Compaction Characteristics and Shear Parameters of Pond Ash

Abstract

With the increase in the number of coal based thermal power plants in India, generation of coal ash has reached enormous proportions. India at present produces around 120 Million tonnes of Ash per annum. The power requirements of the country are rapidly increasing with increase in growth of the industrial sectors. India depends on Thermal power as its main source (around 80% of power produced is thermal power), as a result the quantity of Ash produced shall also increase. Indian coal on an average has 35 % Ash and this is one of the prime factors which shall lead to increased ash production and hence, Ash utilization problems for the country. Out of the total ash produced.

Fly ash contributes to a small percentage, majority being Pond ash and bottom ash. Ash disposal involves design and installation of ash ponds, which in addition to covering quite large area at each plant site, creates aesthetic as well as hygienic environmental impacts. This has warranted the scientific and industrial community to initiate research and development work for finding avenues for the innovative use and safe disposal of the pond ash so that instead of a waste product, the pond ash could be considered as a usable by-product. Though a lot of research has been carried out for the effective utilization of pond ash like its use in construction industry etc, little literature is available on pond ash utilization particularly its use as a foundation material. One way of disposing off pond ash would be its use as a structural fill material and use as embankment material in highways.

The present work aims at evaluating the response of pond ash to various compactive efforts. The compactive efforts have been varied as 595 kj/m3 to 2674 kj/m3 of sample and effect of compaction energy on MDD and OMC have been evaluated by conducting proctor compaction tests, the shear strength parameters of pond ash samples compacted to different dry densities and moisture contents.





Based on experimental findings the following conclusions are drawn.


 Increase in compaction energy facilitates closer packing of pond ash particles resulting in an increase in MDD
 MDD of compacted samples shows a linear relationship with the amount of compaction energy.

 The OMC of the samples is found to decrease with increase in compactive effort increased compaction energy forces the particles to come closer resulting in a reduced void space hence OMC is found to be 28%-39%.

 It is shown in results,With increase in compaction energy from 3639 to 35554 kg-cm, MDD of pond ash increases, but at the same time OMC decreases.

 shear strength tests on freshly compacted pond ash specimens at various water contents and different dry densities show that most of the shear strength is due to internal friction.

 Angle of friction doesn’t change much when we applied different compactive efforts

 With increase of compaction energy from 595 kj/m3 to 2674 kj/m3 per 1000 cc of compacted sample the MDD is found to change from 1.09 gm/cc and 1.27 gm/cc