Predicting the Unconfined Compressive Strength of Stabilised Soils Sourced from Six Road Borrow Pits in Arusha region, Tanzania

Abstract

Soil stabilization is an important civil engineering applications such as sub-grade construction, road construction, backfill and foundation construction to improve the physical, mechanical and chemical properties of soil by admixtures. Therefore, the objective of this paper is to predict the unconfined compressive strength (UCS) of stabilised soils sourced from six road borrow pits in Arusha region, Tanzania using appropriate standard techniques including Dynamic Cone Penetration (DCP), Grading Modulus (GM), Dry Density and Plastic Index (PI) Tests. The UCS values of soils ranges from 0.62 to 2.59 MPa and DCP-DN values varies from 3.88 to 10.20 mm/blow. The grading modulus of soils varies between 1.99 and 2.71 whereas, PI values from 0% to 14% and the Maximum Dry Density (MDD) ranges from 1520 to 2106 kg/m3. The analysis shows adequate model fit, indicating a significant relationship between UCS and DCP DN values (Average penetration rate in mm/blow). The developed relationship will be suitable in estimating in-place strength of soils and reduce some tests, cost and time for performing quality assurance and quality control on stabilization for road works.

Keywords

• Laboratory Dynamic Cone Penetration; Unconfined Compressive Strength; Classification Test; Soil Chemical Stabilisation; Low Volume Roads