Calcium Sulfoaluminate, Geopolymeric, and Cementitious Mortars for Structural Applications

Abstract

This paper deals with the study of calcium sulfoaluminate (CSA) and geopolymeric (GEO) binders as alternatives to ordinary Portland cement (OPC) for the production of more environmentally-friendly construction materials. For this reason, three types of mortar with the same mechanical strength class (R3 ≥ 25 MPa, according to EN 1504-3) were tested and compared; they were based on CSA cement, an alkaline activated coal fly ash, and OPC. Firstly, binder pastes were prepared and their hydration was studied by means of X-ray diffraction (XRD) and differential thermal-thermogravimetric (DT-TG) analyses. Afterwards, mortars were compared in terms of workability, dynamic modulus of elasticity, adhesion to red clay bricks, free and restrained drying shrinkage, water vapor permeability, capillary water absorption, and resistance to sulfate attack. DT-TG and XRD analyses evidenced the main reactive phases of the investigated binders involved in the hydration reactions. Moreover, the sulfoaluminate mortar showed the smallest free shrinkage and the highest restrained shrinkage, mainly due to its high dynamic modulus of elasticity. The pore size distribution of geopolymeric mortar was responsible for the lowest capillary water absorption at short times and for the highest permeability to water vapor and the greatest resistance to sulfate attack.

Innovative hydraulic lime-based finishes with unconventional aggregates and TiO2 for the improvement of indoor air quality

“…Low value of activated carbon based mortars are well explained thanks to Kats and Thompson relation [25]: the lower the pore radius, the lower the transpirability [26].…”

Valorisation of GRP Dust Waste in Fired Clay Bricks

“…Water is the medium and the main carrier of aggressive ions that can cause degradation of construction materials [39,40]. Furthermore, porous media are more susceptible to salt crystallization and freeze-thaw cycles.…”

Use of Potabilized Water Sludge in the Production of Low-Energy Blended Calcium Sulfoaluminate Cements

“…Three different approaches have been proposed for the manufacture of low-CO2 cements: (1) the utilization of non-carbonated sources of CaO instead of limestone as a constituent of Portland clinker (PC)-generating raw mix [10,11]; (2) the increased production of blended cements, obtained by mixing ordinary Portland cement (OPC) with high amounts of supplementary cementitious materials (SCMs) [12][13][14][15][16][17]; (3) the larger use of special cements (SCs), namely, hydraulic binders obtained from non-PCs [18][19][20][21][22][23][24][25].…”