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研究了快硬硫铝酸盐水泥、减水剂种类和掺量以及缓凝剂和早强剂等对快硬型超高性能混凝土(UHPC)性能的影响。结果表明,硫铝酸盐水泥可明显提高UHPC的早期抗压强度,其最佳掺量为15%;3种市售聚羧酸减水剂在快硬型UHPC中发挥的减水效果差异显著,宜选用减水剂B,且其最佳掺量为0.6%;快硬型UHPC制备时宜掺加早强剂碳酸锂和膨胀剂氧化钙。按硫铝酸盐水泥取代15%硅酸盐水泥、掺0.2%酒石酸作为缓凝剂、0.2%碳酸锂作为早强剂、3%氧化钙膨胀剂制备快硬型UHPC,其28 d抗压和弯拉强度分别为124.7、17.8 MPa、抗冻等级达到F800,磨耗量仅为0.5 kg/m^(2),具有较好的力学性能和耐久性。 相似文献
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含偏高岭土水泥与高效减水剂相容性研究 总被引:6,自引:0,他引:6
研究了含偏高岭土水泥与高效减水剂的相容性,结果表明,在硅酸盐水泥中单独加入偏高岭土时,水泥与减水剂的相容性有所降低,但若将偏高岭土与矿渣适当配合后再加入硅酸盐水泥之中,则可以改善水泥与减水剂的相容性;研究了偏高岭土单掺及其与矿渣复掺对水泥物理、力学性能的影响,并用DTA,SEM分析了水泥的水化产物。 相似文献
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《重庆建筑》2020,(6)
减水剂与水泥容易出现相容性不良的问题,而添加适量矿物掺合料有助于改善水泥与减水剂的相容性。该文研究了三种减水剂和粉煤灰、硅灰和矿渣粉与水泥的相容性,通过测定相应时间的水泥净浆流动度表征相容性。通过改变减水剂的种类和掺量,确定了减水剂的最佳掺量(饱和点掺量),改变矿物掺合料的掺量,确定了粉煤灰、硅灰和矿渣粉的最佳掺量。采用TOC法测试了矿物掺合料对聚羧酸减水剂吸附量的影响;采用电声法测定了水泥-聚羧酸减水剂体系浆体的zeta电位,分析了矿物掺合料影响聚羧酸减水剂与水泥相容性的机理。结果表明:两种聚羧酸系高性能减水剂与水泥和粉煤灰、硅灰和矿渣粉的相容性比萘系减水剂效果好,在一定掺量范围内,粉煤灰和矿渣粉能够明显增加水泥浆体的流动度,硅灰显著降低了水泥浆体的流动性,复掺效果较好,矿物掺合料的最佳掺量为:粉煤灰15%,硅灰5%,矿渣粉10%,粉煤灰与矿渣粉有利于增加聚羧酸减水剂的有效吸附量,降低水泥-聚羧酸减水剂浆体的zeta电位,改善水泥浆体的和易性。 相似文献
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通过常温养护条件下活性粉末混凝土力学性能正交试验,选用普通硅酸盐水泥和超细矿渣粉作为主要胶凝材料,研究了水胶比、粉煤灰掺量、硅灰掺量、石英粉掺量、胶砂比、钢纤维掺量和减水剂含量对活性粉末混凝土抗压强度和抗折强度等基本力学性能的影响。试验结果表明,水胶比、钢纤维掺量和减水剂含量对活性粉末混凝土的力学性能影响最为显著,粉煤灰掺量对改善活性粉末混凝土的抗压和抗折性能效果最好。在此基础上,以常温养护条件下活性粉末混凝土的高强度为目标,通过大量的力学试验,得到优化的最佳因素水平组合为水胶比0.18、粉煤灰掺量20%、硅灰掺量25%、石英粉掺量20%、胶砂比1∶1.0、钢纤维掺量3.0%、减水剂含量2.0%。 相似文献
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结合混凝土工程实际,考虑水灰比因素,选取硼酸缓凝剂、聚羧酸高效减水剂和萘系高效减水剂,进行了"水泥+缓凝剂"、"水泥+减水剂"的二元体系和"水泥+缓凝剂+减水剂"的三元体系的相容性对比试验,并探究延时加入碳酸锂速凝剂对已缓凝水泥浆凝结时间重塑的影响。结果表明:减水剂饱和掺量选取可只进行"水泥+减水剂"的二元体系适应性试验;缓凝剂凝结时间试验应进行"水泥+缓凝剂+减水剂"的三元体系适应性试验;引入时间重塑率Pt的概念,描述速凝剂的促凝效果。试验可知碳酸锂有良好的促凝作用,但对时间重塑能力有极限,存在一个最佳掺量。 相似文献
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缓凝剂与高效减水剂对水泥水化性能的影响 总被引:1,自引:0,他引:1
系统地研究了葡萄糖酸钠与三种高效减水剂复合对水泥水化性能的影响,结果表明:与空白水泥相比,缓凝剂与高效减水剂无论是单掺还是复合使用,对水泥的水化及其水化产物均有不同程度的影响;缓凝剂与高效减水剂复合后的协同效应与单掺缓凝剂、单掺高效减水剂时温峰出现时间有关. 相似文献
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提高水泥胶合剂强度的研究试验 总被引:1,自引:1,他引:0
为了提高水泥胶合剂的强度,对硅酸盐水泥和硫铝酸盐水泥胶合剂进行了研究试验。结果表明:采用高标号早强PⅠ型硅酸盐水泥可提高胶合剂强度;在硅酸盐水泥胶合剂中加入适量的微集料,能明显提高胶合剂强度;硫铝酸盐水泥胶合剂在强度上比硅酸盐水泥胶合剂具有显著的优势,而且硫铝酸盐水泥体积膨胀率与硅酸盐水泥胶合剂相近,不存在后期强度倒缩现象,能够用于高强度绝缘子生产。 相似文献
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苯丙共聚乳胶粉水泥砂浆的性能研究 总被引:1,自引:0,他引:1
研究了苯乙烯-丙烯酸丁酯共聚物乳胶粉(简称苯丙共聚乳胶粉或SAE乳胶粉)改性水泥砂浆的减水性、引气性、保水性、力学强度等物理性能.研究表明:SAE乳胶粉具有一定的减水作用,在同一流动度下,水泥砂浆用水量随SAE乳胶粉掺量增加而降低;SAE乳胶粉的掺入可在新拌水泥砂浆中引入9.8%~13.0%的含气量;水泥砂浆在新拌阶段以及硬化阶段的保水能力随SAE乳胶粉的掺入可显著改善;SAE乳胶粉明显提高了水泥砂浆的抗折和黏结抗拉强度,降低了水泥砂浆的抗压强度,从而改善了水泥砂浆的柔韧性并提高了水泥砂浆-混凝土以及砂浆-EPS板系统的界面区黏结抗拉强度. 相似文献
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The water-reducing agent better known as superplasticizer is a recent development. A number of base materials have been used for the development of such water-reducing agents which can act better than ordinary plasticizers in concrete. The sulphonated salts of melamine, napthalene, lignin, hydroxycarboxylic acids and hydroxylated polymers are some typical compounds. Recently cashew nutshell liquid obtained from a natural product waste as a thick black phenolic compound has been converted into a water-reducing agent. This paper describes the results obtained on its effectiveness in influencing the rheological properties of flow, viscosity, particle size distribution, etc, of cement particles in hydrating cements and the water-reducing capabilities in cement mortars and concretes. 相似文献
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浅析高效减水剂和水泥之间适应性的影响因素 总被引:1,自引:0,他引:1
主要叙述了高效减水剂和水泥之间适应性的影响因素,指出主要影响因素涉及高效减水剂性能、水泥的物化性能、混凝土拌合物性能、环境条件四个方面,简要介绍了适应性定义及适应性的检测方法,并提出了改善二者适应性的措施. 相似文献
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In this research the performance of cement paste and concrete mixes incorporating 7% and 10% of silica fume (SF) as a cement replacement was investigated in three exposure conditions. The results showed that plain type II portland cement performed better than blended SF cement under cyclic wetting and drying conditions. Silica fume specimens under cyclic wetting and drying conditions in simulated seawater exhibited higher strength loss compared to plain type II portland cement where cured under potable water. In addition, the greater the silica fume amount used in the mixes, the more the capillary water absorption under tidal zone exposure or/and under wetting and drying simulation. Further, the ternary blended ground granulated blast furnace slag (GGBS) mix was the worst performing mix in all exposure conditions. 相似文献
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通过采用方差分析与多重比较的方法,研究了水灰比、缓凝组分、减水促硬组分对修补混凝土的抗压强度和混凝土拌合物流动性的影响。通过回归分析法讨论修补混凝土抗压强度的增长规律,总结出了修补混凝土1,2,4h的抗压强度经验公式;给出了配制1h设计强度为30MPa,2h设计强度为40MPa修补混凝土的水泥、缓凝组分和减水促硬组分的材料用量;讨论了修补混凝土的养护问题。 相似文献
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《Construction and Building Materials》1999,13(5):285-292
The cement particles which were modified to a round-shape were prepared by a dry impact blending method in which the surface of the cement particles were modified by strong impact. The properties of the powder, paste and mortar of surface modified cement (namely spherical cement), which was prepared in most suitable treatment time (20 min), were examined. As a result, it was found that the cement was more fluid than normal portland cement, and that the water/cement ratio was decreased by 10 wt.%. In addition, the process for formation of the surface modified cement was presumed to be embedding of fine cement particles under 3 μm onto other larger core particle surfaces. Furthermore, though a decrease in the crystallinity of the cement and the dehydration of the gypsum in the cement took place due to the surface modification of the cement particles, the amount of change was slight. The hardened mortar of surface modified cement was approximately 45% stronger than that of normal portland cement. 相似文献
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从物理和化学两方面出发,阐述了硅酸盐水泥的技术指标及评定方法,通过将硅酸盐水泥的品质指标加以严格控制,从而确保出厂水泥符合国家标准要求,进而推广硅酸盐水泥的广泛应用。 相似文献