Abstract. Mechanical properties of polymer based concrete exposed to high temperature effects are evaluated in the present study. Concrete mixtures were prepared using styrene butadiene rubber (SBR) latex and reinforced with polypropylene (PP) fibres. "Latex polymer modified concrete mixes consisting of different aggregate proportions, polymeric fibre contents (0.1 and 0.3% Vf) and fly ash contents (25 and 50%) were investigated for high temperature performance. Concrete specimens after required curing were subjected to different high temperature effects from 200°C to 800°C and the corresponding weight loss and residual strength was determined. In addition, the residual elastic modulus of polymer concretes was determined from the compressive stress-strain properties. Experimental observations showed that, compared to plain concrete the residual strength characteristics of polymer fibre concretes were affected when exposed to high temperature. Strength degradation occurred with increase in temperature and the test results indicated that the temperature sustainability of polypropylene fibre concretes were observed up to 200°C. A maximum compressive strength loss upto 56.75% for plain concrete and 9.87% for polymer fibre concrete was noticed when exposed to high temperature upto 800°C. Further, microscopic analysis of fibre concretes exposed to high temperature showed possible melting of PP fibres resulting in filling the pore spaces which possibly improved the matrix hardening. Also, the high volume fibre incorporated concrete mixes showed maximum residual strength gain due to favourable matrix strengthening and demonstrated high temperature performance of polymer concretes.

Fibre reinforcement in concrete is an effective solution for improving tensile properties of concrete. Different types of fibres such as steel, polypropylene, glass and polyester were commonly used in concrete. In the present study, the effect of adding crimped polypropylene fibres on the improvement in the compressive properties of hardened concrete was studied. Crimped polypropylene fibres with different levels of reinforcements index was investigated systematically with designed concrete mixtures consisting of various fibres dosages of 0.1 to 0.5% by volume of concrete. The effect of crimped profile of polypropylene fibres on the improvement in failure properties of concrete in compression and flexural tension were evaluated. Test results showed that polypropylene fibres showed higher fracture energy absorption and exhibited a marginal improvement in strength index and sudden failure is prevented resulting in multiple splitting cracks. The ultrasonic pulse velocity test results were also found to be consistent and exhibited a good integrity for all CPFRC concrete specimens. A maximum compressive strength was noted at an optimum dosage of 3.0% of CPFRC specimens with a strength value of 24.67 and 34.92 MPa at 7 and 28 days respectively.

Synthetic polymer latexes, such as styrene-butadiene rubber (SBR) latex addition in Portland cement has gained wider acceptance in many applications in the construction industry. Polymer-modifi ed cementitious systems seals the pores and micro cracks developed during hardening of the cement matrix, by dispersing a fi lm of polymer phase throughout the concrete. A comprehensive set of experimental test were conducted for studying the compressive properties of SBR latex polymer with crimped polypropylene fi bres at relative volume fractions of 0.1 and 0.3%. The results indicated that the addition of polypropylene fi bre has little effect on the reduction in the workability of concrete composite containing fl y ash and SBR Latex. Increase in polypropylene fi bres upto 0.3% V f showed increase in compressive strength upto 57.5MPa. The SBR concrete without fi bre showed an increase in strength upto 20 % compared to plain concrete. Test results also indicated that the compressive strength was increased in SBR fi bre concrete by means of an ordinary dry curing process than wet curing because of their excellent water retention due to polymer fi lm formation around the cement grains. On the contrary the compressive strength reduces for SBR fi bre concretes under wet curing compared to dry curing.

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