Lin Wang

Bio: Lin Wang is an academic researcher from Xi'an University of Architecture and Technology. The author has contributed to research in topics: Medicine & Loess. The author has an hindex of 5, co-authored 9 publications receiving 78 citations.

Improvement of the Shearing Behaviour of Loess Using Recycled Straw Fiber Reinforcement

Abstract: Reinforcing structural members and construction materials using recycled fibers has become popular in the past decades due to sustainable development concerns. The recycled fibers as soil reinforcement elements contribute to the increase in shear strength by distributing stresses exerted in the soil along the length of the recycled fibers. Loess, widely spread over the Chinese Loess Plateau, is featured with metastable structure, large porosity, and high water sensitivity. This study presents the results of applying the large-scale stress-controlled direct shear tests on the recycled straw fiber-reinforced loess. The formation mechanism of shearing behaviour enhancement of the loess by straw fiber inclusion is revealed. The associated strain-hardening behaviour can be manifested using the dilation angle or the difference in friction angle between the large-displacement friction angle and the peak friction angle. Further, the shear strength using the displacement-controlled direct shear tests presents good correspondence with that using the stress-controlled direct shear tests. The test results explore the potential of using the recycled straw fiber-reinforced loess to protect the fragile loess environment in the northwest of China.

Micro-structural characteristics deterioration of intact loess under acid and saline solutions and resultant macro-mechanical properties

Abstract: When exposed to chemicals, the micro-structural evolution of the loess and the impacts on the macro-mechanical properties are considered crucial for contaminated land reclamation. In this study, the micro-structural characteristics of the loess specimens that are exposed to acetic acid or sodium sulfate, are studied using scanning electron microscopy, X-ray diffraction, and energy dispersive spectroscopy analyses. Further, their macro-mechanical properties are determined by direct shear tests. The corrosion of the cement between particles under acetic acid environments and the salt-induced swelling under saline conditions play an important role in the micro-structural deterioration. The cohesion and friction angle for the wetted loess are about 16 kPa and 19° respectively, while for the acetic acid-contamianted loess, they reduce to 10 kPa and 15° respectively. They, for the sodium sulfate-contaminated loess, reduce further to below 10 kPa and 13° respectively. The macro-mechanical properties show good correspondence with the micro-structural deterioration.

The Effect of Calcium Source on Pb and Cu Remediation Using Enzyme-Induced Carbonate Precipitation

Abstract: Heavy metal contamination not only causes threat to human health but also raises sustainable development concerns. The use of traditional methods to remediate heavy metal contamination is however time-consuming, and the remediation efficiency may not meet the requirements as expected. The present study conducted a series of test tube experiments to investigate the effect of calcium source on the lead and copper removals. In addition to the test tube experiments, numerical simulations were performed using Visual MINTEQ software package considering different degrees of urea hydrolysis derived from the experiments. The remediation efficiency degrades when NH4 + and OH− concentrations are not sufficient to precipitate the majority of Pb2+ and Cu2+. It also degrades when CaO turns pH into highly alkaline conditions. The numerical simulations do not take the dissolution of precipitation into account and therefore overestimate the remediation efficiency when subjected to lower Pb(NO3)2 or Cu(NO3)2 concentrations. The findings highlight the potential of applying the enzyme-induced carbonate precipitation to lead and copper remediations.

Effects of chemical contamination on microscale structural characteristics of intact loess and resultant macroscale mechanical properties

Abstract: Soil contamination not only can cause environmental problems but also lead to a notable change in the mechanical properties of soil. Loess widely distributed over North-West (NW) China is featured with the metastable structure, and chemical contaminants produced especially during the rapid development of NW China in recent years seriously threaten the fragile loess environments. When exposed to chemical contaminants, the impacts on the microstructural characteristics of the loess and the resultant mechanical properties are deemed critical for land reclamation in NW China. In light of this, the microscale structural characteristics of the loess exposed to acetic acid, phosphoric acid, sodium hydroxide, and sodium sulfate respectively are studied using scanning electron microscopy, X-ray diffraction, and energy dispersive spectroscopy tests. Additionally, their resultant macroscale mechanical properties are determined by direct shear tests. The deterioration mechanism regarding the microscale structural characteristics when exposed to the contaminants is revealed, and the resultant macroscale mechanical properties present a good correspondence with the deteriorated microscale structural characteristics. The findings of this work provide some guideposts for contaminated land reclamation in NW China.

Improvement of the Shearing Behaviour of Loess Using Recycled Straw Fiber Reinforcement

Abstract: Reinforcing structural members and construction materials using recycled fibers has become popular in the past decades due to sustainable development concerns. The recycled fibers as soil reinforcement elements contribute to the increase in shear strength by distributing stresses exerted in the soil along the length of the recycled fibers. Loess, widely spread over the Chinese Loess Plateau, is featured with metastable structure, large porosity, and high water sensitivity. This study presents the results of applying the large-scale stress-controlled direct shear tests on the recycled straw fiber-reinforced loess. The formation mechanism of shearing behaviour enhancement of the loess by straw fiber inclusion is revealed. The associated strain-hardening behaviour can be manifested using the dilation angle or the difference in friction angle between the large-displacement friction angle and the peak friction angle. Further, the shear strength using the displacement-controlled direct shear tests presents good correspondence with that using the stress-controlled direct shear tests. The test results explore the potential of using the recycled straw fiber-reinforced loess to protect the fragile loess environment in the northwest of China.

The remediation efficiency of heavy metal pollutants in water by industrial red mud particle waste

Abstract: This study aims to treat heavy metal pollutants in water by applying red mud particle waste. An experiment on the static adsorption of heavy metal ions Pb 2 + (or Cd 2 + and Cu 2 + ) by red mud particles was carried out, and the influences of the type of heavy metal ion, ion concentration, pH value, red mud dosage, reaction time, and temperature on adsorption performance were explored. The competitive adsorption mechanisms of various coexisting heavy metal ions by red mud particles were compared. The red mud samples loaded and not loaded with heavy metal ions were detected by zeta potential measurement, scanning electron microscopy, and Fourier transform infrared spectrometry. The adsorption strength of red mud particles for heavy metal ions was ranked in the sequence of Pb 2 + , Cd 2 + , and Cu 2 + , while increasing temperature enhanced their adsorption. When the initial pH values were 4.3, 5.0, and 3.6 for Pb 2 + , Cd 2 + , and Cu 2 + solutions, the removal peaks were 94.5%, 92.8%, and 78.1%, respectively. The preferred order of adsorption for red mud was Pb 2 + , Cd 2 + and then Cu 2 + under the competitive mechanism of binary/ternary systems due to the discrepancy in the functional groups of red mud particles loaded with different heavy metal ions. • A concept for purifying heavy metal pollutants in water using red mud is proposed. • The competitive adsorption mechanism of various heavy metal ions is revealed. • The influence of temperature on the interaction of heavy metal ions and red mud is emphasized. • An adsorption–desorption model with hysteresis is verified by experimental results.