共查询到19条相似文献,搜索用时 156 毫秒
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研究了粉煤灰、矿粉对引气混凝土气泡特征参数的影响.结果表明:无论是单掺还是双掺粉煤灰和矿粉,新拌及硬化引气混凝土的含气量均有不同程度的降低;单掺粉煤灰引气混凝土的气泡间距系数和气泡平均直径降低,有利于提高混凝土抗冻性;矿粉对引气混凝土的气泡特征影响较大,且气泡特征参数的影响无明显的规律性;矿物掺合料一定程度上能改善引气混凝土的气泡结构,有利于提高抗冻性能,但掺量不宜超过30%. 相似文献
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为了研究含气量对大掺量粉煤灰混凝土强度的影响,制备了掺量为30%、40%、50%及水胶比为0.41、0.36、0.34、0.28的粉煤灰引气混凝土标准试件,进行了3、7、28 d抗压强度试验.结果显示,随着含气量增加,混凝土抗压强度下降1.07%~7.49%,不同掺量及水胶比的混凝土在不同龄期强度下的降低幅度存在差异. 相似文献
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针对高寒地区混凝土抗冻耐久性问题,在混凝土中加入不同掺量的粉煤灰研究其抗冻性能,通过非金属声波检测仪进行冻融循环过程中混凝土强度无损测试,研究了冻融循环作用下混凝土强度损伤和动弹性力学参数的演化特征,分析了冻融循环过程中混凝土声波波速与力学性能变化规律.研究结果表明:掺入引气剂能够提高混凝土的抗冻性,相同引气剂掺量下,... 相似文献
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《Construction and Building Materials》2006,20(8):586-590
In order to assure the outer concrete of Longtan dam in China possesses excellent of frost resistance, the losses of strength, mass and air void characteristics of roller compacted concrete (RCC) containing fly ash, superplasticizer and a novel MgO-bearing expansive agent (HNM) were studied using the freezing–thawing method ASTM C666. The results show that there is a linear correlation between strength and mass losses in RCC subjected to cycles of freezing and thawing.There is a relationship between the air void spacing factor and the frost resistance of RCC. However, for RCC containing fly ash and superplasticizer a spacing factor of 0.25 mm is not necessary. Using a water:binder ratio of 0.48 in RCC containing 50% fly ash and 8% HNM a durability factor of over D300 can be achieved provided the spacing factor is less than 0.4 mm. 相似文献
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《Construction and Building Materials》2007,21(5):1034-1039
An experimental investigation was conducted using an air-entraining agent and pozzolans such as silica fume and fly ash, to meet the design strengths 50 and 60 MPa, as well as frost resistance to 300 cycles of freezing and thawing. Among a series of concretes of grade 50 or 60 MPa, only a small part could resist 300 cycles of freezing and thawing. It was demonstrated that frost resistance might be independent on strength of concrete. By means of mercury intrusion porosimeter, the pore structure characteristics of six concretes were identified. Air entrainment, no matter whether the pozzolans were used, caused an increase in cumulative pore volume, and also an increase in the mean pore size. It is revealed that, as to concrete at a 0.32 water/binder ratio, air entrainment should be a main approach to enhance frost resistance, although the pozzolans could be used to increase long-term strength of concrete. 相似文献
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矿物掺合料对再生混凝土抗冻性影响的试验研究 总被引:1,自引:0,他引:1
研究了单掺粉煤灰、双掺石灰粉和粉煤灰在不同介质下(淡水、海水、硫酸盐溶液)对再生混凝土抗冻性能的影响,试验结果表明:单掺粉煤灰掺量为20%或双掺石灰粉和粉煤灰比例为3∶7时,可明显提高再生混凝土的抗冻性能,不同介质溶液下抗冻性能最好的为淡水、最差的为海水。同时得出在不同掺量的粉煤灰、不同掺量的石灰粉和粉煤灰与再生混凝土抗冻性相关关系及其变化规律,可供理论研究和工程应用参考。 相似文献
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通过将不同组成的引气剂应用于普通混凝土中,测定其对混凝土含气量和泌水率的影响,从而证明本研究所研制的新型引气剂在混凝土中的适用性,再针对最佳引气剂进行强度和抗冻性的测试.结果表明:通过表面张力、气泡容量和泡沫稳定性以及液膜强度的测定来确定引气剂的最佳组分的合成方法切实可行;当10号引气剂的掺量为0.036%,可使混凝土含气量达到5.1%,混凝土的强度损失小于10%,且经过100次冻融循环后,相对动弹模量为97.14%.综合评价本文所合成的引气剂是一种性能较优值得推广应用的新型引气剂. 相似文献