CEMENT MORTAR IMPROVEMENT USING RUBBER LATEX AS AN ADDITIVE

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Department of Engineering

ABSTRACT
This thesis presents the results obtained on the effectiveness of rubberlatex as a means of improving cement mortar performance. Mortar cubes of the two principal mix-ratios 1:3 and 1:6 were prepared and cured in ordinary moist environment and in an aggressive environment (untreated A.B.U dam water) for control strength and that of the defective cubes respectively. Another set of the cement mortar cubes of both mixes, modified with the polymer rubber latex-were also cured in the aggressive media in order to determine the effectiveness of the latex as a means of improvement. The curing periods for all samples in both the ordinary and the aggressive media were 7, 21, 28 and 56 days. A significant change in the compressive strength was observed between control identical cubes (cubes without an addition of polymer) which were immersed in the two curing media correspondingly. The 7 day control strength is 24.74N/mm2 while that of the defective cubes falls to 18.06N/mm2 (a reduction of 27.0%). Similarly, the average variation in strength figures for the subsequent curing ages are 14.7%, 13.8%, and 24.5% (i.e. for 21, 28 and 56 days respectively). The reductions in the strength figures between the compared sets were as a result of the deterioration effect of the aggressive water used. The effect of the rubber latex is witnessed from the results of the modified cubes obtained. Taking ratio 1:3 mix with an addition of 1.5% latex, the corresponding modified cubes strength are 27.42N/mm2, 29.43N/mm2, 30.09N/mm2, and 33.77N/mm2. thereby depicting increase in strengths of 51.8%, 25.7%, 20.0% and 36.5% respectively. Much higher strength increase were observed from the cubes of the ration 1:6 mix. The increases in the strength values between the non modified and the modified cubes were as a results of the protection qualities of the modified agent.