共查询到17条相似文献,搜索用时 234 毫秒
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为探讨骨料裹浆厚度对混凝土性质的影响,并验证富勒致密配比法之可行性,采用富勒致密配比法设计了3种水胶比(mw/mb=0.28,0.32,0.40)与不同裹浆厚度(t=10,20,30 μm),共计9组混凝土配比.结果显示:利用富勒曲线为理论基础设计之骨料架构及表面积理论估算浆量方式可应用于一般混凝土设计,并可进一步符合自密实混凝土高流动性之要求;而骨料裹浆厚度愈大者,表示浆量愈多,虽然混凝土早期强度较高,但在龄期达56 d后却是骨料裹浆厚度越小,混凝土强度与耐久性越佳. 相似文献
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采用纳米增强骨料裹浆技术制备了纳米SiO2增强骨料裹浆混凝土,并测试了其浆体流变性、抗压强度、质量损失和动弹性模量.采用扫描电子显微镜(SEM)和压汞仪(MIP)研究了纳米SiO2增强骨料裹浆混凝土界面过渡区的微观结构和浆体孔结构.结果表明:纳米SiO2显著增加了浆体黏度,增强了骨料裹浆能力;纳米SiO2增强骨料裹浆混凝土的力学和抗冻性能得以提升,强度损失和质量损失均低于普通纳米改性混凝土;纳米SiO2增强骨料裹浆混凝土界面过渡区更加致密,有害孔比普通纳米改性混凝土减少了10.1%,无害孔增加了14.7%. 相似文献
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作为钢纤维混凝土配合比直接设计方法的研究工作的重要内容,采用4个平行于棱柱体试件对称放置的弹簧作为刚性辅助架,在普通压力试验机上成功地测得了纤维体积率0~2.0%、裹浆厚度0.8~1.2 mm、强度等级为CF40的钢纤维混凝土轴压应力-应变全曲线.根据试验结果,分析了纤维体积率和纤维裹浆厚度对钢纤维混凝土轴压强度、应力-应变曲线以及轴压韧性比的影响.表明钢纤维混凝土的轴压强度和韧性比随着纤维体积率的增加而提高,存在合理的纤维裹浆厚度使得钢纤维混凝土获得优良的轴压韧性.提出了与试验结果符合良好的钢纤维混凝土轴压应力-应变曲线计算理论模型. 相似文献
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通过离散元模拟,利用正弦波模拟振动成型方式,采用分层浆体占比对地质聚合物再生骨料透水混凝土(GRAPC)的浆体内部组成结构进行有效表征,实时分析了GRAPC试件内部浆体的迁移运动规律与孔隙结构变化规律,并采用相关室内试验对模拟分析结果进行了验证,分析测试了GRAPC试件各层内部浆体占比与裹浆厚度随振动时间的变化规律.结果表明:振动波初始加载后,GRAPC试件浆体开始向下迁移,并且在振动时间为0.4 s时,试件各层浆体分布最为均匀;相比附加用水组,骨料强化组各层浆体占比和孔隙率浮动范围更小,且在振动作用下其内部的各层浆体占比和孔隙结构分布更为均匀,从而有效保证GRAPC材料同时具有优异的透水性能与力学性能. 相似文献
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混凝土浆体用量越少,其体积稳定性越好。混凝土浆体用量与粗骨料的表面分维有关.采用所提出的试验方法,可得到粗骨料的比表面积、粗骨科表面积形状因子与体积形状因子的比值,代入理论公式可求出粗骨料表面分维.采用所提出的试验和理论相结合的方法,可以较准确得到粗骨料表面分维.研究成果可用于混凝土配合比的设计和优化. 相似文献
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Bedard Claude Ballivy Gérard Aitcin Pierre-Claude 《Bulletin of Engineering Geology and the Environment》1984,30(1):187-191
The construction of very high buildings in concrete instead of steel is now quite common and it requires very high strength concretes (100 MPa and over). This new field of utilization of concrete requires a deeper evaluation of the physico-mechanical properties of concrete. The report presents an experimental study about the production of 100 MPa concretes with different kinds of aggregates quarried in Saint Laurent Lowlands in Québec (Canada) and identified as devonian sedimentary rocks and cretaceous basic intrusive rocks. It appears that the higher strengths are obtained when aggregates and cement paste have similar mechanical properties and if coarse and fine aggregates are produced with the same type of rock, preferably a microgranular limestone; there is no noticeable advantage to utilize aggregates with a strength much more higher than that one of the cement paste. 相似文献
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Recycled concrete aggregate (RCA) used for pavement construction can ease aggregate shortage problem and reduce environmental pollution. The mechanical properties of hot mix asphalt (HMA) with RCA are usually inferior to those of HMA with river crushed stone (CS). In this research, slag cement paste used for pre-coated RCA (PCRCA) with coating thickness of 0.25 mm, 0.45 mm and 0.65 mm to reinforce its ability is evaluated. The result shows that the PCRCA with coating thickness of 0.25 mm has the optimum coating paste volume for HMA mixture. The indirect tensile strength (ITS) test, moisture sensitivity test and wheel-track rutting test of HMA with substitution ratios of 25%, 50%, 75% and 100% PCRCA mixture are discussed. The results indicate that the properties of PCRCA have highly pores contents, absorption of water and asphalt contents. However, the physical properties of the PCRCA used as aggregate and test of HMA with PCRCA are within the range of the specification requirements. 相似文献
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Xuan Hong Vu Laurent Daudeville Yann Malecot 《Construction and Building Materials》2011,25(10):3941-3949
When massive concrete structures (high-rise buildings, tunnels, dams, nuclear power plants, bridges, protection structures, …) are subjected to extreme loadings (aircraft shocks, rock falls, near-field detonations, ballistic impacts, …), the material undergoes triaxial compression loading at a high confinement. In order to reproduce high stress levels with well-controlled loading paths, static triaxial tests are carried out on concrete samples by mean of a very high-capacity triaxial press. It is a well-known fact that the cement paste volume and the coarse aggregate size are two important parameters of concrete formulation. This article focuses on identifying the effect of coarse aggregate size and cement paste volume on concrete behavior under high triaxial compression. This article shows that at low confinement, the concrete strength slightly increases as the coarse aggregate size increases. At high confinement, the coarse aggregate size has a slight influence on concrete deviatoric behavior and a significant influence on concrete strain limit-state. The higher the coarse aggregate size, the lower is the mean stress level corresponding to concrete strain limit-state. Furthermore, this article highlights that at low confinement, the concrete strength significantly increases with an increase in cement paste volume. Increasing confinement tends to reduce cement paste volume effect on concrete strength. At high confinement, contrary to what has been observed in unconfined compression, the cement paste volume has little effects on concrete deviatoric behavior. Otherwise, decreasing cement paste volume increases concrete deformation capacity. At very high confinement levels and at very high deviatoric stress levels, the axial tangent stiffness of concrete increases as the coarse aggregate size or the cement paste volume is reduced. 相似文献
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