混凝土材料完全循环利用的策略研究

随着社会经济的不断发展与进步,城市化的进程逐渐加快,随处可见的是高楼林立。在建筑过程中,一系列浪费问题等造成了混凝土材料的利用效率低下,不仅造成了投资商资金的浪费,同时也不利于有效资源的二次利用。目前,促进混凝土材料的完全循环利用,是建筑企业,社会各界的重要要求,是节约资源,坚持可持续发展的重要步骤,亟需合理的,完善的予以解决。本文就混凝土材料完全循环利用的策略方面进行分析与探讨。     

混凝土循环利用及其对环境影响的初探

利用混凝土循环设计思想并通过一系列实验,探索废混凝土实现完全闭路循环再利用的可能性。运用寿命周期评价方法对混凝土进行了环境性能评估．结果表明,采取合适的混凝土配合比设计和适当工艺,可基本实现生态环境混凝土和水泥的无限循环利用,所得生态环境混凝土的环境性能明显优于一般混凝土。     

绿色高性能商品再生混凝土的开发研究

利用废弃混凝土循环再生骨料和粉煤灰、矿渣等配制绿色高性能再生混凝土可以很好地解决资源和环境的协调发展。本文对绿色高性能再生混凝土的工作性能和抗压强度进行了试验研究,结果表明,采用常规材料和适当的途径完全可以使再生混凝土实现高性能化,再生骨料不宜用来配制高强和超高强再生混凝土,高性能再生混凝土的破坏基本是界面破坏,且高性能再生混凝土轴心抗压强度与立方体抗压强度的比值高于普通混凝土的这一比值。     

废弃灰浆循环再利用系统在混凝土搅拌站中的应用

现在大部分混凝土生产企业均实现了生产废水循环利用,但沉淀后产生的灰浆却一直没有得到有效解决.为有效解决混凝土搅拌站生产过程中产生的灰浆,充分考虑混凝土生产特点,自行设计和研发了废弃灰浆循环再利用系统,完全实现了生产废水零排放,达到了节能环保的目的.     

硫酸盐腐蚀混凝土的损伤演化

基于腐蚀断裂试验,建立硫酸盐腐蚀下混凝土断裂韧度损伤理论,分析和预测了硫酸盐腐蚀损伤特性;构建了混凝土材料损伤预测模型和计算公式。研究不同硫酸盐浓度对混凝土材料的损伤影响。分析结果表明,随着腐蚀时间的增加,溶液腐蚀影响加剧,腐蚀影响造成的损伤都使得混凝土构件的性能完全劣化,只是在时间上有所差异。尤其在干湿循环条件下,腐蚀时间在6个月时,混凝土已经接近完全损伤。     

再生集料混凝土循环利用的试验研究

随着再生集料混凝土技术的成熟知大量应用，今后对于到了使用年限的废弃的再生集料混凝土的处理又将成为一个新的课题。本试验研究了再生集料多次循环利用的可能性。本文通过大量实验证实：用废弃混凝土作为集料来配制再生混凝土是对废弃混凝土利用的最为经济可行的方法，所配制的再生混凝土完全能满足相应施工要求，而且对废弃混凝土可实现真正的循环利用。本试验研究为再生集料混凝土实现真正的资源化循环利用提供了实用的参考数据。     

生态环境与混凝土技术

本文阐述了生态环境与混凝土技术之间的关系,提出生态水泥,再生骨料混凝土,绿化混凝土等概念。倡导用先进的科学技术,循环利用混凝土材料,保护生态环境。     

陶瓷饰面砖混合废料再生循环利用之实践探索

在两个实验性项目中,将建筑立面改造产生的陶瓷饰面砖混合废料回收后,加工制成再生骨料,结合技术创新和设备改良,分别备制纤维增强混凝土墙板和空心混凝土砌块。通过经济、环境和社会效益评估,探讨建筑废弃材料再生循环利用的适宜途径。应考虑材料生命周期,用长远眼光实现材料的可持续循环利用。     

绿色高性能混凝土的技术支持

结合绿色高性能混凝土的特征，从水泥性能及生产过程，废渣应用技术，高性能混凝土生产，可完全循环利用混凝土的生产等角度，论述了在我国发展绿色高性能混凝土必须的技术支持。     

沥青混合料再生技术的的应用及其技术进步

在沥青混凝土道路的日常维护、改造升级和翻新作业的路面重铺工程中,会产生大量的沥青混凝土废旧材料。这些废旧材料的数量与路面工程中挖切路面的厚度成正比。如此大量的废旧沥青混凝土材料,只有通过再生利用才能变废为宝,实现筑路材料的循环利用。自20世纪90年代以来,已引起了世界范围内公路工程和道路养护部门的高度重视,并已在道路工程中取得了良好的应用效果。     

碱胶凝材料的哲学基础

碱胶凝材料是利用磨细的高炉矿渣、粉煤灰、电热磷渣等工业废料或火山灰等天然矿物为原料,碱化合物或含碱工业废渣为激发剂制得的水硬性的胶凝材料。目前,社会上普遍关注的是环境问题和可持续发展问题,而碱胶凝材料的研制与开发实现了水泥工业的可持续发展和人与环境的相互协调,利用碱胶凝材料制备的生态混凝土工艺简单,原料来源广泛,同时在制备过程中能实现低造价和低能耗。     

New construction material from concrete production and demolition wastes and lime production waste

New construction materials were developed and patented in Brazil, based on concrete production and demolition wastes mixed with lime production waste. The main objective of this research is to utilize these two types of industrial wastes on as large a scale as possible as a new raw materials for the production of concrete. The lime waste is characterized by a high content of SiO₂, Al₂O₃, CaCO₃ and other elements. After 90 days of aging in open air, the water absorption value of the sample mixtures was 12% and the uniaxial compression strength reached up to 33 MPa, with an average of 29 MPa. XRD and SEM analyses of the compositions reveal various reasons for the material’s increased strength, including transformation of the initial mineral mixture (lime and Portlandite) into calcium, magnesium and amorphous ferrous and crystalline carbonates (Calcite, Dolomite and Ancerite), and chemical interactions of the concrete waste with the lime component, which led to the growth of new amorphous and crystalline calcium hydrosilicates such as Tobermorite, Afwillite and the CSH mineral group. Although this research does not include an economic feasibility study, the zero cost of these novel raw materials for concrete is self-explanatory. However, the main advantage expected from these materials is the environmental conservation they afford, represented by the use of concrete production and demolition wastes and lime production waste.     

建筑固体废弃物治理全生命周期环境影响评价—以废旧粘土砖为例

为定量评价建筑固体废弃物治理的环境影响,基于生命周期评价（LCA）理论和建筑工程环境表现评价系统（BEPAS）,综合考虑废弃物治理过程的环境代价以及再生材料的环境收益,以净环境代价为指标,建立了建筑固体废弃物治理环境影响评价框架。根据实际案例,定量评价了废旧粘土砖几种典型治理方式的环境影响,结果表明:填埋的净环境代价较高,其次是重复利用,而再生利用的代价相对较低;在再生利用方式中,净环境代价从小到大依次为水泥混合料、混凝土砌块原料、免烧砌筑水泥原料、混凝土骨料、烧砖瓦原料,其中烧砖瓦原料的净环境代价为正值,即所得到环境收益不足以弥补其环境代价。     

Effect of used engine oil on properties of fresh and hardened concrete

There is a current trend all over the world to investigate the utilization of processed and unprocessed industrial by-products and domestic wastes as raw materials in cement and concrete. This has a positive environmental impact due to the ever-increasing cost of waste disposal and stricter environmental regulations. Historically, reference books on concrete technology and cement chemistry indicate that the leakage of oil into the cement in older grinding units resulted in concrete with greater resistance to freezing and thawing. This effect is similar to adding an air-entraining chemical admixture to the concrete. Such information is not backed by any research study reported in the literature. The objective of the research reported in this paper was to investigate the effects of used engine oil on properties of fresh and hardened concrete. The main variables included the type and dosage of an air-entraining agent (commercial type, used engine oil, or new engine oil), mixing time, and the water/cement ratio of the concrete. Results showed that used engine oil increased the slump and percentage of entrained air of the fresh concrete mix, and did not adversely affect the strength properties of hardened concrete.     

Use of waste marble aggregates in concrete

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.     

Properties of blended cements with thermally activated kaolin

Kaolin, one of the materials of major importance for the ceramic and paper industry, is also used in the construction industry as a raw material for the production of white cement clinker and, in the form of metakaolin, as an artificial pozzolanic additive for concrete. Metakaolin is a vital component of high-performance and architectural concrete; however, its application in regular concrete is very limited due to relatively high production costs. This report evaluates the performance of a low-cost metakaolin-based additive called thermally activated kaolin (TAK), in cement. Due to its pozzolanic properties and the densification of cement matrix, the application of TAK provides a 15% improvement of the compressive strength. It was shown that TAK of optimal quality can be manufactured by the thermal treatment of raw kaolin with 74% of kaolinite at 750 °C without the intermediate beneficiation stage. The application of a developed approach can significantly reduce production expenditures and make the application of such an additive feasible even in regular-grade cement and concrete.     

电厂生物质燃料余灰对水泥瓦性能的影响研究

对电厂生物质燃料余灰在压制成型水泥基材料(瓦)中的应用进行研究,并在水泥瓦实际生产线上进行了试生产,结果表明:在灰砂比2∶3、水灰比为0.26的条件下,随着余灰掺量的增加,水泥试块的抗折强度呈明显下降趋势,而吸水率却逐渐增大;余灰取代30%水泥、憎水剂硬脂酸钙掺量为1.0%,水泥试块抗折强度、吸水率及抗冻性指标综合最优。在掺有憎水剂硬脂酸钙的情况下,余灰取代部分水泥(30%)生产水泥瓦是可行的。     

水泥粉煤灰复合发泡轻质保温砌块的研制

以水泥、粉煤灰为主要原料,掺加适量激发剂、促凝剂和胶粉,利用自主研制的高效发泡剂,采用先独立发泡,再将泡沫与料浆混合的工艺方法制作水泥粉煤灰复合发泡轻质保温砌块,研究了砌块的生产工艺流程。进行了砌块试样制作,性能测试,结果表明,水泥粉煤灰复合发泡轻质保温砌块的干密度为318 kg/m3,28 d抗压强度为1.2 MPa,导热系数为0.088 W/m.K,各性能指标均满足GB/T 11969-2006《蒸压加气混凝土砌块》标准要求。     

Effect of different fibers on the mechanical properties of concrete containing fly ash

The results of an experimental investigation to study the effects of replacement of cement (by weight) with three percentages of fly ash and effects of addition of steel and polypropylene fibers are presented. Current day knowledge of concrete technology focuses attention primarily on the use of different materials in the production of concrete, industrial wastes in particular. The use of fly ash in concrete today is an important subject and is growing in importance day by day. Using fly ash in concrete may both provide economical advantages and better properties in the production of concrete. Besides, concretes produced with three different replacement ratios of fly ash and three different types of steel and polypropylene fibers were compared to those without fibers used in concrete with FA. According to the results of the study, addition of fibers provide better performance for the concrete, while fly ash in the mixture may adjust the workability and strength losses caused by fibers, and improve strength gain.     

C50高性能混凝土在箱梁施工中的应用

从主要原材料选取与配合比设计两方面介绍了高性能混凝土制备的要点,并结合工程实例,阐述了C50高性能混凝土在箱梁施工中的技术要求,指出高性能混凝土减少了水泥用量,降低了生产成本,非常适合钢筋密集位置混凝土的施工。