PSI - Issue 71

Garima Choudhary et al. / Procedia Structural Integrity 71 (2025) 424–429

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complex formwork arrangements, or when transporting concrete over long distances (Cheng et al. 2023 and Kabus et al. 2018). Currently, sodium gluconate is one of the most widely used chemical retarders in the concrete industry due to its strong chelating ability and effective performance in extending setting time Plank, J., and Sachsenhauser, B. (2009). However, it has several drawbacks, including high cost, limited domestic production, and heavy reliance on imports - particularly from China, which is the dominant global supplier (Shah et al. 2016 and Yousuf et al. 2014). In cementitious systems, sodium gluconate dissociates to release gluconate ions, which interact with calcium ions to delay hydration (Zingg et al. 2008). Gluconic acid, being the parent compound of sodium gluconate, behaves similarly by producing gluconate ions upon dissociation in alkaline environments (Ouyang et al. 2006). Despite this functional similarity, GA remains underutilized in concrete applications, even though its production technology is available within India, making it a more accessible and potentially economical alternative. This research paper explores the potential of GA as an effective retarder in concrete mixtures. The study aims to evaluate the impact of varying GA dosages on the setting time, workability, compressive strength, and durability of concrete. By systematically analysing these parameters, the research seeks to provide a comprehensive understanding of how gluconic acid can be optimized to enhance concrete performance in specific construction conditions. The findings of this study will contribute to the broader knowledge base on concrete admixtures, offering practical insights for the development of high-performance, durable concrete mixtures tailored to the demands of modern construction practices. 2. Materials Gluconic acid (GA) is a mild organic acid, with the molecular formula C 6 H 12 O 7 , that is produced through the oxidation of glucose. Due to its chelating abilities and non-corrosive nature, it is well-suited for use as a retarding agent in concrete mixtures. For this study, industrial-grade GA was sourced from Kaison Chemicals, Mumbai. The structural formula of GA is depicted in Fig.1. The materials used in the concrete mix included cement, coarse aggregates (10mm and 20mm), and fine aggregate (river sand). Ordinary Portland Cement (OPC 53) conforming to IS 12269:1987 (2013) (BIS 2013) was sourced locally. The river sand used was also procured locally. Crushed stone aggregates, sourced from Panchgaon, Nagpur, were obtained from local suppliers and were used in compliance with IS 383:2016 (BIS 2016). Preliminary tests for the use of GA as a retarding admixture were conducted in accordance with IS 9103:1999(2019) (BIS 2019), and the results are presented in table 1.

Fig. 1. Structural formula of Gluconic acid. Table 1. Physicochemical Properties of Gluconic Acid (GA).

Properties

Gluconic Acid

Chemical Formula

C 6 H 12 O 7 196 g/mol

Molar Mass

Density

1260 kg/m 3

pH

1.88 15 2̊ C

Melting Point Physical state

Viscous liquid Light Yellow

Colour

3. Methodology