The role of mix design and short glass fiber content on mode-I cracking characteristics of polymer concrete

Suitable resistance against fracture and cracking is a primary requirement for using polymeric concrete materials in practical applications. The main aim of this research is to investigate the effect of mix-design on mode I cracking behavior. A total number of 72 different Polymer Concrete (PC) mix-designs made of four ingredients (epoxy resin, coarse silica aggregate, fine sand filler and chopped strand E-glass fibers) were considered for conducting fracture experiments using the Semi-Circular Bend (SCB) specimen. The weight percentages of the ingredients were varied in the following range: 17–25% resin, 75–81% fine and coarse aggregates and 0–2% glass fibers. The investigated mix-designs were categorized into six groups (ultra-high, high, medium-high, medium-low, low and ultra-low) in terms of the adhesive agent content (i.e. the ratio of resin plus fiber content to the weight of the whole mixture). The experiments showed the noticeable dependency of both fracture toughness and fracture energy values (KIf and GIf) on the PC mix-design. In addition, the effect of substituting 1 and 2% of resin content with glass fiber was investigated. It was found that adding the fiber cannot necessarily enhance the performance of PC mixture against cracking and for some mix-designs; the addition of fiber can even reduce both KIf and GIf values.