Dissertation > Industrial Technology > Hydraulic Engineering > Hydraulic material > Hydraulic concrete and mortar > Hydraulic concrete

Study on Low-hot High Performance High Belite Cement Large Dam Concrete

Author PengXiaoPing
Tutor PuXinChengï¼›LiJinYu
School Chongqing University
Course Materials Science
Keywords high belite cement concrete low-heat and high performance crack resistance pore structure analysis C-S-H gel structure
Type PhD thesis
Year 2002
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On the basis of comprehensive analyzing the factors affecting the properties of ordinary and dam concrete, with applying the achievements of the subproject "Study on New Cementitious Material" of the key science and technology project in the national ninth five-year plan, that is the High Belite Cement (HBC), a new low-heat and high performance dam concrete, called as High Belite Cement Concrete (HBCC), has been developed.According to the requirements of testing regulation, design and construction specifications for hydraulic engineering concrete, the macro properties such as workability, mechanical and thermal properties and durability of HBCC were tested and compared with those of high performance dam concrete for the Three Gorges Project, the Medium-Heat Cement Concrete (MHCC). The crack resistance of both concretes was calculated and analyzed, also the micro-properties of HBCC were studied using the pore-structure analysis, MS, TEM and IRS. Meanwhile, the strength performance of HBCC inside the dam was studied by simulating the adiabatic temperature rise of dam concrete.Test results and theoretical analysis show that the properties of HBCC are excellent; it is a new high performance concrete with low heat and high crack resistance and suitable for use in large dam and other large volume concrete projects.A discussion was carried out as follows:1. In a course of 200 year study and application, the cement and concrete materials experienced several steps of progress and the properties of concrete were improved greatly. The range of application for the concrete becomes wider and wider. The study on ordinary and dam concretes shows, that:1) The optimization of material selecting, mix proportion, concrete casting and curing are the key points for gaining the high performance of dam concrete.2) The temperature crack of concrete is one of the main factors affecting the integral performance and durability of dam concrete. Therefore, reduction of water and cement contents in concrete and use of low-heat cement etc are important ways to produce high performance concrete.2. Based on the success in research on cement and concrete with referring to<WP=9>the experience in construction of dam both at home and abroad, a study was carried out on the dam concrete for the Three Gorges Project to ensure the properties of concrete for the project to be on the world advanced level.Test results and engineering inspection show that the dam concrete for the Three Gorges Project is a high performance one and on a world advanced level. The water content and cement content are 80-90kg/m3 and 100kg/ m3 respectively. However there still is a problem with temperature crack.3. The study on the High Belite Cement is an achievement of the key science and technology project in the national ninth five-year plan performed by the China Building Materials Research Institute, conforming to the trend of development of the cement materials. This cement has a lot of advantages such as low energy consumption, less environmental pollution, low heat of hydration, high strength at later age and high durability. This makes the production of a new low-heat and high performance dam concrete possible.4. Compared with the high performance dam concrete for the Three Gorges Project, the low-heat and high performance dam concrete with High Belite Cement has excellent properties as follows:1) WorkabilityUnder the normal test conditions, the initial slump of High Belite Cement Concrete (HBCC) or VC value is similar to that of medium-heat cement concrete (MHCC) as well as the slump loss with time. That is, its absolute value of slump after 1-2 h. is close to that of MHCC, which illustrates the good workability of HBCC.On the condition of adding suitable super plasticizer and air entraining agent, the workability of HBCC is better than that of MHCC used for the Three Gorges Project.2) Mechanical propertiesStrength. Under the standard curing condition and with the same mix proportion, the strength of HBCC at early age (7 da

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