Yang, W.*;Marshall, A. M.;Wanatowski, D.;Stace, L. R.
ADVANCES IN MATERIALS SCIENCE AND ENGINEERING,2017年 ISSN：1687-8434
[Yang, W.] Minist Educ, Key Lab Transportat Tunnel Engn, First North Sect 111,Erhuan Rd, Chengdu 610031, Peoples R China.;[Yang, W.; Stace, L. R.; Marshall, A. M.] Univ Nottingham, Univ Pk, Nottingham NG7 2RD, England.;[Wanatowski, D.] Southwest Jiaotong Univ, Leeds Joint Sch, Xipu Campus, Chengdu 611756, Peoples R China.
[Yang, W.] Minist Educ, Key Lab Transportat Tunnel Engn, First North Sect 111,Erhuan Rd, Chengdu 610031, Peoples R China.;[Yang, W.] Univ Nottingham, Univ Pk, Nottingham NG7 2RD, England.
Many shaft collapses are related to the deterioration and failure of the masonry shaft lining materials. In modern mine shaft, concrete is widely used to provide support. To analyse shafts stability, the properties of the lining need to be well defined. The behaviour of masonry and concrete can be considerably affected by long-term exposure to harsh mine water. This paper presents a study which focuses on the weathering effects of mine water on lining materials (brick, mortar, and concrete). To reproduce the weathering process, samples were placed into solutions of potable water, artificial mine water, and a more aggressive mine-water solution for just less than one year. Four phases of laboratory tests were conducted throughout the time period to assess the degradation of mechanical properties of the lining materials. Particular attention is given to the degradation of material strength and stiffness. Results indicate that the harsh acidic mine water has pronounced detrimental effects on the strength and stiffness of mortar. The weathering process is shown to have the most significant effect on the stiffness of concrete and mortar. It is also shown that the use of mass loss as an index for evaluation of mechanical properties may not be appropriate.
geochemical model;leaching;leaching control mechanism;pH;red mud
This study analyzes the leaching behavior of elements from red mud (bauxite residue) at pH values ranging from 2 to 13. The leaching characteristics of metals and contaminated anions in five red mud samples produced by Bayer and combined processes were analyzed using the batch leaching technique following the US Environmental Protection Agency (USEPA) Method 1313. In addition, the geochemical model of MINTEQ 3.1 was used to identify the leaching mechanisms of metals. The results showed that Ca, Mg, and Ba follow the cationic leaching pattern. Al, As, and Cr show an amphoteric leaching pattern. The leaching of Cl(-) is unaffected by the pH. The maximum leaching concentration of the proprietary elements occurs under extremely acidic conditions (pH = 2), except for As. The leaching concentration of F(-) reaches 1.4-27.0 mg/L in natural pH conditions (i.e., no acid or base addition). At the same pH level, the leaching concentrations of Pb, As, Cr, and Cu are generally higher from red mud produced by the combined process than that those of red mud from the Bayer process. The leaching concentration of these elements is not strongly related to the total elemental concentration in the red mud. Geochemical modeling analysis indicates that the leaching of metal elements, including Al, Ca, Fe, Cr, Cu, Pb, Mg, Ba, and Mn, in red mud are controlled by solubility. The leaching of these elements depended on the dissolution/precipitation of their (hydr)oxides, carbonate, or sulfate solids.
Ultrahigh molecular weight polyethylene (UHMWPE) bearings are used widely in orthopaedic joint replacement as a prominent material for improving the longevity, which is dramatically influenced by wear of polyethylene. Polyethylene tibial knee components from knee simulators under two different input conditions were analyzed using CMM and Micro-CT measurement techniques for volumetric loss with gravimetric measurement as reference. Based on the coordinates and image slices obtained, the surface curve fitting and image digitization methodology were used for the creation of nominal "original" surface in the case of no prewear data provided. The comparison results indicate that gravimetric remains the gold standard and the CMM measurement took less time and had better precision, accuracy, and repeatability compared to Micro-CT measurement technique.