Preliminary research on strength of polymer modified concrete with copolymer natural rubber as concrete additives

Polymer modified concrete is one of the alternative material of construction to obtain better performance in strength and durability of concrete. There are some types of PMC such as natural rubber, synthetic rubber, modified rubber and asphalt.  In this work, copolymer of natural rubber styrene and copolymer of natural rubber methacrylate were used as PMC added to Portland cement concrete and Portland Pozzolan cement concrete up to 1 wt%. The aims of this work were to investigate the effects of curing methods (air curing and saturated lime curing) and addition of plasticizer on the compressive strength of concrete. Interactions among parameters were observed using factorial design analysis with Minitab (software) and strength value in concrete age of 28 days as a yield. The result showed that by saturated lime curing, calcium hydroxide as side product of cement hydration could be reacting with pozzolanic material of cement. So, there would be more calcium silicate hydrate (CSH) crystal that improve bond in the interfacial zone.  It was found that the saturated lime curing produced concrete with compressive strength 20% higher than concrete produced by air curing.  This result was supported by results from Scanning Electron Spectroscopy (SEM) that prove there were compactness factor of concrete structure. It was also found that plasticizer did not significantly influence compressive strength of concretes.   Key words: Polymer modified concrete, copolymer of natural rubber, strength development, saturated lime curing.