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《Construction and Building Materials》2010,24(3):326-331
This paper reports results of a study conducted to investigate the effect of dust, contributed by the coarse aggregates, on the corrosion of reinforcing steel in concrete. The concrete specimens were prepared with up to 10% dust in the coarse aggregates. Two other batches of reinforced concrete specimens were also prepared. In one batch of specimens the aggregates were washed with raw water (total dissolved solids: 3338 ppm) while the dust in the second batch was removed by vacuum suction. Reinforcement corrosion was monitored by measuring corrosion potentials and corrosion current density. The results indicated that up to 10% dust in the coarse aggregates did not cause any corrosion of the reinforcing steel. Similarly, reinforcement corrosion was not noted in the concrete specimens prepared with coarse aggregates washed with raw water or cleaned with vacuum suction. 相似文献
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粗集料性能对路面混凝土抗折强度的影响 总被引:5,自引:0,他引:5
本文研究了粗集料的最大粒径、级配和压碎指标值等对路面混凝土抗折强度的影响,结果表明,合适的最大粒径和连续级配有助于提高混凝土的抗折强度,粗集料的压碎指标值与混凝土的抗折强度没有明显的相关关系。 相似文献
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在粗集料掺量相同的前提下,变动混凝土的粗集料级配和水胶比,以考察粗集料级配对混凝土强度发展历程的影响.试验结果表明:从提高混凝土强度的角度,随着混凝土水胶比的降低,其胶凝材料用量增大,同时,宜采用最大粒径较小的粗集料,反之亦然. 相似文献
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研究5~10 mm小粒径再生粗骨料对预制混凝土抗压强度、劈裂抗拉强度和弹性模量的影响。结果表明,抗压强度随龄期延长而提高,且主要发生在前7 d,7 d抗压强度达到其28 d抗压强度的77%;劈裂抗拉强度随龄期的延长而提高,3 d劈裂抗拉强度达到其28 d强度的64%;弹性模量也随龄期的延长而提高,龄期为1、3、7和14 d时,弹性模量分别为其28 d弹性模量的32%、46%、62%和91%。通过与欧洲规范对比,基于试验结果,建议了劈裂抗拉强度和弹性模量的计算模型。研究结果更好的实现再生混凝土在小截面预制混凝土构件上的工程应用。 相似文献
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Many structures in the middle-east’s Gulf region are now either reaching the end of their design life or were not constructed according to the specifications. Demolition or maintenance work on such structures results in large amount of concrete rubbles. Recycling concrete wastes will lead to reduction in valuable landfill space and savings in natural resources. The objective of this study is to investigate the strength of concrete made with recycled concrete coarse aggregate. The variables that are considered in the study include the source of the recycled concrete and target concrete strength. The toughness and soundness test results on the recycled coarse aggregate showed higher percentage loss than natural aggregate, but remained within the acceptable limits. The compressive and splitting tensile strengths of concrete made with recycled coarse aggregate depend on the mix proportions. In general, the strength of recycled concrete can be 10–25% lower than that of conventional concrete made with natural coarse aggregate. 相似文献
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分析了影响道路混凝土抗折强度的因素,研究了粗集料级配对道路混凝土抗折强度的影响,通过三种不同级配粗集料的对比试验表明:合理的级配能大幅度提高道路混凝土的抗折强度。 相似文献
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《Construction and Building Materials》2003,17(2):97-103
This paper reports results of a study conducted to evaluate the effect of four types of coarse aggregates, namely calcareous, dolomitic, quartzitic limestone, and steel slag, on the compressive and tensile strength, and elastic modulus of high strength concrete. The highest and lowest compressive strength was obtained in the concrete specimens prepared with steel slag and calcareous limestone aggregates, respectively. Similarly, the split tensile strength of steel slag aggregate concrete was the highest, followed by that of dolomitic and quartzitic limestone aggregate concretes. The lowest split tensile strength was noted in the calcareous limestone aggregate concrete. The type of coarse aggregate also influences the modulus of elasticity of concrete. Weaker aggregates tend to produce a more ductile concrete than stronger aggregates do. 相似文献
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《The IES Journal Part A: Civil & Structural Engineering》2013,6(3):175-183
The recycling of concrete is an important means to a sustainable material flow. The limited reuse of recycled aggregates is due to the lower quality of concrete production. Various methods have been attempted to minimise the negative effect. In this paper, the effect of adding fly ash as well as incorporating polyethylene terephthalate (PET) fibres in a concrete mix to mitigate the lower quality of recycled aggregates in concrete is presented. The study consists of two stages: in stage 1 the effects on some of the fresh and hardened concrete properties were studied and the percentage replacement of the natural coarse aggregate (NCA) by the recycled coarse aggregate (RCA) was established. From a chosen percentage of 10%, 20%, 30%, 50% and 100%, we found that the 20% replacement (RCA20) did not seem to jeopardise the compressive strength and water absorption of RCA concrete. Experimental studies were further carried out in stage 2 on the improvement on the mechanical properties of RCA20 concrete by incorporating 25% fly ash and 0.5% and 1.0% PET fibre. Beneficial effects of appropriated fly ash and PET fibre content applied on the RCA were obtained. 相似文献
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《Construction and Building Materials》2010,24(1):11-16
This paper presents the development of lightweight aggregate self-consolidating concrete (SCC) using two types of lightweight aggregates having different densities. Lightweight aggregate SCC properties have been evaluated in terms of flowability, segregation resistance and filling capacity of fresh concrete as per the standards of the Japanese Society of Civil Engineering (JSCE). The measurement of the mechanical properties of hardened lightweight aggregate SCC, including compressive strength, splitting tensile strength, elastic moduli and density, as well as its specific strength were also carried out. The characteristics of lightweight aggregate SCC at the fresh state showed that as the density of the lightweight coarse aggregate decreases, the flowability improves but the segregation resistance tends to decrease. The 28-days compressive strength of the lightweight SCC was found to be 32 MPa or higher. The relationship between the compressive strength and the splitting tensile strength was found to be similar to the expression presented by CEB-FIP, and the relationship between the compressive strength and the elastic moduli was found to be similar to the expression suggested by ACI 318-05 which takes into consideration the density of concrete. The density of the lightweight aggregate SCC decreased by up to 14% compared to that of the control SCC, and the specific strength decreased by up to 20%. 相似文献
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不同取代率再生粗骨料混凝土的和易性 总被引:4,自引:0,他引:4
系统研究了不同再生粗骨料取代率对混凝土和易性的影响,试验中再生粗骨料的掺入量分别为0,30%,50%和100%,试验结果表明粗骨料取代率对混凝土的流动性、粘聚性与保水性有不同的影响。 相似文献
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为了探讨水胶比和碎石体积取代率对次轻页岩陶粒混凝土的物理力学性能影响,通过正交试验得到了LC20最佳配合比,然后再通过不同水胶比(0.30、0.35、0.40)和不同碎石体积取代率rg(0、10%、20%、30%、40%、50%)进行试验,并通过干表观密度、抗压强度、抗折强度、劈拉强度、比强度和折压比,以及断截面破坏形态,探讨其变化规律。结果表明,当碎石取代率为30%,水胶比为0.30时,次轻页岩陶粒混凝土的上述各项指标除折压比外均为最优,并能同步提高强度和韧性,而且还可以有效弥补页岩陶粒产量有限、价格较高和施工性能较差的缺陷。 相似文献