EFFECT OF DELAYED COMPACTION ON LIME-FLYASH-SOIL MIXES

Abstract

Flyash is a finely divided residue produced in huge amounts as a waste by -product due to combustion of pulverised coal in Thermal Power Plants. As a result of improper disposal, serious environmental pollution has taken place leading to a steep degradation of our eco-system. In India, efforts have been made since the early seventies to utilize this waste product in different fields, but unfortunately only 3 to 5% utilization has been achieved till date which is far below the world average of 16%. Recently, in some major construction projects, flyash has been suitably used in embankment as well as in base and sub base courses of pavement. To achieve a high value of strength in the stabilized mix, proper quality control measures should be undertaken by strictly adhering to the recommended specifications. Again proper conditions of curing, moisture and temperature should be maintained for favourable pozzolanic reaction between soil, lime and flyash, otherwise the above exercise will become futile. Out of the many factors influencing the properties of lime-flyash-soil mixes, delay in compaction after wet mixing is generally over-looked in construction sites which makes a considerable effect on the strength development process in the mixes. This time-lag may take place due to some unavoidable interruptions in construction, non-availability of rollers in proper time and lack of proper supervision. There has been a long felt need to interpret the effect in strength development due to delayed compaction in lime-flyash-soil mixes and the present study is an effort to gather information in this direction.