Abstract
AbstractSands reinforced by hydraulic binders (cement) have constituted in recent decades a major asset for the expansion of several areas of engineering. The mechanical behavior of sand-cement mixtures has undergone some controversies studied on the Chlef sand. In this paper, we present an experimental study to investigate the mechanical behavior of a sandy soil reinforced by a hydraulic binder (cement), using the direct shear apparatus emphasizing on the shear strength characteristics and the vertical deformation variation of cemented reinforced sand. The parameters used in this study are mainly: relative density (Dr = 80%), normal stress (σn = 100, 200, 400 kPa), water content (3, 7 and 10%), cement content (2.5, 5, 7.5 and 10 %) and cure time (7, 14 and 28 days). The experimental results show that the mechanical characteristics in terms of internal cohesion (C) and internal frication angle (φ) give a better mechanical performance with the binder inclusion, and the cure conditions play an effective role on the improvement of the shear strength. This result also showed that 10% of the cement content gave us a maximum value of shear strength and an optimal influence on the mechanical characteristics. The addition of cement not only improves the shear strength of soil, but also provides diversity in the resistance against the deformations imposed load, which can be established by a dilatant character.
Highlights
The results show that the shear strength of the unreinforced samples increases with increasing horizontal displacement without a peak appearance, while for samples reinforced with cement, it is found that the resistance increases significantly with the increase of the cement content up to a resistance peak of 80, 90, 100 and 110 kPa for Cc equal to 2.5, 5, 7.5 and 10%, respectively; the resistance drops followed by a residual resistance to the shear end for samples with water content of 3% (Figure 5(a))
The results of the tests of the samples made with a water content ω of 7 and 10% are illustrated in Figures 5(b) and 5(c); a very significant increase in the strength of the mixture is observed with the increase in the cement content where the shear strength reaches values of 106, 181 and 189 for water contents of 3, 7 and 10% for the samples mixed with 10% cement
We present the laboratory results of a series of direct shear tests carried out on unreinforced and cement-reinforced Chlef sand, the reinforced sand samples prepared with cement contents of 2.5, 5, 7.5, 10% and with different water content (ω = 3, 7 and 10%) in order to study the mechanical behavior of a sand-cement mixture and their influence on the mechanical characteristics, that is, maximum shear strength, intercept cohesion and friction angle
Summary
The reinforcement of soil in place remains an important activity area in the field of geotechnical engineering It aims to improve the mechanical qualities of soil by increasing its resistance, reducing its permeability and controlling its deformability. The method of including a hydraulic binder to improve the mechanical characteristics of soils is to homogeneously mix the cement in the soil with certain water content and play the role of reinforcement locally. Several researchers have demonstrated the effectiveness of adding cement to the mechanical behavior of soils (such as Coop et al, 1993; Consoli et al, 1998; Schnaid et al, 2001; Asghari et al, 2003; Haeri et al, 2006; Sharma et al, 2011; Baxter et al, 2011; Heathcote et, 1994) They showed that cemented sands show brittle behavior with an apparent peak in the stress-strain curve.
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