The performance of fiber GGBS based alkali-activated concrete

The fast construction and renovation of roads and bridges and the infrastructures in Egypt and developing countries cause concrete and cement production on a large scale. This huge market demand for precast units and concrete production harms the environment and global warming. Thus, the Ordinary Portland Cement (OPC) should reduce by developing new materials such as geopolymer concrete or alkali-activated concrete. This study investigated alkali-activated slag concrete (AAC) performance reinforced with structural polypropylene and steel fibers cured at ambient room temperature. The structural polypropylene and steel fibers were incorporated into the alkali-activated mix by 1.5% and 5% of the total binder weight, respectively. A wide range of engineering properties was assessed, including compressive strength, split tensile strength and stress-strain behavior, density, water absorption, and porosity. Microstructural analysis of the AAC samples was evaluated through scanning electron microscopic (SEM). The results showed that compressive strength at 1-day curing developed about 85% of the compressive strength for ACC at 28-days, which was considered as early high strength. A 10% enhancement of the AAC specimens' average compressive strength was reported after 7 and 28 days while fiber addition. The split tensile strength significantly increased by 19.28 and 26.80% by incorporating structural polypropylene and steel fibers, respectively. Comparison between the ACI 318 and ECP 203 provisions was handled along with those experimental results obtained elastic and rupture modulus. The ACI 318 provisions provided a more conservative prediction to the experimental results than the ECP 203 provision, which overestimated the experimental values by an average value of 1.1. The electron microscopy images confirmed the improvement in the engineering properties by showing a proper and coherent bond between the mortar matrix and the added fibers.