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1.
This paper presents the results of a study to compare the properties of concretes prepared with the use river sand, crushed fine stone (CFS), furnace bottom ash (FBA), and fine recycled aggregate (FRA) as fine aggregates. Two methods were used to design the concrete mixes: (i) fixed water–cement ratio (W/C) and (ii) fixed slump ranges. The investigation included testing of compressive strength, drying shrinkage and resistance to chloride-ion penetration of the concretes. The test results showed that, at fixed water–cement ratios, the compressive strength and the drying shrinkage decreased with the increase in the FBA content. FRA decreased the compressive strength and increased the drying shrinkage of the concrete. However, when designing the concrete mixes with a fixed slump value, at all the test ages, when FBA was used as the fine aggregates to replace natural aggregates, the concrete had higher compressive strength, lower drying shrinkage and higher resistance to the chloride-ion penetration. But the use of FRA led to a reduction in compressive strength but increase in shrinkage values. The results suggest that both FBA and FRA can be used as fine aggregates for concrete production. 相似文献
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This paper investigates the influence of the use of coal bottom ash as a replacement for natural fine aggregates on the properties of concrete in the fresh state. Tests for water loss through bleeding, and the determination of the setting times and plastic shrinkage, were carried out in order to evaluate the material in the presence of bottom ash. The influence of the porosity of bottom ash on the potential water absorption and water loss of the material, as well as on the water consumption of concretes produced with bottom ash, is also discussed. The results showed that in the fresh state the concretes produced with the bottom ash are susceptible to water loss by bleeding and the higher the percentage of bottom ash used as a natural sand replacement the lower the deformation through plastic shrinkage. The results also showed that the setting time is affected by the presence of bottom ash in the concrete. In conclusion, different forms of bottom ash mix result in concretes with different properties in the fresh state, but the behavioral tendencies are maintained when bottom ash is employed as a replacement for natural aggregates. 相似文献
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The paper presents investigation of how the usage of bottom ash (BA), granulated blast furnace slag (GBFS), and combination of both of these materials as fine aggregate in concrete affects the concrete durability. To assess durability characteristics of concrete, durability tests were conducted and the results were evaluated comparing with reference concrete. Three series concrete were produced. GBFS, BA and GBFS+BA are replaced the 3–7 mm-sized aggregate. Five test groups were constituted with the replacement percentages as 10%, 20%, 30%, 40% and 50% in each series. These by-products were used as non-ground form in the concrete. Durability properties of the concretes were compared in order to study the possible advantages of different replacement ratios. According to results, GBFS and BA affects some durability properties of concrete positively in case of it is used as fine aggregate. Resistance to high temperature and surface abrasion are positively affected properties. Capillarity, drying-wetting and freezing-thawing resistance of the concrete can be accepted to some extent. Properties of by-products and its replacement ratio are controlling the influence level and direction. Comparison of the SEM images and test results show that chemical and physical properties of GBFS and BA are the main factors affecting the concrete durability. It is concluded that it is possible to produce durable concrete by using GBFS and BA as fine aggregate. 相似文献
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Strength and drying shrinkage properties of concrete containing furnace bottom ash as fine aggregate
《Construction and Building Materials》2005,19(9):691-697
The strength and drying shrinkage of concretes with the natural sand replaced with furnace bottom ash (FBA) at 0%, 30%, 50%, 70% and 100% by mass, were studied at fixed water–cement ratios (W/C) and fixed slump ranges.The results showed that, at fixed water–cement ratios, the compressive strength and the drying shrinkage decreased with the increase of the FBA sand content. However, at fixed workability, the compressive strength was comparable with that of the control concrete, while the drying shrinkage increased with the increase of the FBA sand content beyond 30% replacement level. Nevertheless, 30% of the natural sand can be beneficially replaced with the FBA sand to produce concrete in the compressive strength range from 40 to 60 N/mm2 without detrimentally affecting drying shrinkage properties of the concrete. 相似文献
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R. J. Kettle 《Bulletin of Engineering Geology and the Environment》1984,30(1):421-424
Consideration has been given to the use of alternative materials, including industrial waste, in pavement construction. One such material is furnace bottom ash. In view of its comparatively low strength, some form of improvement is necessary and this paper is concerned with cement stabilisation. Tests on four furnace bottom ashes indicated that they satisfy the requirements materials to be stabilised. The suitability of the stabilised mixtures has been assessed using the characteristics of strength and durability. The stabilised ashes produced materials suitable for pavement construction, with cement contents of approximately 80 kg/m3. At cement contents of 10%, the mixtures developed 28 days cube strengths in excess of 20 MPa, and the results indicated further strength development by pozzolanic reactions. 相似文献
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Weerachart Tangchirapat Chai Jaturapitakkul Prinya Chindaprasirt 《Construction and Building Materials》2009,23(7):2641-2646
The objective of this study is to investigate the use of ground palm oil fuel ash with high fineness (GPA) as a pozzolanic material to produce high-strength concrete. Samples were made by replacing Type I Portland cement with various proportions of GPA. Properties such as the compressive strength, drying shrinkage, water permeability, and sulfate resistance, were then investigated. After aging for 28 days, the compressive strengths of these concrete samples were found to be in the range of 59.5–64.3 MPa. At 90-day the compressive strength of concrete containing GPA 20% was as high as 70 MPa. The drying shrinkage and water permeability were lower than those of high-strength concrete made from Type I Portland cement. When the concrete samples were immersed in a 10% MgSO4 solution for 180 days, the sulfate resistance in terms of the expansion and loss of compressive strength was improved. The results indicated that GPA is a reactive pozzolanic material and can be used as a supplementary cementitious material for producing high-strength concrete. 相似文献
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Copper slag is a by-product obtained during the matte smelting and refining of copper. Current options of management of this slag are recycling, recovering of metal, production of value added products and disposal in slag dumps or stockpiles. This paper presents the results of a study undertaken to investigate the feasibility of using copper slag as coarse aggregates in high-strength concrete. The effects of replacing limestone coarse aggregate by copper slag coarse aggregate on the compressive strength, splitting tensile strength, and rebound hammer values of high-strength concretes are evaluated in this work. Concrete mixtures containing different levels of silica fume were prepared with water to cementitious materials ratios of 0.40, 0.35, and 0.30. The percentages of the cement replacements by silica fume were 0%, 6%, and 10%. The use of copper slag aggregate compared to limestone aggregate resulted in a 28-day compressive strength increase of about 10–15%, and a splitting tensile strength increase of 10–18%. It can be concluded from the results of this study that using copper slag as coarse aggregate in high-strength concrete is technically possible and useful. 相似文献
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Jingwei YING Yijie HUANG Xu GAO Xibo QI Yuedong SUN 《Frontiers of Structural and Civil Engineering》2021,15(3):754
Typical effects of coarse and fine aggregates on the long-term properties of sea sand recycled aggregate concrete (SSRAC) are analyzed by a series of axial compression tests. Two different types of fine (coarse) aggregates are considered: sea sand and river sand (natural and recycled coarse aggregates). Variations in SSRAC properties at different ages are investigated. A novel test system is developed via axial compression experiments and the digital image correlation method to obtain the deformation field and crack development of concrete. Supportive results show that the compressive strength of SSRAC increase with decreasing recycled coarse aggregate replacement percentage and increasing sea sand chloride ion content. The elastic modulus of SSRAC increases with age. However, the Poisson’s ratio reduces after 2 years. Typical axial stress–strain curves of SSRAC vary with age. Generally, the effect of coarse aggregates on the axial deformation of SSRAC is clear; however, the deformation differences between coarse aggregate and cement mortar reduce by adopting sea sand. The aggregate type changes the crack characteristics and propagation of SSRAC. Finally, an analytical expression is suggested to construct the long-term stress–strain curve of SSRAC. 相似文献
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《Construction and Building Materials》2006,20(3):149-157
This paper reports the results of experimental investigation carried out on the effect of reducing coarse aggregate (CA) quantity in mix proportions on the compressive strength of concrete. It also presents empirical formulas aimed at optimizing a concrete mix design for desert regions. Intensive laboratory experiment of 1350 samples of 30 different concrete mixes using three curing methods was carried out. The influences of the water/cement (W/C) ratio, coarse and fine aggregates (FA), CA/total aggregate (CA/TA) ratio, TA/C ratio, and curing methods (air curing, oven curing, and water curing) on the compressive strength of concrete were characterized and analyzed. Mathematical formula was developed for concrete strength as a function of CA quantity that ranges from the standard quantity to null, and another formula was developed for the quantity of FA as a function of compressive strength. 相似文献
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《Construction and Building Materials》2008,22(12):2393-2399
Lightweight aggregates have been manufactured by sintering fly ash and crushing the product into suitable sizes. These aggregates possess unique characteristics that make them suitable for high strength and high performance concrete. Concrete produced using these aggregates is around 22% lighter and at the same time 20% stronger than normal weight aggregate concrete. Drying shrinkage is around 33% less than that of normal weight concrete. Moreover, the aggregates possess high durability characteristics required in high performance structures. The importance of the new aggregates lies mostly in the fact that superior qualities are achieved without having to increase the cement content. Thus it is possible to reduce the amount of cement by as much as 20% without affecting the required strength. Weight reduction may reduce precast concrete transportation costs as well as provide slender and spacious construction. Utilising fly ash to produce quality aggregates should yield significant environmental benefits. 相似文献
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通过对40^m、63^m、800^t,3个大型动力设备基础混凝土中掺30%粉煤灰的应用证明:高掺量粉煤灰不仅可降低大体积混凝土的水化热、延缓凝结时间,使必须连续浇灌又不能留施工缝的实心块体动力基础施工变得简单,并且提高了混凝土与钢筋的握裹力、弹性模量、抗折强度以及后期抗压强度,对承受动力冲击负荷亦有良好的力学性能。 相似文献
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废混凝土作粗集料、废砖作细集料制备再生混凝土的实验研究 总被引:4,自引:0,他引:4
曾路春 《墙材革新与建筑节能》2006,(8):35-36
将实验室检测用废混凝土试块和废黏土砖经破碎、筛分后,作为再生混凝土粗细集料应用。结果表明,经过合适的配比。配制出满足强度和工作性能要求的混凝土:在严格控制试验用水量的条件下,采用预加水浸泡再生细集料的方法,能够得到工作性能良好的再生混凝土。 相似文献
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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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《Construction and Building Materials》2008,22(9):1922-1928
The present study aims to determine and evaluate the applicability of an industrial bottom ash (CBA), supplied from Tunçbilek Power Station-Turkey, in concrete industry. In the laboratory experiments, the bottom ash was used up to 25% as a partial substitute for the Portland cement. In order to be able to reduce the unburned carbon content, CBA was treated by three different processes (particle size classification, heavy medium separation and electrostatic separation). Based on the obtained results, it was concluded that the addition of CBA up to 10% as a replacement material for Portland cement could improve the mechanical properties of concrete, and thus, could be used in the concrete industry. The effect of operating parameters on treatment processes has also been discussed in the paper. 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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H. Hebhoub H. Aoun M. Belachia H. Houari E. Ghorbel 《Construction and Building Materials》2011,25(3):1167-1171
Today we are faced with an important consumption and a growing need for aggregates because of the growth in industrial production, this situation has led to a fast decrease of available resources. On the other hand, a high volume of marble production has generated a considerable amount of waste materials; almost 70% of this mineral gets wasted in the mining, processing and polishing stages which have a serious impact on the environment. The processing waste is dumped and threatening the aquifer. Therefore, it has become necessary to reuse these wastes particularly in the manufacture of concrete products for construction purposes. The main goal of this study is to demonstrate the possibility of using marble wastes as a substitute rather than natural aggregates in concrete production. The paper presents the study methodology, the characterization of waste marble aggregates and various practical formulations of concrete. This experimental investigation was carried out on three series of concrete mixtures: sand substitution mixture, gravel substitution mixture and a mixture of both aggregates (sand and gravel). The concrete formulations were produced with a constant water/cement ratio. The results obtained show that the mechanical properties of concrete specimens produced using the marble wastes were found to conform with the concrete production standards and the substitution of natural aggregates by waste marble aggregates up to 75% of any formulation is beneficial for the concrete resistance. 相似文献