New sustainable mortar compositions containing perlite waste

Powdered and coarse perlite wastes (PP and CP) were used to develop new sustainable mortar compositions. The as-received PP and CP wastes were characterized by X-ray diffraction and granulometry distribution. First, the compressive strength and water/agglomerate factor were measured from 21 mortar traces with different component proportions [cement, lime, perlite waste (PP and CP)]. Afterwards, we applied experimental planning of the design type for constrained mixtures, the trace compositions with proportions 1:3 (cement: 100% CP); 1:3 (cement: 85% CP + 15% PP); 1:1:6 (cement: lime: 100% CP) and 1:1:6 (cement: lime: 85% CP + 15% PP) were chosen for the assessment of resistance to sulfate attack as they are commonly used in construction civil. Then, the chosen traces of mortar were immersed in a sulfate sodium solution for 42 days and evaluated for their linear expansion, X-ray diffraction, differential thermal analysis, thermal gravimetry, and compressive strength experiments. The greater linear expansion and the loss of mechanical resistance were credited to the appearance of the ettringite phase. Despite this, the new sustainable traces of mortar developed presented compressive strength > 2 MPa (ASTM C452) and, therefore, can be used as alternative coating mortars in civil construction.