Influence of zeta potential on the properties of ready-mix mortars with waste addition

The disposal of industrial waste is an environmental problem. Incorporating this waste into construction materials is an alternative to disposal and also reduces the extraction of raw materials. When incorporating waste into mortars, the characteristics of the waste particles, such as zeta potential, can interfere with the material’s properties. This paper investigates the influence of zeta potential on the properties of mortars stabilised with the addition of silica and fly ash. During the 72 h of stabilisation, the incorporated air content and consistency were evaluated. In the hardened state, mechanical strength, water absorption, and void index were evaluated. The zeta potentials of cement (−3.04 mV) and silica (−10.5 mV) were closer to the isoelectric point, while the fly ash presented the highest potential in modulus (−20.3 mV). The effects of the zeta potential were observed in the content of incorporated air, since the high modulus hinders the action of the air-incorporating additive. Thus, the mortar with fly ash incorporated an air content of 5.85%, while other mortars finished the stabilisation period with at least 8.25%. In the hardened state, it was possible to realise the indirect influence caused by the zeta potential.