Determination of Optimum Strength of Red Soil and Mixed Soil using Soil-Cement (S/C) Mix Ratio

Abstract

The research paper is focused on the improvement of the palaeo
lateritic red soil, clayey silt of low plasticity (ML) from Ratmate
area incorporating mixed with poorly graded sand with gravels
(SP) from Helipad area inside the premises of Devghat
hydropower station, Nuwakot District, Nepal. With the
confirmation of maximum dry density (MDD) and optimum
moisture content (OMC), 20% of SP was mixed homogenously
with 80% of ML and experimented by adding cements at 3%,
5%, 7% and 10% respectively. Hence ML and mixed soil
(H20:R80) have been cured for 7, 14 and 28 days for the
determination of undrained strength by UCS and pulse velocity
by passing Pundit ultrasonic pulse velocity to check the
compactness of specimens. The Pearson’s coefficient of
correlation between UCS test and UPV revealed the strong
positive correlation linear relationship of 0.78. The linear
regression model elucidates that for every additional undrained
strength determined by UCS, the pulse velocity is expected to be
enlarged by an average of 0.5135 m/s. Since, the cement
admixture of more than 7% impedes the rapid increase in pulse
velocity which was also confirmed by UCS tests due to the
presence of high capillary porosity of cement when excess
cement was added. The study predicts that the optimum cement
content for both soils in this research are best suitable at 7%
admixture of cement when cured for 28 days.