Foad Shokri

Laboratory investigation on the strength characteristics of cement treated base

Cement-Treated Base (CTB) is a non-conventional method used in road bases materials to improve its engineering properties due to the hardening of cement when moisture is present and extends the period of curing times. This study investigates the effects of cement additive on properties of base layer using laboratory mechanistic evaluation of stabilized soil mixtures. Laboratory tests conducted were Unconfined Compressive Strength (UCS), Indirect Tension test for Resilient Modulus (ITRM) and Flexure Strength (FS) tests. The results revealed that by adding Portland cement, the mechanical properties of the mixture have improved where the UCS is found to be an important quality indicator. In addition, the variables that influenced these tests, which are cement content, curing time, moisture content, and dry density, play important role to determine the performance of CTB. This paper presents the finding of a correlation conducted to analyse the influences of these variables using regression and ANOVA to establish significant models with the aim of predicting the strength base on mixture parameters. Keywords: Cement-Treated Base, Unconfined Compressive Strength, Indirect Tension test for Resilient Modulus, Flexure Strength, Moisture Content, Dry Density, Regression Analysis.

Effects on engineering properties of cement-treated road base with slow setting bitumen emulsion

Abstract This study investigated the effects of the type and amount of Portland cement and cationic slow setting bitumen emulsion additives on the short- and long-term performance of road-based properties using laboratory mechanistic evaluation. Stabilised specimens with Portland cement (0–6%) and bitumen emulsion (0–6%) were compacted, cured for 7, 28 and 60 days; and finally subjected to different stress sequences to study their unconfined compressive strength, indirect tensile resident modulus and indirect tensile strength tests. The durability of stabilised soil specimens was investigated by conducting wetting and drying (WD) cycling test on 7 days cured specimens. The results showed the added 4% portland cement–3% bitumen emulsion mix was ideal and produced a 179.4% reduction in the water absorption and permeability, 256.3% reduction in volume changes and 211.95% reduction in weight losses relative to a 4% cement sample. This paper presents the findings of a correlation that was conducted using non-linear regression analysis regarding the influences of the affected variables in order to establish models to predict the mixture strength parameters.