Development of a high strength cementitious grout for filling the joints of UHPC permanent formwork. (March 2023)

• Record Type: Journal Article
• Authors: Yang, Yibo; Chen, Baixi; Chen, Yong; Liu, Fucai; Xie, Xiangming; Guo, Wenying; Wang, Hengchang
• Is Part Of: Developments in the built environment. Volume 13(2023)
• Publication Date: 2023-03
• Subjects: UHPC -- Formwork -- Cement -- Grout -- Admixture -- PVA; Civil engineering -- Periodicals; Sustainable construction -- Periodicals; 624.05
• DOI: 10.1016/j.dibe.2023.100120
• Languages: English
• ISSNs: 2666-1659

Abstract

Abstract: The utilization of ultra-high-performance concrete (UHPC) permanent formwork could facilitate the construction of hydraulic concrete structures. However, the joints between UHPC formwork are the vulnerable parts of a whole permanent formwork system. This study aimed to develop a High Strength Cementitious Grout (HSCG) for filling these joints, integrating the formwork system, and minimizing the adverse influence on these joints. The aggregate size for the HSCG was optimized, and four kinds of admixtures (i.e., hydrophobic powder (HP), expansive agent (EA), redispersible polymer powder (RPP), and cellulose ether (CE)) and PVA fibers were used to improve the HSCG. The HSCG with different aggregate sizes, admixture dosages, and PVA fiber contents were experimentally investigated. By evaluating the compressive, tensile, flexural, and adhesive strengths of the prepared grout, the aggregate size range was recommended to be 0.15–0.30 ​mm, while the suggested contents of HP, EA, RPP, and CE were 0%, 6%, 2%, and 0.1%, respectively, by weight of binding materials. In addition, the optimal volume content of PVA fibers was 0.45%. In order to avoid the introduced foams, 0.2% of the defoamers were used in combination with the CE. After that, six combinations were tested to consider the coupled effect of different admixtures and PVA fibers on the HSCG. In consideration of the strengths, shrinkage, and abrasion resistance to water impact, the HSCG with the combination of (EA ​+ ​RPP ​+ ​CE), the aggregate size of 0.15–0.30 ​mm showed the optimal overall performance and was regarded as the most suitable HSCG for grouting. Highlights: Four commonly used admixtures and PVA fiber were used to improve the HSCG separately. The effect of aggregate sizes on the High Strength Cementitious Grout (HSCG) was investigated. Coupled effect of admixtures and PVA fibers were studied for HSCG optimization. The strength, shrinkage, and abrasion resistance of the HSCG were optimized.