Incorporation of treated municipal solid waste incineration electrostatic precipitator fly ash as partial replacement of Portland cement: Effect on early age behaviour and mechanical properties

• Experimental approach to evaluate the potential reaction of ESPFA as partial replacement of Portland cement.
• Blended cements were designed with increasing electrostatic precipitator fly ash proportions (from 3.13% to 18.75%).
• Acid leaching tests showed a leaching of chromium.
• Similar mechanical properties compressive strength of ESPFA and GS.

The use of municipal solid waste incineration (MSWI) electrostatic precipitator fly ash (ESPFA) as partial replacement of cement was studied in this work in order to provide a method to assess its potential reactivity in presence of cement. Thermal fly ash (TFA) and ground sand (GS), respectively pozzolanic and chemically inert materials, were also used as partial replacement of Portland cement in order to understand the effects of ESPFA on cementitious materials properties. In this study, cement pastes were designed keeping the sulphate content constant. Isothermal calorimetry was used to characterize the early-age behaviour. The results showed the influence of the mix design of cement pastes. Compressive strength tests, mercury intrusion porosimetry, thermogravimetry, and calorimetric measurements were carried out on mortars and cement pastes containing one of the three mineral additions. ESPFA had a chemically inert behaviour but the strength and thermogravimetric analyses showed their physical effect. The high specific surface of ESPFA actually leads to relatively good activity coefficient and enhanced portlandite formation. The leaching of calcium, chromium, lead and zinc was studied by tests at controlled pH. Results showed that ESPFA do not affect durability. Moreover, the concentrations of heavy metals in the leaching solution were lower than allowed concentrations.