg establecido en ASTM C39.

F. Conseguida la rotura del testigo y registrada la carga máxima el técnico registra el

tipo de falla según ASTM C39 y autoriza que el software grabe la información, con lo que se calcula el esfuerzo máximo sobre la base del diámetro del testigo ingresado previamente al sistema y el área correspondiente de la sección.

2.6 ETAPA 6 : EMISIÓN Y ENVÍO DEL CERTIFICADO DE ENSAYOS

A. Cada vez que se completa la rotura de un grupo de 3 testigos de 4" x 8", (cuyo promedio es considerado por ACI 318 como representativo de la resistencia en compresión de la muestra), el software procede a generar y emitir en formato pdf, el certificado o reporte correspondiente acorde con el acápite 9. de ASTM C39, avalado con la firma de Ingeniero Civil Colegiado Especialista, Responsable Técnico, tal como lo consideran los dispositivos legales vigentes.

B. El certificado generado y emitido como se menciona anteriormente es almacenado

en una base de datos de uso y acceso exclusivo del cliente, a quién el software le envía de inmediato un correo electrónico a las casillas que haya declarado previamente, con el aviso de la disponibilidad del certificado de ensayos y un enlace para que proceda a descargarlo en formato pdf e imprimirlo a voluntad.

C. En el Anexo IV se incluye un formato de certificado de ensayos.

D. Por razones de seguridad informática y resguardo, toda la información registrada y

generada por el software es almacenada simultáneamente en un servidor residente en las Oficinas de CME en Miraflores, un segundo servidor en el Laboratorio en Villa El Salvador y un tercer servidor alojado en un servicio por internet contratado en USA.

E. Se adjunta como documento gráfico en el Anexo V el link de descarga de un video

ilustrativo del Sistema Control Mix, y en el website www.controlmixexpress.com se puede acceder a un demo de los servicios mencionados.

3. SERVICIOS COMPLEMENTARIOS DE CONTROL MIX EXPRESS S.A.C.

A. CME pone a disposición gratuita para uso exclusivo de sus clientes el Módulo Informático Control Data que evalúa según ACI-318 la estadística generada.

B. Como servicios complementarios Control Mix Express SAC realiza extracción,

recorte y ensayos de núcleos de concreto con brocas diamantinas de 2", 3" y 4" de diámetro en conformidad con la norma ASTM C 42.


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C. Se cuenta con 2 perforadoras diamantinas marca Hilti Modelo DD-150 U y una sierra

circular con disco diamantado de 20" para acondicionar los testigos dentro de los parámetros de geometría, planitud y verticalidad establecidos por ASTM C 42 y ASTM C 39.

D. También provee de servicio de monitoreo de ubicación de acero de refuerzo con

equipo Hilti Ferroscan PS 200. E. Se proporciona adicionalmente el servicio de determinación de Número de Rebote

Comparativo en estructuras de concreto (esclerometría) con equipo Forney acorde con la norma ASTM C 805.

4. RESPONSABLES TÉCNICOS

A. El responsable técnico del Sistema Control Mix Express y Gerente General es el Ing. Enrique Pasquel Carbajal con Registro del Colegio de Ingenieros del Perú Nº 19480.

B. El responsable Técnico - Operativo y Gerente Comercial es el Ing. Carlos Cook

Acevedo con Registro del Colegio de Ingenieros del Perú Nº 37308. C. La responsable Técnica del Área de Laboratorio y Soporte Técnico es la Ingeniera

Mercedes Neyra Palomino con Registro del Colegio de Ingenieros del Perú Nº 154020.

D. El Técnico responsable de Ensayos es el Sr. Richard Lino Nuñez con Registro de

Certificación Nº 01164309 del American Concrete Institute.

E. En el Anexo VI se adjunta el Resumen de Hoja de vida del Responsable Técnico que avala la experiencia mínima de 5 años en el ensayo de materiales de construcción requerida por ASTM para dirigir empresas de control de calidad de concreto.

F. En el Anexo VII se incluyen copias de las normas ASTM mencionadas previamente. G. En el Anexo VIII se puede apreciar un detalle de los clientes atendidos por nuestra

empresa. Lima, 09 de Enero del 2015

Responsable Técnico Gerente General Control Mix Express S.A.C.


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ANEXO I Documento Instructor Certificado ASTM Documento de Técnico Certificado ACI

y Ejemplo de Certificado de Capacitación

oPtroEoL'gI

]g. o =@{ = EE-A Y tn I! r E[B E ZEI :E Bib H ;9R U E'b2 I 'Ego E trP5 P .qUCt {= = tr'= E g8FoE'(E(J

a-l+r.E.99tn

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___________________________________________ Instructor

Ing. CIP Enrique Pasquel Carbajal

Control Mix Express S.A.C. certifica que el Señor :

CERTIFICADO DE CAPACITACIÓNCERTIFICADO DE CAPACITACIÓNCERTIFICADO DE CAPACITACIÓNCERTIFICADO DE CAPACITACIÓN

Juan Juan Juan Juan Ernesto Ernesto Ernesto Ernesto PéPéPéPérez Canalesrez Canalesrez Canalesrez Canales Ha aprobado el "Programa de Capacitación Teórico-Práctico para Muestreo y Moldeo de Testigos de Concreto en Obra", en conformidad con las normas ASTM C 172 y ASTM C 31, por lo que está acreditado para la ejecución de estas labores dentro del Sistema Control Mix® con el Código Nº 101

______________________ Fecha

17 /09/2012


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ANEXO II Formato de Orden de Servicio

W& LfiIIX ORDEN DE SERVICION9 000251EXPRESSENSATI/EEi EN EEINEEE?EI

MODULO

&,


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ANEXO III Certificados de Calibración de Prensas


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ANEXO IV Formato de Certificado de Ensayos

GoNTROL iflX EXPRESS S.A.C.Bapda Balta 169, Oficina 702, Miraflores - Lima 18

Centrel telef6nica i 243-041 4, emdl: [email protected]

CEHTIFICADO Nr CME-F201 3-0m4

T.IOTAS:

1) Lc Esdgc hen sldo moldegdG sr cor{orn*rad con h Noma ASTIti O 31/C311rr[12 po peeonal i6a{co oapacibdo ycartfrcdo por ConEd Mh E)pross SAC.

e) B o.rado d€ los bdig6 ha ddo €l,6ct edo en c{maras-econdidsEdas con tllmEdd y tEmpordtra contldedai 6n conlormtsadcon h Norma ASTM C 51 1-OS, y manbdendo hs condcbnG (b ol,ado BElaillarizEdo srtablecuas por la t{oma ASTM C31/C31[[12 ha& su bdra d€ enEayo.3) Lo6 ensayos so etectrson €n una prEnsa aubmatizada marca VJ TECH lilodslo VJT6fiXl"2A N! d€ S€rle o#tl I 38 (b arco kNde capeddd con ceilncado & calbrad6n fazatrle, adcando une velocldad & 6rgE de 2.0 kws€g on corilormEd con la NomaASTM C 3SIGFT+,12.

4) Como elerftenbs de dkftlbud6n d€ carga en hs extEmos d6 lc t6s0!os 8€ €rtpl€aron Fds de nogano Bn coflfo.miled con lal,lomaASTM C 1231/C t231M-l(h.

ENR1OUE PASOTJEL C.lngeniero Cirdl

Regisro clP 19480

EMPRESA CO].ISTRUCTORA HABIAT S"A.C. GUIA DEBEMlsl6N 3(XcoDtGoCLIENTE 6

OBHA Edifbio Boslrencial Alameda San lrnbnio GUIACAMl6N (M01t53ACUERDOCOITERCIAL l3'101

ESTRUCTURA dso sotano t'c (kg/HP) 210.0 FECHAf,OLDEO 23fi1m13

)BRA)rRECCrof{ U. Ricado Palma980 - Mirallore

FECHAENSAYO 201o2f2013

(Norma de Ensayo ASTU Ctlgrc3gltiFra


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ANEXO V Video Sistema Control Mix

Enlace : http://www.youtube.com/watch?v=z_9VWWXXfp0

Demo Sistema Control Mix

Enlace : http://www.controlmixexpress.com/interno_demo/home.php


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ANEXO VI Resumen Hoja de Vida del

Responsable Técnico de Control Mix Express SAC

Jr. Bajada Balta 169 – Oficina 702 - Miraflores - Lima 18 Teléfono : 243-0414, Celular : 998133533, e-mail : [email protected]

RESUMEN HOJA DE VIDA

DATOS PERSONALES .-

♦ Nombre : Enrique Néstor Pasquel Carbajal ♦ Fecha de nacimiento : 27 de Febrero de 1952 ♦ Lugar : Lima ♦ Nacionalidad : Peruano ♦ Domicilio : Batallón Callao Norte 105 Dpto. 402 – Surco ♦ Teléfono : 2751307 ♦ Oficina : Bajada Balta 169 Oficina 702 - Miraflores ♦ Teléfono : 2430414 ♦ Celular : 998133533 ♦ E-mail : [email protected] ♦ RUC : 10102721531

FORMACION PROFESIONAL .- ♦ Ing. Civil, Pontificia Universidad Católica del Perú – PUCP- Promoción 1975 ♦ Especialización en investigación experimental en concreto en la Universidad

Tecnológica de Delft - Holanda. ♦ Cursos de especialización en tecnología de concreto y procesos constructivos

especiales en USA, Colombia, Argentina, Brasil y Suiza. ACTIVIDADES ACADEMICAS.- ♦ Ex Jefe Laboratorio de Ensayo de Materiales PUCP ♦ Ex Jefe Laboratorio Estructuras Antisísmicas PUCP ♦ Profesor en la especialidad de Tecnología del Concreto en la Universidad Católica del

Perú 1997 a la fecha ♦ Profesor en la especialidad de Tecnología del Concreto en la Universidad Peruana de

Ciencias Aplicadas 2005 a la fecha. ♦ Profesor en la Escuela de Posgrado PUCP, 2005 a la fecha ♦ Profesor en la Escuela de Postgrado UPC, 2006 a la fecha. ♦ Profesor en CENTRUM - PUCP en la Maestría de Gestión y Dirección de Empresas

Constructoras e Inmobiliarias, 2012 a la fecha. ACTIVIDADES PROFESIONALES.- Participación durante los últimos 30 años como Ingeniero especialista de Impresit del Pacífico (Grupo IMPREGILO) o Consultor privado en los principales proyectos de Aeropuertos, Muelles, Irrigaciones, Puentes, Carreteras etc. desarrollados en nuestro país, destacando entre otros : Reactor Nuclear Huarangal (Lima), Muelle Conchán (Lima), Aeropuerto de Juliaca (Puno), Carretera Pomata-Yunguyo (Puno), Rehabilitación Aeropuerto de Piura, Irrigación Ilpa (Puno), Ampliación embalse y Túnel Corani (Cochabamba-Bolivia), Bocatoma Proyecto de Irrigación Chavimochic (La Libertad), Túnel Proyecto Chavimochic (La Libertad), Proyecto Integral de Irrigación Majes


(Arequipa), Tunel Jachacuesta Proyecto Pasto Grande (Moquegua), Proyecto de Irrigación Pampa Baja-Majes (Arequipa), Rehabilitación Carretera Panamericana Sur Tramo Puente Haway - Acceso Microondas (Arequipa), Represa Lagunillas (Puno), Rehabilitación Carretera Panamericana Norte Tramo Límite Regional-Empalme Ruta 1N (Lambayeque), Nuevo Aeropuerto de Cochabamba (Bolivia), Bocatoma Cabana-Mañazo (Juliaca – Puno), Puente Aguaytía (Aguaytía), Proyecto Vilavilani (Tacna), Proyecto Pasto Grande (Moquegua), Proyecto Carretera Transoceánica Tramo 3 (Madre de Dios), Proyecto Cerro Corona (Cajamarca), Proyecto Central Termoeléctrica Ilo (Moquegua), Rehabilitación Aeropuerto del Cusco (Cusco) JJcamet, Proyecto Tren Eléctrico (Lima) Odebrecht, Proyecto Estación Central (Lima), GyM, Proyecto Edificio Capital (Lima), Proyecto Morococha (Junín), Proyecto Ampliación Cementos Lima (Lima), Proyecto Ampliación Cemento Andino (Junín), Proyecto Fuerabambas (Apurimac), Proyecto Melchorita (Pisco), Proyecto Muelle Sur (Callao), Proyecto de Vivienda Masiva La Pólvora (Lima), Proyecto Quitaracsa (Lambayeque), Proyecto Rehabilitación Aeropuerto Jorge Chávez – LAP (Callao), Proyecto Edificio Alto Caral (Lima), Proyecto Central Termoeléctrica Chilca (Lima), Proyecto Nueva Planta Tratamiento de Efluentes ALICORP (Lima). Proyecto Carretera Intereoceánica Tramo 1 – Puerto Maldonado- CONIRSA, Proyecto Hotel Decamerón Punta Sal – Tumbes, JJCAMET, Proyecto Hidroeléctrico Quitaracsa- La Libertad, JJCAMET, Proyecto I.E. san José de Chiclayo, COSAPI, Proyecto Carretera Callejón de Huaylas-Chacas-San Luis, Odebrecht Perú, Proyecto Línea Amarilla, Lima , Construtora OAS Ltda., Proyecto Ciudad Verde, Paz Centenario, Proyecto Real Plaza Pucallpa, InRetail, Proyecto Real Plaza Chiclayo, InRetail, Proyecto Mina Inmaculada, Grupo Hochschild, Proyecto Clínica Delgado, Constructora San José, Proyecto Morococha, JJ Camet, Proyecto Ampliación Central Hidroeléctrica Machupicchu, Graña y Montero, Proyecto Almacenes Inkafarma, Sigral, Proyecto Lima Tower, Inmobiliari. ♦ Ex Gerente de Investigación & Desarrollo de Unión de Concreteras S.A. ♦ Ex Director Ejecutivo del Centro de Investigación Tecnológica del Cemento y el

Concreto – CITEDEC. ♦ Director Ejecutivo de Pasquel Consultores – Especialistas en concreto. ♦ Gerente General de Control Mix Express SAC – Ensayos en Concreto ACTIVIDADES INSTITUCIONALES.- ♦ Miembro del American Concrete Institute (ACI) – 1993 a la fecha ♦ Miembro del American Society for Testing and Materials (ASTM) – 1993 a la fecha ♦ Miembro del Consejo Directivo del Colegio de Ingenieros del Perú – Consejo Nacional

– 2004-2005 ♦ Presidente del Capítulo Peruano del ACI (2001 – 2005) ♦ Miembro del Consejo Directivo del ACI-PERU desde 2005 a la fecha ♦ Miembro del Comité Técnico INDECOPI de Normalización de Agregados, Hormigón

(Concreto), Hormigón Armado y Hormigón Pretensado ♦ Miembro del Comité Técnico de la Norma NTE E.060 Concreto Armado. ♦ Miembro del Comité ACI 318 WA - International Workshop - Concrete in the Americas ♦ Miembro del Comité ACI 318 0L International Liasson ♦ Miembro del Comité ACI 318 0S Spanish Translation Task Group ♦ Miembro del Comité ACI 318 Structural Concrete Building Code


♦ Miembro del Comité ASTM C 09 Concrete and Concrete Aggregates ♦ Líder del Grupo de Trabajo 01 de ASTM para traducción de normas de concreto en el

Código ACI 318. ♦ Instructor Certificado ASTM para dictado de Cursos en Latinoamérica ♦ Conferencista Nacional e Internacional en temas de su especialidad.

PUBLICACIONES.- ♦ Autor del Libro “Tópicos de Tecnología del Concreto” y coautor de 5 libros sobre Tecnología

del Concreto, Supervisión de Obras y Procesos Especiales. Ha publicado alrededor de 70 artículos y trabajos de investigación en revistas especializadas del Perú y el extranjero.

PREMIOS Y DISTINCIONES.- ♦ Distinción Pontificia Universidad Católica del Perú – Departamento de Ingeniería

“Destacada Labor Académica”- Periodo Académico 2001-1 ♦ Premio “Exalumno Distinguido Asociación de Egresados y Graduados de la Pontificia

Universidad Católica del Perú” - 2004 ♦ Premio Universidad Peruana de Ciencias Aplicadas – UPC al mejor Profesor Periodo

Académico 2006-1 ♦ Distinción Fellow ACI International – “In Recognition of Oustanding Contributions to the

American Concrete Institute and to Concrete Technology” - 2006 ♦ Medalla Henry C. Turner – ACI International “For Notable Achievement in the Concrete

Industry” - 2007 ♦ Premio “Chapter Activities” ACI International – “ For Oustanding Leadership, Promotion and

Growth of the ACI Peru Chapter” - 2007 ♦ Medalla Miembro Distinguido – Colegio de Ingenieros del Perú Consejo Departamental de

Lima – 2007 ♦ Orden de la Ingeniería Peruana – Colegio de Ingenieros del Perú – Consejo Nacional -

2012 IDIOMAS.- ♦ Inglés Avanzado ♦ Italiano Intermedio

Lima, Enero 2014


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ANEXO VII Copias de Normas ASTM empleadas por el

Sistema Control Mix Express

Designation: C31/C31M − 12

Standard Practice forMaking and Curing Concrete Test Specimens in the Field1

This standard is issued under the fixed designation C31/C31M; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon (´) indicates an editorial change since the last revision or reapproval.

This standard has been approved for use by agencies of the Department of Defense.

1. Scope*1.1 This practice covers procedures for making and curing

cylinder and beam specimens from representative samples offresh concrete for a construction project.

1.2 The concrete used to make the molded specimens shallbe sampled after all on-site adjustments have been made to themixture proportions, including the addition of mix water andadmixtures. This practice is not satisfactory for making speci-mens from concrete not having measurable slump or requiringother sizes or shapes of specimens.

1.3 The values stated in either SI units or inch-pound unitsare to be regarded separately as standard. The values stated ineach system may not be exact equivalents; therefore, eachsystem shall be used independently of the other. Combiningvalues from the two systems may result in non-conformancewith the standard.

1.4 This standard does not purport to address all of thesafety concerns, if any, associated with its use. It is theresponsibility of the user of this standard to establish appro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use. (Warning—Freshhydraulic cementitious mixtures are caustic and may causechemical burns to exposed skin and tissue upon prolongedexposure.2)

1.5 The text of this standard references notes which provideexplanatory material. These notes shall not be considered asrequirements of the standard.

2. Referenced Documents2.1 ASTM Standards:3

C125 Terminology Relating to Concrete and Concrete Ag-gregates

C138/C138M Test Method for Density (Unit Weight), Yield,and Air Content (Gravimetric) of Concrete

C143/C143M Test Method for Slump of Hydraulic-CementConcrete

C172 Practice for Sampling Freshly Mixed ConcreteC173/C173M Test Method for Air Content of Freshly Mixed

Concrete by the Volumetric MethodC231 Test Method for Air Content of Freshly Mixed Con-

crete by the Pressure MethodC330 Specification for Lightweight Aggregates for Struc-

tural ConcreteC403/C403M Test Method for Time of Setting of Concrete

Mixtures by Penetration ResistanceC470/C470M Specification for Molds for Forming Concrete

Test Cylinders VerticallyC511 Specification for Mixing Rooms, Moist Cabinets,

Moist Rooms, and Water Storage Tanks Used in theTesting of Hydraulic Cements and Concretes

C617 Practice for Capping Cylindrical Concrete SpecimensC1064/C1064M Test Method for Temperature of Freshly

Mixed Hydraulic-Cement ConcreteC1077 Practice for Agencies Testing Concrete and Concrete

Aggregates for Use in Construction and Criteria forTesting Agency Evaluation

2.2 American Concrete Institute Publication:4309R Guide for Consolidation of Concrete

3. Terminology

3.1 For definitions of terms used in this practice, refer toTerminology C125.

4. Significance and Use

4.1 This practice provides standardized requirements formaking, curing, protecting, and transporting concrete testspecimens under field conditions.

1 This practice is under the jurisdiction of ASTM Committee C09 on Concreteand Concrete Aggregates and is the direct responsibility of Subcommittee C09.61on Testing for Strength.

Current edition approved July 1, 2012. Published September 2012. Originallyapproved in 1920. Last previous edition approved in 2009 as C31/C31M–10. DOI:10.1520/C0031_C0031M-12.

2 See Section on Safety Precautions, Manual of Aggregate and Concrete Testing,Annual Book of ASTM Standards, Vol. 04.02.

3 For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at [email protected]. For Annual Book of ASTMStandards volume information, refer to the standard’s Document Summary page onthe ASTM website.

4 Available from American Concrete Institute (ACI), P.O. Box 9094, FarmingtonHills, MI 48333-9094, http://www.aci-int.org.

*A Summary of Changes section appears at the end of this standardCopyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States

1

Copyright by ASTM Int'l (all rights reserved); Sat Feb 23 22:42:38 EST 2013Downloaded/printed byEnrique Pasquel (none) pursuant to License Agreement. No further reproductions authorized.

4.2 If the specimens are made and standard cured, asstipulated herein, the resulting strength test data when thespecimens are tested are able to be used for the followingpurposes:

4.2.1 Acceptance testing for specified strength,4.2.2 Checking adequacy of mixture proportions for

strength, and4.2.3 Quality control.

4.3 If the specimens are made and field cured, as stipulatedherein, the resulting strength test data when the specimens aretested are able to be used for the following purposes:

4.3.1 Determination of whether a structure is capable ofbeing put in service,

4.3.2 Comparison with test results of standard cured speci-mens or with test results from various in-place test methods,

4.3.3 Adequacy of curing and protection of concrete in thestructure, or

4.3.4 Form or shoring removal time requirements.

5. Apparatus

5.1 Molds, General— Molds for specimens or fasteningsthereto in contact with the concrete shall be made of steel, castiron, or other nonabsorbent material, nonreactive with concretecontaining portland or other hydraulic cements. Molds shallhold their dimensions and shape under all conditions of use.Molds shall be watertight during use as judged by their abilityto hold water poured into them. Provisions for tests of waterleakage are given in the Test Methods for Elongation,Absorption, and Water Leakage section of Specification C470/C470M. A suitable sealant, such as heavy grease, modelingclay, or microcrystalline wax shall be used where necessary toprevent leakage through the joints. Positive means shall beprovided to hold base plates firmly to the molds. Reusablemolds shall be lightly coated with mineral oil or a suitablenonreactive form release material before use.

5.2 Cylinder Molds— Molds for casting concrete test speci-mens shall conform to the requirements of SpecificationC470/C470M.

5.3 Beam Molds—Beam molds shall be of the shape anddimensions required to produce the specimens stipulated in 6.2.The inside surfaces of the molds shall be smooth. The sides,bottom, and ends shall be at right angles to each other and shallbe straight and true and free of warpage. Maximum variationfrom the nominal cross section shall not exceed 1⁄8 in. [3 mm]for molds with depth or breadth of 6 in. [150 mm] or more.Molds shall produce specimens at least as long but not morethan 1⁄16 in. [2 mm] shorter than the required length in 6.2.

5.4 Tamping Rod—A round, smooth, straight, steel rod witha diameter conforming to the requirements in Table 1. Thelength of the tamping rod shall be at least 4 in. [100 mm]greater than the depth of the mold in which rodding is beingperformed, but not greater than 24 in. [600 mm] in overalllength (see Note 1). The rod shall have the tamping end or bothends rounded to a hemispherical tip of the same diameter as therod.

NOTE 1—A rod length of 16 in. [400 mm] to 24 in. [600 mm] meets therequirements of the following: Practice C31/C31M, Test Method C138/C138M, Test Method C143/C143M, Test Method C173/C173M, and TestMethod C231.

5.5 Vibrators—Internal vibrators shall be used. The vibratorfrequency shall be at least 9000 vibrations per minute [150 Hz]while the vibrator is operating in the concrete. The diameter ofa round vibrator shall be no more than one-fourth the diameterof the cylinder mold or one-fourth the width of the beam mold.Other shaped vibrators shall have a perimeter equivalent to thecircumference of an appropriate round vibrator. The combinedlength of the vibrator shaft and vibrating element shall exceedthe depth of the section being vibrated by at least 3 in. [75mm]. The vibrator frequency shall be checked periodicallywith a vibrating-reed tachometer or other suitable device.

NOTE 2—For information on size and frequency of various vibratorsand a method to periodically check vibrator frequency see ACI 309R.

5.6 Mallet—A mallet with a rubber or rawhide head weigh-ing 1.25 6 0.50 lb [0.6 6 0.2 kg] shall be used.

5.7 Placement Tools—of a size large enough so each amountof concrete obtained from the sampling receptacle is represen-tative and small enough so concrete is not spilled duringplacement in the mold. For placing concrete in a cylinder mold,the acceptable tool is a scoop. For placing concrete in a beammold, either a shovel or scoop is permitted.

5.8 Finishing Tools—a handheld float or a trowel.5.9 Slump Apparatus— The apparatus for measurement of

slump shall conform to the requirements of Test MethodC143/C143M.

5.10 Sampling Receptacle—The receptacle shall be a suit-able heavy gauge metal pan, wheelbarrow, or flat, cleannonabsorbent board of sufficient capacity to allow easy remix-ing of the entire sample with a shovel or trowel.

5.11 Air Content Apparatus—The apparatus for measuringair content shall conform to the requirements of Test MethodsC173/C173M or C231.

5.12 Temperature Measuring Devices—The temperaturemeasuring devices shall conform to the applicable require-ments of Test Method C1064/C1064M.

6. Testing Requirements6.1 Cylindrical Specimens—Compressive or splitting tensile

strength specimens shall be cylinders cast and allowed to set inan upright position. The number and size of cylinders cast shallbe as directed by the specifier of the tests. In addition, thelength shall be twice the diameter and the cylinder diametershall be at least 3 times the nominal maximum size of thecoarse aggregate. When the nominal maximum size of the

TABLE 1 Tamping Rod Diameter RequirementsDiameter of Cylinder

or Width of Beamin. [mm]

Diameter or Rodin. [mm]

coarse aggregate exceeds 2 in. [50 mm], the concrete sampleshall be treated by wet sieving through a 2-in. [50-mm] sieveas described in Practice C172. For acceptance testing forspecified compressive strength, cylinders shall be 6 by 12 in.[150 by 300 mm] or 4 × 8 in. [100 × 200 mm] (Note 3).

NOTE 3—When molds in SI units are required and not available,equivalent inch-pound unit size mold should be permitted.

6.2 Beam Specimens— Flexural strength specimens shall bebeams of concrete cast and hardened in the horizontal position.The number of beams cast shall be as directed by the specifierof the tests. The length shall be at least 2 in. [50 mm] greaterthan three times the depth as tested. The ratio of width to depthas molded shall not exceed 1.5. The standard beam shall be 6by 6 in. [150 by 150 mm] in cross section, and shall be used forconcrete with nominal maximum size coarse aggregate up to 2in. [50 mm]. When the nominal maximum size of the coarseaggregate exceeds 2 in. [50 mm], the smaller cross sectionaldimension of the beam shall be at least three times the nominalmaximum size of the coarse aggregate. Unless required byproject specifications, beams made in the field shall not have awidth or depth of less than 6 in. [150 mm].

6.3 Field Technicians—The field technicians making andcuring specimens for acceptance testing shall meet the person-nel qualification requirements of Practice C1077.

7. Sampling Concrete7.1 The samples used to fabricate test specimens under this

standard shall be obtained in accordance with Practice C172unless an alternative procedure has been approved.

7.2 Record the identification of the sample with respect tothe location of the concrete represented and the time of casting.

8. Slump, Air Content, and Temperature8.1 Slump—Measure and record the slump of each batch of

concrete from which specimens are made immediately afterremixing in the receptacle, as required in Test Method C143/C143M.

8.2 Air Content— Determine and record the air content inaccordance with either Test Method C173/C173M or TestMethod C231. The concrete used in performing the air contenttest shall not be used in fabricating test specimens.

8.3 Temperature— Determine and record the temperature inaccordance with Test Method C1064/C1064M.

NOTE 4—Some specifications may require the measurement of the unitweight of concrete. The volume of concrete produced per batch may bedesired on some projects. Also, additional information on the air contentmeasurements may be desired. Test Method C138/C138M is used tomeasure the unit weight, yield, and gravimetric air content of freshlymixed concrete.

9. Molding Specimens9.1 Place of Molding— Mold specimens promptly on a

level, rigid surface, free of vibration and other disturbances, ata place as near as practicable to the location where they are tobe stored.

9.2 Casting Cylinders—Select the proper tamping rod from5.4 and Table 1 or the proper vibrator from 5.5. Determine the

method of consolidation from Table 2, unless another methodis specified. If the method of consolidation is rodding, deter-mine molding requirements from Table 3. If the method ofconsolidation is vibration, determine molding requirementsfrom Table 4. Select a scoop of the size described in 5.7. Whileplacing the concrete in the mold, move the scoop around theperimeter of the mold opening to ensure an even distribution ofthe concrete with minimal segregation. Each layer of concreteshall be consolidated as required. In placing the final layer, addan amount of concrete that will fill the mold after consolida-tion.

9.3 Casting Beams— Select the proper tamping rod from5.4 and Table 1 or proper vibrator from 5.5. Determine themethod of consolidation from Table 2, unless another methodis specified. If the method of consolidation is rodding, deter-mine the molding requirements from Table 3. If the method ofconsolidation is vibration, determine the molding requirementsfrom Table 4. Determine the number of roddings per layer, onefor each 2 in.2 [14 cm2] of the top surface area of the beam.Select a placement tool as described in 5.7. Using the scoop orshovel, place the concrete in the mold to the height required foreach layer. Place the concrete so that it is uniformly distributedwithin each layer with minimal segregation. Each layer shall be

TABLE 2 Method of Consolidation RequirementsSlump in. [mm] Method of Consolidation

$ 1 [25] rodding or vibration< 1 [25] vibration

TABLE 3 Molding Requirements by Rodding

Specimen Typeand Size

Number of Layers ofApproximately Equal Depth

Number ofRoddingsper Layer

Cylinders:Diameter, in. [mm]

4 [100] 2 256 [150] 3 259 [225] 4 50

Beams:Width, in. [mm]6 [150] to 8 [200] 2 see 9.3

>8 [200] 3 or more equal depths,each not to exceed

6 in. [150 mm].

see 9.3

TABLE 4 Molding Requirements by Vibration

Specimen Typeand Size

Number ofLayers

Number ofVibrator

Insertionsper Layer

Approximate Depth ofLayer, in. [mm]

Cylinders:Diameter, in. [mm]

4 [100] 2 1 one-half depth of specimen6 [150] 2 2 one-half depth of specimen9 [225] 2 4 one-half depth of specimen

Beams:Width, in. [mm]6 [150] to 8 [200] 1 see 9.4.2 depth of specimen

over 8 [200] 2 or more see 9.4.2 8 [200] as near aspracticable

C31/C31M − 12

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consolidated as required. In placing the final layer, add anamount of concrete that will fill the mold after consolidation.

9.4 Consolidation— The methods of consolidation for thispractice are rodding or internal vibration.

9.4.1 Rodding—Place the concrete in the mold in therequired number of layers of approximately equal volume. Rodeach layer uniformly over the cross section with the roundedend of the rod using the required number of strokes. Rod thebottom layer throughout its depth. In rodding this layer, usecare not to damage the bottom of the mold. For each upperlayer, allow the rod to penetrate through the layer being roddedand into the layer below approximately 1 in. [25 mm]. Aftereach layer is rodded, tap the outsides of the mold lightly 10 to15 times with the mallet to close any holes left by rodding andto release any large air bubbles that may have been trapped.Use an open hand to tap light-gauge single-use cylinder moldswhich are susceptible to damage if tapped with a mallet. Aftertapping, spade each layer of the concrete along the sides andends of beam molds with a trowel or other suitable tool.Underfilled molds shall be adjusted with representative con-crete during consolidation of the top layer. Overfilled moldsshall have excess concrete removed.

9.4.2 Vibration—Maintain a uniform duration of vibrationfor the particular kind of concrete, vibrator, and specimen moldinvolved. The duration of vibration required will depend uponthe workability of the concrete and the effectiveness of thevibrator. Usually sufficient vibration has been applied as soonas the surface of the concrete has become relatively smooth andlarge air bubbles cease to break through the top surface.Continue vibration only long enough to achieve proper con-solidation of the concrete (see Note 5). Fill the molds andvibrate in the required number of approximately equal layers.Place all the concrete for each layer in the mold before startingvibration of that layer. In compacting the specimen, insert thevibrator slowly and do not allow it to rest on the bottom orsides of the mold. Slowly withdraw the vibrator so that no largeair pockets are left in the specimen. When placing the finallayer, avoid overfilling by more than 1⁄4 in. [6 mm].

NOTE 5—Generally, no more than 5 s of vibration should be required foreach insertion to adequately consolidate concrete with a slump greaterthan 3 in. [75 mm]. Longer times may be required for lower slumpconcrete, but the vibration time should rarely have to exceed 10 s perinsertion.

9.4.2.1 Cylinders—The number of insertions of the vibratorper layer is given in Table 4. When more than one insertion perlayer is required distribute the insertion uniformly within eachlayer. Allow the vibrator to penetrate through the layer beingvibrated, and into the layer below, about 1 in. [25 mm]. Aftereach layer is vibrated, tap the outsides of the mold at least 10times with the mallet, to close holes that remain and to releaseentrapped air voids. Use an open hand to tap cardboard andsingle-use metal molds that are susceptible to damage if tappedwith a mallet.

9.4.2.2 Beams—Insert the vibrator at intervals not exceed-ing 6 in. [150 mm] along the center line of the long dimensionof the specimen. For specimens wider than 6 in., use alternat-ing insertions along two lines. Allow the shaft of the vibrator topenetrate into the bottom layer about 1 in. [25 mm]. After each

layer is vibrated, tap the outsides of the mold sharply at least 10times with the mallet to close holes left by vibrating and torelease entrapped air voids.

9.5 Finishing—Perform all finishing with the minimummanipulation necessary to produce a flat even surface that islevel with the rim or edge of the mold and that has nodepressions or projections larger than 1⁄8 in. [3.3 mm].

9.5.1 Cylinders—After consolidation, finish the top surfacesby striking them off with the tamping rod where the consis-tency of the concrete permits or with a handheld float or trowel.If desired, cap the top surface of freshly made cylinders with athin layer of stiff portland cement paste which is permitted toharden and cure with the specimen. See section on CappingMaterials of Practice C617.

9.5.2 Beams—After consolidation of the concrete, use ahandheld float or trowel to strike off the top surface to therequired tolerance to produce a flat, even surface.

9.6 Identification— Mark the specimens to positively iden-tify them and the concrete they represent. Use a method thatwill not alter the top surface of the concrete. Do not mark theremovable caps. Upon removal of the molds, mark the testspecimens to retain their identities.

10. Curing10.1 Standard Curing— Standard curing is the curing

method used when the specimens are made and cured for thepurposes stated in 4.2.

10.1.1 Storage—If specimens cannot be molded at the placewhere they will receive initial curing, immediately afterfinishing move the specimens to an initial curing place forstorage. The supporting surface on which specimens are storedshall be level to within 1⁄4 in. per ft [20 mm per m]. If cylindersin the single use molds are moved, lift and support thecylinders from the bottom of the molds with a large trowel orsimilar device. If the top surface is marred during movement toplace of initial storage, immediately refinish.

10.1.2 Initial Curing— Immediately after molding andfinishing, the specimens shall be stored for a period up to 48 hin a temperature range from 60 and 80 °F [16 and 27 °C] andin an environment preventing moisture loss from the speci-mens. For concrete mixtures with a specified strength of 6000psi [40 MPa] or greater, the initial curing temperature shall bebetween 68 and 78 °F [20 and 26 °C]. Various procedures arecapable of being used during the initial curing period tomaintain the specified moisture and temperature conditions. Anappropriate procedure or combination of procedures shall beused (Note 6). Shield all specimens from the direct sunlightand, if used, radiant heating devices. The storage temperatureshall be controlled by use of heating and cooling devices, asnecessary. Record the temperature using a maximum-minimumthermometer. If cardboard molds are used, protect the outsidesurface of the molds from contact with wet burlap or othersources of water.

NOTE 6—A satisfactory moisture environment can be created during theinitial curing of the specimens by one or more of the followingprocedures: (1) immediately immerse molded specimens with plastic lidsin water saturated with calcium hydroxide, (2) store in properly con-structed wooden boxes or structures, (3) place in damp sand pits, (4) cover

C31/C31M − 12

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with removable plastic lids, (5) place inside plastic bags, or (6) cover withplastic sheets or nonabsorbent plates if provisions are made to avoiddrying and damp burlap is used inside the enclosure, but the burlap isprevented from contacting the concrete surfaces. A satisfactory tempera-ture environment can be controlled during the initial curing of thespecimens by one or more of the following procedures: (1) use ofventilation, (2) use of ice, (3) use of thermostatically controlled heating orcooling devices, or (4) use of heating methods such as stoves or lightbulbs. Other suitable methods may be used provided the requirementslimiting specimen storage temperature and moisture loss are met. Forconcrete mixtures with a specified strength of 6000 psi [40 MPa] orgreater, heat generated during the early ages may raise the temperatureabove the required storage temperature. Immersion in water saturated withcalcium hydroxide may be the easiest method to maintain the requiredstorage temperature. When specimens are to be immersed in watersaturated with calcium hydroxide, specimens in cardboard molds or othermolds that expand when immersed in water should not be used. Early-agestrength test results may be lower when stored at 60 °F [16 °C] and higherwhen stored at 80 °F [27 °C]. On the other hand, at later ages, test resultsmay be lower for higher initial storage temperatures.

10.1.3 Final Curing:10.1.3.1 Cylinders—Upon completion of initial curing and

within 30 min after removing the molds, cure specimens withfree water maintained on their surfaces at all times at atemperature of 73.5 6 3.5 °F [23.0 6 2.0 °C] using waterstorage tanks or moist rooms complying with the requirementsof Specification C511, except when capping with sulfur mortarcapping compound and immediately prior to testing. Whencapping with sulfur mortar capping compound, the ends of thecylinder shall be dry enough to preclude the formation of steamor foam pockets under or in cap larger than 1⁄4 in. [6 mm] asdescribed in Practice C617. For a period not to exceed 3 himmediately prior to test, standard curing temperature is notrequired provided free moisture is maintained on the cylindersand ambient temperature is between 68 and 86 °F [20 and 30°C].

10.1.3.2 Beams—Beams are to be cured the same as cylin-ders (see 10.1.3.1) except that they shall be stored in watersaturated with calcium hydroxide at 73.5 6 3.5 °F [23.0 6 2.0°C] at least 20 h prior to testing. Drying of the surfaces of thebeam shall be prevented between removal from water storageand completion of testing.

NOTE 7—Relatively small amounts of surface drying of flexuralspecimens can induce tensile stresses in the extreme fibers that willmarkedly reduce the indicated flexural strength.

10.2 Field Curing— Field curing is the curing method usedfor the specimens made and cured as stated in 4.3.

10.2.1 Cylinders—Store cylinders in or on the structure asnear to the point of deposit of the concrete represented aspossible. Protect all surfaces of the cylinders from the elementsin as near as possible the same way as the formed work.Provide the cylinders with the same temperature and moistureenvironment as the structural work. Test the specimens in themoisture condition resulting from the specified curing treat-ment. To meet these conditions, specimens made for thepurpose of determining when a structure is capable of being putin service shall be removed from the molds at the time ofremoval of form work.

10.2.2 Beams—As nearly as practicable, cure beams in thesame manner as the concrete in the structure. At the end of

48 6 4 h after molding, take the molded specimens to thestorage location and remove from the molds. Store specimensrepresenting pavements of slabs on grade by placing them onthe ground as molded, with their top surfaces up. Bank thesides and ends of the specimens with earth or sand that shall bekept damp, leaving the top surfaces exposed to the specifiedcuring treatment. Store specimens representing structure con-crete as near the point in the structure they represent aspossible, and afford them the same temperature protection andmoisture environment as the structure. At the end of the curingperiod leave the specimens in place exposed to the weather inthe same manner as the structure. Remove all beam specimensfrom field storage and store in water saturated with calciumhydroxide at 73.5 6 3.5 °F [23.0 6 2.0 °C] for 24 6 4 himmediately before time of testing to ensure uniform moisturecondition from specimen to specimen. Observe the precautionsgiven in 10.1.3.2 to guard against drying between time ofremoval from curing to testing.

10.3 Structural Lightweight Concrete Curing—Cure struc-tural lightweight concrete cylinders in accordance with Speci-fication C330.

11. Transportation of Specimens to Laboratory11.1 Prior to transporting, cure and protect specimens as

required in Section 10. Specimens shall not be transported untilat least 8 h after final set. (See Note 8). During transporting,protect the specimens with suitable cushioning material toprevent damage from jarring. During cold weather, protect thespecimens from freezing with suitable insulation material.Prevent moisture loss during transportation by wrapping thespecimens in plastic, wet burlap, by surrounding them with wetsand, or tight fitting plastic caps on plastic molds. Transporta-tion time shall not exceed 4 h.

NOTE 8—Setting time may be measured by Test Method C403/C403M.

12. Report12.1 Report the following information to the laboratory that

will test the specimens:12.1.1 Identification number,12.1.2 Location of concrete represented by the samples,12.1.3 Date, time and name of individual molding

specimens,12.1.4 Slump, air content, and concrete temperature, test

results and results of any other tests on the fresh concrete andany deviations from referenced standard test methods, and

12.1.5 Curing method. For standard curing method, reportthe initial curing method with maximum and minimum tem-peratures and final curing method. For field curing method,report the location where stored, manner of protection from theelements, temperature and moisture environment, and time ofremoval from molds.

13. Keywords13.1 beams; casting samples; concrete; curing; cylinders;

testing

C31/C31M − 12

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SUMMARY OF CHANGES

Committee C09 has identified the location of selected changes to this practice since the last issue,C31/C31M–10, that may impact the use of this practice. (Approved July 1, 2012)

(1) Revised 6.3 and Referenced Documents.

ASTM International takes no position respecting the validity of any patent rights asserted in connection with any item mentionedin this standard. Users of this standard are expressly advised that determination of the validity of any such patent rights, and the riskof infringement of such rights, are entirely their own responsibility.

This standard is subject to revision at any time by the responsible technical committee and must be reviewed every five years andif not revised, either reapproved or withdrawn. Your comments are invited either for revision of this standard or for additional standardsand should be addressed to ASTM International Headquarters. Your comments will receive careful consideration at a meeting of theresponsible technical committee, which you may attend. If you feel that your comments have not received a fair hearing you shouldmake your views known to the ASTM Committee on Standards, at the address shown below.

This standard is copyrighted by ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959,United States. Individual reprints (single or multiple copies) of this standard may be obtained by contacting ASTM at the aboveaddress or at 610-832-9585 (phone), 610-832-9555 (fax), or [email protected] (e-mail); or through the ASTM website(www.astm.org). Permission rights to photocopy the standard may also be secured from the ASTM website (www.astm.org/COPYRIGHT/).

C31/C31M − 12

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Designation: C39/C39M − 12a

Standard Test Method forCompressive Strength of Cylindrical Concrete Specimens1

This standard is issued under the fixed designation C39/C39M; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon (´) indicates an editorial change since the last revision or reapproval.

This standard has been approved for use by agencies of the Department of Defense.

1. Scope*1.1 This test method covers determination of compressive

strength of cylindrical concrete specimens such as moldedcylinders and drilled cores. It is limited to concrete having adensity in excess of 800 kg/m3 [50 lb/ft3].

1.2 The values stated in either SI units or inch-pound unitsare to be regarded separately as standard. The inch-pound unitsare shown in brackets. The values stated in each system maynot be exact equivalents; therefore, each system shall be usedindependently of the other. Combining values from the twosystems may result in non-conformance with the standard.

1.3 This standard does not purport to address all of thesafety concerns, if any, associated with its use. It is theresponsibility of the user of this standard to establish appro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use. (Warning—Meansshould be provided to contain concrete fragments duringsudden rupture of specimens. Tendency for sudden ruptureincreases with increasing concrete strength and it is more likelywhen the testing machine is relatively flexible. The safetyprecautions given in the Manual of Aggregate and ConcreteTesting are recommended.)

1.4 The text of this standard references notes which provideexplanatory material. These notes shall not be considered asrequirements of the standard.

2. Referenced Documents2.1 ASTM Standards:2C31/C31M Practice for Making and Curing Concrete Test

Specimens in the FieldC42/C42M Test Method for Obtaining and Testing Drilled

Cores and Sawed Beams of Concrete

C192/C192M Practice for Making and Curing Concrete TestSpecimens in the Laboratory

C617 Practice for Capping Cylindrical Concrete SpecimensC670 Practice for Preparing Precision and Bias Statements

for Test Methods for Construction MaterialsC873 Test Method for Compressive Strength of Concrete

Cylinders Cast in Place in Cylindrical MoldsC1077 Practice for Agencies Testing Concrete and Concrete

Aggregates for Use in Construction and Criteria forTesting Agency Evaluation

C1231/C1231M Practice for Use of Unbonded Caps inDetermination of Compressive Strength of Hardened Con-crete Cylinders

E4 Practices for Force Verification of Testing MachinesE74 Practice of Calibration of Force-Measuring Instruments

for Verifying the Force Indication of Testing MachinesManual of Aggregate and Concrete Testing

3. Summary of Test Method3.1 This test method consists of applying a compressive

axial load to molded cylinders or cores at a rate which is withina prescribed range until failure occurs. The compressivestrength of the specimen is calculated by dividing the maxi-mum load attained during the test by the cross-sectional area ofthe specimen.

4. Significance and Use4.1 Care must be exercised in the interpretation of the

significance of compressive strength determinations by this testmethod since strength is not a fundamental or intrinsic propertyof concrete made from given materials. Values obtained willdepend on the size and shape of the specimen, batching, mixingprocedures, the methods of sampling, molding, and fabricationand the age, temperature, and moisture conditions duringcuring.

4.2 This test method is used to determine compressivestrength of cylindrical specimens prepared and cured in accor-dance with Practices C31/C31M, C192/C192M, C617, andC1231/C1231M and Test Methods C42/C42M and C873.

4.3 The results of this test method are used as a basis forquality control of concrete proportioning, mixing, and placing

1 This test method is under the jurisdiction of ASTM Committee C09 onConcrete and Concrete Aggregatesand is the direct responsibility of SubcommitteeC09.61 on Testing for Strength.

Current edition approved Sept. 1, 2012. Published October 2012. Originallyapproved in 1921. Last previous edition approved in 2012 as C39/C39M–12. DOI:10.1520/C0039_C0039M-12a.

2 For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at [email protected]. For Annual Book of ASTMStandards volume information, refer to the standard’s Document Summary page onthe ASTM website.

*A Summary of Changes section appears at the end of this standardCopyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States

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operations; determination of compliance with specifications;control for evaluating effectiveness of admixtures; and similaruses.

4.4 The individual who tests concrete cylinders for accep-tance testing shall meet the concrete laboratory technicianrequirements of Practice C1077, including an examinationrequiring performance demonstration that is evaluated by anindependent examiner.

NOTE 1—Certification equivalent to the minimum guidelines for ACIConcrete Laboratory Technician, Level I or ACI Concrete StrengthTesting Technician will satisfy this requirement.

5. Apparatus5.1 Testing Machine—The testing machine shall be of a type

having sufficient capacity and capable of providing the rates ofloading prescribed in 7.5.

5.1.1 Verify calibration of the testing machines in accor-dance with Practices E4, except that the verified loading rangeshall be as required in 5.3. Verification is required:

5.1.1.1 Within 13 months of the last calibration,5.1.1.2 On original installation or immediately after

relocation,5.1.1.3 Immediately after making repairs or adjustments

that affect the operation of the force applying system or thevalues displayed on the load indicating system, except for zeroadjustments that compensate for the mass of bearing blocks orspecimen, or both, or

5.1.1.4 Whenever there is reason to suspect the accuracy ofthe indicated loads.

5.1.2 Design—The design of the machine must include thefollowing features:

5.1.2.1 The machine must be power operated and mustapply the load continuously rather than intermittently, andwithout shock. If it has only one loading rate (meeting therequirements of 7.5), it must be provided with a supplementalmeans for loading at a rate suitable for verification. Thissupplemental means of loading may be power or hand oper-ated.

5.1.2.2 The space provided for test specimens shall be largeenough to accommodate, in a readable position, an elasticcalibration device which is of sufficient capacity to cover thepotential loading range of the testing machine and whichcomplies with the requirements of Practice E74.

NOTE 2—The types of elastic calibration devices most generallyavailable and most commonly used for this purpose are the circularproving ring or load cell.

5.1.3 Accuracy—The accuracy of the testing machine shallbe in accordance with the following provisions:

5.1.3.1 The percentage of error for the loads within theproposed range of use of the testing machine shall not exceed61.0 % of the indicated load.

5.1.3.2 The accuracy of the testing machine shall be verifiedby applying five test loads in four approximately equalincrements in ascending order. The difference between any twosuccessive test loads shall not exceed one third of the differ-ence between the maximum and minimum test loads.

5.1.3.3 The test load as indicated by the testing machine andthe applied load computed from the readings of the verification

device shall be recorded at each test point. Calculate the error,E, and the percentage of error, Ep, for each point from thesedata as follows:

E 5 A 2 B (1)

Ep 5 100~A 2 B!/B

where:A = load, kN [lbf] indicated by the machine being verified,

andB = applied load, kN [lbf] as determined by the calibrating

device.

5.1.3.4 The report on the verification of a testing machineshall state within what loading range it was found to conformto specification requirements rather than reporting a blanketacceptance or rejection. In no case shall the loading range bestated as including loads below the value which is 100 timesthe smallest change of load estimable on the load-indicatingmechanism of the testing machine or loads within that portionof the range below 10 % of the maximum range capacity.

5.1.3.5 In no case shall the loading range be stated asincluding loads outside the range of loads applied during theverification test.

5.1.3.6 The indicated load of a testing machine shall not becorrected either by calculation or by the use of a calibrationdiagram to obtain values within the required permissiblevariation.

5.2 The testing machine shall be equipped with two steelbearing blocks with hardened faces (Note 3), one of which is aspherically seated block that will bear on the upper surface ofthe specimen, and the other a solid block on which thespecimen shall rest. Bearing faces of the blocks shall have aminimum dimension at least 3 % greater than the diameter ofthe specimen to be tested. Except for the concentric circlesdescribed below, the bearing faces shall not depart from a planeby more than 0.02 mm [0.001 in.] in any 150 mm [6 in.] ofblocks 150 mm [6 in.] in diameter or larger, or by more than0.02 mm [0.001 in.] in the diameter of any smaller block; andnew blocks shall be manufactured within one half of thistolerance. When the diameter of the bearing face of thespherically seated block exceeds the diameter of the specimenby more than 13 mm [0.5 in.], concentric circles not more than0.8 mm [0.03 in.] deep and not more than 1 mm [0.04 in.] wideshall be inscribed to facilitate proper centering.

NOTE 3—It is desirable that the bearing faces of blocks used forcompression testing of concrete have a Rockwell hardness of not less than55 HRC.

5.2.1 Bottom bearing blocks shall conform to the followingrequirements:

5.2.1.1 The bottom bearing block is specified for the pur-pose of providing a readily machinable surface for mainte-nance of the specified surface conditions (Note 4). The top andbottom surfaces shall be parallel to each other. If the testingmachine is so designed that the platen itself is readily main-tained in the specified surface condition, a bottom block is notrequired. Its least horizontal dimension shall be at least 3 %

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greater than the diameter of the specimen to be tested.Concentric circles as described in 5.2 are optional on thebottom block.

NOTE 4—The block may be fastened to the platen of the testingmachine.

5.2.1.2 Final centering must be made with reference to theupper spherical block. When the lower bearing block is used toassist in centering the specimen, the center of the concentricrings, when provided, or the center of the block itself must bedirectly below the center of the spherical head. Provision shallbe made on the platen of the machine to assure such a position.

5.2.1.3 The bottom bearing block shall be at least 25 mm [1in.] thick when new, and at least 22.5 mm [0.9 in.] thick afterany resurfacing operations.

5.2.2 The spherically seated bearing block shall conform tothe following requirements:

5.2.2.1 The maximum diameter of the bearing face of thesuspended spherically seated block shall not exceed the valuesgiven below:

Diameter of Maximum DiameterTest Specimens, of Bearing Face,

mm [in.] mm [in.]

50 [2] 105 [4]75 [3] 130 [5]100 [4] 165 [6.5]150 [6] 255 [10]200 [8] 280 [11]

NOTE 5—Square bearing faces are permissible, provided the diameter ofthe largest possible inscribed circle does not exceed the above diameter.

5.2.2.2 The center of the sphere shall coincide with thesurface of the bearing face within a tolerance of 65 % of theradius of the sphere. The diameter of the sphere shall be at least75 % of the diameter of the specimen to be tested.

5.2.2.3 The ball and the socket shall be designed so that thesteel in the contact area does not permanently deform whenloaded to the capacity of the testing machine.

NOTE 6—The preferred contact area is in the form of a ring (describedas “preferred bearing area”) as shown on Fig. 1.

5.2.2.4 At least every six months, or as specified by themanufacturer of the testing machine, clean and lubricate thecurved surfaces of the socket and of the spherical portion of themachine. The lubricant shall be a petroleum-type oil such asconventional motor oil or as specified by the manufacturer ofthe testing machine.

NOTE 7—To ensure uniform seating, the spherically seated head isdesigned to tilt freely as it comes into contact with the top of the specimen.After contact, further rotation is undesirable. Friction between the socketand the spherical portion of the head provides restraint against furtherrotation during loading. Petroleum-type oil such as conventional motor oilhas been shown to permit the necessary friction to develop. Pressure-typegreases can reduce the desired friction and permit undesired rotation of thespherical head and should not be used unless recommended by themanufacturer of the testing machine.

5.2.2.5 If the radius of the sphere is smaller than the radiusof the largest specimen to be tested, the portion of the bearingface extending beyond the sphere shall have a thickness notless than the difference between the radius of the sphere andradius of the specimen. The least dimension of the bearing faceshall be at least as great as the diameter of the sphere (see Fig.1).

5.2.2.6 The movable portion of the bearing block shall beheld closely in the spherical seat, but the design shall be suchthat the bearing face can be rotated freely and tilted at least 4°in any direction.

5.2.2.7 If the ball portion of the upper bearing block is atwo-piece design composed of a spherical portion and abearing plate, a mechanical means shall be provided to ensurethat the spherical portion is fixed and centered on the bearingplate.

5.3 Load Indication:5.3.1 If the load of a compression machine used in concrete

testing is registered on a dial, the dial shall be provided with agraduated scale that is readable to at least the nearest 0.1 % ofthe full scale load (Note 8). The dial shall be readable within1 % of the indicated load at any given load level within theloading range. In no case shall the loading range of a dial beconsidered to include loads below the value that is 100 timesthe smallest change of load that can be read on the scale. Thescale shall be provided with a graduation line equal to zero andso numbered. The dial pointer shall be of sufficient length toreach the graduation marks; the width of the end of the pointershall not exceed the clear distance between the smallestgraduations. Each dial shall be equipped with a zero adjust-ment located outside the dialcase and easily accessible from thefront of the machine while observing the zero mark and dialpointer. Each dial shall be equipped with a suitable device thatat all times, until reset, will indicate to within 1 % accuracy themaximum load applied to the specimen.

NOTE 8—Readability is considered to be 0.5 mm [0.02 in.] along the arcdescribed by the end of the pointer. Also, one half of a scale interval isreadable with reasonable certainty when the spacing on the load indicatingmechanism is between 1 mm [0.04 in.] and 2 mm [0.06 in.]. When thespacing is between 2 and 3 mm [0.06 and 0.12 in.], one third of a scaleinterval is readable with reasonable certainty. When the spacing is 3 mm[0.12 in.] or more, one fourth of a scale interval is readable withreasonable certainty.

5.3.2 If the testing machine load is indicated in digital form,the numerical display must be large enough to be easily read.

NOTE 1—Provision shall be made for holding the ball in the socket andfor holding the entire unit in the testing machine.

FIG. 1 Schematic Sketch of a Typical Spherical Bearing Block

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The numerical increment must be equal to or less than 0.10 %of the full scale load of a given loading range. In no case shallthe verified loading range include loads less than the minimumnumerical increment multiplied by 100. The accuracy of theindicated load must be within 1.0 % for any value displayedwithin the verified loading range. Provision must be made foradjusting to indicate true zero at zero load. There shall beprovided a maximum load indicator that at all times until resetwill indicate within 1 % system accuracy the maximum loadapplied to the specimen.

5.4 Documentation of the calibration and maintenance ofthe testing machine shall be in accordance with PracticeC1077.

6. Specimens6.1 Specimens shall not be tested if any individual diameter

of a cylinder differs from any other diameter of the samecylinder by more than 2 %.

NOTE 9—This may occur when single use molds are damaged ordeformed during shipment, when flexible single use molds are deformedduring molding, or when a core drill deflects or shifts during drilling.

6.2 Prior to testing, neither end of test specimens shalldepart from perpendicularity to the axis by more than 0.5°(approximately equivalent to 1 mm in 100 mm [0.12 in. in 12in.]). The ends of compression test specimens that are not planewithin 0.050 mm [0.002 in.] shall be sawed or ground to meetthat tolerance, or capped in accordance with either PracticeC617 or, when permitted, Practice C1231/C1231M. The diam-eter used for calculating the cross-sectional area of the testspecimen shall be determined to the nearest 0.25 mm [0.01 in.]by averaging two diameters measured at right angles to eachother at about midheight of the specimen.

6.3 The number of individual cylinders measured for deter-mination of average diameter is not prohibited from beingreduced to one for each ten specimens or three specimens perday, whichever is greater, if all cylinders are known to havebeen made from a single lot of reusable or single-use moldswhich consistently produce specimens with average diameterswithin a range of 0.5 mm [0.02 in.]. When the averagediameters do not fall within the range of 0.5 mm [0.02 in.] orwhen the cylinders are not made from a single lot of molds,each cylinder tested must be measured and the value used incalculation of the unit compressive strength of that specimen.When the diameters are measured at the reduced frequency, thecross-sectional areas of all cylinders tested on that day shall becomputed from the average of the diameters of the three ormore cylinders representing the group tested that day.

6.4 If the purchaser of the testing services requests measure-ment of density of test specimens, determine the mass ofspecimens before capping. Remove any surface moisture witha towel and measure the mass of the specimen using a balanceor scale that is accurate to within 0.3 % of the mass beingmeasured. Measure the length of the specimen to the nearest 1mm [0.05 in.] at three locations spaced evenly around thecircumference. Compute the average length and record to thenearest 1 mm [0.05 in.]. Alternatively, determine the cylinderdensity by weighing the cylinder in air and then submerged

under water at 23.0 6 2.0 °C [73.5 6 3.5 °F], and computingthe volume according to 8.3.1.

6.5 When density determination is not required and thelength to diameter ratio is less than 1.8 or more than 2.2,measure the length of the specimen to the nearest 0.05 D.

7. Procedure7.1 Compression tests of moist-cured specimens shall be

made as soon as practicable after removal from moist storage.7.2 Test specimens shall be kept moist by any convenient

method during the period between removal from moist storageand testing. They shall be tested in the moist condition.

7.3 All test specimens for a given test age shall be brokenwithin the permissible time tolerances prescribed as follows:

Test Age Permissible Tolerance

24 h ± 0.5 h or 2.1 %3 days 2 h or 2.8 %7 days 6 h or 3.6 %

28 days 20 h or 3.0 %90 days 2 days 2.2 %

7.4 Placing the Specimen—Place the plain (lower) bearingblock, with its hardened face up, on the table or platen of thetesting machine directly under the spherically seated (upper)bearing block. Wipe clean the bearing faces of the upper andlower bearing blocks and of the test specimen and place the testspecimen on the lower bearing block. Carefully align the axisof the specimen with the center of thrust of the sphericallyseated block.

7.4.1 Zero Verification and Block Seating—Prior to testingthe specimen, verify that the load indicator is set to zero. Incases where the indicator is not properly set to zero, adjust theindicator (Note 10). After placing the specimen in the machinebut prior to applying the load on the specimen, tilt the movableportion of the spherically seated block gently by hand so thatthe bearing face appears to be parallel to the top of the testspecimen.

NOTE 10—The technique used to verify and adjust load indicator to zerowill vary depending on the machine manufacturer. Consult your owner’smanual or compression machine calibrator for the proper technique.

7.5 Rate of Loading—Apply the load continuously andwithout shock.

7.5.1 The load shall be applied at a rate of movement (platento crosshead measurement) corresponding to a stress rate onthe specimen of 0.25 6 0.05 MPa/s [35 6 7 psi/s] (See Note11). The designated rate of movement shall be maintained atleast during the latter half of the anticipated loading phase.

NOTE 11—For a screw-driven or displacement-controlled testingmachine, preliminary testing will be necessary to establish the requiredrate of movement to achieve the specified stress rate. The required rate ofmovement will depend on the size of the test specimen, the elasticmodulus of the concrete, and the stiffness of the testing machine.

7.5.2 During application of the first half of the anticipatedloading phase, a higher rate of loading shall be permitted. Thehigher loading rate shall be applied in a controlled manner sothat the specimen is not subjected to shock loading.

7.5.3 Make no adjustment in the rate of movement (platen tocrosshead) as the ultimate load is being approached and thestress rate decreases due to cracking in the specimen.

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7.6 Apply the compressive load until the load indicatorshows that the load is decreasing steadily and the specimendisplays a well-defined fracture pattern (Types 1 to 4 in Fig. 2).For a testing machine equipped with a specimen break detector,automatic shut-off of the testing machine is prohibited until theload has dropped to a value that is less than 95 % of the peakload. When testing with unbonded caps, a corner fracturesimilar to a Type 5 or 6 pattern shown in Fig. 2 may occurbefore the ultimate capacity of the specimen has been attained.Continue compressing the specimen until the user is certainthat the ultimate capacity has been attained. Record themaximum load carried by the specimen during the test, andnote the type of fracture pattern according to Fig. 2. If thefracture pattern is not one of the typical patterns shown in Fig.2, sketch and describe briefly the fracture pattern. If themeasured strength is lower than expected, examine the frac-tured concrete and note the presence of large air voids,evidence of segregation, whether fractures pass predominantlyaround or through the coarse aggregate particles, and verifyend preparations were in accordance with Practice C617 orPractice C1231/C1231M.

8. Calculation

8.1 Calculate the compressive strength of the specimen bydividing the maximum load carried by the specimen during thetest by the average cross-sectional area determined as de-scribed in Section 6 and express the result to the nearest 0.1MPa [10 psi].

8.2 If the specimen length to diameter ratio is 1.75 or less,correct the result obtained in 8.1 by multiplying by theappropriate correction factor shown in the following table Note12:

L/D: 1.75 1.50 1.25 1.00Factor: 0.98 0.96 0.93 0.87

Use interpolation to determine correction factors for L/Dvalues between those given in the table.

NOTE 12—Correction factors depend on various conditions such asmoisture condition, strength level, and elastic modulus. Average values aregiven in the table. These correction factors apply to low-density concreteweighing between 1600 and 1920 kg/m3 [100 and 120 lb/ft3] and tonormal-density concrete. They are applicable to concrete dry or soaked at

FIG. 2 Schematic of Typical Fracture Patterns

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the time of loading and for nominal concrete strengths from 14 to 42 MPa[2000 to 6000 psi]. For strengths higher than 42 MPa [6000 psi] correctionfactors may be larger than the values listed above3.

8.3 When required, calculate the density of the specimen tothe nearest 10 kg/m3 [1 lb/ft3] as follows:

Density5WV (2)

where:W = mass of specimen, kg [lb], andV = volume of specimen computed from the average diam-

eter and average length or from weighing the cylinder inair and submerged, m3 [ft3]

8.3.1 When the volume is determined from submergedweighing, calculate the volume as follows:

V 5W 2 Ws! w

(3)

where:Ws = apparent mass of submerged specimen, kg [lb], and!w = density of water at 23 °C [73.5 °F] = 997.5 kg/m3

[62.27 lbs/ft3].

9. Report9.1 Report the following information:9.1.1 Identification number,9.1.2 Average measured diameter (and measured length, if

outside the range of 1.8 D to 2.2 D), in millimetres [inches],9.1.3 Cross-sectional area, in square millimetres [square

inches],9.1.4 Maximum load, in kilonewtons [pounds-force],9.1.5 Compressive strength calculated to the nearest 0.1

MPa [10 psi],9.1.6 Type of fracture (see Fig. 2),9.1.7 Defects in either specimen or caps, and,9.1.8 Age of specimen.9.1.9 When determined, the density to the nearest 10 kg/

m3 [1 lb/ft3].

10. Precision and Bias10.1 Precision10.1.1 Within-Test Precision—The following table provides

the within-test precision of tests of 150 by 300 mm [6 by 12in.] and 100 by 200 mm [4 by 8 in.] cylinders made from awell-mixed sample of concrete under laboratory conditions andunder field conditions (see 10.1.2).

Coefficient ofVariation4

Acceptable Range4 ofIndividual Cylinder Strengths2 cylinders 3 cylinders

150 by 300 mm[6 by 12 in.]

Laboratory conditions 2.4 % 6.6 % 7.8 %Field conditions 2.9 % 8.0 % 9.5 %

100 by 200 mm[4 by 8 in.]

Laboratory conditions 3.2 % 9.0 % 10.6 %

10.1.2 The within-test coefficient of variation represents theexpected variation of measured strength of companion cylin-ders prepared from the same sample of concrete and tested byone laboratory at the same age. The values given for thewithin-test coefficient of variation of 150 by 300 mm [6 by 12in.] cylinders are applicable for compressive strengths between2000 and 15 to 55 MPa [8000 psi] and those for 100 by 200mm [4 by 8 in.] cylinders are applicable for compressivestrengths between 17 to 32 MPa [2500 and 4700 psi]. Thewithin-test coefficients of variation for 150 by 300 mm [6 by 12in.] cylinders are derived from CCRL concrete proficiencysample data for laboratory conditions and a collection of 1265test reports from 225 commercial testing laboratories in 1978.5The within-test coefficient of variation of 100 by 200 mm [4 by8 in.] cylinders are derived from CCRL concrete proficiencysample data for laboratory conditions.

10.1.3 Multilaboratory Precision—The multi-laboratory co-efficient of variation for compressive strength test results of150 by 300 mm [6 by 12 in.] cylinders has been found to be5.0 %4; therefore, the results of properly conducted tests bytwo laboratories on specimens prepared from the same sampleof concrete are not expected to differ by more than 14 %4 of theaverage (See Note 13). A strength test result is the average oftwo cylinders tested at the same age.

NOTE 13—The multilaboratory precision does not include variationsassociated with different operators preparing test specimens from split orindependent samples of concrete. These variations are expected toincrease the multilaboratory coefficient of variation.

10.1.4 The multilaboratory data were obtained from sixseparate organized strength testing round robin programswhere 150 x 300 mm [6 x 12 in.] cylindrical specimens wereprepared at a single location and tested by different laborato-ries. The range of average strength from these programs was17.0 to 90 MPa [2500 to 13 000 psi].

NOTE 14—Subcommittee C09.61 will continue to examine recentconcrete proficiency sample data and field

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