Compressibility of Four Types of Granular Bentonite Materials

Ma, Guoliang; Su, Zhenyan

doi:10.1007/978-981-13-2224-2_39

Cited by 2 publications

(1 citation statement)

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“…Compared with other clays, bentonite has a relatively concentrated particle size distribution and poor compactness. Some researchers found that the compactness of bentonite is related to the value of compaction pressure and moisture content [7]. Torbjörn et al [8] carried out the compaction tests on the full-scale bentonite blocks with the block size of 500 × 571 × 400 mm, the bulk density of the compacted block reached about 2.0 g/cm 3 , and the compaction stress was as high as 50-100 MPa (approximately 5700-14250 kN).…”

Section: Introductionmentioning

confidence: 99%

Granular Bentonite Preparation and Effect of Granulation Behavior on Hydromechanical Properties of Bentonite

Tan

Sun

et al. 2020

Advances in Civil Engineering

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Compacted bentonite is regarded as a suitable buffer/backfill material in a high-level radioactive waste disposal repository due to its low permeability, high swelling, and strong adsorption capacity, but the bentonite powder is difficult to compact to a high density only by increasing the compaction energy. Hence, a proposal is made to improve the compactness of bentonite by changing its grain size distribution. To obtain bentonite granules with different sizes, a granulation method is proposed in this paper, in which bentonite powders experience the processes of wetting and drying into plate bentonites, which are then crushed into granules. Furthermore, in this paper, the hydromechanical behavior of granular bentonite is evaluated to verify the feasibility of the method for preparing granules. For this purpose, the granular and original bentonite powder with similar grain sizes were prepared; then, various laboratory tests, including measurements of free swelling ratio, swelling pressure, water retention capacity, and compactness, were carried out. The test results show that the free swelling ratio, swelling pressure, permeability coefficient, and water retention capacity of granular bentonite are almost similar to those of original bentonite, and after compaction, the maximum dry densities of granular and original bentonites are 1.72 and 1.64 g/cm3 at the optimum moisture content (20%) and the energy consumption was reduced by 38% with the void ratio decreased from 1.30 to 0.8 compared with the original bentonite. It indicates that, compared with the original bentonite, the hydromechanical behavior of granular bentonites changed a little, but its compaction performance has been significantly improved. To investigate the differences in pore size distributions of granular bentonite and original bentonite, MIP and NA tests were performed on samples produced with the wetting-drying agglomerate method, and the results show that the pores with a size of 10.0 μm almost disappear and the pores mainly exist with a size of approximately 1.0 μm. It can be verified that preparing granules by the wetting-drying agglomeration method is feasible, the granulation process has little effect on the hydromechanical properties of bentonite, and after granulation, not only the compactness is improved but also the energy consumption is saved.

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Section: Introductionmentioning

confidence: 99%