Recovery of Industrial Waste: Paving Stones Made from Hardened Cement Base

Abstract

Industrial waste management constitutes a major challenge for sustainable development. This study aims to transform hardened cement waste stored in cement warehouses and in real estate construction sites into paving stones. This innovative solution will contribute to the protection of the environment and the reduction of inert industrial waste. To do this, paving stones based on hardened cement have been developed and characterized. The raw materials were subjected to physical and mechanical characterization tests. The hardened cement aggregates previously crushed with the 5/15 granular class were used as substitutes to replace the natural 5/15 aggregates in the hardened paving stones at contents ranging from 0 to 100%. The mechanical characterization results on the raw material showed that the hardened cement aggregate is made from lightweight aggregates. On the prepared mortar, in the fresh state, the Abrams cone slump test showed an increase in the quantity of waste water with the increase in the content of hardened cement aggregate. In the hardened state, physical (porosity, absorption and dry density) and mechanical (compression, splitting traction, 3-point bending traction and wear) characterization tests were carried out at periods of 7, 14 and 28 days of maturation in water on the cobblestones. These results show that the substitution of natural aggregates by hardened cement aggregates in increasingly large proportions leads to an improvement in compressive, flexural, splitting and wear resistance. In addition, the incorporation of hardened cement aggregate considerably slows down the mechanical degradation of the paving stones. They can, therefore, be used in road and interior or exterior floor coverings.