Recycling of foundry sand wastes in self-compacting concretes: Use as cementitious materials and fine aggregates

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Abstract This paper discusses waste recycling as a compound in building materials. Foundry sand-based self-compacting concretes (SCC) were investigated to see the possibility of recycling foundry sand wastes (FSW). FSW was used as a cementitious addition (by partial cement replacement: 10%, 20% and 30% wt. cement), then as a fine aggregate (by partial sand substitution: 10%, 30% and 50% wt. sand). For this, an experimental study was carried out to evaluate physical and mechanical properties of SCC at fresh and hardened states. The results show that the FSW also played the role of a filling material, which slightly improved the compactness of the concrete while saving part of the cement. According to the results of the non-destructive tests by ultrasonic tests, all concretes gave a dynamic modulus of elasticity that was almost identical and which was greater than 36 GPa. Compressive strength value slightly reduced with the cement substitution by the crushed foundry sand waste. However, up to 30% FSW, the compressive strength recorded after 28 days was around 30 MPa. A slight decrease in the fluidity of concrete at 10% substitution of natural sand by FSW was observed. After up to 30% replacement of sand by foundry sand wastes, the fluidity of the concrete was improved. The improvement in the fluidity of the concretes was perhaps due to the fineness of the natural sand and that of the foundry sand. When used as up to 50% of sand substitution, FSW can be used as a fine aggregate for concretes without affecting the essential proprieties of concretes.