Sulfate and acid resistance of lithomarge-based geopolymer mortars

Abstract

2018). Sulfate and acid resistance of lithomarge-based geopolymer mortars. Construction and Building Materials, 166,[537][538][539][540][541][542][543][544][545][546][547][548][549][550][551][552][553] ABSTRACTThe resistance of room temperature cured geopolymer mortars (GPM) against chemical attacks, i.e. sodium and magnesium sulfate solutions, and sulfuric and hydrochloric acid solutions, was evaluated. GPMs were formulated using a lithomarge precursor (low-purity kaolin) to achieve 28-day characteristic compressive strengths of 37.5 and 60 MPa. Their performance was compared with those of equivalent Portland cement mortars (PCMs) having the same paste volume and strength grade. GPMs with both strength grades showed superior performance against sulfate attack when compared to PCMs. No visual deterioration was observed in GPMs, the mass and length changes were relatively small, and no changes to the microstructure were detected -in contrast to severely deteriorated PCMs.As confirmed by visual observations and lower mass loss, GPMs showed better resistance to attack by both acids than PCMs. GPMs provided a better quality (lower permeability) of an acid-degraded layer, lowering the degree of further deterioration. The main mechanisms of the matrix deterioration of GPMs in both acids was dealumination of the hardened binder, with a higher degree of changes detected for sulfuric acid.

Evaluation of sulfate and salt resistance of ferrochrome slag and blast furnace slag‐based geopolymer concretes

“…It was seen from Figures that the samples in the salt solution do not suffer any damage and no color change. Similar to our work, although there are weight and length changes in the concrete produced by Kwasny et al, they have stated that there is no deterioration in the external appearance of the samples exposed to sulfate solutions for 52 weeks. Khan et al reported that in geopolymer concrete samples containing 70% BFS + 30% PC, there were fewer cracks and less visual deterioration than samples containing other binary binders.…”

“…Ren et al produced samples metakaolin based geopolymer added wollastonite, tremolite, and short basalt fiber composition at different rates. Kwasny et al produced solid clay based geopolymer mortar samples with two different compressive strengths (37.5 and 60 MPa). The samples were immersed in 0.352 mol sodium sulfate and magnesium sulfate solutions for 52 weeks.…”

Pore Structure Degradation of Different Cement Mortars Exposed to Sulphuric Acid

“…The zinc stearate mortar was the least affected with an increment of 7.7 points. These results are coherent with previous studies where it was observed that mortars exposed to acid attacks suffered mass ( Figure 6a) and strength losses (Figure 6b) due to the increase in porosity and permeability [47]. (Figure 6a) indicates that the higher the open porosity of the mortars, the higher is the mass loss.…”

Effect of slag content and activator dosage on the resistance of fly ash geopolymer binders to sulfuric acid attack

“…The mortar mix proportions used are presented in Table 3. The GP mixes are based on mix design optimisation carried out by Rafeet et al [43]- [45] and Vinai et al [19] and the PC mix proportions were obtained from work carried out by Kwasny et al [46]- [48]. The paste content was kept constant at 50% for all mortars, so that a fair comparison could be carried out between different mixes.…”