Sulfate Resistance in Cements Bearing Ornamental Granite Industry Sludge

Abstract

This study explores the effect on sulfate resistance of the use of ornamental granite industry waste as a supplementary cementitious material (at replacement ratios of 10% and 20%) in cement manufacture. The present paucity of scientific knowledge of the behaviour of these new cements when exposed to an external source of sulfates justifies the need for, and the originality of, this research. After characterising the waste chemically and mineralogically, cement paste specimens were prepared in order to determine the durability of the newly designed eco-cements using Köch–Steinegger corrosion indices. The new hydration products, which might induce microstructural, mineralogical, or morphological decay in the specimens, were also analysed by comparing the samples before and after soaking in a sodium sulfate solution for different test periods. Respect to the results, the damage to pastes bearing 10% granite sludge (GS) is the same as observed in OPC, whilst the former exhibit a higher Köch-Steinegger corrosion rate (1.61) than both OPC and OPC+20GS. Soaking the pastes in sodium sulfate induces matrix densification due to ettringite formation and gypsum precipitation in the pores. Further to those results, at an optimal replacement ratio of 10%, these alternative, eco-friendlier materials can be used in the design and construction of non-structural cement-based (mortar or concrete) members exposed to an external source of sulfate.

Experimental Study on the Strength and Durability for Slag Cement Mortar with Bentonite

“…In both pictures, some crystallized sodium sulfate(S) can be found among the C-S-H colloid. Moreover, some gypsum (G) plates, a compound of sulfate and calcium cation, are observed on the sample [31]. The lower water absorption and the higher compressive strength were obtained at an additional level of 0.25% bentonite in each w/b ratio.…”

“…In both pictures, some crystallized sodium sulfate(S) can be found among the C-S-H colloid. Moreover, some gypsum (G) plates, a compound of sulfate and calcium cation, are observed on the sample [31].…”

Durability of Ternary Cements Based on New Supplementary Cementitious Materials from Industrial Waste

“…Components: 70%OPC + 20%U C&DW + 10%BA, yielding a type II/B blended portland cement (21 % to 35 % total additions) or a type IV/A pozzolanic cement (11 % to 35 % total additions) in different proportions in keeping with European standard EBA, at replacement ratios of 10 % to 20 % according to the classification set out in standard EN 197-1 [8] Physical, mechanical characteristics: [37,40]), deemed optimal for assessing blended cement resistance to such agents as it simultaneously accommodates the pozzolanic reaction and the assessment of its most prominent advantages [41] Soaking…”

Recent Advances in the Reutilization of Granite Waste in Various Fields

“…Reports of controlled experiments indicate that it also has higher resistance to corrosion, frost and abrasion [12,13]. Soaking in a sulfuric acid solution produces ettringite and precipitates gypsum in the pores, which increases the corrosion resistance of concrete components [14]. With a dense matrix in concrete, the expansion of concrete containing granite waste was reduced by 38%.…”