Designing epoxy viscosity for optimal mechanical performance of coated Glass Textile Reinforced Mortar (GTRM) composites. (10th February 2020)

• Record Type: Journal Article
• Authors: Signorini, Cesare; Nobili, Andrea; Sola, Antonella; Messori, Massimo
• Is Part Of: Construction & building materials. Volume 233(2020)
• Publication Date: 2020-02-10
• Subjects: TRM -- Epoxy coating -- Dilution -- Optimization -- Viscosity; Building materials -- Periodicals; 624.18
• DOI: 10.1016/j.conbuildmat.2019.117325
• Languages: English
• ISSNs: 0950-0618

Abstract

Highlights: Epoxy coating is a recognized technology to improve fabric-to-matrix interphase. Unexpectedly, epoxy dilution may benefit mechanical performance by improving resin penetration in the fabric yarns. A threshold viscosity is identified that prevents telescopic failure by bonding core filaments. Data scattering is similarly affected and design values are obtained and discussed. Optimally diluted epoxy composites score comparably to FRP in terms of cost-to-performance. Abstract: Preliminary epoxy coating of the reinforcing fabric provides an effective approach for improving matrix-to-fabric strength in inorganic matrix composites. We investigate the effect of epoxy resin dilution in acetone on uni-axial tensile performance of coated alkali-resistant (AR) glass fabric embedded in a lime-based matrix. Remarkably, it is found that dilution has a mixed effect on performance and this trend is consistently retrieved for strength, ductility and energy dissipation. Indeed, performance initially decays and then it suddenly raises to a level close to or even exceeding that of the undiluted specimens. It is postulated that this behaviour is caused by resin viscosity, that falls off exponentially with the dilution degree. Once a viscosity threshold is breached, epoxy is capable of penetrating inside the yarn and thereby prevents telescopic failure, that is the sliding of the outer over the inner glass filaments. Furthermore, the interphase surface area increases dramatically and this enhances performance and narrows scattering. Besides, optimal viscosity is reached at an unexpectedly high dilution degree, whence material cost is significantly reduced. A cost-to-performance comparison of common strengthening technologies is presented, which shows that diluted epoxy composites score comparably to FRPs. It is concluded that epoxy coating optimization plays an important role in designing inorganic matrix composites.