Abstract
Sulphate attack is one of the key issues in geotechnical engineering. This study aims to investigate the efficacy of the seashell to reduce negative impacts of the magnesium sulphate concentration on the cement-stabilized clay mixtures by performing a series of unconfined compressive strength (UCS) tests. Three percent of cement (3, 5 and 7%) was utilized in this study. In addition, the benchmark and exposed specimens were cured for 7, 14, and 28 days before testing and exposure, respectively. A series of the compaction tests were conducted and the optimum moisture content (OMC) and maximum dry density (MDD) values were achieved. In the next stage, the UCS tests were performed on the specimens containing 10, 20, or 30% seashell contents and the specimens were exposed to sulphate concentration. Scanning electron microscope morphology had indicated that seashells are a suitable replacement for cement. Qualitative X-ray diffraction had shown that the presence of magnesium sulphate reduces the formation of calcium silicate hydrate, which causes durability issues in cement-stabilized soils. The results indicated that seashell is effective to improve the sulphate resistance of cement-stabilized soil.
Highlights
The concentrated magnesium sulphate in soil has destructive impacts on infrastructure, especially in the transport sector
As far as there is no contact between magnesium-sulphate-contaminated soil with air, there is no issue with this soil, when these types of soil are subject to construction of new infrastructures, like roads or highways, destructive impacts can be shown over time
Sulphate attacks occurred in cement-stabilized soil when the main hydration product of soil stabilization, calcium silicate hydrate (CSH) reacted with the sulphate ions present in the soil when the sulphates such as magnesium sulphate occurred naturally in the environment
Summary
The concentrated magnesium sulphate in soil has destructive impacts on infrastructure, especially in the transport sector. Sulphate attacks occurred in cement-stabilized soil when the main hydration product of soil stabilization, calcium silicate hydrate (CSH) reacted with the sulphate ions present in the soil when the sulphates such as magnesium sulphate occurred naturally in the environment. This phenomenon is known as the decalcification, and a new product is generated out of this process which is known as magnesium silicate hydrate (MSH), which reduces the strength of the soil [3,4,5]. It is known that lesser considerations have been given towards its impacts from a geotechnical point of view, on the application of seashells as partial replacement of cement on stabilized clays to improve the UCS properties of the cement-stabilized soils
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