共查询到20条相似文献,搜索用时 109 毫秒
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为了促进泡沫混凝土在严寒地区的应用,对不同容重的单质泡沫混凝土试块及不同容重泡沫混凝土组合试块、钢纤维混凝土与泡沫混凝土复合试块进行冻融试验。本文通过对比单质试块、复合试块冻融前后质量损失率和抗压强度损失率,研究各类试块的冻融性能。结果表明,试块抗冻性能的优劣与泡沫混凝土容重有关;低容重芯材与高容重面层的复合试块其抗冻性能优于低容重单质试块;纤维混凝土复合试块的抗冻标号可达到D50。因此,可以将低容重泡沫混凝土作为芯材应用于严寒及寒冷地区的外墙保温材料。 相似文献
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本文提出了用边长12厘米立方体试块作为实验室测定混凝土抗压强度的一种通用尺寸,来取代15厘米和10厘米立方体混凝土试块的设想。为此,文章对这三种规格的立方体试块强度作了一系列的对比,求出了三者间的强度换算关系和各自的离散系数,并分析了集料粒径和混凝土标号与试件尺寸效应的联系。 相似文献
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通过制作不同龄期、不同强度等级混凝土试块,按照《超声回弹综合法检测混凝土强度技术规程》(CECS 02:2005)要求分别进行超声波和回弹检测,再对试块进行抗压强度试验。对上述试验确定的混凝土试块回弹值、波速、抗压强度值统计分析,建立郑州地区公路工程混凝土测强专用曲线,并应用于实例工程进行验证。经过对比,其精度高于全国通用测强曲线。 相似文献
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自密实钢管混凝土的设计及应用研究 总被引:1,自引:0,他引:1
介绍了自密实钢管混凝土的试配研究,对混凝土拌合物的流动性能、力学性能和变形特点进行丁试验测定,并对自密实混凝土进行了密封试块与非密封试块的力学性能对比试验,设汁了满足施工要求的钢管混凝土配合比,且成功地应用在江西某大桥的施工中。现场施工情况表明:混凝土具有可泵性好,坍落度损失低、高强、早强、自密实等性能。 相似文献
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Effectiveness of technogenic waste usage in products of building ceramics and expanded clay concrete
J. Malaiškienė M. Vaičienė R. Žurauskienė 《Construction and Building Materials》2011,25(10):3869-3877
In this paper the influence of the burned and the unburned mullite wool waste on the properties of ceramics and expanded clay concrete has been analysed. It has been determined, that this waste could be successfully used in the manufacture of expanded clay concrete and wall ceramic products. Increasing the quantity of mullite wool in the mix of expanded clay concrete, the forecasted frost resistance decreased and the water absorption increased. Products without waste and those having 10% of the waste have similar compressive strength. The performed research has shown that the unburned mullite wool waste is the active micro filler, however it does not decrease the quantity of portlandite formed, but performs a framing function. Modifying the composition of ceramics with the burned mullite wool waste, the density of samples decreased, but the parameters of water absorption and compressive strength increased. To receive stronger ceramic products, 15% of the burned mullite wool waste should be added, then the compressive strength is 23 MPa, however the forecasted frost resistance of such ceramic body would be only 65 cycles. The highest frost resistance (about 200 cycles) of ceramic samples was received applying 5% of the waste additive, then compressive strength is about 16 MPa. The unburned mullite wool waste decreases the frost resistance and density of expanded clay lightweight concrete samples, and increases the water absorption. Replacing 10% of cement with the unburned mullite wool waste almost does not change the compressive strength and density, but decrease frost resistance 36% and increase water absorption 4%. 相似文献
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采用化工废料铬酐渣(C渣)和制糖工业下脚料糖蜜研制了混凝土复合早强减水剂.实验结果表明,该外加剂能明显地改善新拌水泥混凝土的和易性,大幅度地提高混凝土制品的早期强度,改善混凝土抗冻性;同时,具有利用工业废料、制作简单、成本低廉等优点. 相似文献
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《Construction and Building Materials》2007,21(1):164-175
The use of recycled aggregates for preparing concrete products has been successfully implemented and gaining wider acceptance. However, the allowable level of contaminating materials (e.g., crushed clay bricks, crushed ceramic tiles, waste glass cullet, wood chips, etc.) in the recycled concrete aggregate, in the some of the current specifications, is low (<1%) due to stringent quality control standards that are usually taken from specifications for raw granular virgin materials. This paper presents a recent study on the properties of concrete paving blocks prepared with recycled concrete aggregates that are contaminated by materials (tiles, clay bricks, glass, wood) commonly found in the construction and demolition waste. The density, compressive strength, tensile splitting strength, water absorption value, abrasion resistance, skid resistance and some durability parameters were measured for laboratory prepared samples. The results show that it is feasible to allow a higher level of contamination in the recycled concrete aggregates for making the concrete products. Recommendations are made on how the specifications could be revised to facilitate a wider application of recycled aggregates that is contaminated by foreign materials. 相似文献
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针对商品混凝土搅拌站中废弃新拌混凝土的合理再生利用始终受到凝结时间限制的问题,通过掺加水化抑制剂使废弃新拌混凝土的水化反应延缓至接近停滞,之后在合适的时间掺加水化唤醒剂及附加减水剂使其恢复正常的水化反应速度,然后按照一定的取代率取代新拌混凝土进行再生利用,延长了废弃新拌混凝土的可利用时间窗口,使废弃新拌混凝土再生利用更灵活。通过分析废弃新拌混凝土再生利用结果,得到再生新拌混凝土坍落度、凝结时间和抗压强度的变化规律。结果表明:采取适当休眠措施能使废弃新拌混凝土的可利用时间延长至48 h; 如果不使用唤醒措施,经过长休眠的废弃新拌混凝土不能直接使用; 在再生利用的过程中,随着取代率的增加,再生新拌混凝土的初凝时间和终凝时间逐渐增加,初凝时间的最大增加幅度为95 min,终凝时间的最大增加幅度为80 min; 除了休眠时间12 h、取代率50%和100%以外,其余的坍落度损失要好于基准样; 抗压强度有降低趋势,7 d抗压强度比减少了12%~14%,28 d抗压强度比减少了7%~10%,56 d抗压强度比减少了4%~6%。 相似文献
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水泥石对废混凝土蒸压试样强度的影响 总被引:2,自引:0,他引:2
模拟废混凝土进行蒸压处理,研究了水泥石对蒸压试样强度的影响.结果表明,水泥石的存在显著提高了蒸压试样的强度.当水泥石量较少(<12.5%)时,其蒸压试样强度随着水泥石量的增加而增加;水泥石量>12.5%以后,其蒸压试样强度随着水泥石量的增加没有明显变化.由于普通混凝土的水泥用量按水化水泥量计算均超过12.5%,普通混凝土磨细制成蒸压试样的强度受废混凝土中水泥石量的影响很小. 相似文献