Effect of pH Value on Mechanical Properties and Microstructure of Yunnan Laterite

Abstract

Abstract: In order to explore the evolution law of mechanical properties and microstructure of soil under acid and alkali pollution, the Yunnan laterite polluted by different concentrations of hydrochloric acid (HCl) and sodium hydroxide (NaOH) was investigated. Then, the effects of full range of pH values and their action duration time on the shear strength of the Yunnan laterite were studied. The microstructure changes were detected by scanning electron microscopy (SEM). The test results show that the shear strength (τ_f) and the strength parameters (cohesion (c) and internal friction angle ()) all decrease with the decrease or increase of pH values compared with pH=8.2. The τ_f, c and  all decrease with extension of action duration time and come into stable after 7 d. SEM images and characteristic parameters of laterite polluted by acid and alkali were analyzed. The results show that the degradation of shear strength is caused by the corroded soil structure resulted from the acid and alkali pollution. The worse of engineering properties is most significant in alkali soils. This research can give guiding significance for the understanding and prevention of water environment deterioration engineering hazards in Yunnan laterite regions.

Key words: laterite, acid and alkali pollution, shear strength, microstructure, HCl, NaOH

CLC Number:

TU446

PAN Tai, ZHAO Guitao, HUANG Ying. Effect of pH Value on Mechanical Properties and Microstructure of Yunnan Laterite[J]. BULLETIN OF THE CHINESE CERAMIC SOCIETY, 2021, 40(10): 3427-3434.

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