共查询到19条相似文献,搜索用时 103 毫秒
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引气型浮石混凝土强度特征张宝生,郑秀华普通混凝土中掺入适量引气剂,可以明显改善混凝土的和易性,提高耐久性,这在国内外早已被公认并得到广泛应用。但是在轻骨料混凝土领域,研究和应用甚少。人们担心掺入引气剂后会使原本强度不太高的轻骨料混凝土进一步引气而降低... 相似文献
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引气混凝土的抗冻性和气泡结构的关系研究 总被引:2,自引:0,他引:2
对不掺加引气剂和掺引气剂的中砂混凝土和细砂混凝土的坍落度、含气量、抗压强度、冻融循环以及硬化混凝土气泡结构进行了试验与测试。试验结果表明,混凝土掺入引气剂后增加了大量微小气泡(直径小于100μm),明显提高了混凝土的抗冻性;当含气量相同时,随着水灰比的增大, 小于100μm 的气泡个数逐渐减少,大于100μm的气泡个数逐渐增多。同时,W/C为0.45或大于0.45时,气泡之间有连通现象,导致引气混凝土的抗冻性逐渐降低;当引气混凝土的气泡间距系数小于200μm 时,混凝土具有较高的抗冻性。 相似文献
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以内蒙古地区的天然浮石为粗骨料配制天然浮石混凝土,采用?100分离式霍普金森压杆(SHPB)试验分析了不同聚乙烯醇(PVA)纤维体积掺量(0、0.15%、0.30%)天然浮石混凝土在冲击荷载下的动态力学性能.结果表明:随着PVA纤维掺量的增加,天然浮石混凝土的静态抗压强度增强,动态冲击压缩下破坏程度减弱;当应变率低于9... 相似文献
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碳纤维改善浮石混凝土力学特性的试验研究 总被引:1,自引:0,他引:1
以内蒙古地区天然浮石作为粗骨料,对碳纤维掺量(质量比)为1/100,1/300,1/500,1/800,1/1000的天然浮石轻骨料混凝土进行3,7,14,28,90,180d抗压强度、峰值荷载和弹性模量试验,分析了冻融后纤维轻骨料混凝土的力学性能,总结了碳纤维对轻骨料混凝土早期强度、变形量及弹性模量和冻融循环的影响及改善轻骨料混凝土微观结构性能的作用.从微观角度探讨了在冻融循环过程中,纤维表面及纤维与浆体界面的黏结情况.结果表明:纤维可以改善轻骨料混凝土的稳定性能,提高其脆性性能,且能改善抗冻性,确定1/1000的掺量最为适宜. 相似文献
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以天然浮石作为粗骨料,粉煤灰分别以0、20%、30%、40%等体积替代砂,配制天然浮石轻骨料混凝土.对混凝土在不同龄期的抗压强度进行测试,得出粉煤灰最优替代率为30%;选取基准组与粉煤灰最优替代率为30%试件进行抗硫酸盐侵蚀试验,得出粉煤灰替代率为30%时,轻骨料混凝土的抗硫酸盐侵蚀效果较好. 相似文献
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大掺量粉煤灰海工混凝土含气量与气泡参数研究 总被引:1,自引:0,他引:1
《混凝土》2015,(8)
引用胶凝系数(β)的概念,将粉煤灰作为混凝土中一种独立组分进行大掺量粉煤灰混凝土配合比设计。研究了在海水和标准养护下,粉煤灰掺量40%~70%,等强度(C40)设计的粉煤灰混凝土含气量、气泡参数和强度。研究结果表明,粉煤灰的掺量、细度以及含碳量都能够影响引气剂的作用效果,而粉煤灰的掺量是影响引气效果的主要因素。海水养护比标准养护的HFCC气泡间距系数大,粉煤灰火山灰反应程度高,强度略高。新拌混凝土和硬化混凝土含气量两者没有准确的对应关系。 相似文献
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This study investigated the effect of elevated temperature on the mechanical and physical properties of concrete specimens obtained by substituting cement with finely ground pumice (FGP) at proportions of 5%, 10%, 15% and 20% by weight. To determine the effect of silica fume (SF) additive on the mechanical and physical properties of concrete containing FGP, SF has been added to all series except for the control specimen, which contained 10% cement by weight instead. The specimens were heated in an electric furnace up to 400, 600 and 800 °C and kept at these temperatures for one hour. After the specimens were cooled in the furnace, ultrasonic pulse velocity (UPV), compressive strength and weight loss values were determined. The results demonstrated that adding the mineral admixtures to concrete decreased both unit weight and compressive strength. Additionally, elevating the temperature above 600 °C affected the compressive strength such that the weight loss of concrete was more pronounced for concrete mixtures containing both FGP and SF. These results were also supported by scanning electron microscope (SEM) studies. 相似文献
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为了研究入模温度和引气剂对混凝土抗压强度和微观孔结构的影响,进行了标准养护下5、10、15、20℃这4组入模温度和0、0.05%、0.10%、0.15%、0.20%这5组引气剂掺量下的强度试验,以及测试了28 d龄期下混凝土的微观孔隙结构.结果表明:28 d龄期时,入模温度从5℃提高到20℃时,混凝土的抗压强度提高了51.3%,入模温度提高加快了水泥的水化反应,改变了混凝土的密实性,提高了混凝土的抗压强度;与之相反,引气剂含量增加到0.20%时,混凝土的抗压强度下降了50.9%(入模温度为20℃),引气剂含量偏大时混凝土总孔隙率明显增加,密实性下降抗压强度降低.研究结果为掺入引气剂提高抗冻性的混凝土的设计提供参考. 相似文献
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引气剂能有效改善普通混凝土的耐久性,但对大孔混凝土性能的影响不明确。本文通过试验,研究不同掺量引气剂对大孔混凝土力学性能及耐久性能的影响。结果表明,适量的引气剂能够增强大孔混凝土的抗压强度和改善抗冻性能。 相似文献
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从理论上对泡沫混凝土气孔结构及其分布进行数学分析,认为该类气孔分布理论上符合正态分布,得出计算公式.并结合体视学,使用图像分析法对孔分布进行模拟.在此基础上,依旧结合体视学相关内容以及各力学性能之间的关系,建立引气量与水泥基材料力学性能之间的数学联系,使泡沫混凝土甚至其他多孔材料抗拉与抗压强度的理论计算成为可能,而非传统的通过大量数据拟合曲线法获得两者之间关系. 相似文献
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《Construction and Building Materials》2007,21(6):1191-1197
This study examines the suitability of ceramic industrial wastes and huge amounts of basaltic pumice as a possible substitute for conventional crushed fine aggregates. Experiments were carried out to determine abrasion resistance, chloride penetration depths and the compressive strengths of concrete with crushed ceramic waste and basaltic pumice fine aggregates and to compare them with those of conventional concretes. Test results indicated that ceramic wastes and basaltic pumice concretes had good workability. Furthermore, it was found that abrasion resistance of crushed ceramic (CC) and crushed basaltic pumice (CBP) concretes was lower than that of conventional concretes. Test results also showed that maximum abrasion rate was obtained from specimen control (Mo), while minimum abrasion rate is obtained from M3 (60% crushed ceramic concrete) specimens. Abrasion resistance was increased as the rate of fine CC was decreased. Abrasion resistance of concrete was strongly influenced by its compressive strengths and CC and crushed CBP content. The crushed ceramic addition percentage decreased as the chloride penetration depth increased. Results of this investigation showed that CC and CBP could be conveniently used for low abrasion and higher compressive strength concretes. 相似文献
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本文对硬化混凝土的气泡参数的研究方法、气泡参数对混凝土抗冻性能的影响作了综述。主要介绍了利用显微镜法测定气泡参数来评判混凝土的抗冻性能,并分析了气泡间距系数的发展方向。 相似文献