Upgraded Mineral Sand Fraction from MSWI Bottom Ash: An Alternative Solution for the Substitution of Natural Aggregates in Concrete Applications

Abstract

This paper presents the results of an experimental investigation on the substitution of natural sand by municipal solid waste incineration (MSWI) bottom ash in concrete applications in order to preserve non-renewable natural resources and then, reduce the carbon footprint of buildings sector. First of all, physical, chemical and leaching test have been performed on upgraded MSWI bottom ash and the obtained results were compared to natural sand usually used in France in concrete applications. In the second time, a preliminary campaign carried out by utilizing 100% MSWI bottom ash 0-2 mm for the substitution of natural sand in the mortar applications. Physical characterization revealed that grain size distribution and specific gravity of MSWI bottom ash are similar to natural sand identified. However, water absorption content (WAb equal to 7.50%) of bottom ash is higher than natural sand. In order to improve the workability of mixing, a superplasticizer has been used at 0%, 1.5%, 2% and 3% by weight of cement. After 14 days of curing, compressive and flexural strengths were performed on hardened samples. Results showed compressive strength of bottom ash samples ranging from 19.4 MPa (without superplasticizer) to 33.3 MPa (3% of superplasticizer), following a linear trend while flexural strength ranging 4.7 MPa to 5.4 MPa. No health threat has been detected for the MSWI bottom ash 0-2 mm fraction and it was categorized as non-hazardous waste according to European legislation of waste. Study developments are currently oriented towards the analysis of physical, mechanical and thermal properties of concrete containing bottom ash and durability assessment.