Durability and microstructure studies of styrene acrylate co-polymer modified ready-mix concrete

Abstract

The Reinforced Concrete (RC) terrace slab is the most vulnerable element in RC structures and is subjected to distress at early ages due to the corrosion of embedded steel rebars. An overlay of Polymer Modified Concrete (PMC) is a viable option to protect the reinforced concrete slab from water penetration and prevent premature corrosion of steel rebars. This study investigates the influence of styrene acrylate co-polymer modification at 2% by weight of binder (bwob) on the durability and microstructure properties of Ready-Mix Concrete (RMC). Concrete specimens were cast to perform compressive strength and durability tests such as water sorptivity, absorption, and accelerated corrosion tests. Samples were also characterized at 7,14, and 28 days using SEM with EDS and FT-IR. Test results revealed that the styrene acrylate modification in RMC at the dosage of 2% did not negatively alter the compressive strength of the concrete at 28 days. The Polymer-modified Ready-Mix Concrete (PRMC) exhibited (i) increased time for initiation of cracks and high resistance to the passage of electric current; (ii) improved water impermeability as compared to RMC, and hence improved durability properties. The SEM with EDS analysis revealed that the Ca/Si ratio of both control and PMC concrete was in the range of 1.5 to 2.3. The polymer modification in RMC modified the morphology of the hydrated product at 28 days, and the CSH gel formed appeared to be thick needle-like structures as compared to plate-like CSH gel formation in RMC. From this study, it can be concluded that polymer modification at 2% bwob appreciably improved the durability properties of RMC with similar 28 days strength development and hence recommended for use as an overlay for corrosion protection in reinforced concrete terrace slabs.