Abstract
Calcareous sand is characterized by low strength, multiporosity, and high‐pressure shrinkage. This often leads to poor engineering properties. Therefore, it is often necessary to reinforce the calcareous sand in order to meet the actual engineering demand for bearing capacity. To study the modification effect of calcareous sand of nanoclay by cement, mechanical tests and microscopic tests of the cement calcareous sand (CCS) modified by different nanoclay content and cement content were conducted. Through the unconfined compressive test, the mechanical properties of nanoclay and cement compound modified calcareous sand (NCCS) were studied. The micromechanism of nanoclay and cement composite modified calcareous sand was analyzed by SEM. Representative curves of data groups of stress and strain data were obtained by the fusion algorithm, which effectively circumvented the discrete distribution of determined data. Test results showed that the following: (1) The compressive property of CCS could be improved by the admixture of nanoclay, and the optimum admixture ratio was 8%. (2) The admixture of nanoclay could enhance the deformation modulus of CCS and improve the resistance of CCS against external load deformation capacity. (3) Nanoclay could increase the density of the internal structure of CCS and improve its mechanical properties.
Highlights
In the category of rock soil, calcareous sand belonged to carbonate soil or calcareous soil, which was mainly composed of bone fragments of sea organism skeleton under the impact of sea water, such as cay, seaweed, shell, and so on [1,2,3]
In the 1960s, the unfavorable effect of calcareous sand gradually occurred in practical engineering [5]. e pile sliding of the petroleum platform in Iran did not cause an unfavorable effect on practical engineering. us, the engineering problem caused by calcareous sand did not draw great attention
Zhang et al [10] studied the mechanical properties of calcareous sand through a drained triaxial test. e results showed that the dilation phenomenon was obvious and the particle breakage index was the smallest under the same consolidation pressure
Summary
In the category of rock soil, calcareous sand belonged to carbonate soil or calcareous soil, which was mainly composed of bone fragments of sea organism skeleton under the impact of sea water, such as cay, seaweed, shell, and so on [1,2,3]. Many researches [13,14,15] showed that calcareous sand still has the characteristics of low strength, easy breakage, and high compressibility in practical engineering. Ismail et al [22] studied the influence of different cementation materials on the mechanical properties of calcareous sand through a triaxial test. E results demonstrated that the appropriate admixture of nano-MgO could improve the mechanical performance of cement silty clay. E results showed that the bending strength was the best with the 2% admixture of nanoclay at 400°C. e above researches showed that nanoclay could improve the mechanical performance of cemented material. The influence of the nanoclay admixture on the compressive strength of cement solidifying calcareous sand was mainly studied. The influence of the nanoclay admixture on the compressive strength of cement solidifying calcareous sand was mainly studied. e resistance against external load deformation capacity of the nanoclay modified cement calcareous sand was studied, which was anticipated to provide a reference for the usage of nanoclay and cement compound modified calcareous sand in the job site
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