Evaluation of sulfate resistance of cement mortars containing black rice husk ash

In this paper, black rice husk ashes (BRHAs), which are agrowastes from an electricity generating power plant and a rice mill, were ground and used as a partial cement replacement. The durability of mortars under sulfate attack including expansion and compressive strength loss were investigated. For parametric study, BRHA were used as a Portland cement Type 1 replacement at the levels of 0%, 10%, 30%, and 50% by weight of binder. The water-to-binder ratios were 0.55 and 0.65. For the durability of mortar exposed to sulfate attack, 5% sodium sulfate (Na₂SO₄) and magnesium sulfate (MgSO₄) solutions were used. As a result, when increasing the percentage replacement of BRHA, the expansion and compressive strength loss of mortar decreased. At the replacement levels of 30% and 50% of BRHA, the expansion of the mortars was less than those mixed with sulfate-resistant cement. However, the expansion of the mortars exposed to Na₂SO₄ was more than those exposed to MgSO₄. Increasing the replacement level of BRHA tends to reduce the compressive strength loss of mortars exposed to Na₂SO₄ attack. In contrary, under MgSO₄ attack, when increasing the replacement level of BRHA, the compressive strength loss increases from 0% to 50% in comparison to Portland cement mortar. Results show that ground BRHA can be applied as a pozzolanic material to concrete and also improve resistance to sodium sulfate attack, but it can impair resistance to magnesium sulfate attack.     

清洁生产分析与评价实践

本文以某大型水泥生产企业为例进行了清洁生产分析与评价的探讨 ,提出了包括原材料指标、产品指标、能源指标和污染物排放指标的水泥生产企业清洁生产评价指标体系和指标值 ,进行了定量分析和评价 ,并在此基础上提出了企业清洁生产建议     

“十二五”水泥行业NOx总量减排形势分析及对策探讨

分析“十二五”水泥行业NOx减排形势,探讨积极应对措施,对推进水泥行业NOx减排工作及实现减排目标具有重要意义.本研究在对水泥行业NOx排放控制现状分析的基础上,结合水泥行业产业政策和环境管理要求,采用情景分析法,对“十二五”水泥行业NOx新增排放量进行了预测,探讨了不同减排途径下水泥行业可实现的减排目标及面临的减排形势,并从激励机制、政策引导、循环经济、监督管理等方面提出了相应的意见和建议.     

Use of silicon and ferrosilicon industry by-products (silica fume) in cement paste and mortar

With increased environmental awareness, recycling/utilization of industrial byproducts is gaining ground. One such by-product is silica fume (SF), which is byproduct of the smelting process in the silicon and ferrosilicon industry. By-products of the production of silicon metal and the ferrosilicon alloys having silicon contents of 75% or more contain 85-95% non crystalline silica. Silica fume is very useful in the design and development of high quality cement paste/mortar and concrete.This paper presents comprehensive details of the physical, chemical, properties, and its reaction mechanism. It also covers the hydration characteristics, consistency, setting times, workability and compressive strength of cement paste and mortar.     

An analysis of the use of life cycle assessment for waste co-incineration in cement kilns

Life cycle assessment, LCA, has become a key methodology to evaluate the environmental performance of products, services and processes and it is considered a powerful tool for decision makers. Waste treatment options are frequently evaluated using LCA methodologies in order to determine the option with the lowest environmental impact. Due to the approximate nature of LCA, where results are highly influenced by the assumptions made in the definition of the system, this methodology has certain non-negligible limitations. Because of that, the use of LCA to assess waste co-incineration in cement kilns is reviewed in this paper, with a special attention to those key inventory results highly dependent on the initial assumptions made. Therefore, the main focus of this paper is the life cycle inventory, LCI, of carbon emissions, primary energy and air emissions. When the focus is made on cement production, a tonne of cement is usually the functional unit. In this case, waste co-incineration has a non-significant role on CO₂ emissions from the cement kiln and an important energy efficiency loss can be deduced from the industry performance data, which is rarely taken into account by LCA practitioners. If cement kilns are considered as another waste treatment option, the functional unit is usually 1 t of waste to be treated. In this case, it has been observed that contradictory results may arise depending on the initial assumptions, generating high uncertainty in the results. Air emissions, as heavy metals, are quite relevant when assessing waste co-incineration, as the amount of pollutants in the input are increased. Constant transfer factors are mainly used for heavy metals, but it may not be the correct approach for mercury emissions.     

Utilisation of high volumes of limestone quarry wastes in concrete industry (self-compacting concrete case)

In limestone quarries, considerable amounts of limestone powders are being produced as by-products of stone crushers. High amounts of powders are being collected and utilisation of this by-product is a big problem from the aspects of disposal, environmental pollution and health hazards. In conventional concrete, the introduction of high volumes of limestone quarry dust to concrete mixes is limited due to its negative effects on water demand and strength of concrete. However, these fines can be efficiently utilised as viscosity enhancer particularly in special concrete (like self-compacting concrete—SCC) applications. Thus, the successful utilisation of this quarry dust in SCC could turn this material into a valuable resource.In this paper the usability of a quarry dust limestone powder in self-compacting paste and concrete applications was investigated. In the first part, the physical and mechanical properties of cement pastes incorporating quarry waste limestone powder (QLP) and a powder produced by direct grinding of limestone (PLP) were compared. In the second part, the performance of quarry waste limestone powder in SCC applications were tested and discussed. Results showed that, it is possible to successfully utilise high amounts of quarry waste limestone powder in producing normal-strength SCCs. Among its observed mechanical advantages, employment of quarry waste limestone powders improved the economical feasibility of SCC production.     

中小型水泥厂大气污染防治初探

根据机械化立窑水泥生产工艺和设备的特声、，分析中小型水泥厂大气污染的因素和污染防治措施，供环境影响评价和环保工程设计参考．     

旋流板分离技术在水泥除尘中的应用研究

对旋流板分离技术在水泥除尘中的应用进行研究，通过试验工程验证其适用性，并在总结工程经验的基础上进行系统的中试实验，得到除尘器的合理结构形式和最佳设计参数。     

发展散装水泥的环境和经济效益分析

中国是水泥生产和使用大国，但在包装上却主要采用落后的纸袋包装，水泥散装率同世界工业化国家相距甚远。发展散装水泥具有明显的环境、经济和社会效益。对散装水泥在国内外的发展状况及发展散装水泥的效益进行了论述分析；以天津市为例，说明水泥尘对空气环境质量产生的影响，通过对比分析阐述散装水泥的环境效益；并提出推动散装水泥发展的措施与建议。     

水泥工业项目竣工环保验收监测中应关注的问题

根据建设项目竣工环境保护验收规范要求,结合工作实践,从验收监测工况的控制、废水监测、废气监测、噪声监测、环境质量监测几方面归纳了水泥工业项目竣工环境保护验收监测工作中应注意的技术问题,并从环保法律法规制度执行、污染防治设施、企业环境管理、排污口规范化、卫生防护距离、总量控制、淘汰落后设备、公众参与等几方面提出环境保护检...