基于水热固化技术的海砂利用研究

模拟地下水热系的成岩机理,利用水热固化技术在反应釜中将海砂固化成高强度(抗折强度≥20MPa)的新型建筑材料.结果表明:硅酸钙水合物(C-S-H)和托勃莫来石相的生成提高了海砂固化体的强度;消石灰掺量、固化时间和温度均影响C-S-H和托勃莫来石的生成;水热固化可使海砂固化体的氯离子溶出量大大降低,达到了中国建设部制定的建筑用海砂中氯离子含量(溶出量)标准.     

水热固化城市生活垃圾焚烧飞灰的研究

利用水热技术对城市生活垃圾飞灰进行资源化利用研究,将其固化成一种高强度的建筑材料。向飞灰中加入石英来引入硅质,使其于100℃水热固化,从而生成水化硅酸钙(CSH)等新的晶体。针对石英的添加量、水热反应时间和添加水的量等因素对样品抗折强度的影响进行试验与分析。研究结果表明,在100℃条件下,CSH的生成是影响固化体强度的主要原因,并且CSH生成量越多,样品强度越高。水热技术有望成为处理城市生活垃圾飞灰的有效方法。     

托勃莫来石与硬硅钙石的晶体结构与性质

水热合成的建筑材料,其中的胶结料主要是各种结晶形态的水化硅酸钙,最常见的是各种结晶程度的托勃莫来石(又称雪硅钙石)。托勃莫来石是一族水化硅酸钙,这族水化硅酸钙主要区别是结晶程度的差异,从几乎是无定形的化合物直到结晶良好的托勃莫来石。各种原材料的加气混凝土,蒸压养护制成的灰砂     

城市生活垃圾焚烧飞灰在建筑材料中的资源化利用

填埋处理生活垃圾飞灰造成对土地资源的大量消耗,并且垃圾飞灰中含有的重金属、二噁英及溶解性盐类对环境造成极大的安全隐患,对垃圾飞灰进行资源化利用是目前最有效的手段。综述了国内外对城市生活垃圾焚烧飞灰在建材领域的资源化利用现状,尤其对飞灰作为水泥混凝土、地聚合材料、微晶玻璃及陶粒的应用情况进行探讨。采用飞灰制备地聚合材料时利用率较高,成本及能耗较低,对重金属等有害物质固化效果明显,是最为有利的资源化利用方式之一。     

陶瓷废料水热固化技术在室内薄板材料上的应用

基于"元素循环"理念,模拟地下成岩机理,将陶瓷废弃物中的Si、Al和Ca元素,经水热固化技术转换为硅酸钙铝水合物(C-A-S-H)和铝代托勃莫来石,用于制作室内薄板材料,并采用万能材料试验机对薄板样品进行三点法抗折强度测试,同时采用X射线衍射(XRD)仪、傅里叶变换红外光谱(FTIR)仪、扫描电子显微镜(SEM)及湿度应答测试设备等研究其晶相、官能团、微观形貌和调湿性能.结果表明:原材料配合比和水热反应条件均会影响样品的抗折强度,当陶瓷废料掺量为70%,在约200℃、12h的水热固化环境下,样品的抗折强度最高可达23MPa;水热固化过程中生成的铝代托勃莫来石可以提升样品的孔隙率,使材料在具有高强度的同时还具备调湿功能.     

生活垃圾焚烧飞灰固化稳定化安全处置及建材资源化利用进展

生活垃圾焚烧发电是城市生活垃圾未来的主要发展方向,但其排放的飞灰属危险废物,含重金属等有害物质,对自然环境和人类健康存在潜在危害.飞灰的固化稳定化是当前主要的处置方式,同时也是资源化利用的主要途径.综述了目前国内外固化稳定化安全处置飞灰的主要方式,分析了各个方法的优缺点,总结了飞灰在建筑材料领域中的研究现状,探讨了未来...     

水热固化煅烧造纸污泥建筑材料的研究

纸制品在当今社会中的大量使用无可避免,而纸类产品的大量生产必然产生相应数量庞大的造纸污泥。进行了利用水热技术对煅烧造纸污泥灰固化方面的实验和探索。在200℃、9 h水热固化条件下合成了抗折强度达13 MPa的固化材料,研究表明,托勃莫来石的生成提高了样品的强度。有望利用于建筑材料,从而为环保、废弃物循环再利用和节能减排作出贡献。     

水热处理黄土制备多孔材料的研究

为了不破坏黄土本身的微细孔结构,进行了低温(200℃)水热合成黄土为多孔材料的研究。研究结果表明,Ca(OH)2添加量、水热合成时间对水热合成后样品的抗折强度有很大影响。样品强度增加的主要因素是托勃莫来石的生成。水热合成过程中,由于溶解/析出以及晶体生成等原因,可以产生大量微细孔,这使得控制多孔材料的孔径大小与分布成为可能。     

碳酸钙基建筑材料的水热法制备及硬化机理研究

为实现中国可持续发展,解决既可使用丰富石灰石资源制造建筑材料、又不使石灰石高温分解排放CO_2的矛盾,模拟了地底堆积岩的形成过程,在水热条件下将石灰石粉末与废玻璃混合,在低温(≤200℃)下固化成具有高强度的建筑材料,由于低温下石灰石不分解从而实现了CO_2零排放.研究表明:无机添加剂的含量、固化时间以及固化温度均会影响产品强度,生成的硅酸钙水合物(C-S-H)和托勃莫来石被证明是产品强度增加的主要原因.     

垃圾焚烧飞灰砂浆试验研究

随着城市生活垃圾焚烧处理方式的不断推广,焚烧飞灰的产生量也不断增加。由于垃圾焚烧飞灰中富含有害重金属,属于危险废物,必须进行无害化处理。应用常规的工艺方法,用飞灰取代部分水泥制备砌筑砂浆;研究了飞灰对砂浆拌合物稠度、凝结时间等基本性能以及砂浆的力学性能和重金属浸出规律的影响,并进行了微观分析。试验结果表明,虽然飞灰会损失砂浆部分强度,但是砂浆能大幅度地减少重金属的浸出量;水泥对飞灰中重金属的固化效果良好,同时以飞灰作为辅助材料制备砂浆可以作为飞灰资源化利用的有效途径。     

Characteristics of municipal solid wastes incineration (MSWI) fly ash–cement matrices and effect of mineral admixtures on composite system

An experimental work was carried out to investigate the feasibility of application of MSWI fly ash as an auxiliary cementitious material. The water demand for normal consistency, setting time, volume stability, flexural and compressive strength of MSWI fly ash–cement compound matrices were tested. And, the composite effect and the influence of mechanical properties and heavy metals solidification are studied by mixing MSWI fly ash–cement matrices with common mineral admixtures. The results show that the MSWI fly ash has some cementitious activity, but the reactivity is relatively lower and its addition to cement may lead to retardation of cement hydration. After incorporation of common mineral admixtures, the strength of solidified body was enhanced, and the effect of the heavy metals-immobilizing may be reinforced.     

焚烧灰中重金属溶出行为及水泥固化机理

垃圾焚烧飞灰是生活垃圾焚烧后烟气除尘器收下的物质，因其中含有水浸出性的重金属物质而被认为是危险废物，必须对之进行稳定化处理．主要研究了焚烧飞灰中重金属物质的浸出问题，考察了水泥对焚烧飞灰中重金属物质固化的效果．研究表明，用水泥稳定固化焚烧飞灰中重金属物质的效果良好，重金属物质通过物理固封、替代或吸附等形式可固化进水泥水化产物结构中．     

掺烧生活垃圾焚烧灰对生态水泥熟料物相及性能的影响

分别对掺烧生活垃圾焚烧炉渣及生活垃圾焚烧飞灰的熟料进行化学成分、XRD、水化性能与浸出毒性的分析,并与用化学纯试剂制备的熟料基准样进行对比研究。结果表明,灰渣中硫、氯等阴离子会降低熟料实际KH值;微量重金属元素则使灰渣掺烧熟料的铁相中C4AF特征峰的d值偏移。掺烧焚烧灰渣的熟料的安定性、标准稠度用水量、凝结时间、抗折强度与基准样相差不大,但是3d和28d抗压强度略有下降,应适当调高KH值予以抵销。掺烧灰渣熟料中重金属的长期浸渍溶出主要集中在早期,熟料对重金属的固化效果良好。     

水洗磷酸盐预处理后飞灰中重金属的热稳定性

探讨了磷酸盐对城市生活垃圾焚烧(MSMI)飞灰中重金属在常温下的稳定作用以及高温挥发抑制作用.结果表明,经水洗磷酸盐预处理后,常温下,飞灰中重金属Pb,Cd,Zn,Cr在毒性浸出程序(TCLP)中的浸出浓度低于美国EPA标准限值;高温下,飞灰中重金属Cd,Pb,Zn的挥发率分别由未处理参比样的97.2%,94.3%和79.3%降低至10.2%,23.5%,13.5%,均小于25%.     

垃圾焚烧飞灰研制硫铝酸盐水泥及其水化特性

以城市垃圾焚烧飞灰(以下简称焚烧飞灰)为主要原料,在实验室电炉里成功烧成了硫铝酸盐水泥熟料.研究了硫铝酸盐水泥熟料的烧成过程、组成及其形貌特征,并分析掺加适量石膏的硫铝酸盐水泥水化及重金属浸出特性.结果表明:将焚烧飞灰作为主要原料可以煅烧出以C4A3(-S)和C2S为主要矿物的硫铝酸盐水泥熟料,焚烧飞灰在生料中的掺量不...     

Geo-environmental application of municipal solid waste incinerator ash stabilized with cement

The behavior of soluble salts contained in the municipal solid waste incinerator (MSWI) ash significantly affects the strength development and hardening reaction when stabilized with cement. The present study focuses on the compaction and strength behavior of mixed specimens of cement and MSWI ash. A series of indices such as unconfined compressive strength, split tensile strength, California bearing ratio (CBR) and pH value was examined. Prior to this, the specimens were cured for 7 d, 14 d, and 28 d. The test results depict that the maximum dry density (MDD) decreases and the optimum moisture content (OMC) increases with the addition of cement. The test results also reveal that the cement increases the strength of the mixed specimens. Thus, the combination of MSWI ash and cement can be used as a lightweight filling material in different structures like embankment and road construction.     

Analysis of the genotoxicity of municipal solid waste incinerator ash.

Combined bottom and fly ash obtained from a Chicago, IL, municipal solid waste incinerator (MSWI) was extracted with organic solvents, water or acidified water. The mean amounts of organic material isolated from each extraction procedure were 688.2, 91.8 and 167.7 micrograms/g MSWI ash. These extracts were evaluated for toxicity and mutagenicity in Salmonella typhimurium strains TA98 and TA100. We developed and calibrated a micropreincubation assay to evaluate small concentrations of the organic extracts. No direct-acting mutagens were found, however the acid-treated aqueous extracts were toxic. Materials isolated with methylene chloride methanol were mutagenic after hepatic microsomal activation (S9). The mutagenic potencies of the organic extract normalized to a per gram ash basis was the induction of 103.46 revertants in TA98 and 247.5 revertants in TA100. The aqueous extracts were neither toxic nor mutagenic. However, the acid-treated aqueous extract was mutagenic to TA100. The organic material isolated from the acidic extract had an induced mutagenic potency of 44.2 revertants/mg extract. Normalizing these data indicate a mutagenic potency of 7.4 revertants/g MSWI ash leached.     

Interactions between municipal solid waste incinerator bottom ash and bacteria (Pseudomonas aeruginosa)

Municipal solid waste incinerator bottom ash (MSWI BA) can be used in road construction where it can become exposed to microbial attack, as it can be used as a source of oligoelements by bacteria. The extent of microbial colonization of the bottom ash and the intensity of microbial processes can impact the rate of leaching of potentially toxic elements. As a consequence, our objective was to highlight the mutual interactions between MSWI bottom ash and Pseudomonas aeruginosa, a common bacteria found in the environment. Experiments were carried out for 133 days at 25 degrees C using a modified soxhlet's device and a culture medium, in a closed, unstirred system with weekly renewal of the aqueous phase. The solid products of the experiments were studied using a laser confocal microscopy, which showed that biofilms formed on mineral surfaces, possibly protecting them from leaching. Our results show that the total mass loss after 133 days is systematically higher in abiotic medium than in the biotic one in proportions going from 31 to 53% depending on element. Ca and Sr show that rates in biotic medium was approximately 19% slower than in abiotic medium during the first few weeks. However, in the longer term, both rates decreased to reach similar end values after 15 weeks. By taking into account the quantities of each tracer trapped in the layers we calculate an absolute alteration rate of MSWI BA in the biotic medium (531 microg m(-2) d(-1)) and in the abiotic one (756 microg m(-2) d(-1)).     

考虑颗粒破碎影响的粗粒土的剪切强度理论

由于粗粒土的粒径相差很大,通过剪切试验测量粗粒土的剪切强度很麻烦,且剪切试验费时费力、试验数据离散性大;另外,已有剪切强度经验公式中的参数没有明确的物理含义,工程应用中难以确定。本文根据颗粒破碎的分形模型,揭示单颗粒破碎强度的尺寸效应,假设剪切强度是颗粒接触面上的摩擦力,导出用正应力幂函数表示的粗粒土剪切强度公式,幂函数的指数是颗粒破碎分维的函数,并采用垃圾炉渣的颗粒破碎分维和剪切强度试验结果进行验证。     

Comparison between laboratory and field leachability of MSWI bottom ash as a road material

The leaching properties of bottom ash from municipal solid waste incineration (MSWI) used as an aggregate substitute in unbound pavement layers are evaluated. The mechanical behaviour of bottom ash is acceptable for this application, but the potential environmental consequences constitute the most important limitation on the use of bottom ash as a road material. The environmental properties of bottom ash are assessed by means of the Dutch availability test NEN 7341 and the single-batch and two-stage batch European EN 12457 laboratory leaching tests. Furthermore, an experimental unbound pavement stretch is constructed to provide information on leaching behaviour under field conditions. In this high infiltration scenario, the results from predicted (based upon laboratory leaching tests) and measured releases (under field conditions) are compared, evidencing that predictions based on compliance leaching tests may be highly realistic. The depletion period of the extractable fraction of a number of elements in these field conditions is also quantified.