2003.6 foreign building materials technology shrinks, the contraction is small between 7 days and 15 days, and it produces a large contraction from 15 days to 21 days, and basically reaches a stable state after 21 days. The shrinkage rate of cement putty mortar at 42 days is about 7×10-4. It is 22%~36% less than cement mortar; the shrinkage rate of fly ash cement mortar is 6～6.5×10-4. It can be considered that the addition of quantitative fly ash or putty in cement mortar can reduce shrinkage, and then Control the cracking of the mortar surface layer. Observing the shrinkage curve of cement lime mortar in the experiment, the shrinkage rate under natural curing is large, 9×10-4 at 42 days, and still continues to increase; under standard conditions, the shrinkage in the later stage of curing tends to be stable. At 42 days, it is 7×10-4. Therefore, when using lime mortar to plaster, the choice of curing method is very important.
Analysis and discussion of test results It is generally believed that the mortar plaster layer shrinks due to evaporation of water in the mortar. Moreover, the shrinkage process of the mortar layer is gradually extended from the surface to the inside, and a water gradient is present in the plaster layer. Therefore, uneven shrinkage of the surface shrinkage and small internal shrinkage are caused, so that the surface of the plaster layer is subjected to tensile force and the inside is subjected to pressure. When the tensile force of the surface mortar exceeds its tensile strength, cracks are generated, and the outward warpage causes a decrease in the adhesion to the base layer, thereby causing separation from the base layer, resulting in an empty drum and a falling off phenomenon. Based on the above analysis, we believe that to solve the shrinkage problem, it is to reduce the porosity in the mortar and control the water dispersion in the mortar.
Shanghai: Tongji University Press, 19962. Editor-in-Chief Yuan Runzhang. Gelling materials. Wuhan: Wuhan University of Technology Press, 19963. Editor-in-Chief Peng Shenghao. Handbook on Quality Control of Construction Engineering (Second Edition). Beijing: China Building Industry Press, 19904. Wang Fuyuan, Wu Zhengyan, editor. Fly ash utilization manual. Beijing: China Electric Power Press, 1997 Received: December 2003 Qingdao Haierkeda Nanotechnology Development Co., Ltd. is Haier Group and Institute of Nanomaterials of Qingdao University of Science and Technology and Shandong Provincial Key Laboratory of Nanomaterials Engineering Technology, Shandong Province Nanomaterials The High-tech Company, which is jointly established by Engineering Technology Research Center, Qingdao Nanotechnology Key Laboratory and Qingdao Nanomaterials Industry Technology Center, is engaged in research and development of nanomaterials, nanomaterial preparation and production and industrial application.
The universal expansion bolt series of the German Tox Construction Fastening Technology Company can achieve the friction locking effect in the solid wall; the expansion, twisting and knotting in the hollow wall body can realize the deformation locking. Fundamentally solved in hollow walls (such as hollow bricks), soft walls (such as insulation benzene board), sheet walls (such as gypsum board) and fragile walls (such as aerated concrete) and fluffy (such as gray sand) Hollow block) The thorny problem of not being able to fix items (such as doors and windows, wall cabinets, ceilings, chandeliers, curtain walls, sanitary ware, air conditioners, pipes, equipment, etc.) on the wall. After entering the Chinese market, in order to provide timely delivery, technical advice and after-sales service, a sales company and office were established in Shenyang. In response to the requirements of 50% and 65% of China's building energy efficiency, it has launched a series of external thermal insulation fasteners, which fully meet the requirements of European and Chinese standards. It has been widely used in many insulation and energy conservation projects.
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