Effects of lactic and citric acid on early-age engineering properties of Portland/calcium aluminate blended cements

Kastiukas, Gediminas and Zhou, Xiangming and Castro-Gomes, João and Huang, Shifeng and Saafi, Mohamed Ben Salem (2015) Effects of lactic and citric acid on early-age engineering properties of Portland/calcium aluminate blended cements. Construction and Building Materials, 101 (1). pp. 389-395. ISSN 0950-0618

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In this study, Portland/calcium aluminate blended cement (PC/CAC) was combined with citric acid or lactic acid as additives to investigate the effects of the aforementioned carboxylic acids on the hydration reactions of PC/CAC as a potential fast hardening and low cost repair material for concrete. Mortar specimens with the carboxylic acid additives of either 0.5%, 1% or 3% by weight, prepared with a binder:sand:water ratio (by weight) of 1:3:0.5, were subjected to flexural and compressive strength tests at early ages up to 28 days. In order to understand the phase composition of the hydrates in the PC/CAC systems, XRD analyses were conducted on ground PC/CAC mortars with and without carboxylic acid at 7, 14 and 28 days. In combination with this, SEM images of selected mortar specimens were also taken at the same times for visual analyses of hydrates. Citric acid did not have any beneficial effect on enhancing the calcium silicate phase as initially assumed and instead reduced the strength of PC/CAC cement at all levels of concentration. The experiment analyses revealed that Portlandite crystals were the major hydrate phase in PC/CAC with lactic and citric acids. Lactic acid below 2% wt. improved both compressive and flexural strength gained at early ages due to improved crystallinity of the calcium hydroxide crystals. Combined with its inherent rapid setting time, PC/CAC blended cements have a potential to be developed into a suitable repair material for concrete.

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Journal Article
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Construction and Building Materials
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This is the author’s version of a work that was accepted for publication in Construction and Building Materials. Changes resulting from the publishing process, such as peer review, editing, corrections, structural formatting, and other quality control mechanisms may not be reflected in this document. Changes may have been made to this work since it was submitted for publication. A definitive version was subsequently published in Construction and Building Materials, 101, 1, 2015 DOI: 10.1016/j.conbuildmat.2015.10.054
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12 Nov 2015 14:34
Last Modified:
21 Sep 2023 01:56