Mortar intended for the production of cementitious slabs: use of waste green foundry sand and polymeric fibers

The development of cementitious cover slabs with replacement of natural sand (NS) by waste green foundry sand (WGFS) and with addition of polyester fibers was the main objective of this work. Different percentages of replacement of NS by WGFS (0, 25, 50, 75 and 100%), different cements (CP-V ARI and CP-II Z 32) and addition of polyester fibers (0% and 0.6%) were employed as factors in the experimental design. The results showed that the apparent specific mass decreased when the percentage of aggregate replacement was increased, however, the air void and water absorption of the composite increased with replacement. The highest compressive strengths were obtained for the mortars made entirely with NS, which reached 20.4 MPa and 12.9 MPa for cements CP-V ARI and CP-II Z, respectively. The addition of fibers showed no evidence of significant influence on the properties of prismatic specimens, but the fibers were significantly influential on the properties of cementitious plates. Evaluating the results, it is observed that the total replacement of NS by WGFS, in cementitious cover slabs, is not recommended, because the mechanical strengths reduce around 60% when compared to the reference material