Combination of polypropylene fibre and superabsorbent polymer to improve physical properties of cement mortar

Polypropylene (PP) fibres are commonly used to restrict early shrinkage and control micro-crack propagation in mortars. However, increased porosity along with reduction in mechanical properties due to PP fibre addition is a concern. The study explores application of superabsorbent polymers (SAPs) to improve mechanical properties and permeability of PP fibre-reinforced mortar. The effect of SAP addition on fresh and hardened properties of fibre-reinforced mortar including flow, mechanical strength, elastic modulus and permeability are investigated. Experimental results show that a combination of SAP and PP fibre offers about 20% improvement in compressive strength. SAP addition increases the resistance of mortar to water penetration by up to 60%, whereas water absorption and coefficient of sorptivity is reduced by up to 46% and 66%, respectively, compared to the control. Improvement in permeability is linked to increased hydration due to SAP addition and blocking of voids by swelled SAP particles upon contact with incoming moisture. In a nutshell, a combination of SAP and PP fibre offers improvement in mechanical properties and permeability of cementitous composite, which is crucial to the serviceability and longer service life of civil infrastructure.