Investigation of the Optimum Shotcrete Mixing Ratio for Slope Protection using Fly Ash

Abstract

Shotcrete has now grown in popularity and can replace cast-in-place (CIP) concrete in applications such as retaining walls and slope stabilisation. However, due to the problems like cracking due to shrinkage and the durability concern, this practise is still limited. So, cementitious material such as fly ash is used in this situation to increase the strength of the concrete and also to make sure it is high durability and safe to use in construction. Fly ash can be known as a coal combustion residual which is commonly occur in thermal power plant and it had been widely used as an alternative material during the production of Portland cement concrete. Supplementary cementitious materials is widely used in the mixing of concrete due to its unique properties which can harden the concrete via its hydraulic and pozzolanic activity. A series of experiments will be conducted to make sure that the fly ash that had been mixed with Portland cement is safe to use and also can increase the compressive strength of the cement. Throughout the experiments, a series of data will be display with the addition of 5%,10%,15%,20%,25%,30%,35% of pozzolans in the cement mixing ratio. The addition of fly ash during the mixing of concrete will indirectly reduce the cost of construction and also the rate of pollution to the environment as it is being classified as a scheduled waste in Malaysia according to the Environmental Quality Act 1974.This research will mainly focus on the performance of shotcrete with the addition of cementitious material which is fly ash as an alternative product compare to the tradition concrete and compare the differences in the achievement of shotcrete with and without the addition of fly ash so that the comparison is more clearly and more understandable. Next, the utilization of the nominal aggregates will be 10-20mm.The amount of fly ash added to the mixing of concrete will be in the range of 5% to 35%.