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排序方式: 共有412条查询结果,搜索用时 15 毫秒
1.
Superabsorbent polymers (SAP) can be used as a means for internal curing of concrete. In the present study, the development of transport properties of concrete with SAP is investigated. The chloride migration coefficient according to NT BUILD 492 is used as a measure of this. Twenty concrete mixtures are tested 7, 14, and 28 days after casting. The development of degree of hydration is followed for 20 corresponding paste mixtures.Both when SAP is added with extra water to compensate the SAP water absorption in fresh concrete and without extra water, the internal curing water held by SAP may contribute to increase the degree of hydration. No matter if SAP is added with or without extra water, it appears that the so-called gel space ratio can be used as a key parameter to link age and mixture proportions (water-to-cement ratio and SAP dosage) to the resulting chloride migration coefficient; the higher the volume of gel solid relative to the space available for it, the lower the chloride migration coefficient, because the pore system becomes more tortuous and the porosity becomes less. 相似文献
2.
Tanveer Ahmed Khan Munirah Ezzah Tuan Zakaria Hyun-Joong Kim Suriati Ghazali Saidatul Shima Jamari 《应用聚合物科学杂志》2020,137(8):48396
Recently, the use of controlled release fertilizers in agriculture has resulted in huge benefits in plant growth and cultivation. Superabsorbent polymer (SAP)-coated fertilizers have the added advantage in retaining water in soil after irrigation and also reduce the nutrient release rate from soil in a controlled manner. This study aimed to produce a nitrogen–phosphorus–potassium (NPK) fertilizer coated with superabsorbent carbonaceous microspheres polymer (SPC) by inverse suspension polymerization method with water-retention and controlled release properties. Two sets of experiments were conducted: (1) three different weight percentages and (2) different materials. NPK coated with SPC showed increasing water-retention ability with respect to carbon microsphere percentages and retains >80% water at the 30th day of experiment compared with pure NPK and NPK coated with SAP. The slow release behavior of all samples was investigated by induced coupled plasma mass spectrometry spectrometry and results showed that NPK coated with SAP and SPC has a low release rate with <50% nutrient release compared with uncoated NPK at the 30th day. The release mechanism kinetics of NPK coated with SAP and SPC were studied based on the Kosmeyer–Peppas model. The mechanisms approached Fickian diffusion-controlled release as the n value for both samples was less than 0.5. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020 , 137, 48396. 相似文献
3.
采用SAP2000程序,对铁路淮河特大桥进行了反应谱分析和时程分析,分析表明地震力不控制主梁结构设计,但地震力直接作用于墩底,须对连续梁的墩底进行抗震应力验算,连续梁桥的支座承担较大剪力,建议采用抗震支座,以策安全。 相似文献
4.
采用结构分析软件SAP2000中的分层壳单元模型对3个剪力墙构件试验进行数值模拟,在考虑不同龄期的影响下进行了Pushover分析,将最终所得Pushover曲线与试验数据进行对比,发现拟合度较高,进而采用同样方法对某12层剪力墙结构建立数值模型并进行非线性动力时程分析,对其层间位移角等相关性能指标进行分析,发现在不同龄期下,其性能退化表现与实际结构的宏观性能退化表现相符。结果表明:利用分层壳单元在基于劣化的情况下对RC剪力墙结构进行数值模拟的方法是可行的。 相似文献
5.
针对高水胶比混凝土早期开裂严重影响混凝土耐久性能的问题,研究了掺量(质量分数)为0.2%,0.3%和0.4%的高吸水性树脂(SAP)对高水胶比(质量比0.5)混凝土特定状态下的早期抗裂性能、力学性能和体积稳定性能的影响,并结合水分蒸发试验,研究了掺入SAP后混凝土的失水规律.结果表明:掺入SAP后,可显著提高高水胶比混凝土的早期抗裂性能,SAP掺量为0.2%,0.3%和0.4%的混凝土早期开裂面积分别降低了81%,88%和98%,SAP的掺入能够明显减缓混凝土的水分挥发,抑制其体积收缩,并且不会对混凝土的力学强度造成较大的负面影响. 相似文献
6.
以贵州省遵义市某县棚户区(城中村)改造项目为研究算例,利用SAP2000有限元分析软件建立框架剪力墙结构-桩筏基础-地基共同作用的三维有限元模型和不考虑三者共同作用的一般三维模型。与不考虑共同作用的一般模型相比,考虑共同作用后,上部结构的内力和桩顶的反力都增大,筏板沉降和筏板内力都减小,说明筏板沉降和筏板内力的安全储备较大。因此,在结构工程设计过程中,考虑上部结构、基础和地基共同作用的设计理念和方法与建筑物实际受力特征更相符,设计结果也更合理,同时也要考虑三者共同作用时上部结构和桩顶反力的不利影响。 相似文献
7.
曹玲莉 《柴油机设计与制造》2012,18(3):53-56
发动机因其开发周期长,科技含量高,材料材质、工艺路线复杂、环保要求高等原因,而成为高成本的制造行业。因此,有效的成本控制已是发动机制造企业在激烈的市场竞争中成败的关键。SAP系统因其数据集成性、资源共享性、传输及时性等特点,摈弃了以往发动机制造企业传统成本管控中的数据多源、信息屏蔽、权限分散等弊端,做到了研发、工艺、生产、物流、财务数据同源、资源共享、责权分担,为柴油机制造企业从产品研发源头就实施有效的成本控制提供了手段,极大地提高了企业成本管控的质量和效益。 相似文献
8.
9.
Andrew Stone David Shipworth Phill Biddulph Tadj Oreszczyn 《Building Research & Information》2014,42(6):725-738
In the UK, the Standard Assessment Procedure (SAP) is used to rate the energy performance of existing dwellings whenever they are let or sold. This study investigates which of the inputs to SAP account for the most variance in energy rating across existing gas central heated houses in England. Data from the English Housing Survey (EHS) 2009 are used to generate a representative set of dwellings and variance-based global sensitivity analysis is then applied to assess each input's contribution to the variance in the calculated ratings. It is demonstrated that heating system efficiency, external wall U-value and dwelling geometry account for 75% of the variance of the energy rating of gas central heated houses in England. This suggests that improving heating system efficiencies and wall U-values of the worst performing dwellings will go a long way towards improving their energy rating and potentially reducing their energy consumption. It is also demonstrated that dwelling geometry has a much bigger influence on the calculated carbon emissions (accounting for 80% of the variance) than it does on the SAP energy rating (accounting for 30%), meaning that significant improvements in energy rating might not be accompanied by significant reductions in carbon emissions. 相似文献
10.