Experimental Approach Regarding the Potential of Spent Garnets Use as Mineral Addition in Cement-Based Construction Products

Garnet, a silicate rock-forming mineral, is present in many rock types. Regular sands contain low Garnet amounts, excepting for the Garnet sands, where the forming mineral is Garnet. They are granular, abrasive materials, having a pink to reddish range of colors, mostly derived from rock crushing processes. Due to their abrasive properties (hardness, edge sharpness, etc.) they started to be used as complementary material in waterjet material processing, for abrasive waterjet (AWJ) cutting and also blasting operations, for quality, speed and accuracy gain in the specific procedures. In the last decades the AWJ cutting processes expended their covering area to a variety of materials: stone, granite and marble, metalworking (Carbon and Stainless Steel, Copper and Aluminum, etc.), glass and ceramic materials, Carbon fibers, wood and even plastic, etc. The AWJ cutting operations are generating Spent Garnets (SG) as waste, namely an initial sludge, unutilized and therefore deserted in a random manner and transformed by natural drying into Spent Garnets damps. The current study considers the SG recycling possibilities by using them as addition into cement-based materials, as partial fine grain aggregate replacement/addition. The experimental procedure considers several replacing percentages with respect to the reference (R, no SG addition), by using two distinct, local SG sources (Timisoara, Romania), in order to obtain a pertinent, preliminary evaluation of the considered substitution. Fresh state properties (visual aspect, consistency) and also mechanical performance in terms of tensile and compressive strengths, are evaluated. Long term mechanical properties and durability performance is also considered as future perspective of this preliminary study, which generally aims valorization of SG into construction products (like pavements or masonry blocks, etc.), thus determining the SG waste prevention and their transition towards by-products for the building materials industry, considering the Circular Economy principles.