ABSTRACT


Use of construction masonry unit has got wide acceptance in construction industry to deal with the numerous issues associated with burnt clay bricks. Normally cement, Bolhari sand and crush are used as the ingredients of CMU. However availability of Bolhari sand in many regions is made by transporting it from far distances which makes the resulting product expensive. To this end use of alternative material in place of Bolhari sand remained active area of research since long.In this experimental work partial replacement of Bolhari sand with local sand is proposed and studied. In this experimental work 0% - 70% (with 10% increment) replacement of Bolhari sand with local sand is used. Local sand is washed in purpose made tank with # 200 sieve at outlet. Eight batches of concrete masonry units are prepared. Each batch contains 6 specimen.All specimen are prepared in the sizeof 4" x 8" x 12". Concrete mix 1:4:8 with W/C ratio of 0.45 used for production of the CMU. Local sand is obtained from the vicinity of Nawabshah region and washed in tank with No. 200 sieve at outlet before using it. Ingredients are mixed in mixer and molds are prepared in standard fashion using concrete masonry unit making machine. Curing of sample is done for 7 and 28 days period. Finally compressive strength of all specimen are evaluated using universal load testing machine both in horizontaJ and vertical position.

Concluded outcome discovered that compressive strength of concrete masonry unit tested in horizontal position is recorded 720 psi (minimum) for 70% replacement and 1385 psi (maximum) 40% replacement. Minimum and maximum compressi ve strength results recorded for vertical position are 500 psi for 70% and 1206 psi for 40% replacement respectively. On the other hand 28 day cured CMU tested in horizontal position gave 747 psi for 70% and 1511 psi for 40% replacement as minimum and maximum compressive strength values. The same for vertical position are recorded as 554 psi for 70% and 1315 psi for 40% replacement respectively.

Final results confirmed use of local sand as replacement of Bolhari sand with posi tive effect on compressive strength and it is also found that 40% replacement of the Bolhari sand with local sand gives better results.