Valorization of the crushed sand and of the desert sand in the composition of the self compacting concrete

Self-compacting concretes (SCC) are highly fluid concretes that require high proportions in sand and fine particles with respect to the ordinary concrete (OC). The crushed sand (CS), spread granulometry, is a by-product of crushing rock mass. The desert sand (DS) is an extra fine sand, characterized by a tight distribution of grain size. Containing significant levels of fine sand, these two sands can be both interesting components of the SCC. This research is to incorporate the CS in the composition of concrete and to study the effect of its gradual replacement by the DS on the behavior of the fresh and hardened SCC. The experimental study shows that parameters of SCC workability are improved when the SC is partially replaced by the DS (<30%). However, at high levels of DS (>30%), additional quantities of water and superplasticizer are necessary to meet the self-compacting properties. The mechanical strength decreases when adding DS to CS, but they are reaching acceptable values for DS in moderate proportioning. The performance of SCC is much better than those of OC using the same aggregates. Specification tests of durability show that the coefficients of water absorption by capillarity and by immersion increase when adding DS to CS, while the coefficient of permeability decreases.