Coal ash Portland Cement Mortars Sulphate Resistance

Abstract

Coal fly ash (CFA), coal bottom ash (CBA) are residues produced in thermo-electrical power stations as result of the coal combustion in the same boiler. Therefore, some characteristics of the coal fly ash (CFA) are comparable with those of the coal bottom ash (CBA). Nevertheless, coal bottom ash size is larger than coal fly ash one. Consequently, it was found that it is necessary to grind the coal bottom ash (CBA) to reach a similar size to that one of the CFA. The objective of this paper is to evaluate the performance of Portland cement mortars made with coal fly ash (CFA), coal bottom ash (CBA) or mixes (CFA+CBA), against sulphate attack. The methodology is based on the expansion of slender bars submerged in a sodium sulphate solution (5%) according to the ASTM C-1012/C1012-13 standard. It has been found that mortars elaborated with CEM I 42.5 N (without ashes) presented the largest expansion (0.09%) after a testing period of 330 days. Mortars made with CEM II/A-V exhibited lower expansion (0.03%). Summing up, it can be established that mortar expansion decreases when the coal ash amount increases, independently of the type of coal ash employed. The novelty of this paper relies on the comparison between the performances of Portland cement mortars made with coal fly ash (CFA) or coal bottom ash (CBA) exposed to external sulphate attack. Doi: 10.28991/cej-2021-03091640 Full Text: PDF

Influence of Coal Gangue Powder on the Macroscopic Mechanical Properties and Microstructure of Recycled Aggregate Concrete

“…[9] Argiz and Menéndez introduced CBA as a gel material into cement and found that the concrete's resistance to chloride and sulfate corrosion improved with an increase in the CBA content (within the range of 25%). [10,11] Özkılıç et al [12] introduced varying proportions of waste glass aggregate (WGA) into a fixed ratio of alkali-activated fly ash-based geopolymer concrete. They conducted tests on its physical properties and observed that the concrete's performance was inversely related to the proportion of WGA but directly proportional to the NaOH concentration.…”

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