Development of Non-Clinker Based Cement for Hazard Reduction

开发非熟料基水泥以减少危害

• 批准号: 0086819
• 负责人: Surendra Shah
• 金额: $ 20万
• 依托单位: Northwestern University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2000
• 资助国家: 美国
• 起止时间: 2000-09-15 至 2003-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0086819&HistoricalAwards=false
• 关键词: Development; Non; Clinker; Based; Cement

Concrete has been the material of choice for the nation's $1.4 trillion infrastructure. The rapid growth of human population, industrialization, and urbanization has led to more cement being used in concrete materials to meet the increasing needs of infrastructure. As a result, the environmental concerns related to portland cement clinker production, such as greenhouse gas (carbon dioxide, CO Z) emission and disposal of cement kiln dust (CKD), a by-product of cement manufacturing, have become increasingly important. The United States cement industry generates about 80 million tons of CO 2 and 5 million tons of CKD every year. The disposal of waste CKD is not only associated with the problem of land use but also with the contamination of ground water from leaching of chemicals (especially heavy metals) in the material. Similarly, another industrial by-product, fly ash, collected from the stack gases of power plants burning pulverized coal, is also commonly considered an extensive waste material. About 59 million tons of fly ash are generated annually in the United States and 80% is placed in landfills. The goal of the proposed research is to explore an effective way to substantially utilize CKD and fly ash by developing an environmentally friendly, sufficiently performing, and cost effective cementitious product (without portland cement clinker) for future concrete materials.CKD and fly ash have been used as a supplementary cementitious material in concrete in small amounts. Usage is limited due to deficiencies of the two materials. For example, CKD contains an excessive amount of fine particles and a high alkali content, which often impart a,,,,erse effects on concrete workability and durability. Most fly ash hydrates slowly and some contain a high unburned carbon content. These inadequacies are unacceptable for strength development and volumetric stability of cement and concrete materials. However, if the two materials are blended together, the alkalis from CKD may activate hydration of fly ash. The proposed research involves properly blending CKD with fly ash to create a cementitious material in which the material deficiencies will be converted into benefits.The proposed research program includes six major tasks: (1) raw material characterization, (2) statistical design and optimization of blend proportions, (3) the grinding process, (4) testing and evaluation for effectiveness of chemical and mechanical activation of the blends, (5) developing criteria for acceptance of new products, and (6) testing and evaluation for performance of concrete made with the new products. Task 2 contains four successive steps: design, preliminary optimization, refinement, and conformation, thus developing optimal blends orderly. A series of chemical, physical, and mechanical experiments will be used to evaluate product performance at each step of optimization, thus leading to the next optimal step of blend proportioning continuously. A systematical study of different grinding processes and their affect on alkali activation and cement hydration will be conducted along with the curing conditions that promote such hydration. Thus, four key issues, (a) alkali activation, (b) high-energy grinding, (c) proportion optimization, and (d) product performance, are brought together into the proposed development of a non-clinker CKD-fly ash cement. The new product performance is engineered by tailoring the chemistry, microstructure, and manufacturing process.An interdisciplinary collaborative research team has been formed, consisting of members from the Center for Advanced Cement-Based Materials (ACBM) at Northwestern University (NU), Evanston, Illinois, and Construction Technology Laboratories, Inc. (CTL ), Skokie, Illinois. The team members have complementary strengths needed for the proposed research, with expertise in the areas of concrete material science, statistical design and analysis, cement chemistry, manufacturing, guideline development, and concrete testing and properties. Working together, they expect the successful conversion of CKD and fly ash from a current environmental burden and industrial profit "thief' into a viable construction material.

混凝土一直是美国1.4万亿美元基础设施的首选材料。人口、工业化和城市化的快速增长导致更多的水泥被用于混凝土材料，以满足基础设施日益增长的需求。因此，与波特兰水泥熟料生产有关的环境问题，如温室气体（二氧化碳，CO Z）排放和水泥窑粉尘（CKD）的处置，水泥生产的副产品，已变得越来越重要。美国水泥工业每年产生约8000万吨CO2和500万吨CKD。废弃水泥窑粉尘的处置不仅与土地使用问题有关，而且还与材料中化学品（特别是重金属）沥滤造成的地下水污染有关。同样，另一种工业副产品飞灰，从燃烧粉煤的发电厂的烟道气中收集，也通常被认为是一种广泛的废物。美国每年产生约5900万吨粉煤灰，其中80%被填埋。本研究的目的是探索一种有效的方法来充分利用CKD和粉煤灰，通过开发一种环境友好的、性能足够的、成本效益高的水泥产品（不含波特兰水泥熟料）用于未来的混凝土材料。由于这两种材料的不足，使用受到限制。例如，CKD含有过量的细颗粒和高碱含量，这通常会对混凝土的工作性和耐久性产生不利影响。大多数飞灰水化缓慢，有些含有高未燃碳含量。这些不足对于水泥和混凝土材料的强度发展和体积稳定性是不可接受的。然而，如果两种材料混合在一起，来自CKD的碱可能会激活粉煤灰的水化。建议的研究包括适当地将CKD与粉煤灰混合，以创造一种胶凝材料，其中材料的不足将转化为利益。建议的研究计划包括六个主要任务：（1）原材料表征，（2）混合比例的统计设计和优化，（3）研磨过程，（4）测试和评估混合物的化学和机械活化的有效性，（5）开发新产品的验收标准，和（6）测试和评估用新产品制成的混凝土的性能。任务2包括四个连续的步骤：设计，初步优化，细化，和构象，从而开发最佳的共混物有序。一系列的化学、物理和机械实验将用于评估每个优化步骤的产品性能，从而导致下一个连续的混合配料优化步骤。本文将沿着系统地研究不同粉磨工艺对碱激发和水泥水化的影响，以及促进这种水化的养护条件。因此，四个关键问题，（a）碱活化，（B）高能粉磨，（c）比例优化，和（d）产品性能，被带到一个非熟料CKD-粉煤灰水泥的拟议发展。新产品的性能是通过定制化学、微观结构和制造工艺来设计的。一个跨学科的合作研究团队已经成立，成员包括来自伊利诺伊州埃文斯顿西北大学（NU）先进水泥基材料中心（ACBM）和建筑技术实验室公司的成员。(CTL），Skokie，Illinois.团队成员具有拟议研究所需的互补优势，在混凝土材料科学，统计设计和分析，水泥化学，制造，指南开发以及混凝土测试和性能等领域具有专业知识。通过共同努力，他们希望将CKD和粉煤灰从当前的环境负担和工业利润“小偷”成功转化为可行的建筑材料。