Elevated curing temperature-associated strength and mechanisms of reactive MgO-activated industrial by-products solidified soils     

Dongxing Wang  Xiangyun Gao  Ruihong Wang  Stefan Larsson  Mahfoud Benzerzour 《Marine Georesources & Geotechnology》2020,38(6):659-671

Abstract

Alkali-activated industrial by-products (granulated blast furnace slag, Class F fly ash) by traditional alkali activator (such as NaOH and Na₂SiO₃) serves as a partial replacement for Portland cement in soil stabilization projects and suffers from environmental and technical problems. Reactive MgO – a greener and more practical alternative has recently emerged as a potential activator for slag and fly ash, but its micromechanisms of alkaline activation still need to be deeply investigated for strength improvement of soils. Hence, this study focuses on the strength and hydration properties of reactive MgO-slag and MgO-fly ash solidified soils, especially incorporating the impact of elevated curing temperature. Reactive MgO is proved to be excellent as a novel activator for activation of slag and fly ash, and their activating efficiency increases with elevated curing temperature that helps to remarkably enhance the compressive strength of soils. The major hydration products for reactive MgO-slag solidified soils, detected jointly by X-ray diffraction, scanning electron microscopy and thermogravimetric/differential thermogravimetric tests, are calcium silicate hydrate gels and hydrotalcite-like phases. The primary hydration products for MgO-fly ash solidified soils are magnesium silicate hydrate gels and Mg(OH)₂. That is just the intrinsic reason why the microstructure of solidified soils becomes much denser and the mechanical behavior is significantly improved. The minor carbonate phases such as magnesium carbonate and/or calcite are also observed in reactive MgO-slag and MgO-fly ash solidified soils, depending on the period of exposure to air. The curing temperature and binder amount are proved to be the two major factors governing the hydration process of reactive MgO-slag and MgO-fly ash blends. A higher curing temperature and binder amount can generate more hydration products, but their chemical compositions such as accurate element ratios need to be investigated in the future study.  相似文献   

掘进爆破中炮眼的设计探讨          下载免费PDF全文

张拔川 《探矿工程》1995,(2):50-51

对掘进中处于夹制情况下的炮孔爆破进行分析，提出炮眼分阶段设计的原理及有关的参数。  相似文献   

A two-dimensional kinematic model for predicting muckpile shape in bench blasting     

R. L. Yang  A. Kavetsky  C. K. McKenzie 《Geotechnical and Geological Engineering》1989,7(3):209-226

Summary Most existing models of blasting are stress-based and involve many fundamental parameters difficult or impossible to measure in practice. Even a single prediction with such models takes large quantities of computer time, so that calibration becomes a major impediment to their practical use.The model in this paper is based on a simple kinematic approach to modelling muckpile formation. This has the advantage of relative simplicity, while still reflecting the essence of the blasting displacement process. Because of the simple implementation, the model can be calibrated against field data in a straightforward manner and then used for predictions at the same site. The inputs to the model are simply the blast design parameters. The output of the model is a muckpile cross-section, within which contours of diggability or distribution of materials can also be calculated. Case studies have shown that, provided the model is calibrated to the site condition, it will give accurate predictions for altered blast designs.  相似文献   

Remediation of electric arc furnace dust leachate by the use of cementitious materials： A column-leaching test     

Josee Duchesne Guylaine Laforest 《中国地球化学学报》2006,25(B08):99-99

Disposal of industrial solid wastes in a hydrologic environment can cause environmental risks due to the mobility of toxic trace elements. It is increasingly important to find simple and inexpensive treatments to remove undesirable elements from industrial solid wastes. One of the most important problems in the secondary steel mill industry is the disposition of dusts produced from electric arc furnace. A large quantity （10-20 kg） of electric arc furnace dust （EAFD） is generated per ton of steel produced. The Toxicity Characteristic Leaching Procedure （TCLP） shows that the total Cr and Cr （Ⅵ） concentrations （9.7 and 6.1 mg/L respectively） from the EAFD studied exceeded the Toxicity Characteristic Regulatory Level. Some heavy metals of EAFD like chromium are toxics and have high solubility. Chromium （Ⅵ） is particularly problematic because it must initially be reduced before fixed in an insoluble phase. To counter this problem, the use of ordinary Portland cement （OPC） and ground granulated blast furnace slag （GGBFS） was investigated. Column leaching test was performed to evaluate the leaching of EAFD amended with GGBFS and OPC under dynamic conditions simulating heap leaching. The goal of this study is to find a simple and economic way to decrease contaminants in the leachate. Test columns have been set up to evaluate the effect of alkaline additives （OPC and GGBFS） on the geochemistry of drainage water. The control column consists of EADF only. A set of columns presents the effect of the addition of 5% by mass of OPC or GGBFS mixed homogeneously with the EAFD. Another set of columns was set up with the same quantities of OPC and GGBFS but concentrated at the base of the EAFD simulating a liner. Columns were fed three times weakly during 1 month. The parameters monitored after each flush of water include leachate volume, pH, electrical conductance and water quality （Cr-Ni-Pb-Zn concentrations）. The leaching of the control （EAFD only） presents high Cr concentration.  相似文献   

The Use of Waste Materials in the Passive Remediation of Mine Water Polution     

Lesley C. Batty  Paul L. Younger 《Surveys in Geophysics》2004,25(1):55-67

The contamination and resulting degradation of water coursesby effluents from abandoned and active mines is a world-wideproblem. Traditional methods of remediating the dischargesfrom mines involve the addition of chemicals and the utilisationof artificial energy sources. Over the last 15–20 years passivetreatment systems have been developed that harness naturalchemical and biological processes to ameliorate the potentiallytoxic effects of such discharges. There are many different typesof passive system, including compost wetlands, reducing andalkalinity producing systems (RAPS), permeable reactive barriersand inorganic media passive systems. Different waste materialscan be utilised as reactive media within each of these systems,dependent upon the type of mine water and treatment technology.In many cases the reactivity of these recycled waste materialsis key to the remedial performance of these systems. The materialsused may be organic (e.g., composts) or inorganic (e.g., blast furnaceslag) and where possible are sourced locally in order to minimisetransport costs. The remediation of mine waters in itself canproduce large quantities of waste products in the form of ironoxide sludge. Potential uses of this material in the productionof pigments and in the treatment of phosphate contaminatedwaters is also currently under investigation.The exploitation of what are traditionallythought of as waste materials within treatmentsystems for polluted waters is an expandingtechnology which provides great scope for recycling.  相似文献   

最小交叉熵谱在矿震井水位资料中的应用          下载免费PDF全文

赵明  黄积刚  郑治真 《地震工程学报》1994,16(2):29-35,49

文中简述了最小交叉熵谱原理，并用模拟资料检验了最小交叉熵谱计算程序，最后用最小交叉熵谱方法分析了矿震井水位资料。结果表明，矿震井水位资料的最小交叉熵谱中，除了日变化的２Ｈ＿ｚ以外，在震前几小时到几天中均出现８Ｈ＿ｚ的高频分量，这是一般的谱分析方法无法得到的。本文提出的方法为矿震预测提供了新的路径。  相似文献   

高强钢绞线网-聚合物砂浆加固钢筋混凝土板的抗爆性能数值分析   总被引：1，自引：0，他引：1  

杜修力  廖维张 《地震学刊》2010,(6):595-600

为研究高强钢绞线网-聚合物砂浆加固混凝土板的抗爆能力,用混凝土HJC动力本构模型,建立了混凝土板、炸药及考虑空气介质影响的流固耦合有限元计算模型。用动力分析软件ANSYS/LS-DYNA,对在爆炸荷载作用下加固前、后混凝土板的破坏形态和抗爆性能进行了数值分析。研究结果表明：混凝土板用高强钢绞线网-聚合物砂浆加固后,抗爆炸冲击能力明显提高。当小药量爆炸时,板顶、板底同时加固的效果明显优于板底单一加固;当药量较大时,板顶、板底同时加固的效果与板底单一加固相差不大。  相似文献   

空气间隔装药爆炸冲击荷载作用下混凝土损伤分析   总被引：5，自引：1，他引：4  

吴亮  钟冬望  卢文波 《岩土力学》2009,30(10):3109-3114

采用JHC混凝土损伤演化模型,模拟计算了不同空气间隔装药结构情况下炮孔近区岩石损伤破坏机制,分析了空气层比例以及起爆方式对爆破效果的影响。计算表明,不同空气层位置及比例会产生不同的爆破效果,并能运用于不同的爆破目的。空气层比例与炮孔粉碎区大小成反比,空气比较小时可以用于梯段爆破,而空气比较大时可用于预裂或光面爆破。对于梯段爆破、反向起爆（空气层位于上部）和中间起爆（空气层位于中间）的效果要好;起爆方式对梯段爆破效果的影响要比预裂和光面爆破效果明显。  相似文献   

L-M优化算法在爆破振动参数预测中的应用/   总被引：2，自引：0，他引：2       下载免费PDF全文

张艺峰  姚道平  谢志招  杨江峰  叶友权 《地震学报》2008,30(5):540-544

当前,以振动峰值作为单一爆破振动安全指标的回归经验公式,在国内外爆破工程界得到广泛应用.但由于爆破机理和爆破介质环境复杂,影响因素诸多,很难用一个经验公式把这些因素都考虑进去;再加上回归分析方法固有的局限性(要求数据有较好的分布规律和大样本量),经验公式方法进行振动预测的效果不甚理想(李保珍,1997;陈寿如,2001;张继春,2001).  相似文献   

X-射线荧光光谱法测定高炉渣和电炉渣中8种常见元素     

伊志宏  于想琼 《华东地质学院学报》2000,23(4):349-350

研究了借助熔片法制样,将高炉渣、电沪渣两种基体建于同一组工作曲线。所获曲线线性良好。分析结果与标准值或湿分析值吻合。  相似文献