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Recycling and reuse of waste such as building rubble, concrete lumps, etc. generated at construction and demolition sites form part of a wider, complex issue, primarily relating to improving supplies of construction material and solving problems of disposal of waste construction material. Within the framework of the sustainable development of the environment, the use of waste materials with minimum environmental impact has received much attention. The conversion of a large amount of demolished waste into an alternative resource will conserve the depleting natural resources of building materials. Demolished waste is mainly used as a non-stabilized base or sub-base in highway construction. The present paper discusses the recycling process and makes an effort to assess a safe and economic use of recycled concrete as a structural grade material for the construction industry. Extensive tests of structural properties such as compressive strength, flexural strength and split tensile strength of recycled concrete were carried out, in which cement and similarly fine aggregate were partially replaced by demolished waste to obtain recycled concrete and recycled aggregate concrete whose properties were compared with results for the conventional concrete. 相似文献
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An increasing trend towards the use of sustainable processes has led to recycled materials being incorporated into concrete. It is generally recognised that crushed recycled construction aggregate material produces concrete of a lower compressive strength, when used as an aggregate replacement due to deleterious materials within the aggregate.It is generally accepted that in the UK, freeze/thaw attack is, after chloride-induced corrosion, the most common cause of concrete deterioration. This paper addresses the freeze/thaw durability of recycled aggregate concrete using a paired comparison test based upon weight loss and final compressive strength.Recycled aggregate concrete was found to be of at least equal durability to concrete manufactured with virgin aggregates. This was due to careful selection of the replacement aggregate and treatment prior to batching.Durability is an important material property and recycled aggregates need to be widely tested to gain confidence for use within the industry and this work shows future possibilities. 相似文献
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基于生命周期评价方法,考虑混凝土重复再生利用的环境影响分配,对重复再生混凝土的性能和环境影响进行研究,并基于功效系数法优化出混凝土最佳重复再生次数.研究结果表明,再生混凝土的坍落度,强度和电通量随着重复再生循环次数的增加而下降,经3次重复再生后,混凝土28d立方体抗压强度为33.3MPa,满足设计要求,而坍落度和电通量与普通混凝土相比,分别减小和增大了38.9%和85.7%;混凝土材料的生态效率随着混凝土重复再生次数的增加而提高,混凝土材料的GWP、CED和CMR的值均随着混凝土重复再生次数的增加而降低,降低幅度从高到低依次为:CMR > GWP > CED;综合考虑混凝土的坍落度,混凝土抗压强度、电通量、GWP、CED和CMR等6个指标,4种混凝土配合比情景中,混凝土总功效系数从高到低依次为:一次再生混凝土 > 二次再生混凝土 > 三次再生混凝土 > 普通混凝土. 相似文献
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采用正交设计方法设计试验,从而配置再生骨料透水性混凝土。以再生骨料透水性混凝土的抗压强度、透水系数、孔隙率为主要考核指标,分别研究了水灰比、骨灰比、砂率、再生骨料粒径等因素及其不同的水平对再生骨料透水性混凝土各性能指标的影响。并对各考核指标的主要影响因素进一步细分,结果表明,再生骨料透水性混凝土的透水系数和孔隙率的主要影响因素是水灰比;抗压强度的主要影响因素是骨灰比。水灰比的变化与透水系数和孔隙率之间呈现相同的规律,都出现先上升后下降的趋势;骨灰比的变化与抗压强度之间呈现线性下降的趋势。当水灰比介于0.37~0.43之间,骨灰比介于4.0~4.5之间时,混凝土拌和物和易性较好,混凝土的强度较高,透水性较好。 相似文献
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At present glass fibre reinforced plastic (GRP) waste recycling worldwide is very limited due to its intrinsic thermoset properties, lack of characterisation data and non availability of viable recycling and recovery routes. In the present study, efforts were made to recycle GRP waste powder and fibre in concrete and cement composites and assess its quality to comply with the British standards for use in construction applications. Results revealed that the mean compressive strength of concrete composites using 5%–50% GRP waste powder under water curing varied from 37 N/mm2 to 19 N/mm2. Increase in the concentration of GRP waste decreased the compressive strength. However, increase in curing duration (14–180 days) resulted in improving the compressive strength of concrete with 5% GRP application to 45.75 N/mm2. Moreover, the density of concrete with 50% GRP waste was reduced by about 12% as compared to the control sample. The bending strength in terms of modules of rupture (MOR) of 12 mm thickness cement composites developed using 5% GRP waste fibre attained 16.5 N/mm2. The findings of this work pave the way for further GRP waste recycling in precast construction products for use in various applications. 相似文献
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我国城镇化进程持续深入推进,大规模城市更新建造活动消耗了大量水泥等建筑材料.以深圳市为例,采用自下而上的物质流分析方法估算了自特区建设以来(1979~2018年)城市房屋建筑中的水泥存量和流量,并分析了其产生的综合环境影响(以碳排放当量为度量指标).研究结果表明:1979~2018年间,深圳市建筑水泥历史累积消耗约为8120万t,年均消耗超过200万t,水泥累计流出量(建筑废弃物)约为总流入量的25%~29%;截至2018年,深圳市建筑水泥存量达到6200万t,人均水泥存量达到4.7t.相应地,全部所消耗的水泥材料在生产阶段的碳排放累计可达6880万tCO2eq,其中仅有9%的碳排放量可被既有存量建筑“自然”吸附,但仍有至少约11%的碳排放量可通过废弃混凝土(流量)再生骨料进行“逆向”吸附封存.最后,基于建筑水泥存流量、碳排放及碳汇量等量化数据,提出了加强水泥使用管理、实现水泥生产碳减排以及水泥材料碳汇能力提升等相关措施建议. 相似文献
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为实现工业固废的资源化利用,研究了以钢渣、水渣和脱硫石膏为原料制备的复合胶凝材料作为掺合料替代水泥制备C30混凝土。考察复合胶凝材料的掺入量对胶材标准稠度用水量、凝结时间、混凝土性能的影响。结果表明:净浆的标准稠度用水量和凝结时间与复合胶凝材料的掺入量呈正相关;所制备混凝土的抗压强度随着复合胶凝材料替代水泥量的增加而下降,全部使用胶凝材料制备混凝土试块的28 d抗压强度达到43.5 MPa,为水泥对照组的78.3%。钢渣微粉和脱硫石膏能够促进水渣水化生成钙钒石和水化硅酸钙等水化产物,起到良好的胶结作用,使得混凝土结构致密。该复合胶凝材料可替代部分水泥,减少CO2排放,带来巨大的经济效益和环境效益,具有广阔的市场应用前景。 相似文献
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利用废弃物铜尾矿与抛光泥复合取代粉煤灰,与水泥、石灰、石膏等材料制备蒸压加气混凝土。重点研究了铜尾矿与陶瓷抛光泥的颗粒细度、掺加量、工艺参数等对蒸压加气混凝土砌块抗压强度、绝干密度等性能的影响,通过XRD、SEM对其微观机理进行研究。结果表明:铜尾矿与抛光泥粉磨时间为20 min时,铜尾矿的比表面积达到244.5 m2/kg,抛光泥比表面积为350.4 m2/kg。原材料中铜尾矿、抛光泥、水泥、石灰、石膏的质量比为45∶20∶10∶22∶3时,制备的砌块最大抗压强度达到5.1 MPa,平均抗压强度达到4.7 MPa,绝干密度低于625 kg/m3,达到A3.5,B06的蒸压加气混凝土砌块的要求。砌块中的托贝莫来石与C-S-H (B)等水化产物与未反应的石英相互致密穿插,使砌块的微观孔结构更加致密,砌块的抗压强度更高。 相似文献
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碎砖骨料再生混凝土配合比研究 总被引:1,自引:0,他引:1
用正交法试验分析了碎砖骨料混凝土的配合比,提出水灰比和碎砖骨料掺量分别是影响混凝土强度和流动性的主要因素。倡导用碎砖做混凝土骨料,保护生态环境。 相似文献
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流化床飞灰在混凝土中大掺量替代水泥的研究 总被引:1,自引:0,他引:1
介绍了采用复合激发剂,对流化床飞灰活性进行激发,在混凝土中以流化床飞灰大掺量替代水泥的试验研究。结果表明:本研究采用的激发方法能够有效激发流化床飞灰活性,当飞灰替代水泥量为30% ̄40%时,不降低水泥的标号,所配制的混凝土强度值与100%水泥的混凝土相当,且和易性能满足施工的要求。 相似文献
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汽车工业的发展和汽车数量的增加,在给人民生活带来方便的同时,也产生了大量的废旧轮胎。废旧轮胎的堆积和不当处理,将对生态环境带来严重的污染,国内外学者对废旧轮胎的综合利用开展了大量的研究,将废旧轮胎经粉碎等处理制成橡胶沥青,应用于道路工程不仅提高了道路的耐热等性能,而且减少了生态环境污染,具有良好的社会效益、经济效益和环境效益。本文介绍了国内外对废旧轮胎在道路工程中的应用情况,通过与国外研究和工程实践的对比,指出了我国在此方面研究中存在的问题,为进一步废旧轮胎在道路工程中综合利用提供指导作用。 相似文献
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绿色高强混凝土——硅灰混凝土 总被引:4,自引:0,他引:4
硅灰是冶金厂生产硅铁和工业硅过程中产生的废灰,硅灰混凝土为绿色混凝土,它不仅节约了水泥熟料,而且改善了环境,大大促进了混凝土和建筑工程的健康发展,混凝土中掺入硅灰可得到高强和超高强混凝土,用此混凝土浇制的结构物其安全度大大提高,经济效益显著,硅灰混凝土还可以有效抑制碱骨料反应,提高结构物的安全度和耐久性,延长使用寿命。 相似文献
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Paving blocks from ceramic tile production waste 总被引:1,自引:0,他引:1
D. Wattanasiriwech A. Saiton S. Wattanasiriwech 《Journal of Cleaner Production》2009,17(18):1663-1668
This paper presents the use of waste mud from ceramic tile production as the main component in paving blocks. Compressive strength values of the blocks were compared with the standard value as prescribed by the Thailand Industrial Standard. The waste mud was first characterized using XRD, XRF, SEM, Laser diffraction particle size analyzer and sieve analysis. Paving blocks were subsequently prepared by mixing the waste mud with Ordinary Portland cement (OPC) and compacted using a hydraulic press. Water was added to the cement–mud mix to assist compaction and to strengthen the blocks by hydration of OPC. Effects of water and cement content, immersion in water, as well as compaction pressure on compressive strength were subsequently studied. Increasing compaction pressure and also immersion in water for 5 min every 24 h were found to enhance densification and thus compressive strength of the test samples. The blocks containing 15 wt% cement required a long curing period of up to 28 days for their compressive strength to reach the standard requirement while the compressive strength of the blocks containing 25–30 wt% cement exceeded the standard requirement after curing for only 7 days. 相似文献
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Vivian W.Y. Tam 《Journal of Cleaner Production》2009,17(7):688-702
Environmental problems have been considered to be serious in the construction industry. Waste management pressures are pressing very hard with alarming industrial warming signals. Among the different types of construction and demolition wastes, concrete is about 81 percent of the volume of construction and demolition waste in Australia. To minimize the concrete waste generated from construction activities, recycling of concrete waste is one of the best methods to improve the environment. However, situations of concrete recycling in different countries vary considerably. Japan is a leading country in recycling concrete waste, with 100 percent recycling of the wastes that are used for new structural applications. This paper investigates the current concrete recycling situations in Australian and Japanese construction industries. A questionnaire survey and structured interviews were conducted. In comparing the current concrete recycling situations between Australia and Japan, it should be noted that major difficulties found from Australian and Japanese construction industries are on different phases of the transition to recycling of construction wastes. Therefore, it is suggested that the Australian construction industry should be: i) developing a unified policy in concrete recycling; ii) providing financial governmental support; iii) developing clear technical specifications or standards on the use of recycled aggregate for structural applications. 相似文献