Properties of Green Concrete Mixes Containing Metakaolin, Micro Silica, Steel Slag, and Recycled Mosaic Tiles

Recently, the constructions industry begins to make concrete more sustainable, side by side, with making its high performance. This paper aims to investigate the effect of (Metakaolin and Micro Silica) when they replace cement by (8, 12 and 16) % and (6, 9 and 12) % respectively, recycled steel slag when replaces fine aggregate by (10, 20 and 30) %, and recycled mosaic tiles when replaces coarse aggregate by (33.33, 66.67 and 100) % each one another on the slump, density, absorption and compressive strength of concrete. The experimental results showed that the maximum reduction ratio of cement reach (17%) (8% of metakaolin and 9% Micro Silica) while the optimum percentage of mosaic tiles and steel slag is (100%) and (20%) respectively. The optimum percentages obtained are combining to produce three basic green mixes: 1) 17% (8% of Metakaolin and 9% of Micro Silica) only, (2) A mix containing 17% of (Metakaolin and of Micro Silica) plus 100% of recycled mosaic, (3) 17% of (Metakaolin and Micro Silica), 100% of recycled mosaic and 20% of slag. Compressive strength at (7, 28, and 60) days, modulus of rupture at (28) days, absorption, fresh and hardened density are investigated. The best improvement in compressive strength compared with reference concrete was recorded (20.06, 10.855 and 9.983) % at (7, 28 and 60) days respectively for the mix containing (17% of cementitious materials plus 100% of recycled mosaic) while the ultimate flexure strength (24) % appeared in green mix containing (17% of cementitious materials, 100% of recycled mosaic and 20% of slag). Generally, an inverse relationship between density and absorption in all trail mixes which are conducted