Solid wastes generation in India and their recycling potential in building materials

Presently in India, about 960 million tonnes of solid waste is being generated annually as by-products during industrial, mining, municipal, agricultural and other processes. Of this ∼350 million tonnes are organic wastes from agricultural sources; ∼290 million tonnes are inorganic waste of industrial and mining sectors and ∼4.5 million tonnes are hazardous in nature. Advances in solid waste management resulted in alternative construction materials as a substitute to traditional materials like bricks, blocks, tiles, aggregates, ceramics, cement, lime, soil, timber and paint. To safeguard the environment, efforts are being made for recycling different wastes and utilise them in value added applications. In this paper, present status on generation and utilization of both non-hazardous and hazardous solid wastes in India, their recycling potentials and environmental implication are reported and discussed in details.     

磷石膏的工业资源化利用进展

本文综述了废弃物磷石膏的产生和含有的杂质对其再利用的影响,以及磷石膏在工业上的应用情况,分析了磷石膏在应用发展中存在的问题并提出展望。对磷石膏的综合利用,既能将磷石膏再次资源化,节约资源,还能消除磷石膏堆积对环境造成的负面影响。实现磷石膏大规模综合利用迫在眉睫。     

磷石膏预处理工艺研究

经济、有效的预处理是磷石膏建材资源化的关键。系统研究了水洗、石灰中和、球磨、浮选、筛分以及煅烧等预处理工艺,分析了不同预处理工艺的效果,存在的问题及其可行性。提出了磷石膏建材资源化的预处理原则。磷石膏年利用量超过１０万吨,推荐采用水洗工艺,否则拟采用石灰中和球磨工艺。     

镁基固废再生材料的技术研究

镁基胶凝材料具有可多元改性的特点,与各种材料表面的亲和兼容性较好,力学强度优于钙质胶凝材料,防火性能达A1级。将镁基胶凝材料与固体废弃物资源化再生利用相结合,制备建筑材料,既可解决固废大量堆放占用土地和影响环境的问题,又能节约生产建材消耗的部分资源,具有重要的环境效益和社会效益,实现了环境保护、资源节约、循环经济的多赢。     

固体废弃物在软土加固中的应用现状

人口增长、迅速城镇化、工业化和经济发展导致在全球范围内以惊人的速度产生大量固体废弃物(以下简称固废),所以最大限度地利用固废生产绿色建材是当今材料业的一个研究热门。水泥作为一种最常见的软土固化剂,大量的生产造成了一定的环境破坏和资源消耗,而一些固废经过粉化之后,存在较好的水化活性,具有一定的胶凝性能,故利用这些固废替代水泥用于制作软土固化剂存在可能性。目前关于固废在软土固化剂上的研究较少,因此,利用固废研制一种软土固化剂,用来替代水泥,不仅能够节约资源,而且能够有效的保护环境。     

Cement-bonded composites from lignocellulosic wastes

A large quantity of lignocellulosic wastes is generated worldwide from various sources such as agriculture, construction, wood and furniture industries leading to environmental concerns. Use of these wastes in making cement-bonded construction materials can reduce the magnitude of the problems. However, in this effort there are various restraints like compatibility of these wastes with cement, their toxicity, and limited composite strength. This paper reviews the results of recent research into the use of these wastes in making cement-bonded composites used as building materials. The approaches like pre-treatments, use of chemical admixtures and modified manufacturing process, adopted to overcome the aforementioned drawbacks are described. The benefits and limitations of the use of such materials in building are also discussed.     

工业固体废弃物在建筑材料领域的应用

综述了工业固体废物在水泥、墙体材料、陶瓷材料及轻骨料生产中的利用现状,总结出在建筑材料领域工业固体废弃物资源化利用的主要出路。     

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.     

Cleaner phosphogypsum,coal combustion ashes and waste incineration ashes for application in building materials: A review

Application of phosphogypsum, coal combustion ashes and waste incineration ashes in building materials has been limited by the presence of minor components that are hazardous, such as radioactive substances, chlorinated dioxins and heavy metals, or have a negative impact on product quality or production economics, such as phosphate, fluoride, carbon and chloride. Source reduction, destruction of persistent organics and separation techniques may reduce the concentrations of such components. With a few exceptions, separation techniques currently lead to significantly higher (private) costs. Higher waste disposal costs, tighter regulations and higher prices for competing virgin minerals could make the use of the purified phosphogypsum and ashes in building materials more attractive.     

Study on lime–fly ash–phosphogypsum binder

In this study a new type of lime–fly ash–phosphogypsum binder was prepared to improve the performances of lime–fly ash binder which was a typical semi-rigid road base material binder in China. The modified lime powder had much higher activity than ordinary quick lime or slaked lime powder, it was the best alkali activator to prepare lime–fly ash–phosphogypsum binder. The optimum formulation of this binder was consisted of 8–12% modified lime, 18–23% phosphogypsum and 65–74% fly ash. The parallel experiments shown that lime–fly ash–phosphogypsum binder had higher strength than ordinary lime, cement, and lime–fly ash stabilized soils road base materials, granular soils stabilized with this binder had higher later strength than that of lime–fly ash or cement stabilizing granular soil, it had higher early strength and steady strength development. The phosphogypsum hastened the pozzuolana reactions between the lime and fly ash, it reacted with lime and fly ash also, this reaction formed some AFt and the formation of AFt brought on a slight expansivity which could compensate the shrinkage of the binder. The pore structure of this binder was finer than that of the lime–fly ash, so the strength and performances of the road base material stabilized with lime–phosphogypsum–fly ash binder was much higher than those of the lime–fly ash road base material.     

磷石膏不同预处理方法的效果比较

通过对比磷石膏最具代表性的3种预处理方法——水洗法、石灰中和法和煅烧法的预处理效果,经过3种预处理方式处理的磷石膏都满足建材制品使用要求,其中石灰中和对去除磷石膏中可溶性磷(P2O5)效果较好;煅烧法对去除磷石膏中可溶性氟(F)的效果较好,相比之下石灰中和法更加经济和适用。     

建筑与环保

阐述了化学、建筑工程与环境保护之间的联系。建筑材料生产、建筑施工、住房装饰、装修都要产生“三废”和对环境的污染。反之,环境污染对建筑物危害也不能忽视。加强环保意识,提倡化学建材、绿色建材、绿色建筑,势在必行。     

Utilization of Mn–Fe solid wastes from electrolytic MnO2 production in the manufacture of ceramic building products

The aim of this work is to evaluate the utilization of Mn–Fe solid wastes, originating from electrolytic manganese oxide production plants, as raw materials in the manufacturing process and on the properties of traditional ceramic building products such as bricks, roof or floor tiles. The Mn–Fe solid wastes are chemically and morphologically characterized. Subsequently, ceramic test specimens incorporating 2.5, 5, 7.5 and 10 wt.% solid wastes are made. Two different shaping technologies are used, namely compaction and extrusion. The green specimens are finally fired to different peak temperatures ranging from 950 to 1100 °C. The final products are characterized concerning important properties such as modulus of rupture, water absorption, weight loss and color. It appears that Mn–Fe solid wastes when used up to a percentage of 7.5 wt.% improve the basic properties of traditional building ceramic products. The results of this study are demonstrated by the successful pilot production of real size ceramic products.     

石灰改性磷石膏的工程性质研究

磷石膏改性后力学性质会大为改善,可用于多种类型的填方工程.文章分析了磷石膏的化学组分.提出了石灰含量与最优含水率的线性关系;试验表明石灰可以降低磷石膏的压缩性质,提高磷石膏的抗剪性能中.还分析了石灰改性磷石膏性质变化的化学机理,以及加入石灰的环境保护作用,综合比较提出了的石灰含量的变化对磷石膏工程性质的影响.     

重庆市工业固体废物的建材资源化

工业固体废物的简单填埋或直接堆放,不仅占用大量土地,而且严重污染周围的环境,因此工业固体废物的资源化利用是实现城市可持续性发展的关键环节之一,在多年的应用研究和广泛调查的基础上,本文介绍了重庆市的主要工业固体废物粉煤灰,脱硫石膏、矿渣、铬渣等的产业情况,以及它们在重庆建材行业的应用和研究情况,对重庆市工业固体废物的建材资源化过程中存在的问题和对策及工业固体废物建材资源化前景进行了探讨。     

胶凝材料复合早强剂开发及混合料浆配比优化

利用矿山周边矿渣、磷石膏、废石等固废开发早强胶凝材料用于矿山充填，可降低采矿成本，且实现固废资源化利用。首先基于试验材料物化分析，对胶凝材料复合早强剂进行开发；然后通过正交试验对多固废混合充填料浆进行试配，利用遗传规划获得最优配比。结果表明，复合早强剂可有效提高充填体早期强度，最优配比为芒硝1%～2%、NaOH 1%～1.5%、NaCl 1.5%；充填料浆最优配比为废砂比1:9、胶砂比1:5，料浆浓度80%；此时3d强度为2.04MPa,7d强度为4.19MPa，坍落度为28.6cm，分层度为0.75cm，强度和管输特性满足要求且成本最低。     

Environmental experts in the motor industry

Hazardous wastes are posing the greatest threat to the environment than ever before. Indiscriminate transfer of technology from the Developed Nations for the production of highly hazardous chemicals can lead to a frequent contamination of the environment with the hazardous wastes. The situation appears to be very serious in many of the Third World Nations, where basic problems of water supply and sanitation still need a solution. Contamination of the ground and surface waters with hazardous materials is likely to increase in the developing countries, owing to lack of suitable monitoring techniques. Location of the industries producing hazardous chemicals in the crowded cities has to be prevented to obviate recurrence of serious catastrophes in future. The situation appears to be equally alarming in the developed countries, where ground and surface waters are at a greater risk of contamination with the hazardous wastes. Co disposal of solid chemical wastes with the municipal solid wastes will result in a greater contamination of the ground and surface waters, with longer lasting environmental effects. Hazardous gaseous spills can have serious environmental effects, particularly if the spills contain radioactive contaminants. The intensity of a hazardous gaseous spill can be greatly enhanced under abnormal meteorological conditions.     

Use of animal proteins as foaming agent in cementitious concrete composites manufactured with recycled PET aggregates

Manufacturing of lightweight building materials is identified as an alternative procedure for valorising reused materials. With intent to valorise two wastes of food industry at the same time, this paper describes an innovative use of animal protein as foaming agent while consumed plastic bottle wastes are introduced as light aggregates.Relative changes in properties of concrete composites due to introducing proteins are experimentally investigated here.The results presented show that the two wastes clearly improve the flowability of the mortar. Both mechanical properties and bulk density of the composites are affected too, but thermal conductivity is improved. In this way, the obtained composites would appear to be low-cost materials which would contribute to resolving some of the solid waste problems in addition to conserving energy.     

城市大宗固废制备建材的环境评价体系研究

城市大宗固废资源化于制备建材是消纳固废的重要手段,本研究初步建立起科学合理的城市大宗固废制备绿色建筑材料的环境评价体系,以企业为主体,结合生产过程中的大气排放和建材产品使用和废弃时可浸出重金属进行评价,有助于提升我国固废资源化利用的整体技术水平,促进我国建材和建筑业的可持续发展。     

固体废弃物在蒸压加气混凝土中的利用与研究进展

大宗工业固体废物的量在逐年增加,占用环境资源,由于处理不当给社会生产带来了严重的环境问题。相关研究表明,大部分固体废物的成分中含有大量的SiO2和Al2O3等有效成分,可作为硅质材料投入蒸压加气混凝土生产使用。综述搜集了各种固体废物在蒸压加气混凝土中的应用研究,并对各种固体废物进行分类,分析固体废物应用于蒸压加气混凝土生产的可行性,并提出了当下存在的问题以及未来的方向。