INFLUENCE OF LIMESTONE FILLERS ON THE MECHANICAL PERFORMANCES OF CEMENT PASTES

摘要

In Algeria, there are more than one thousand plants that produce annually a total of 68 million tons of aggregates, essentially of calcareous nature. Unfortunately, more than 20% of manufactured sands are unsuitable for construction use because of there fines content being higher than 12% (current normative limit). In the same way, the limestone fillers, which also result from the process crushing of the limestone rocks, are regarded as unusable residues and thus not exploited . To improve the situation, it is important to develop as for as possible all these added fillers to aggregates and more particularly sands containing filler. This is of interests not only for the economy of the country, but also for safeguarding of the environment. In the field of the building construction, the valorisation may include these fines in the cementations matrices; possibly replacing part of the cement, as shown in other research works in other countries. Thus, our study presents the influence of the characteristics of Algerian limestone fines (size distribution, fineness) on the physical properties and the mechanical performance of cement pastes made at various waters to binder ratios. The obtained results show that the replacement of part of cement by these limestone fillers can significantly improve the mechanical resistances and even the workability. The study also shows that limestone fillers do not only have a physical effect but also represent certain chemical activity, by providing new hydrated compounds such as carboaluminates .