Resilient modulus testing with application of cyclic CBR test for road subgrade materials

Abstract In this article the cyclic CBR test as a reference method in determination of resilient modulus (Mr) is confronted with results of cyclic triaxial and unconfined uniaxial cyclic test. The main idea of conducted experiments is establish relationship between cyclic loading tests in testing of natural subsoil and road materials. The article shows results of investigation on cohesive soil, namely sandy silty clay, commonly problematic soil in Poland. The results of repeated loading triaxial test resilient modulus were displayed in order to compare them with cyclic CBR test results by using the Mr–Ө model. Some empirical correlation between factors obtained from triaxial test or uniaxial unconfined cyclic test and cyclic CBR test was introduced here. The behavior of resilient modulus was also examined in this paper.

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Effects of Plastic Waste Materials on Geotechnical Properties of Clayey Soil

Transportation Infrastructure Geotechnology ◽

10.1007/s40515-020-00145-4 ◽

2021 ◽

Author(s):

Hussein Jalal Aswad Hassan ◽

Jabar Rasul ◽

Maleaha Samin

Keyword(s):

Clayey Soil ◽

Resilient Modulus ◽

Deformation Behaviour ◽

Fibre Content ◽

Waste Materials ◽

Dry Density ◽

Maximum Dry Density ◽

Soil Stabilisation ◽

Laboratory Test Results ◽

Cbr Test

AbstractRecently, the use of plastic products, such as polyethylene (PE) bottles and polypropylene (PP), has been significantly increased, which may lead to many environmental issues. Therefore, it is important to find methods to manage these waste materials without causing any ecological hazards. One of these methods is to use plastic wastes as soil stabiliser materials. In this study, PE and PP have been used in the form of fibres. The effect of the stabilisation was evaluated through carrying out standard laboratory tests. These tests have been conducted on natural and stabilised soils with four fibre contents (1%, 2%, 3%, and 4%) of the soil weight. The tests included the standard compaction test, unconfined compressive strength (UCS) test, California Bearing Ratio (CBR) test, and resilient modulus (Mr) tests. In all these tests, the fibre content was added in two lengths, which were 1.0 cm and 2.0 cm. Laboratory test results revealed that the plastic pieces decrease maximum dry density (MDD) and optimum moisture content (OMC) of the stabilised soils, which are required for the construction of embankments of lightweight materials. In addition, there was a significant improvement in the UCS of soils by 76.4 and 96.6% for both lengths of PE fibres and 57.4% and 73.0% for both lengths of PP fibres, respectively. Results of the CBR tests demonstrated that the inclusion of plastic fibres in clayey soils improves the strength and deformation behaviour of the soil especially with 4% fibre content for both lengths 1.0 cm and 2.0 cm, respectively, to a figure of 185 to 150% for PE and PP, respectively. Furthermore, the results of the Mr tests demonstrated that the mechanical properties improved to an extent. For an increase in fibre content, the resilient modulus increased by about 120% at 4% fibre content for PE. However, for PP, improvement in resilient modulus declined at 3% fibre content. Therefore, for soil stabilisation with fibre material, optimum fibre content shall be sought.

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