混凝土外加剂的能.doc

混凝土外加剂的性能 目前，混凝土外加剂已经成为混凝土中的重要组成部分，对外加剂的研究和应用，会对改善新拌和硬化混凝土起到重要的作用，同时，也促进了混凝土施工新技术的不断发展，使得新品种混凝土不断出现。在现代化建筑工程建设中，对混凝土的要求越来越高，这也就更加需要混凝土外加剂的性能更好，功能更完善，以满足高新更混凝土的需求。因此，混凝土外加剂已经成为我国优质工程建设中必不可少的新材料。一、混凝土外加剂的分类：混凝土外加剂的定义是在混凝土、砂浆和净浆的制备过程中，掺入少量的（不超水泥用量的5）能对混凝土、砂浆或净浆改变性能的一种产品。按其主要功能可分为以下4类： （1）改善混凝土拌和物流变性能的外加剂。包括普通减水剂和高效减水剂、引气剂和泵送剂等。（2）调节混凝土凝结时间、硬化性能的外加剂。包括缓凝剂、早强剂和速凝剂等。（3）改善混凝土耐久性的外加剂。包括引气剂、防水剂和阻锈剂等。（4） 改善混凝土其他性能的外加剂。包括膨胀剂、防冻剂、着色剂等。2、 混凝土外加剂的性能有以下几种： （1） 、高效减水剂 从总产量来看高效减水剂的种类80%以上是萘系减水剂，由于原材料供应充足，价格合理估计在今后很长一段时间内，仍将是我国高效减水剂的主要品种。但是，随着工程上对混凝土制备强度有更高的要求，水泥和高效减水剂之间的相容性已经逐渐成为人们终点关注的问题，现在，在施工中多采用减水剂的饱和点掺量、流动度强度和损失来判定高效减水剂在混凝土拌合物中的相容性。（2） 、膨胀剂 膨胀剂的主要性能是拌入混凝土后能使混凝土具有抗裂防渗的作用，它的膨胀性能可弥补混凝土在硬化过程中收缩问题，在限制条件下可成为自应力混凝土。（3） 、速凝剂 速凝剂是对凝结和硬化的速度进行调节的外加剂，它能够让水泥的水化作用加快，缩短混凝土的凝结时间，主要用于喷射混凝土施工当中。（4） 、普通型减水剂 普通型减水剂的主要材料是木质素类，同时也是某些复合型外加剂主要原材料之一。因其价格便宜，所以使用较为广泛。（5） 、缓凝剂 目前施工中使用的缓凝剂，主要有糖钙、糖密等产品，这些缓凝剂主要作用是用于缓凝或者添加到其他外加剂中作为复合外加剂使用。（6） 、复合型外加剂 复合型外加剂是根据施工工程需要，已上述各种混凝土外加剂的成分为主，再加入其它组分复合而成，生产这些复合型外加剂的设备和生产工艺简单、投资较少、效益很好。（7） 、阻锈剂 掺入阻锈剂是防止建筑钢筋锈蚀最为有效的办法，阻锈剂通过增加铁元素的自然电位，降低氯离子浓度或者让建筑钢筋保持钝化状态，从而起到保护建筑钢筋并提高建筑钢筋的耐久性。（8） 、改善特殊性能的外加剂 在目前施工中，用于特殊环境或要求具有特殊性能的混凝土越来越多，这就要求我们加快相应的外加剂的发展，例如堵塞混凝土内部毛细孔隙的密实剂、便于混凝土脱模的脱模剂、给混凝土上色的着色剂、在对建筑养护时，防止混凝土水分损失的养护剂等等，这些外加剂对于施工建筑非常重要，所以，我们必须大力研究。3、 混凝土的发展趋势（1） 、环保型外加剂 近年来，随着外加剂在建筑混凝土中的使用量不断提高，也是得工业副产品的利用率大幅度提高，也能减少建筑混凝土中水泥的使用量，从而降低对环境带来的污染。对于木质素磺酸盐的应用，大大促进了造纸工业废液的利用使得这些废料变废为宝。所以，大力发展混凝土外加剂绿色化生产技术是我国混凝土外加剂的必然要求。（2） 、对外加剂进行矿物复合化 目前，混凝土的单一组分已经不能满足高性能混凝土的发展需要，施工材料的复合化将是外加剂未来的发展趋势，例如：硅灰+优质粉煤灰，5%硅灰+5%粉煤灰相当于10%硅灰，在性能上超叠加效果十分明显，同时也降低了成本。总之，建筑混凝土外加剂的发展对我国建筑产业会有相当大的作用，加大对外加剂的研究我国工科高等院校和科研研究所的迫切任务，也是我国房地产行业和建筑工程行业发展的必然要求。The performance of the concrete admixturesAt present, the concrete additive has become an important part of the concrete, the research and application of admixture, will be to improve the new mixing sclerosis concrete play an important role, at the same time, but also promote the new concrete construction technology unceasing development, make new concrete appear constantly. In the modern construction project construction, to the concrete demand more and more high, this also more need of concrete admixtures better performance, the function is more perfect, in order to meet the needs of high more concrete. Therefore, concrete additive has become our country quality engineering construction of the new materials and essential.A concrete additive, the classification of the:Concrete additive is defined in the concrete, mortar and net plasma the fabrication process, mixed with a small amount of (no more than 5% of the amount of cement) to concrete, mortar or net plasma change performance of a product. According to the main function can be divided into the following four types:(1) improve concrete mixing logistics performance of additives for change. Including ordinary water reducing agent and efficient jianshuiji, air-entraining agent and pumping agent, etc.(2) the concrete setting time and hardening of additives for performance. Including retarder, early strength agent and accelerating, etc.(3) improve the durability of concrete admixture. Including air-entraining agent, waterproof agent and inhibitors, etc.Improve other properties of the concrete admixture. Including expansion agent, antifreeze, colorants, etc.The performance of the concrete admixtures have the following kinds:, efficient jianshuijiFrom see efficient jianshuiji production of more than 80% of species is naphthalene water reducing agent, because the raw material supply, price reasonable estimates that in the future for a long time, still will be the countrys efficient jianshuiji main varieties. But, with engineering of concrete strength on the preparation of a higher request, cement and superplasticizer compatibility between has become the people concerned problems, now, in construction, use more water reducing agent dosage, the saturation point fluidity strength and loss to determine superplasticizer in concrete things as the compatibility., expansion agentThe main properties of expansive agent is stir in concrete can make concrete with after percolating-proof role, it can be made up to the expansion of the performance of concrete in sclerotic process shrink problem, in the constraints can become self-stressing concrete., acceleratingHerein is the setting and hardening the speed of the regulation of admixture, it can let cement hydration speed up the role, shorten the concrete the setting time, mainly for the injection of concrete construction., regular water reducing agentRegular water reducing agent is the main material of lignin, but also some compound admixtures one of main raw materials. Because its cheaper price, so use more widely.Retarder,Currently used in the construction retarder, basically have sugar sugar products such as calcium, dense, these retarder main function is used to slow or added to other admixture of as compound admixtures use.Compound admixturesCompound admixtures is according to the construction engineering need, already the above all kinds of concrete additive ingredients give priority to, add other components compound and into, the production of these complex admixture, the equipment and the production process is simple, with less investment, benefit is very good.Inhibitors,Incorporating inhibitors prevent corrosion of reinforcement is building the most effective way, inhibitors through increased iron natural potential, reduce the chlorine ion concentration or let building reinforced keep passivation state, and so to protect the buildings and improve the building of the reinforced steel durability., improve specific properties admixturesIn the present construction, used for special environment or requirements with special performance of concrete is more and more, this require us to speed up the development of the corresponding admixtures, such as blocking concrete internal wool stoma density agent, facilitate the gap of the concrete stripping tuomoji, to the color of concrete in building maintenance of colorants, to prevent the loss of water concrete curing agent, etc, these buildings are very important for the construction of admixture, so, we must vigorously research.The trend of the development of concrete, environmental protection admixturesIn recent years, as construction of concrete admixtures in use continuously improve, be greatly improve the utilization rate of industrial by-products, also can reduce the use of cement concrete construction, so as to reduce the pollution of the environment pollution caused. For the application of ligin sulfonates, greatly promote the use of waste paper making industry make the waste reuse. Therefore, vigorously develop concrete additive production technology in China is the green is the inevitable requirement of concrete admix