Development of Strength Models for Prediction of Unconfined Compressive Strength of Cement/Byproduct Material Improved Soils

Abstract

This paper presents the possible inclusion of pulverized fuel ash (PFA) and ground granulated blast slag (GGBS) in cement deep soil mixing for enhancement of unconfined compressive strength (UCS) of weak soil materials for construction purposes. The main focus of this paper was to investigate the UCS of cement-, cement/PFA-and cement/PFA/GGBS-improved soils, and development of mathematical and graphical models for prediction of UCS for use in design and construction. Samples of cement, blends of cement and PFA, and cement/PFA/GGBS were prepared using 5 %, 10 %, 15 %, and 20 % by weight of dry soil and tested for UCS after 7, 14, 28, and 56 days. A multiple regression analysis was conducted using the SPSS computer program. The results showed that soil materials with lower plasticity show higher strength development compared to those of higher plasticity for cement improvement. The study has also revealed that the inclusion of PFA and GGBS can cause a reduction in the amount of cement in deep soil mixing, which can result to reduced cost and emission of carbon dioxide (CO 2) during construction. The developed mathematical and graphical models could give reliable predictions of UCS for weak soil materials with initial UCS less than or equal to 25 kPa and for water to binder ratio of unity based on the observed agreement between experimental and predicted data. The developed multiple regression models have also been validated using different mixtures of 6 %, 8 %, 12 %, and 16 % of binders.

Effect of Organic Matter on Swell and Undrained Shear Strength of Treated Soils

“…Apart from potentially aiding the enhancement of the engineering properties of the organic clays, the introduction of wastes or by-product material guarantees a reduction in the cost of construction as well as preservation of the environment. This recommendation is in line with the current growing trend towards the use of alternative binders in soil stabilization [13,14,[25][26][27][28][29][30][31][32][33][34][35][36][37].…”

Swell and microstructural characteristics of high-plasticity clay blended with cement

“…Both man-made and periodic environmental factors work to trigger intrinsic mineral properties of expansive soil, with a resulting increase or decrease in the soil's volume (Nelson and Miller 1992). These soils are very problematic and almost impossible to compact during construction unless they are treated with cement or a combination of cement and other cementitious by-product materials (Abbey et al 2015(Abbey et al , 2016(Abbey et al , 2017(Abbey et al , 2018Rahgozar et al 2018;Ta'negonbadi and Noorzad 2017;Pourakbar et al 2015). Soil stabilisation involves the improvement of the engineering properties of weak soils mechanically, physically or by mixing with binders to achieve some predetermined objectives.…”

A dimensional description of the unconfined compressive strength of artificially cemented fine-grained soils

“…The R 2 and NRMSE indices were also calculated for these combined datasets, which resulted in a net R 2 and a net NRMSE of 0.981 and 2.38%, respectively. A common benchmark for soil-cement UCS modelling, as reported in the research literature, is the use of multiple linear regression (MLR) analysis [1,25,26,65]. For a given soil type blended with cement, a suitable MLR model can be given as:…”

“…More importantly, in view of cement's high energy consumption and carbon footprint, the ability to identify/predict the optimum soil-cement mix design for a desired application can lead to significant cost and environmental benefits. In this context, a number of studies have proposed various forms of empirical/regression, physical and constitutive models capable of simulating the shear strength, mainly unconfined compressive strength (UCS), of compacted soil-cement blends [20][21][22][23][24][25][26][27]. In addition, the use of artificial intelligence (AI) techniques -including artificial neural networks (ANNs), genetic programing (GP), and metaheuristic optimization algorithms such as particle swarm optimization (PSO) -have also shown great promise in describing and hence simulating the UCS of compacted soil-cement blends [28][29][30][31].…”