共查询到19条相似文献,搜索用时 109 毫秒
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为研究在不同养护方式下掺入牡蛎壳代替部分细骨料对混凝土的抗压性能影响规律,通过设计4种不同含掺量的牡蛎壳混凝土,在规定龄期进行立方体抗压试验、劈裂抗拉试验,并对不同海水拌合-养护方式下进行牡蛎壳混凝土抗压强度试验,与普通混凝土进行对比分析并进行机理分析。结果表明:牡蛎壳混凝土抗压性能发展规律与普通混凝土一致,掺入率越多的牡蛎壳碎其混凝土内部结构越疏松,也是导致牡蛎壳混凝土的抗压强度随掺入率升高而降低的主要原因。含有牡蛎壳的混凝土在海水拌合-中性水养护下抗压强度显著提升,为新型混凝土的工程实际应用奠定了理论基础。 相似文献
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研究了再生骨料取代率和牡蛎壳粉取代率对透水混凝土透水性能和抗冻性能的影响。结果表明:透水混凝土的抗冻性能随着再生骨料取代率和牡蛎壳粉取代率的增加而降低,当再生骨料取代率为100%且牡蛎壳粉取代率≤40%时,透水混凝土的透水性能满足相关规范要求,抗冻等级达到D25。 相似文献
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粉煤灰和矿粉比例为2∶1替代20%的水泥,牡蛎壳替代5%~10%的砂子掺入到C40混凝土中能形成良好级配的混凝土材料,标准养护28 d后其抗压强度提高了约8%,快速氯离子迁移系数(RCM法)下降了48%,P8级渗水平均高度降低了44%。为了研究牡蛎壳颗粒在水泥浆的作用机理,采用牡蛎壳制备了水泥沙浆体,利用扫描电子显微镜(SEM)和X射线衍谢仪(XRD)分析不同水化龄期微观形貌的物相成分,采用电化学工作站分析了电化学阻抗谱(EIS),结果表明:牡蛎壳的表面粗糙、吸水性强,用之代替5%~10%河砂可以降低水胶比,能抑制养护初期(7 d)的钙矾石产生,从而提高混凝土的抗压强度,与此同时,牡蛎壳颗粒能大幅提高中频极化电阻和降低低频扩散系数,因此能提高混凝土抗渗透性能。 相似文献
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镁渣取代部分细骨料对混凝土抗压强度的作用效应研究 总被引:2,自引:0,他引:2
针对宁夏镁渣利用问题,在已有研究的基础上,以镁渣消化时间t、镁渣取代率m和粉煤灰掺量f为因素,设计L(934)正交试验方案,试验研究了镁渣取代部分细骨料对混凝土抗压强度的作用效应,揭示了作用规律,并进行了机理分析,为镁渣作为混凝土的细骨料提供了理论支持。试验结果表明:镁渣取代率适量时,镁渣能提高混凝土的强度;镁渣适当时间的消化是非常必要的,但消化时间不宜过久;镁渣取代率对混凝土抗压强度影响的显著,各因素的最优组合为镁渣消化时间3 d,镁渣取代率30%,粉煤灰掺量20%。 相似文献
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针片状骨料对混凝土性能的影响 总被引:2,自引:0,他引:2
李良茂 《混凝土与水泥制品》1990,(1):2-5
本文研究了针片状骨料对混凝土工作性及水泥用量的影响,探讨了针片状骨料的分布排列形成混凝土力学上各向异性的现象,并分析了针片状骨料对不同标号混凝土强度的影响。 相似文献
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陈远远 《建筑·建材·装饰》2014,(18)
本文重点综述了近年来关于再生细骨料对混凝土工作性能、力学性能、耐久性能、抗裂性能影响的研究进展,提出了再生细骨料在混凝土工程中的研究及应用的一些看法和建议。 相似文献
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Failure mechanism of recycled aggregate concrete 总被引:2,自引:0,他引:2
M. Casuccio M.C. Torrijos G. Giaccio R. Zerbino 《Construction and Building Materials》2008,22(7):1500-1506
The use of recycled aggregate concrete (RAC) acquires particular interest in civil construction regarding sustainable development. Recycled aggregates usually present greater porosity and absorption, and lower density and strength than natural aggregates. Microstructural studies on RAC indicate differences in the characteristics of the interfacial transition zones between the cement paste and the aggregates. At the same time most experiences verify that reduction in concrete stiffness is higher than in strength. The failure mechanisms in RAC can be affected by the above stated factors. In this paper, three Series of concretes with different compressive strength levels are presented. Each Series includes a reference concrete prepared with natural crushed stone and two RAC prepared with two coarse aggregates obtained by crushing a normal strength and a high strength concrete. Flexural tests on notched beams and uniaxial compression tests on standard cylinders were performed. In addition, the characteristics of the fracture surfaces were analysed in order to determine the amount of broken aggregates. RAC present lightly lower strengths (1–15%), lower modulus of elasticity (13–18%) and significant reductions in the energy of fracture (27–45%) and, consequently on the fracture zone size, when it is compared with a concrete prepared with natural coarse aggregates. 相似文献
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对水泥、粉煤灰等实验原材料进行了介绍,分析了减水剂、粘合剂和粉煤灰对多孔轻集料植被混凝土性能的影响,并通过试验得出掺加减水剂、粘合剂等可以配制碱度低、合适孔隙率及抗压强度2 MPa~3 MPa以上的多孔轻集料植被混凝土的结论。 相似文献
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通过大量的试验数据分析粗集料的级配、压碎值及含泥量等技术指标对混凝土的性能影响,并对桥梁施工中水泥混凝土用粗集料的质量控制提出了建议,以提高混凝土性能,达到预期目标。 相似文献
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Effects of three types of curing on coconut shell aggregate concrete have been studied for long term performance. The pore structure of coconut shell has been studied through scanning electron microscope (SEM). The pore structures in coconut shell behave like a reservoir. Intermittent curing produced the highest coconut shell aggregate concrete strength, followed by full water, and then by air-dry curing. Biological decay was not evident as the concrete cubes gained strength even after 365 days. Up to an age of 90 days, the samples under all types of curing conditions showed improved response on the pulse velocity and subsequently an insignificant drop. The ultimate bond strength of coconut shell aggregate concrete under all types of curing conditions was much higher compared to the theoretical bond strength as per BS 8110 and IS 456. Bonding between the cement paste and the coconut shell aggregate has been studied by measuring fissure between the coconut shell and the cement paste through SEM analysis. It shows a tendency of narrowing the fissure due to its age, which shows that the bond appears to be better between the coconut shell and the cement paste. 相似文献
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提出了混凝土实现高性能化的基本技术途径,着重研究了粉煤灰、矿渣、硅灰的单掺对轻集料混凝土强度的影响,得出了硅灰对轻集料混凝土强度的贡献比矿渣和粉煤灰的大,并对硅灰的作用机理进行了探讨,以促进高性能混凝土的研究。 相似文献
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Dammika P. K. WELLALA Ashish Kumer SAHA Prabir Kumar SARKER Vinod RAJAYOGAN 《Frontiers of Structural and Civil Engineering》2021,15(1):124-135
This paper presents the fresh and hardened properties of high-strength concrete comprising byproduct fine crushed aggregates (FCAs) sourced from the crushing of three different types of rocks, namely granophyre, basalt, and granite. The lowest void contents of the combined fine aggregates were observed when 40% to 60% of natural sand is replaced by the FCAs. By the replacement of 40% FCAs, the slump and bleeding of concrete with a water-to-cement ratio of 0.45 decreased by approximately 15% and 50%, respectively, owing to the relatively high fines content of the FCAs. The 28 d compressive strength of concrete was 50 MPa when 40% FCAs were used. The slight decrease in tensile strength from the FCAs is attributed to the flakiness of the particles. The correlations between the splitting tensile and compressive strengths of normal concrete provided in the AS 3600 and ACI 318 design standards are applicable for concrete using the FCAs as partial replacement of sand. The maximum 56 d drying shrinkage is 520 microstrains, which is significantly less than the recommended limit of 1000 microstrains by AS 3600 for concrete. Therefore, the use of these byproduct FCAs can be considered as a sustainable alternative option for the production of high-strength green concrete. 相似文献
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目前,纳米材料因其优异的性能已经在水泥基材料中得到了广泛应用。利用两种类型的纳米颗粒,即纳米二氧化硅(NS)和纳米碳化硅(NC)掺入粉煤灰水泥砂浆制备水工混凝土试样,在强度测试的基础上,研究了纳米颗粒含量对不同试样耐冲磨性的影响,并对其作用机理进行理论分析。结果表明,纳米颗粒在提高粉煤灰混凝土抗压和抗弯强度得同时也改善了抗冲磨性能;单掺NS和NC最佳添加量分别为2%和为3%,而双掺2%NS和2%NC的水工混凝土具有最优抗冲磨性能,磨损量仅为0.64 kg/m2,比参照组的磨损量降低了75%;从SEM扫描图像中得到改性机理为纳米颗粒的表面效应、火山灰反应和微观骨料填充效应,增大了骨料得表面能,改变了界面过渡区的结构,同时也填充了微结构孔隙,从而提高了粉煤灰混凝土的耐冲磨性。研究结果对设计高强度和抗冲磨性的水工混凝土具有一定指导意义。 相似文献