The surface treatment of PVA fibres to enhance fibre distribution and mechanical properties of foam concrete

Abstract

Fibres are often used to improve the mechanical properties of foam concrete. However, the poor dispersion of PVA fibres in foam concrete significantly restricts their reinforcement efficiency. Limited studies have been conducted on improving the distribution of PVA fibres in a cementitious matrix, particularly in relation to foam concrete. This is noteworthy because pore structure, which can be significantly influenced by the fibres and fibre treatment agents, is a critical parameter that affects the mechanical properties of foam concrete. Therefore, this study employed polar agents (non-ionic surfactants) to treat the fibre surface, aiming to enhance the distribution and reinforcement efficiency of PVA fibres in foam concrete. In view of safety and feasibility, two non-hazardous polar agents, namely PEG-PPG-PEG (designated as PA A) and Polyoxyethylene (20) cetyl ether (designated as PA B), were used to treat the PVA fibres. The impact of fibre treatments on fibre dispersion and pore structure was investigated, and the compressive strength and flexural behaviour of foam concrete were measured before and after the treatments. PA A was found to be unsuitable for fibre treatment due to its poor bonding with the fibre surface. On the other hand, PA B exhibited good bonding with PVA fibres, resulting in enhanced fibre dispersion and pore structure in the foam concrete. Compared to plain foam concrete, the fibres treated with PA B increased the compressive and flexural strength by 47.4 % and 190.3 %, respectively. Moreover, the treated fibres (by PA B) were observed to improve the 0.8 mm toughness of foam concrete by 27.2 %.