Abstract:
In Western countries, the waste management and the use of mining, metallurgical and industrial by- products are an important aspect of their national policies aimed at reinforcing present trends regarding the conservation of natural resources, environmental protection and energy savings.
The use of waste material in road construction is not only a major source of its disposal but also reduces the road construction cost due to increase in strength. However, in Pakistan this problem is not addressed with the desired concern. The reason for this is that road construction material (aggregate) is found in abundance in Pakistan. Anyhow environmental protection and energy saving are sufficient reasons to find proper disposal of industrial wastes and by-products.
The aim of this study is to find an economical disposal of flyash produced by thermal power station Lakra in road construction using local material. Unconfined compression strength tests were performed to find the compressive strength at different percentages of lime + flyash to the aggregate. Minimum required compressive strength of 400 psi was obtained in case of Petaro aggregate at 6 % lime + flyash and in case of Bolari and Unger this strength was obtained at 5 and 4 % lime + flyash respectively. The ratio of lime to flyash as 1:4 was found to be the most economical with satisfactory results. The cement was added as a strength accelerator and it was determined that addition of cement accelerate the rate of strength gain by about 15 % as compared to lime-flyash aggregate (LFA) mix.
Statistical analysis were performed for various combination of test results and it was revealed that Unger aggregate is most economical for use in LFA mix, followed by Bolari and
Petaro aggregate. Cost benefit analysis was made to compare the cost of road components (AC & Base) for granular and lime-flyash stabilized bases. The results of this study are very encouraging and proves that the use of flyash in stabilized bases is an economical disposal of flyash and will also save the construction cost of road by 1 to 2 %. It is hoped that these results will encourage the designer to use flyash in stabilized bases.
