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砂石是混凝土结构材料的重要组成部分。一直以来我国使用河砂、江砂来拌制混凝土。随着国内建设需求的增多,天然砂资源日趋枯竭,而与此同时,对建筑用砂的要求却越来越高,机制砂的出现缓解了这一矛盾。1973年国家建委在贵州省召开了机制砂在混凝土中应用的论证会,制定了《机制砂混凝土技术规程》,机制砂的应用范围得以扩大;国家标准GB/T14684-2001《建筑用砂》已明确可将机制砂作为一种建筑用砂,并规定了机制砂的技术要求、试验方法、检验规则;目前国内部分省市也已制定了机制砂在混凝土中的应用技术规程。机制砂最大的优点是颗粒级配可调,质量稳定。但与天然砂相比,机制砂颗粒粗糙尖锐、多棱角、细度模数较大,且含有石粉,这些特点对机制砂应用于混凝土有什么影响?砂率控制在多大比较合适?目前,国内机制砂生产主要有两种形式,一种是专门生产的机制砂;再一种是利用各种尾矿附带生产或产生的,这两种不同的生产形式生产的机制砂各有何特点?在应用机制砂时应该注意哪些问题?怎样确保机制砂应用于混凝土的同时还能保证混凝土质量?本期特别策划邀请专家对机制砂在混凝土中的应用进行探讨。
Gravel is an important part of concrete structures. China has been using river sand, river sand to mix the concrete. With the increasing demand for domestic construction, the natural sand resources are depleted. At the same time, the demand for construction sand is getting higher and higher. The emergence of the mechanism sand alleviates this contradiction. In 1973, the State Construction Commission held a demonstration meeting on the application of machine-made sand in concrete in Guizhou Province, formulated the Technical Specification for Machine-made Sand Concrete, and expanded the scope of application of machine-made sand. The national standard GB / T14684-2001 Clearly the mechanism of sand as a sand for construction, and provides the technical requirements of sand, test methods, test rules; At present, some provinces and cities have also developed a mechanism for sand in the concrete application of technical regulations. The biggest advantage of sand is adjustable grain size, quality and stability. However, compared with the natural sand, the coarse and coarse particles of machined sand are sharp, multi-angle, the fineness modulus is large, and contains stone powder. What are the characteristics of these features on the application of sand to the concrete? Sand rate control is more appropriate? At present, There are two main forms of production of sand, one is the specialized production of sand; the other is the use of a variety of tailings attached to produce or produce, the two different forms of production of sand have their own characteristics? In Application of sand should pay attention to what issues? How to ensure that the mechanism of sand used in concrete but also to ensure the quality of concrete? This special planning invited experts on the mechanism of sand in the concrete application.