The incorporation of recycled glass fiber reinforced polymer (rGFRP) in cementitious materials is an interesting recycling and valorization method. However, this incorporation generally results in a significant loss of workability, often compensated by an adjustment of the water to cement ratio, which can affect mechanical performance, particularly compressive strength. The aim of this paper is to examine the effect of different size fractions of rGFRP (0.063 mm, 0.16 mm, 0.63 mm, 1.25 mm and 2 mm) on the mechanical strengths of cement mortars with a mixing method that is likely to maintain the workability of the mix without adjusting the water to cement ratio. For this, a substitution rate of 10% (in volume of sand by rGFRP), supposed to induce workability loss, is chosen. A pre-mixing of rGFRP with water before adding cement and sand is performed and allows for the workability to be maintained without increasing the water content. The results show that compressive and flexural strengths are almost maintained compared with reference mortar for two rGFRP size fractions (2 mm and 0/2 mm). For the 2 mm fraction, a slight improvement (3%) in flexural strength after 7 months of curing and a 5% reduction in compressive strength are observed. After 7 months of curing, fibers or clusters of rGFRP are still observed, although they are not alkali-resistant.

The recycling of glass fiber-reinforced polymer (GFRP) in cementitious materials is an interesting way of managing the end of life of this type of material. As the solutions of landfilling and incinerating have reached their limits, the material recovery by recycling approach appears to be suitable to develop cement-based materials with enhanced properties. Different recycling methods, including mechanical, thermal and chemical recycling, are commonly used for the recovery of fibers and resins. Mechanical recycling is more suitable due to its low cost and ease of implementation. Moreover, mechanical recycling has limited environmental impact and is ideal for use with cementitious materials (fiber and resin). Several studies are being conducted to find the best incorporation method, notably the incorporation of recycled GFRP of different sizes (small, medium, large and coarse) and shapes (fibrous, cubic, random) as a substitute for sand and/or aggregate in mortars and concretes or as reinforcement materials. This article aims to establish a state of the art perspective on the incorporation of rGFRP into cement-based materials. The benefits of this incorporation are highlighted as well as the limitations. The various challenges to be overcome to make this incorporation useful from a practical point of view are reported.