Making Use of Construction Waste in Soil-Cement Mixtures: Granulometric Correction of Clay Soil

Construction is fundamental to human development, but it is the sector of activity that uses the most natural resources and produces around 50% of the solid waste generated by human activity. In this research, mixed recycled aggregate (MRA) with the granulometry of small aggregate was used for the physical-mechanical investigation of different mixtures of soil-cement and MRA. The granulometry of the soil and the MRA were characterized, followed by a two-level factorial experimental design complete with a central point. The ratio of MRA to soil was 1.00, 1.67, and 2.33. The cement content added to the mixture varied between 10% and 14%. The best result was obtained by incorporating 60.2% MRA with 25.8% soil (MRA/soil of 2.33) and 14% cement (mass % of solids), achieving a compressive strength of 3.4 MPa and water absorption of 18.1%. The prediction of the values for the MRA/soil and % cement factors considering the minimum compressive strength of 2.1 MPa by the multiple regression model indicated a mixture with an MRA/soil ratio of 1.71 and 10.22% cement. This mixture indicated a predictable maximum water absorption of less than 22%. The predictability results are promising as they allow the incorporation of CDW in the manufacture of soil-cement blocks to be scaled up, increasing its recyclability. This highlights the need to correct clay soils and the potential for recycling of construction and demolition waste.