[Purposes]This study uses coal gangue as subgrade fill material and explores the release-migration-solidification characteristics of heavy metal pollutants under the influence of natural rainfall.[Methods]Laboratory experiments were conducted to determine the basic properties of coal gangue fill material,identify the types of heavy metal pollutants,and investigate the release-migration characteristics of heavy metal pollutants during natural rainfall.Based on porous media solute transport theory,a numerical model was established to predict the impact of pollutants on the soil-water environment under extended rainfall.The solidification effects of geopolymers on pollutants in coal gangue fill material were examined at different mass fraction levels and curing ages.The effectiveness of geopolymers in chelating heavy metal pollutants in coal gangue fill material was explored.The solidification characteristics of geopolymer-solidified coal gangue fill material were comprehensively evaluated by comparing them against the cement solidification method.[Findings]The leaching mass concentrations of Pb and As heavy metal pollutants in coal gangue exceeded environmental limits,which were 9.1 times and 9.8 times greater than the Class Ⅲ groundwater limit in Standard for Groundwater Quality,respectively.In the early stages of rainfall,various heavy metal pollutants in coal gangue fill material exhibited rapid release rates and substantial leaching,followed by a gradual decrease in release rate until reaching a plateau,with cumulative release amount continuously increasing.Heavy metal pollutants migrated towards the bottom of the subgrade over time.After adding geopolymers,the leaching concentrations of all heavy metals were much lower than the required limit in the environmental standards.[Conclusions]Heavy metal pollutants in coal gangue as subgrade fill material exhibited persistent and long-term environmental impact.With increasing geopolymer content and curing age,the mass concentrations of heavy metals in the leachate significantly reduced and were much lower than the Class Ⅲ water limits.Compared to cement solidification,geopolymers demonstrated a superior solidification effect.The optimal solidification treatment of pollutants was recommended as the addition of 8%geopolymer with 14 curing days.
[目的]为实现工业机器人末端的位型控制,生成光滑末端位姿轨迹,提出一种位姿同步的实时规划策略.[方法]首先,基于非均匀B样条的路径规划方法,并结合基于单位四元数的姿态规划方法,拟合位姿示教点获取机器人末端位姿轨迹参数;然后,基于S形加减速曲线规划机器人末端切向速度;最后,根据曲线长度和曲线参数的对应关系,实时计算末端位姿.[结果]规划所得机器人末端路径通过所有示教点,曲线长度和参数的拟合误差小于0.01 mm,末端速度连续,在其他条件相同时,球面样条插值下的姿态过渡更平滑.[结论]当机器人末端沿算法指定的位姿路径移动时,末端速度可控,关节过渡平稳,这也验证了上述算法的有效性.
The utilization of solid waste to prepare binders that can replace cement has certain practical significance for reducing energy consumption, resource consumption, environmental pollution, and reuse of solid waste. In this study, the design method of alkali-activated binders (AABs) is proposed based on the reaction mechanism of AABs and the activation mechanism of their raw material components, which includes component classification method, component screening method and component distribution ratio design method. According to the basic nature of solid waste, combined with the design method of AABs, the design method of All-Solid-Waste-based alkali-activated binders (ASW-AABs) was developed, whose components are all composed of solid waste. The CGF+P series ASW-AABs are designed, with which calcium carbide slag (CCR) as alkali activator, ground granulated blast furnace slag (GGBS) and fly ash (FA) as pozzolanic material, and phosphogypsum (PG) as supplementary material. The higher the content of alkali activator or pozzolanic material with highly activity, the shorter the initial and final setting time, the paste strength of CGF+P series ASW-AABs is governed by the relative content of alkali activator and pozzolanic material, when the mass ratio of CCR:GGBS:FA is 4:4:2 and 4:5:1, its paste strength is no less than P.O 42.5 under the same condition. Pozzolanic materials with highly activity are mainly involved in early reactions, and the higher their content the higher the early strength, vice versa. The main reaction products of CGF binder are C-A-H, C-S-H, C-A-S-H, and CGFP binder also generated ettringite. The design method of AABs can provide guidance for the design and development of related solid waste-based binder, the design method of ASW-AABs is convenient for the selection and proportioning design of solid waste and has practical value.
[目的]解决橡胶-水泥界面黏结性能不足的问题.[方法]首先采用4种常见的化学改性方法,即氢氧化钠(NaOH)改性、氢氧化钠-尿素(NaOH-Urea)复合改性、硅烷偶联剂KH560改性和硅酸钠(Na2SiO3)改性,分别对橡胶颗粒进行改性;然后采用改性后的橡胶颗粒制备橡胶-水泥稳定碎石试件;最后开展冻融、干缩及温缩试验.[结果]分别经NaOH-Urea和KH560改性后的橡胶-水泥稳定碎石的抗冻强度损失几乎无变化,但其冻融前后的无侧限抗压强度均约增大1.5倍;5种橡胶-水泥稳定碎石按其干缩性能从优到劣排序依次为:NaOH改性橡胶-水泥稳定碎石、KH560改性橡胶-水泥稳定碎石、NaOH-Urea改性橡胶-水泥稳定碎石、Na2SiO3改性橡胶-水泥稳定碎石、未改性橡胶-水泥稳定碎石;NaOH-Urea和KH560可以提高橡胶-水泥稳定碎石的温缩性能,而NaOH和Na2SiO3对其温缩性能的改善效果不太理想.[结论]NaOH-Urea和KH560的改性效果较好,其有效增强了橡胶-水泥稳定碎石的抗冻抗裂性能.
[目的]利用水泥-粉煤灰浆体对钢渣骨料表面进行改性,探究改性钢渣骨料混凝土在硫酸盐侵蚀作用下宏观力学性能的演化规律及劣化机理.[方法]对改性钢渣骨料混凝土开展硫酸盐作用下的侵蚀试验,得到了改性材料的质量损失率、动弹性模量及抗压强度等参数的演变规律,并利用X射线衍射(XRD)、扫描电镜(SEM)技术探究硫酸盐侵蚀作用下改性钢渣骨料混凝土的微观特征.[结果]改性钢渣骨料混凝土质量和相对动弹性模量 随着侵蚀时间的增加均出现先提高后降低的趋势.侵蚀56d时,改性钢渣骨料混凝土的抗压强度比钢渣骨料混凝土和普通混凝土分别提高了5.7%、15.6%.改性钢渣被水泥-粉煤灰浆体包裹导致硫酸根离子难以侵入,显著缓解了硫酸盐侵蚀过程中的损伤进程,这使得改性钢渣骨料混凝土内部的侵蚀产物数量显著减少;同时,改性钢渣中的活性成分能够发生水化反应,生成的水化产物有效填充于孔隙与裂纹中,使改性钢渣骨料混凝土的抗侵蚀性能得到明显提高.[结论]水泥-粉煤灰浆体改性效果较好.改性钢渣骨料稳定性提高,有效增强了改性钢渣骨料混凝土的抗硫酸盐侵蚀性能.本研究可为改性钢渣的应用和推广提供参考.
