Characterization of heat-treated self-compacting concrete containing mineral admixtures at early age and in the long term

摘要

Self-compacting concretes (SCCs) are increasingly used in the field of prefabrication, although the final strength of the heat-treated concrete is less than that of reference samples that have been cured in normal conditions. The aim of this work is to contribute to the improvement of the mechanical behavior of this kind of SCC. This paper presents the effect of the incorporation of local mineral admixtures on the behavior of heat-treated SCC at an early age (1 day) and in the long term (28 and 180 days). The characteristics of the SCC in the fresh and hardened states were also studied. The adopted heat-treatment cycle attained a maximum temperature of 60 ℃ and a total duration of 24 h. Three additions to the cement at the levels of 20% and 40% were used. They were fine limestone (LF), granulated slag (GS), and crystallized slag (CS). The fresh states characteristics of SCC are affected by the nature and dosage of the mineral admixture. In the hardened state, the comparison between the elaborated SCC and the control SCC without addition and without heat treatment showed an overall gain in strength at early age and minimal loss in the long term. The CS with a dosage of 40% allowed to the heat-treated SCC to be the less porous and the more resistant one compared to the elaborated SCCs. The use of LF appears to be more favorable if its incorporation is limited to below 20%. The GS is also favorable with 20% and it can be more beneficial if its fineness exceed that of the cement powder.