Strength and Modulus of Marine Clay-Cement Mixes

This paper examines the strength and modulus of marine clay-cement mixes with high cement content. Although similar studies have been reported, many of these studies were conducted using soil-cement and water-cement ratios which are more applicable to deep cement mixing than jet grouting. The objective of this study is to investigate how the strength and modulus of cement-treated Singapore marine clay vary with cement and water contents at a range of cement contents, which is more representative of that used in jet grouting. To facilitate parametric studies that are relevant to jet grouting operations, a working range of the constituents was proposed for Singapore marine clay based on the liquid and bleeding limits of the soil-cement mixes. Comparison with data from some previous jet grouting studies and projects indicates that the liquid and bleeding limits can encompass most, if not all, of the parameter range normally used in jet grouting operations. The results of unconfined compression tests on cement-treated marine clay showed that water-cement ratio alone cannot adequately account for the variation in measured strength; the influence of the soil-cement ratio must also be included. For a given water-cement ratio, the strength of the cement-treated soil appears to increase with the soil-cement ratio. Based on these results, empirical relations for the strength and modulus of marine-clay-cement mix are proposed. The experiments also show that slurry clay, rather than dried-pulverized clay, should be used in such tests as the two soil states can lead to significantly different strength and modulus of the cement-treated soil.