EFFECT OF WASTE PAPER SLUDGE AS PARTIAL REPLACEMENT OF CEMENT IN CONCRETE

An increase in production of concrete leads to extensive use of cement, its most expensive ingredient. Its production is usually listed among highly environment unfriendly industries which are characterized by depletion of natural virgin resources, consumption of huge amount of energy and emission of CO2 and greenhouse gases to the environment. Hence, this research was conducted trying to solve these cement related problems by reducing the amount of cement used in the concrete through developing the potential use of ash of calcined waste paper sludge at 8000C in concrete as cement replacing cementitious material. Concrete specimens for C-25 mix were prepared from five different mixes with 0%, 5%, 10%, 15% and 20% by weight replacement of ordinary Portland cement by waste paper sludge ash and the basic mechanical characteristics of the concrete were determined after 7 and 28 days of curing in water in order to be evaluated as compared with the control mix. Based on the test results compared to the control mix, the increment in addition of waste paper sludge ash led to continuous reduction in workability of freshly mixed concrete due to its highly water absorbing particles and reduction in unit weight due to its lower density. Improvements in compressive strength at both 7 and 28 days were found up to 15% replacement of cement and the maximum improvements were achieved at the 10% replacement with 33.81% and 31.13% increment respectively compared to the control mix. Up to 15% replacement of the ordinary Portland cement by waste paper sludge ash, a slightly higher flexural strength was observed at 7 days and the maximum result of 6.81% increment was achieved at the 10% replacement, whereas the increment in flexural strength for 28 days test was observed up to 5% replacement of cement