Influence of moisture content on the contact-hardening properties of calcium silicate hydrate by direct compression. (5th April 2021)

• Record Type: Journal Article
• Authors: Wang, Shuping; Peng, Xiaoqin; Tang, Luping; Ji, Guangxiang; Zeng, Lu
• Is Part Of: Construction & building materials. Volume 278(2021)
• Publication Date: 2021-04-05
• Subjects: Moisture content -- Calcium silicate hydrate -- Compaction -- Mechanical properties -- Interparticulate bonding; Building materials -- Periodicals; 624.18
• DOI: 10.1016/j.conbuildmat.2021.122374
• Languages: English
• ISSNs: 0950-0618

Abstract

Highlights: Contact between C-S-H particles with different moisture content is originally described. Water molecules is essential to the hydrogen bonding formation between C-S-H particles. Approximately 20% moisture content in the material is suggested. Abstract: The purpose of this study is to investigate the influence of moisture content on the contact-hardening properties of calcium silicate hydrate. The materials with moisture content ranging from 0 to 76% were directly compressed at the pressure of 40 MPa for three minutes to produce solid compacts. Bulk density, mechanical strength and water-resistant property of the compacts were measured, and temperature evolution of the powders during compaction was evaluated. An obvious increase in bulk density of compacts but a slight decrease in compressive strength was found with moisture content increased up to approximately 25%, ascribed to the lubricant effect of water films on the surface of particles that facilitates the rearrangement and spillage of particles. Moisture could reduce the temperature evolution by reducing surface energy of the particles, and separate the interparticulate bonding. Consequently, for the material with moisture content higher than 25%, the bulk density of the compacts was almost constant, but the compressive strength decreased dramatically. Different tendency was observed in the flexural strength that the value increased with moisture content increased up to 11%, attributed to the consolidation of particles and formation of hydrogen bonding, and the water- resistant property of the compacts was also improved. Subsequent decrease in flexural strength was due to the disruption of hydrogen bonding.