Paper by BALFROID PILATE PLOYAERT from ISCR 12th 2014 Prague Czech Republic
The quality of sand influences in every way the quality of concrete and affects, among others, the workability, the durability as well as the mechanical strength of concrete. It is acknowledged that a sand of good quality to be used in concrete pavements must contain few fine grains and be rich in medium size grains. In addition, all grains should be as round as possible, which means non-crushed sand is an advantage. Today, natural rounded coarse sand is getting rare and is more and more replaced by crushed sand of size 0/4. Knowing that the angularity of the grains affects negatively the workability of concrete, this phenomenon is worth to look at. This article treats in particular sand grading and its influence on water demand in the case of concrete pavements. Based on the analysis of different cases, an optimal grain size is suggested and is then compared to the requirements of the applicable European standard specifications.