Standard Guide for Comparing Performance of Concrete-Making Materials Using Mortar Mixtures

Importancia y uso:

4.1 The results of mortar mixture tests can be suitable for comparing the relative performance of combinations of concrete-making materials such as fine aggregate, chemical admixtures, supplementary cementitious materials (SCMs), water, and hydraulic cement. Furthermore, this guide can be useful to identify unexpected performances due to combination of various materials. The relative trends in performance observed with the mortar method may suggest relative performance in concrete mixtures batched with the same materials and relative mixture proportions.

4.2 While there are a number of ways to proportion and mix mortar mixtures, four procedures described in this guide have been used extensively for evaluating the performance of admixtures. Method A enables evaluation of materials using mixture proportions that correspond to specific job conditions. Method B can be used as a general mixture using fixed amounts of a standard sand, cement, and supplementary cementitious materials. Method C is a modified version of Test Method C359 to evaluate the impact of chemical admixtures on the early stiffening of a mortar prepared with specified amounts of job cement, a standard sand, and an amount of water that will produce a mortar with a specified initial penetration measured in accordance with Test Method C359. The measurements of penetration over time can be related to the early stiffening processes associated with false and flash set. Method D is a modified version of Test Method C185 whereby the mortar mixture can be prepared with various combinations of chemical admixtures, supplementary cementitious materials, and job water. Methods A and B would be most applicable for investigating material incompatibility issues associated with ready mixed concrete, while Method C would be applicable for concrete mixed for a short period of time in stationary mixers and transported to the forms in non-agitating equipment. Method D is suitable for all concrete mixing processes and is most applicable if the focus of a material incompatibility issue is unexpected changes in air content.

Subcomité:

C09.48

Referida por:

C1952-25

Volúmen:

04.02

Número ICS:

91.100.10 (Cement. Gypsum. Lime. Mortar)

Palabras clave:

air content; cementitious material-admixture interactions; hydration kinetics; mortar; mortar-slump; mortar-spread; time of setting;