Development of a life cycle assessment tool for construction and maintenance of asphalt pavements

The increasing use of recycled materials in asphalt pavements calls for environmental assessment of such impacts as the energy input and CO₂ footprint. Life cycle assessment (LCA) is being accepted by the road industry for such purpose. It aims to quantify and collate all the environmental impacts from the life time of the product or process. This paper reviews relevant LCA resources worldwide, identifies the knowledge gap for the road industry, and describes the development of an LCA model for pavement construction and maintenance that accommodates recycling and up-to-date research findings. Details are provided of both the methodology and data acquisition. This is followed by a discussion of the challenges of applying LCA to the pavement construction practice, and recommendations for further work. In the case study, the model is applied to an asphalt paving project at London Heathrow Terminal-5 (LHR), in which natural aggregates were replaced with waste glass, incinerator bottom ash (IBA) and recycled asphalt pavements (RAP). Production of hot mix asphalt and bitumen was found to represent the energy intensive processes. This is followed by data analysis and sensitivity check. Further development of the model includes expanding the database to accommodate the recycling and maintenance practice in the UK, and taking into account the effect that roadwork has on traffic emissions. The LCA model can be further tested and calibrated as a decision support tool for sustainable construction in the road industry.     

废弃混凝土在干混砂浆中的应用研究

废弃混凝土的循环再生利用已日益成为人类关注的重要话题,符合环境保护与可持续发展战略的迫切要求。利用废弃混凝土破碎产生的再生细骨料部分取代天然细骨料来配制干混砂浆。通过试验证明:在固定配合比条件下,再生骨料替代率为50%时,干混砂浆抗压强度、保水率和抗冻融性、强度损失率等均符合M5.0中保水的指标要求。     

纸塑铝复合包装处置方式的生命周期评价

采用生命周期评价(LCA)法研究了纸塑铝复合包装的全生命周期环境影响,并在处置阶段对不同处置方式的环境影响进行评价. 通过现场和资料调研的方式,获得所有生命周期阶段能量物质的输入/输出和环境外排数据. 结果表明:纸塑铝复合包装生命周期阶段中环境影响比重最大的是原料获取阶段,占75%以上. 纸塑铝复合包装的全生命周期环境影响主要集中在化石燃料、土地占用和无机物对人体损害3个方面,在矿产资源、气候变化、酸化富营养化和生态毒性方面影响稍小. 3种处置方式对环境影响由大到小依次为填埋＞焚烧＞再生,其中填埋和焚烧处置分别比纸塑铝复合包装处置阶段前的环境影响增加11%和7%,再生可降低23%,而进一步降低环境影响的方式为发展铝塑分离技术.      

Freeze/thaw durability of concrete with recycled demolition aggregate compared to virgin aggregate concrete

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.     

LCA of spent fluorescent lamps in Thailand at various rates of recycling

This paper presents environmental impact of a fluorescent lamp (a long straight tube 36 watts, 200 g and 13,600 h for mean time before failure) when considering different disposal methods (recycle and non-recycle) of its spent fluorescent lamp (SFL). The study was applied for the case in Thailand using life cycle assessment (LCA) as a tool. All materials, energy use, and pollutant emissions to the environment from each related process were identified and analyzed. Impact assessment was conducted for 10 environmental impact potentials: carcinogens, respiratory organics, respiratory inorganics, climate change, radiation, ozone layer, ecotoxicity, acidification/eutrophication, land use and minerals. The analysis followed Eco-Indicator 99 method, individualist version 2.1. The main focus of the study was to compare the impact of SFL recycling with non-recycling before landfilling. The impact intermittent activities, production of raw material and energy used in all the concerned processes were taken into account. However, transportation activities were excluded. The results showed that for all recycling rates, cement production is the main contributor to the environmental impacts, while sodium sulfide production is second and electrical production, the third. Mercury vapor emission showed a small contribution in carcinogens and ecotoxicity. The impacts are reduced when recycling rate is increased. The reduction of cement consumption in disposal processes or the process improvement of cement production may also help to reduce environmental impacts.     

Life cycle assessment of MSW-to-energy schemes in Thailand

Life cycle assessment was performed to evaluate environmental impacts of two municipal solid waste (MSW) to energy schemes currently practiced in Thailand: incineration and anaerobic digestion. Potential impacts such as global warming, acidification, stratospheric ozone depletion, and photo-oxidant formation were avoided due to net electricity production and also fertilizer production as by-products from the anaerobic digestion scheme. In addition, the anaerobic digestion resulted in the higher net energy output compared to the incineration scheme. However, the incineration had less potential impact for nutrient enrichment. The LCA results were also useful in determining where the improvements could be made for both the schemes. In order to adopt a sustainable waste management system elsewhere in the country, decision makers may need to consider a combination of techniques, or an integrated method of management. LCA could serve as an invaluable tool for such an analysis.     

LCA approach to the automotive glass recycling

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Life cycle assessment applied to egg packaging made from polystyrene and recycled paper

In the present study, the application of life cycle assessment (LCA) for the comparison of two egg packages, from polystyrene and recycled paper, is presented. The input and output streams of mass and energy are examined and the environmental impacts associated with the two systems are analyzed. The application of LCA by using EcoIndicator 95 has made possible the comparison of the environmental impacts of two egg packages. The results of this LCA study are discussed and reveal that the PS packages contribute more to acidification potential, winter and summer smog, while recycled paper egg packages contribute more to heavy metal and carcinogenic substances impact. Nevertheless, it seems that paper eggcups have less environmental impact than the polystyrene ones with the assumption that the accuracy of the results is confined by the credibility of European databases used for primary data.     

废电路板非金属材料再生木塑产品环境安全性评价

为了评价废电路板非金属材料再生产品使用过程中的环境安全性问题,本文针对非金属材料再生产品的特性,参考相关评价标准,结合目前现有的环境危害评价方法和人体健康风险评价,构建了再生产品在使用过程中环境安全性评价模型.收集A、B两种再生木塑产品进行评价试验,评估其对环境和人体健康的潜在风险和危害.结果显示在不考虑水体稀释作用情况下,两种再生木塑产品对I类地表水均存在极度或重度污染的可能,对于其他类地表水环境风险较小,应避免在源头水等区域使用;对于地下水,产品B污染指数大于1,具有一定的环境风险;但是考虑在稀释情况下（5%）,两种再生产品对于地下水的污染指数均小于1;两种再生木塑产品的非致癌风险指数分别为0.03和0.41,均小于1,对人体健康的危害作用不明显.本文可为非金属材料再生木塑产品环境安全性管理提供评价标准和参考,有利于促进废弃电器电子产品资源化和无害化技术的发展．     

废电路板非金属材料再生木塑产品环境安全性评价

为了评价废电路板非金属材料再生产品使用过程中的环境安全性问题,本文针对非金属材料再生产品的特性,参考相关评价标准,结合目前现有的环境危害评价方法和人体健康风险评价,构建了再生产品在使用过程中环境安全性评价模型.收集A、B两种再生木塑产品进行评价试验,评估其对环境和人体健康的潜在风险和危害.结果显示在不考虑水体稀释作用情况下,两种再生木塑产品对I类地表水均存在极度或重度污染的可能,对于其他类地表水环境风险较小,应避免在源头水等区域使用;对于地下水,产品B污染指数大于1,具有一定的环境风险;但是考虑在稀释情况下（5%）,两种再生产品对于地下水的污染指数均小于1;两种再生木塑产品的非致癌风险指数分别为0.03和0.41,均小于1,对人体健康的危害作用不明显.本文可为非金属材料再生木塑产品环境安全性管理提供评价标准和参考,有利于促进废弃电器电子产品资源化和无害化技术的发展．     

Waste management strategies for concrete

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.     

A comparative study on milk packaging using life cycle assessment: from PA-PE-Al laminate and polyethylene in China

A Life Cycle Assessment (LCA) approach was used to compare the environmental impacts in the life cycle of two milk packaging systems, PA-PE-Al laminate—a laminated foil made from paper, polyethylene and aluminum foil—and polyethylene. The data for the mass, energy fluxes and environmental emissions were obtained from published literature and from site investigations, for the two systems being analyzed for environmental impacts. The application of LCA using Eco-Indicator 99 has made the comparison of the environmental impacts of the two milk packages possible. The results of this LCA study are discussed and the results reveal that the composite packaging has a slightly higher environmental impact than the plastic one. In addition, the environmental impact of raw material extraction is the highest in all of the life cycle stages except for disposal. The environmental impact of composite packaging mainly comes from the fossil fuels, land use and respiratory inorganics categories, while the plastic packaging mainly comes from the fossil fuels category. However, the composite packaging has a greater environmental impact because it has not been well recycled and reused. This environmental impact could be decreased by developing the technology to separate out polyethylene and aluminum from the packaging.     

重复再生混凝土性能和环境影响研究

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.     

食用油聚酯包装的生命周期评价

采用生命周期评价法研究了食用油聚酯(PET)包装的生命周期环境影响,并对不同处置方式的环境影响进行比较评价. 通过现场和资料调研的方式获得所有生命周期阶段的能量物质的输入、输出和环境外排数据. 结果表明:PET包装原料获取阶段的环境影响潜值在全生命周期环境影响潜值中所占比例极高,占处置前环境影响潜值的81.8%. PET包装的全生命周期环境影响类别主要集中在化石燃料、无机物对人体损害和气候变化3个方面;在致癌、生态毒性和酸化/富营养化等方面的影响较小. 3种主要处置方式的环境影响潜值为焚烧＞填埋＞再生,其中焚烧和填埋分别增加PET包装处置阶段前环境影响潜值的5.1%和3.6%,而再生可降低63.9%.      

深圳市建筑水泥流量-存量分析及环境影响评估

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8...     

中国电动自行车动力铅酸蓄电池生命周期评价

以近年来中国用量增长最快的电动自行车动力铅酸蓄电池为对象,建立了生命周期环境影响评价模型,分析了从原材料生产、电池生产、电池运输、电池使用和废旧铅酸蓄电池及含铅废物回收处理全生命周期的环境影响.研究采用了大量企业调研数据和中国本土LCA数据库,以期反映整个中国铅酸蓄电池产业链的技术工艺和环境管理水平现状.结果表明,原材料生产和电池使用是资源(含能源)消耗的主要阶段,贡献了电池全生命周期绝大部分的环境影响.原材料生产贡献最多的全生命周期环境影响包括非生物资源耗竭(699%)、富营养化(89%)、光化学烟雾(98%)、臭氧层破坏(117%)、人体毒性(159%)和生态毒性(484%).电池使用过程的电耗间接消耗了83%的一次能源,相应地贡献了最多的气候变暖潜值(86%)和酸化潜值(70%).废旧铅酸蓄电池和含铅废物回收再生铅可抵消很大一部分原材料生产造成的环境影响.延长电池寿命,减少电池生产金属用量及提高废旧电池回收处理过程的工艺技术和污染控制水平也是减少铅酸蓄电池生命周期环境影响的关键.     

基于LCA的废弃手机资源化有效运输范围量化研究

基于生命周期评价方法（LCA）分析了废弃手机资源化过程的环境效益和跨区域运输过程的环境影响,并在此基础上提出了废弃手机跨区域流动的有效运输范围及其量化方法.通过采用IMPACT 2002+评价模型,从人体健康、生态系统质量、气候变化、资源消耗四方面对当前中国废弃手机两种典型资源化利用方案和运输过程的环境表现进行了评估.结果表明,两种资源化方案均表现出显著环境效益;部件再使用和材料再生过程是废弃手机资源化环境效益的主要贡献来源;综合考虑跨区域运输过程,在满足环境效益为正的前提下,包括部件再使用和不包括部件再使用两种资源化方案的有效运输范围分别为0~3094km与0~1248km.同时,对跨区域运输过程关键参数分析后发现,提高铁路运输占比和降低货车运输空返率可以有效扩大废弃手机跨区域转移的运输范围.     

地铁建设环境影响评估及减排效益研究:以深圳市为例

地铁大规模建设和运营消耗了大量资源能源,已逐渐成为城市交通环境影响的主要贡献源。基于生命周期评价(life cycle assessment,LCA)方法,以深圳市为研究区域,定量分析了地铁建设过程的资源与能源消耗强度,选取全球变暖潜能值(global warming potential,GWP)为度量指标,构建了地铁建设碳排放分析框架及测算方法,并基于情景分析法预估了减排潜力。结果表明:截至2020年底,深圳已开通运营的地铁线站建设造成的碳排放量约累积达到2730万t CO₂e,其中地铁车站建设碳排放量占比约为72%,地铁隧道建设碳排放量占比约为28%。建设阶段单位里程盾构隧道碳排放强度约为1.3万t CO₂e/km,单位面积车站碳排放强度约为371 t CO₂e/100 m2。通过推广绿色建造技术,如采用再生混凝土和再生钢材,地铁建设阶段最高碳减排率可达到8.5%/a,2021—2035年累积节碳可达到508万tCO₂e,可一定程度上能缓解地铁建设的碳排放压力。     

废铅酸电池回收制取再生铅合金技术的生命周期评价

废铅酸电池的回收利用已成为铅酸电池行业实现健康持续发展的关键一环.本文采用生命周期评价方法,分析了废铅酸电池回收制取铅合金技术及末端污染控制全过程的环境影响,并与废铅酸电池回收制铅锭再制电池材料和利用原生材料生产电池材料的过程进行了对比研究.结论表明废铅酸电池回收直接制取铅合金过程中铅膏熔炼和合金配制环节在各环境影响指标中的贡献较大(其中全球变暖潜值中占60%和33%,酸化潜值中占33%和54%,人体毒性潜值中占28%和57%),主要为辅助材料及能源动力带来的间接影响;利用原生材料生产电池材料过程的环境影响相对另两个过程更大,归一化的环境影响指标结果中人体毒性潜值、富营养化潜值及酸化潜值最大(分别为2.42×10~(-11)、1.26×10~(-11)和1.08×10~(-11)),其中铅原料生产的贡献比例占绝大部分.废电池回收直接制取再生铅合金与废电池回收制铅锭再制电池材料相比,环境影响表现更优,有利于形成电池生产企业的闭环循环过程,值得应用推广.未来应鼓励以废铅酸电池回收代替相应原生材料生产新电池,同时进一步减少回收过程中使用的资源能源环境影响,以带来更大的环境效益.     

废旧聚氯乙烯再生过程生命周期评价

生命周期评价是对产品、生产工艺以及活动对环境的压力进行评价的客观过程.运用生命周期评价方法,对我国南方某公司废旧聚氯乙烯再生过程的资源消耗和环境影响进行量化估算.结果表明:1 t废旧聚氯乙烯再生的总能源消耗量为6 287 MJ,其中石油消耗量为6 000 MJ,煤消耗量为287 MJ,总的资源耗竭系数为5.77×10-3 a;废旧聚氯乙烯再生的环境影响负荷为0.428 a-1,其中废塑料运输过程主要引起光化学臭氧合成问题,其环境影响潜值为0.190 a-1;工艺过程中主要引起固体废物污染,其环境影响潜值为0.110 a-1.废旧聚氯乙烯再生的主要环境影响为光化学臭氧合成、固体废物、大气颗粒物污染和酸化.