Investigation on the Properties of Sustainable Steel Fiber Reinforced Reactive Powder Concrete by Utilization of Coir Pith Aggregates and Pyrogenic Silica

Abstract

The present study investigates the properties of RPC (Reactive Powder Concrete) developed using low-cost eco-friendly materials such as pyrogenic silica (PS) and coir pith (CP) fine aggregates. This study investigates the effects of PS as silica fume (SF) replacement which is the main constituent for the production of reactive powder concrete which contained coir pith as a fine aggregate replacement instead of quartz sand (QS) up to 25%. The use of silica fume increases the particle packing density of RPC but increases the shrinkage phenomenon in RPC due to the minimum w/b ratio adopted. Therefore, in this research PS is used as a partial substitute for SF up to 30% and its effect on the mechanical and durability properties of coir pith containing RPC is studied. The test results showed that the mechanical strength values decreased with an increase in the addition of CP aggregate beyond 5% whereas the decrement in compressive strength was partially reduced when PS is used as silica fume replacement up to a maximum of 30%. The chloride penetration resistance was also improved with increasing PS substitution in RPC containing CP aggregates. The autogenous shrinkage and drying shrinkage were also significantly reduced due to the internal curing ability of the CP aggregates in combination with PS. The development of dense CSH (Calcium Silicate Hydrate) gels from hydration is also evident from the low CaO/ SiO2 ratio obtained from the EDS (Energy-dispersive X-ray Spectroscopy) analysis. Hence the combination of PS with CP aggregates can reduce the shrinkage characteristics of RPC thereby providing eco-friendly sustainable concrete at low cost.