【作者】 严琳；

【导师】 杨长辉； 王冲；

【作者基本信息】 重庆大学 ， 材料科学与工程， 2008， 硕士

【摘要】 自密实混凝土因其良好的粘聚性、稳定性和匀质性,具有极佳的自密实性能且利于施工等特点,大大简化了混凝土结构的施工工艺、提高了施工效率和施工质量,缩短施工工期,减少噪音污染。自密实混凝土已在国内外得到广泛应用,但在重庆应用自密实混凝土的的工程案例较少。本论文结合重庆地区特殊的自然环境和原材料特点,对自密实混凝土的配制及其性能展开了研究:试验研究了原材料和配制参数对自密实混凝土流变性能、工作性能和力学性能的影响;测试分析了自密实混凝土的微观结构特点。在试验室研究的基础上,开展了自密实混凝土生产与施工模拟试验,测试了模拟结构实体的性能。研究结果对自密实混凝土的配制与应用有较大的借鉴价值。试验结果表明:①本试验条件下,水胶比和胶凝材料总量分别为0.30和580kg/m3时,所配制出的C60自密实混凝土综合性能较优;当水胶比和胶凝材料总量分别为0.30和580Kg/m3,固定粉煤灰和矿渣微粉总替代水泥量为30%,粉煤灰和矿渣质量比为15%:15%和10%:20%时,自密实混凝土流变性能、工作性能和力学性能均较优;固定粉煤灰和矿渣替代水泥量分别为5%和15%,复掺硅灰后,自密实混凝土的拌合物流变性能和工作性能先改善后变差,复掺量为5%～7.5%时,自密实混凝土流变性能、工作性能和力学性能均较优。②不同的细骨料细度模数下,随细骨料砂率增大,自密实混凝土的拌合物流变性能和工作性能均先改善后变差,且其最佳砂率随细度模数的增大而减小。本试验条件下,选用细度模数为Ms=2.4的河砂,自密实混凝土抗压强度较大;河砂细度模数Ms=2.7情况下,砂率为48%时,自密实混凝土流变性能、工作性能和力学性能均较优;使用混合砂配制的自密实混凝土,其工作性能和力学性能均能达到“自密实”要求。其中,当混合砂砂率为48%、机制砂和特细砂质量比1:1时,所配制的C60自密实混凝土流变性能、工作性能和力学性能均较优。③粗骨料颗粒形状指数I越大、级配越好,自密实混凝土拌合物的粘度越小,其流变性能和工作性能越好,力学性能也越好。本试验条件下,10～20mm石子和5～10mm石子质量比为5:5时,自密实混凝土综合性能较优。④留盘试样强度与拌合物入模高度有关,试样制作时,拌合物入模高度控制在50cm以内有利于混凝土均匀性和强度稳定性提高。工程施工质量验收时,自密实混凝土的强度应优先采用统计方法评定。⑤显微硬度测试、ZEISS金相显微镜和SEM扫描电镜观察结果表明,与普通振捣混凝土相比,所配制出的自密实混凝土具有更均一密实的骨料-水泥石界面过渡区结构有利于骨料-水泥石界面过渡区性能稳定,为混凝土提供良好的宏观力学性能和耐久性能。⑥模拟浇筑试验结果表明,混凝土经表面观察、钻芯法检测强度以及超声波检测等测试手段的检验,在暑天高温气候下,高抛浇筑和吊装浇筑所得实物结构均匀密实,留盘试样强度和结构实体强度均满足设计要求,模拟浇筑试验成功。所配制出的自密实混凝土可以用于实际工程施工。更多还原

【Abstract】 Because of the character of good cohesion, stability, Uniform nature,and excellent Self-compacting performance,Self-compacting concrete(SCC) can greatly simplify the construction techniques of the concrete structure, enhance the construction efficiency and quality, shorten the construction period, and reduce the noise pollution. Although SCC is being used comprehensive in many domestic and foreign cities, there are hardly any engineering project cases of using SCC in Chongqing.Combing the characteristics of raw materials and the environment of Chongqing area, the thesis here has been made up SCC with good performance .And then analyzed the impact of raw material and preparation parameters on the rheological properties, the workability, and the mechanical properties through testing, as well as processing an test analysis of microstructure for the SCC with excellent comprehensive performance. Basing on this study, the thesis here also validated the actual quality of SCC in practical project by simulate pouring test in Actual project.The testing result indicated the following conclusions:①In this experimental condition, SCC can be obtained better performance by using water to binder ratio and binding material total are 0.30 and 580 kg/m3. When water to binder ratio and binding material total are 0.30 and 580 Kg/m3, the fixed fire ash and slag total replacements of cement are 30%, The weight ratio of fire ash and slag are 15%:15% and 10%:20%,SCC can be obtained better rheological performance ,workability,and the mechanical properties.when fixed fire ash and slag replacements of cement are 5% and 15%,after replaced silica fume, rheological performance and workability of SCC can be improved first, then be worse after. when silica fume replacements are 5%~7.5%,the rheological performance, workiability and the mechanical properties of SCC are also better.②In different sand modulus of fineness,both of the rheological performance and workability will be firstly improved but deteriorate then, and the best sand-aggregate ratio will decrease with the increase of the sand modulus of fineness. In this experimental condition,while adopting sands which sand modulus of fineness is 2.4, the compressive strength are larger.when sand modulus of fineness is 2.7 and sand-aggregate ratio is 48%, the combination performance of SCC are better. The workability and mechanical properties of SCC can be achieved the requirement of “self-compacting”while confected by hybrid sands. when the sand-aggregate ratio of mixed sands is 48% and the rate of machine-made sinds to extra fine sands is 1:1, all of the rheological performance, workability, and mechanical properties of SCC are well.③When coarse aggregate grain shape index I be bigger, the gradation to be better, the concretes mix viscosity can be smaller, all of the rheological performance, workability, and mechanical properties of SCC are better. In this experimental condition, SCC can be obtained better performance by selecting the weight ratio of two grain size of aggregates (10～20mm and 5～10mm) is 5:5.④The relations of mechanical properties of SCC and its confectioning methods is close. When the samples of SCC are formation, it will be advantageous for SCC with internal uniformity and stability mechanical properties by control the height of enter the mold in 50cm.the are also most superior When construction quality of project are checked and accepted, it should first used the statistical method to evaluate the mechanical properties of SCC.⑤The results of microhardness test,ZEISS metallography microscope and the SEM scanning electron microscope discovered that SCC can be obtained good contact surface transition region by“self-compacting”. And that provided macroscopic mechanical properties and the lasting quality for the concretes.⑥The simulation pouring test results indicated that, After the surface observation, drill core law test method and so on examination intensity as well as ultrasonic wave examinations, we found that, even under the hot summer days megathermal climate, SCC have been obtained internal uniformity construction by pump over construction and hoisting transportation in the mold, and the mechanical properties of SCC were satisfied the design requirements, The simulation pouring test have been successfully. The SCC can be used in the actual project construction.更多还原