Cost effectiveness of clayey soil & moorum, treated with fly ash-lime for construction of low volume roads

Fly ash stabilization has been in use for sometime now. But it is obvious that no mix will be suitable for all types of soil. Depending on area, type of soil & type of fly ash, the optimum mix varies considerably. As the roads of Western Orissa (India) are in very poor condition & there are many big power plants coming up in these regions, fly ash utilization in road construction has a very good potential here. Using locally available weak clayey soil from Burla nearer to Sambalpur (India), fly ash from nearby Hindalco, Hirakud locally available lime manufactured at Katni, moorum (late rite) from “Godbhaga” moorum quarry, sand from Jharsuguda region, various tests were carried out to determine the CBR & other criteria like Liquid limit, Plastic limit, Sieve analysis etc. the intention was to determine the mix giving the maximum CBR value, satisfying the requirement of IRC. Here the cost effectiveness study of utilizing fly ash & lime for low volume roads with special emphasis on roads of Western Orissa (India) over weak clayey soil was carried out. The main aim of the study was to maximize the fly ash utilization in sub-grade & sub-base layers. It was observed that the maximum saving was possible for sub-grade in 70% soil + 30% fly ash + 2% lime combination i.e. Rs 6.85 lakhs may be saved per km (as per 2007 schedule of rate) of road as compared to road using only virgin soil as sub-grade. For sub-base it was seen that the combination giving the maximum CBR i.e. 70% moorum + 15% fly ash + 15% sand + 3% lime, which has 16% extra CBR as compared to the conventional mix of 70:30 moorum: sand combination, that costs 1.22 lakhs per km more than the conventional 70:30 moorum, sand mix.