共查询到17条相似文献,搜索用时 93 毫秒
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本文阐述了KLJ型防裂抗渗复合材料对混凝土拌合物性能、力学、变形、早期抗裂及耐久性的影响规律,分析了复合材料对混凝土性能的影响机理。结果表明:KLJ型防裂抗渗复合材料能改善混凝土的各项性能,尤其混凝土力学性能显著提高,1 kg/m3掺量对混凝土性能改善效果最佳;掺量1 kg/m3,混凝土的干缩收缩率28 d、96 d分别降低42%、29%,早期开裂减少82%,平均渗水高度降低58%,碳化深度减少29%;KLJ型防裂抗渗复合材料中的粉体可以均匀填充混凝土内部孔隙,纤维能够阻止裂缝进一步扩大,进而改善混凝土各项性能。 相似文献
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通过测定水中限制膨胀率和水养7d转干空后的限制膨胀率,计算干燥收缩落差,讨论粉煤灰在等强度条件下对补偿收缩混凝土变形性能的影响.结果表明:等强度条件下掺加适量粉煤灰可以明显地促进限制膨胀率的增长;掺量过大容易导致早期约束不足,降低对限制膨胀的促进作用.粉煤灰可以明显降低混凝土转干空后早期的干燥收缩落差.随着粉煤灰掺量增加,干燥收缩落差进一步降低,空气中放置28 d后均表现为膨胀.对于硫铝酸钙-氧化钙类膨胀剂和粉煤灰复掺的补偿收缩混凝土,膨胀剂最小用量的要求可以适当降低. 相似文献
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为了探究粉煤灰掺量对补偿收缩混凝土的强度和限制膨胀率的影响规律,通过对掺有不同粉煤灰掺量的补偿收缩混凝土与基准混凝土进行对比试验研究,得出了能使补偿收缩混凝土达到最大膨胀率的粉煤灰的最优掺量为30%,并得到粉煤灰掺量与补偿收缩混凝土的强度和限制膨胀率的基本规律并对此作了一定的理论分析。 相似文献
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Evolution of penetration resistance in fresh concrete 总被引:1,自引:0,他引:1
Alvaro García Daniel Castro-Fresno Juan Antonio Polanco 《Cement and Concrete Research》2008,38(5):649-659
The objective of this research was to examine the setting of concrete through its penetration resistance; an experimental device, especially developed for this purpose was used, which consists of a system that lets a sphere fall on concrete from a certain height and then measures the depth of the crater. Forty-five samples were made with four different types of cement varying its quantity, water-cement ratio, at ambient temperature and humidity. A semiempirical model which explains the penetration resistance evolution in fresh concrete was proposed and experimentally demonstrated. The results are compared with the consolidation curves for soils represented by the logarithmic method. The proposed setting time was defined as the elapsed time between the placement of the concrete and the time when the depth of the crater is 18% of the initial one. 相似文献
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P. Mani S. Krishnamoorthy A.K. Gupta 《International Journal of Adhesion and Adhesives》1983,3(2):101-105
Studies on the reduction of setting shrinkage of polyester resin concrete with and without the microfiller CaCO3 by using a styrene/polysterene shrinkage reducing agent are reported. The setting shrinkage of unmodified polyester resin concrete was quite considerable but could be reduced almost to zero by varying the shrinkage reducing agent content. At high shrinkage reducing agent content, expansion of the sample was observed instead of shrinkage. Some differences in the rate of shrinkage in the initial stages of curing were observed, which provides some insight into the role of the two components of the shrinkage reducing agent in the reduction of shrinkage. Reduction of shrinkage was accompanied by a reduction in compressive strength, which suggests the need for a proper compromise between these two properties for developing polyester resin concretes for specific applications. 相似文献
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对混凝土进行了三乙醇胺复合早强剂和煤灰掺量实验,结果表明,采用“双掺”技术既可提高混凝土的早期强度,又可改善制品的外观质量,同时还可降低工程成本。 相似文献
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鉴于各界对混凝土开裂的关注,本文专门就现代混凝土技术对混凝土抗裂性的影响进行了分析、综述。结果表明,减水剂、矿物掺和料的使用以及现代混凝土的低水胶比、低骨胶比增加了混凝土开裂的风险,恶化了混凝土的抗裂性,且随混凝土强度等级的提高混凝土开裂的风险增大。 相似文献
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This paper deals with the effect of a deicing agent (NaCl) at different solution concentrations on the amount of water retained in different types of concrete under various ambient conditions (30%, 47%, 72% and 88% RH) and the resultant frost resistance of concrete treated in this manner. Concrete specimens saturated at the higher salt concentrations were found to retain higher levels of saturation for any given relative humidity condition. However, even when the concretes were conditioned in an atmosphere as high as 88% RH, their retained moisture contents were below critical levels, from the viewpoint of frost resistance. 相似文献
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针对混凝土裂缝问题,采用GB/T 50082中平板法测定混凝土早期抗裂试验。混凝土抗裂试验是一项细致的工作,必须注意很多操作细节问题,否则会导致试件内不同位置混凝土均匀性发生变化,外部试验条件不一致等,造成试验数据失真。应把这些细节问题归纳到操作规程中,以保证操作的统一性。遇到一个刀口上出现多条裂缝的情况,采用各条裂缝最大宽度加权平均值进行结果计算,可使试验数据更接近真值。 相似文献