Materiales de Construcción, Vol 57, No 287 (2007)

Factors affecting early compressive strength of alkali activated fly ash (OPC-free) concrete

A. Fernández-Jiménez
Instituto de Ciencias de la Construcción Eduardo Torroja (CSIC) (Madrid), Spain

A. Palomo
Instituto de Ciencias de la Construcción Eduardo Torroja (CSIC) (Madrid), Spain


This paper presents the findings of experimental research into the chief characteristics of a new type of concrete made solely with alkali activated fly ash (AAFA): i.e., free of ordinary Portland cement (OPC). The results of testing to determine specific properties of the fresh concrete and the development of its mechanical strength showed that most of the factors that affect the manufacture and final properties of Portland cement concrete (water/cement ratio, curing conditions, etc.) also impact the preparation and final quality of this new material. A number of parameters specific to AAFA concrete (nature and concentration of alkali present in the system) were also explored to determine their role in the setting and hardening process.


alkali activation; fly ash; concrete; compressive strength; dosage

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