Surface modification of fibres with silane for enhancing the durability of FRP composites as reinforcement for seawater sea sand concrete (SWSSC): A review

This review discusses the necessity of surface modification to effectively use fibre-reinforced polymers (FRPs) as reinforcements for seawater and sea sand concrete (SWSSC). FRPs can be a viable reinforcement material for SWSSC as an alternative to the traditional carbon steel reinforcement that will suffer unacceptably high rates of corrosion due to the very high chloride content of the SWSSC environment. FRPs exhibit mechanical properties similar to steels but suffer insignificant degradation/corrosion due to chloride. However, the fibres in certain FRPs (such as basalt FRPs and glass FRPs) suffer degradation due to attack by the alkaline environment of concrete, causing degradation in fibre-matrix interfacial strength and loss of FRPs's overall mechanical strength and durability. Therefore, fibres used in such FRPs require suitable surface modification to ameliorate their degradation, enabling their practical use as reinforcements of SWSSC. While carbon fibre-reinforced polymers (CFRPs) demonstrate superior resistance to alkali-induced degradation, their widespread use in large-scale civil engineering is hindered by high costs. In this review, more economic alternatives, i.e., basalt fibre-reinforced polymers (BFRPs) and glass fibre-reinforced polymers (GFRPs) are critically reviewed. To enhance the durability of FRPs and mitigate alkali-induced degradation of the basalt/glass fibres, suitable surface modifications are necessary to safeguard the mechanical properties of FRPs. Underpinned by a comprehensive discussion on the necessity of surface modification of fibres for the use of FRPs in SWSSC environment, this review focuses on the potential of advanced approaches for surface modifications of the fibres, i.e., coatings of silanes, and silanes impregnated with graphene nanoplatelets (GNPs), graphene oxide (GO) and its functionalised derivatives or metal oxides (such as SiO₂, ZrO₂, Al₂O₃, TiO₂ and CeO₂). This review critically discusses the opportunities for suitable surface modification of basalt and glass fibres for enabling the durable use of FRPs as reinforcements for sweater sea sand concrete.