Abstract
Slaking red-bed soft rocks are widely distributed in the south of Anhui Province, China, and several highways will go through this area. It is important to evaluate their physical and mechanical characteristics for the purpose of using this kind of soft rocks as materials for road construction. In this paper, the compacting tests, the resilient modulus tests, the California bearing ratio (CBR) tests, and permeability tests have been carried out on crushed red-bed soft rock mixtures. The test results showed that, for a given degree of compaction, the resilient modulus decreases linearly with the increase of moisture content. For a given moisture content, the resilient modulus and CBR values increase linearly with the increase of compaction degree, while the soaking swelling, water absorption capacity, and permeability coefficient decrease linearly. In other words, the strength and water stability are enhanced with the increase of the degree of compaction. The results demonstrate that the crushed red-bed soft rock mixtures can be directly used as materials for the highway construction by taking corresponding measures.
Highlights
Soft rock is one of the rock types encountered frequently in geotechnical engineering, which is less than the uniaxial compressive strength of 25 MPa, covering a series of sedimentary rocks, such as sandstone, mudstone, argillaceous sandstone, sandy mudstone, and siltstone
With the same moisture content of 9.0%, the specimens with a compaction degree of 99.7%, 97.1%, and 95.0% were prepared for the tests on the resilient modulus
The specimens with different degrees of compaction were prepared with each layer having blows of 30, 50, and 98 with the same moisture content 9.0%, to explore the influences of compaction degree K on California bearing ratio (CBR), the soaking swelling Q, and water adsorption X, which were evaluated by the Chinese Industrial Standard [18]
Summary
Soft rock is one of the rock types encountered frequently in geotechnical engineering, which is less than the uniaxial compressive strength of 25 MPa, covering a series of sedimentary rocks, such as sandstone, mudstone, argillaceous sandstone, sandy mudstone, and siltstone. Soft rocks are prone to slaking, swelling, collapse, breaking, softening, and argillization in the presence of humidity [1,2,3,4,5,6] Such phenomenon can be quite crucial for various geotechnical hazards in roads, slopes, tunnels, and other engineering projects [7,8,9,10]. Some construction measures, such as preslaking or adding lime, have been adopted to make full use of the red-bed soft rock as subgrade fillings [14, 17] Those measures potentially extend the construction duration and increase the costs of the road projects. If the crushed red-bed soft rock in these areas can be directly used as subgrade fillings, the construction duration and investments of the road projects can be reduced. The resilient modulus tests, the California bearing ratio (CBR) tests, and permeability tests were carried out on crushed soft rock mixtures with variable moisture contents or compaction degrees
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