Using recycled concrete aggregates in precast concrete hollow blocks

Among the construction waste that could be recycled, we can mention the aggregates resulting from crushed concrete. While the acquired knowledge about the use of recycled aggregates in new concrete mixes is fairly large, the use of such aggregates in the production of concrete blocks is very limited. This research aims to study the influence of the use of recycled aggregates in precast concrete hollow blocks on their compressive strength. Tests were carried out to determine the rate of recycled aggregates content to be used in the manufacture of concrete blocks in order to obtain blocks having suitable compressive strength. Tests were executed on several series of blocks whose composition includes recycled aggregates and on one series of reference blocks whose composition consisted exclusively of natural aggregates. Tests results have provided the maximum percentage of recycled aggregates that can be included in new concrete block mixes without affecting blocks compressive strength. Tests have shown that the use of recycled aggregates in concrete blocks could give a compressive strength similar to that of blocks manufactured without any recycled aggregates. It has been shown also that using recycled aggregates in the manufacture of concrete blocks without any natural aggregates is not economical at all because of the need to add a relatively high quantity of cement necessary to obtain the required compressive strength.