水泥回转窑固化处理废弃重金属元素的实验研究

废弃的重金属化学试剂是一类危险的固体废物.通过在水泥回转窑中添加质量小于水泥质量的重金属化学试剂的实验研究表明(本实验添加质量约为水泥的0.1%):掺加化学试剂重金属元素后,各水泥熟料的XRD图谱相似,水泥熟料主要矿物相没有发生大的改变;重金属化学试剂的添加对水泥的7 d、28 d抗压强度的影响较小,符合国家标准;熟料试样在其水化28 d时各重金属的浸出量都很低,已低于工业固体废物浸出毒性鉴别标准规定的指标,由此表明利用水泥回转窑处理废弃化学试剂方法可行.     

钢渣掺量对泡沫混凝土砌块性能的影响

泡沫混凝土是一种环保、节能的保温隔热材料，以其优良的保温性能，受到越来越多研究者的关注。对钢渣的特性进行了分析测试，对钢渣不同掺量对泡沫混凝土砌块特性的影响进行了研究，结果表明，采用添加5％～35％钢渣所制备的钢渣泡沫混凝土砌块，其密度等级为JC／T1062—2007中的B10级，掺人5％、15％钢渣的泡沫混凝土抗压强度达到A3．5等级，掺人25％、35％钢渣的泡沫混凝土抗压强度达到A2．5等级。随着钢渣掺量的增大，抗压强度、抗折强度降低，吸水率增大。在同一钢渣掺量的情况下，泡沫混凝土砌块的抗压强度变化率增加显著，而且随着钢渣的加入量升高而增大。钢渣的加入有利于提高泡沫混凝土砌块的后期抗压强度。     

赤泥掺加硅灰用于道路基层材料的试验研究

选用洛阳某铝业尾矿库赤泥为试验材料,添加不同量的水泥、粉煤灰和硅灰,采用单因素正交试验,分析赤泥固化体的无侧限抗压强度、微观形貌及其浸出液的pH、含氟量,得出赤泥道路基层材料的最佳配合比:水泥掺量10%(质量分数,下同),粉煤灰掺量10%,硅灰掺量15%。该配合比在工程上不仅能满足道路基层技术要求,通过掺加硅灰还减小了水泥掺量,使赤泥固化体浸出液的碱性和含氟量降低。     

碱激发电解锰渣制备水泥掺合料

电解锰渣是湿法冶炼金属锰的残渣,为降低其对环境的浸出毒性影响并提高其在水泥产品中的掺入量,利用碱激发技术处理电解锰渣制备水泥掺合料是一种可行的方法。主要研究了碱激发剂种类、掺量对电解锰渣的激发效果,并将碱激发电解锰渣用作水泥掺合料与水泥按不同比例混合研究对水泥抗压强度和浸出毒性的影响。结果表明:碱激发电解锰渣活性显著提高,NaOH中Na_2O当量为10%时试件M-SH10的3、7、28 d抗压强度最高,分别为7.15、9.46、10.03 MPa;将此条件下激发的电解锰渣按质量比取15%与85%的水泥混合制得的掺合料其抗压强度较净水泥试件有一定程度的提高;浸出毒性结果显示Cd、Cr、Pb、Ni、Mn和Zn浓度均下降,且低于GB 8978-1996限值。     

垃圾焚烧飞灰水泥固化体的抗压强度和浸出性研究

利用垃圾焚烧飞灰掺入普通硅酸盐水泥制备水泥固化体,通过浸出性实验,研究了飞灰掺量(0%、20%、40%与60%)、浸出液pH及水洗预处理对水泥固化体抗压强度及重金属(Zn、Pb、Cu、Cd、Cr、Ni)浸出的影响。结果表明:对于非水洗飞灰水泥固化体,pH为4.2和10.0下浸出84 d时,相同组成固化体抗压强度较为接近,飞灰掺量20%,40%和60%的固化体抗压强度分别为41、15和10 MPa左右;除掺量为40%和60%的固化体浸出液中重金属(pH为4.2时Ni和Pb,pH为10.0时Ni)超出生活饮用水卫生标准(GB 5749-2006)外,掺量为40%和60%的固化体的其余浸出液及掺量20%的固化体浸出液中测定的重金属浓度均符合生活饮用水卫生标准。对于水洗飞灰水泥固化体,pH为4.2和10.0下浸出84 d时,相同组成固化体抗压强度较为接近,飞灰掺量20%、40%和60%的固化体抗压强度分别为37、32和10 MPa左右;除掺量为60%的固化体浸出液(pH为4.2和10.0)中Ni和Pb均超出生活饮用水卫生标准外,掺量为60%的固化体的其余浸出液及飞灰掺量20%和40%的固化体浸出液中测定的重金属浓度均符合生活饮用水卫生标准。飞灰水洗预处理提高了飞灰掺量40%水泥固化体抗压强度,同时降低了重金属浸出性。     

采用化学发泡法制备发泡钢渣水泥

以自制的钢渣水泥(钢渣用量达到60%)为主要的胶凝材料,利用双氧水分解反应的化学发泡法制备发泡水泥,分别研究发泡剂掺量、催化剂二氧化锰、发泡时的搅拌水温、水胶比及玻璃纤维对发泡过程及制备的发泡水泥性能的影响。实验结果表明:催化剂二氧化锰对双氧水分解反应的速率影响较大,加入催化剂后的发泡速率成阶段性变化,但发泡后的最终体积趋于一致;当双氧水用量为4%时,发泡水泥7 d的抗压强度为0.61 MPa,干密度达到556 kg·m-3;发泡时搅拌水温控制在30℃时,发泡过程基本在24 min内结束,发泡效果较好;发泡水泥的抗压强度、干密度随着水胶比的增加而降低;玻璃纤维对发泡水泥孔结构的形成有影响,当玻璃纤维量为0.4%时,其在0~1 mm、1~2 mm内分布的孔较多,整体上孔分布较为均匀,7 d的抗压强度达到0.72 MPa。     

电镀污泥基胶凝材料的制备及性质分析

将电镀污泥作为混合材料掺到水泥中,取代部分水泥熟料制备电镀污泥基胶凝材料。测定了胶凝材料试样的标准稠度用水量、凝结时间、胶砂流动度、强度等物理性能指标,同时分析胶凝材料试样的微观水化性能与累积孔体积,测定了胶凝材料的重金属浸出浓度。结果表明,在电镀污泥掺量为0.5%(质量分数,下同)时,制备的胶凝材料试样强度达到《通用硅酸盐水泥》(GB175—2007)规定的52.5R级水泥强度标准;在掺量为1.5%、2.5%时,制备的胶凝材料试样强度达到GB 175—2007规定的42.5R级水泥强度标准,且重金属浸出浓度满足《危险废物鉴别标准浸出毒性鉴别》(GB 5085.3—2007)要求。微观测试表明,电镀污泥的掺入使得水化放热总量降低。     

流化床锅炉飞灰活性激发与建材利用的试验研究

流化床锅炉飞灰活性较差,常规的粉煤灰活性激发方法对该飞灰效果不佳.本研究采用了加入适当激发剂的方法激发其活性,结果表明,加入激发剂后水泥胶砂的早期抗折、抗压强度均有100%的增长,后期抗折强度提高约100%、抗压强度提高60%以上,凝结时间和安定性均符合要求.水泥中飞灰掺量达40%时,其胶砂各龄期强度均达到甚至超过了42.5R水泥的强度;飞灰掺量65%～75%时,胶砂强度显示仍可生产一些低强度要求的建材产品,如砌筑水泥、建筑砂浆等.采用XRD、SEM等微观测试手段对飞灰活性激发机理进行了探讨.     

垃圾焚烧飞灰中Cd、Pb、Zn的螯合稳定与水泥固化处理

采用有机硫稳定剂(DTCR)与水泥对城市垃圾焚烧飞灰进行稳定/固化处理,研究了飞灰中Cd、Pb、Zn的浸出毒性和固化体的抗压强度,比较了螯合稳定与水泥固化对Cd、Pb、Zn的处理效果、养护时间对固化体抗压强度的影响,并对飞灰的结构形貌进行了分析。结果表明,在稳定固化过程中飞灰中发生了复杂的螯合、水化反应,重金属形态由不稳定态向稳定态转变,螯合稳定对Cd的处理效果最好,水泥固化更适用于Pb、Zn。固化时间大于7 d后,飞灰中的重金属以及固化体的抗压强度已较为稳定。螯合稳定协同水泥固化的处理效果优于单一的稳定或固化方法,飞灰在固化7 d后可同时达到重金属浸出毒性和抗压强度标准,满足安全填埋要求。     

利用建筑垃圾和碱渣制备蒸压加气混凝土

为实现建筑垃圾和碱渣二次资源的综合利用,考察利用建筑垃圾和碱渣为主要原料制备蒸压加气混凝土的可行性。通过测试蒸压加气混凝土的干密度和抗压强度,确定适宜的原料配比和蒸压养护条件,并通过XRD、SEM和FTIR对蒸压加气混凝土样品的矿物组成、微观结构进行分析。结果表明,在建筑垃圾、碱渣、石灰、水泥、石膏、铝粉掺量分别为50%、20%、10%、18%、2%和0.1%、蒸压压力1.5MPa、蒸压时间6h的条件下,制备的蒸压加气混凝土性能达到《蒸压加气混凝土砌块》(GB 11968-2006)A7.5、B07级要求,且蒸压加气混凝土样品的主要物相为托贝莫来石、半结晶CSH(I)和少量方解石、石英和硬石膏,托贝莫来石、硬石膏和水化硅酸钙凝胶相互交错形成多孔结构,部分Si—O—Si和Al—O—Al断裂,[AlO4]取代了归属于[SiO4]中的Si—O—Si。碱渣的添加有助于激发建筑垃圾的活性,生成强度更高的含铝托贝莫来石,形成低密度高强度的蒸压加气混凝土。     

典型建筑固体废弃物再生骨料对环保砖性能的影响

随着我国城市化和工业化进程的快速推进,城市建设产生大量的建筑废弃物,燃煤电厂产生大量炉底渣,建筑固废的处置在城市可持续发展过程中备受关注。以建筑垃圾再生骨料、炉底渣和石粉等区域特色的骨料制备环保砖,系统考察了骨料对环保砖力学性能的影响。实验结果表明,再生骨料的种类对环保砖抗压强度的影响显著。再生骨料中混凝土的增加,环保砖抗压强度逐渐增加;而再生骨料中粘土砖含量的增加,环保砖抗压强度明显降低。环保砖抗压强度随炉底渣的含量增加而降低,石粉对环保砖抗压强度有提升作用。     

污泥焚烧灰固化处理技术研究

研究了硅酸盐水泥、高铝水泥、高岭土和β-萘系减水剂在污泥焚烧灰固化技术中的应用效果。考察了污泥焚烧灰固化块(以下简称固化块)的抗压强度,测定了固化块的重金属浸出毒性,并采用X射线衍射(XRD)和扫描电镜(SEM)分析固化块组成和微观结构。结果表明,4种物质对提高固化块的抗压强度均具有较好的效果,硅酸盐水泥、高铝水泥、高岭土和β-萘系减水剂的适宜掺量分别为10、30、20、1.0g(以100g污泥焚烧灰中掺加的质量计)。XRD和SEM分析结果显示,经固化处理后制得的固化块结构密实,存在石英(SiO2)、水化硅铝酸钙(CaAl2Si2O8)和水化硅酸铝钙(Ca2Al2SiO7)等物质,其中水化硅铝酸钙等凝胶物质有利于提高固化块的抗压强度。     

弧叶型旋转窑烧制污泥陶粒实验研究

实验选取污水污泥、粉煤灰和港口淤泥为原辅材料,采取正交实验设计物料质量配合比与烧制工艺参数,遴选出最佳物料配比和优化的烧制工艺;依照选定物料配比和工艺参数采用弧叶型旋转窑烧制污泥陶粒并测定产品的1 h吸水率,软化系数,堆积密度,表观密度,颗粒级配,粒型系数以及产品浸出毒性等技术指标,选取制得陶粒产品替代全部天然石料配制...     

Pozzolanic reactivity of the synthetic slag from municipal solid waste incinerator cyclone ash and scrubber ash

This study investigates the pozzolanic reactions and compressive strength of the blended cement manufactured using synthetic slag obtained from municipal solid waste incinerator (MSWI) cyclone ash and scrubber ash as partial replacement of portland cement. The synthetic slag was made by co-melting the MSWI scrubber ash and cyclone ash mixtures at 1400 degrees C for 30 min. Following pulverization, the different types of slag were blended with cement as cement replacement at ratios ranging from 10 to 40 wt %. The synthetic slag thus obtained was quantified, and the characteristics of the slag-blended cement pastes were examined. These characteristics included the pozzolanic activity, compressive strength, hydration activity, crystal phases, species, and microstructure at various ages. The 90-day compressive strength developed by slag-blended cement pastes with 10 and 20 wt % of the cement replaced by the synthetic slag outperformed ordinary portland cement by 1-7 MPa. X-ray diffraction species analyses indicated that the hydrates in the slag-blended cement pastes were mainly portlandite, the calcium silicate hydrate gels, and calcium aluminate hydrate salts, similar to those found in ordinary portland cement paste. Differential thermal and thermogravimetric analysis also indicated that the slag reacted with portlandite to form calcium silicate hydrate gels.     

脱硫灰用作钙质材料制备蒸压加气混凝土砖块

为实现半干法脱硫灰的资源化利用,采用半干法脱硫灰作为蒸压加气混凝土砖块中的钙质材料。对脱硫灰进行预处理,使其在含水量20%条件下消化2 h后,烘干。在其他条件不变情况下,掺入经过预处理后的脱硫灰,砖块的抗压强度会有明显的提高。增加经过预处理后的脱硫灰的掺入量,可以在不影响砖块的抗压强度性能的基础之上,降低砖块的干燥收缩值和导热系数,同时提高砖块的抗冻性能和保温隔热性能。     

Role of casting and curing conditions on the strength and drying shrinkage of greener concrete

The shrinkage of cement-based materials is a critical dimensional property that needs proper attention as it can influence the corresponding characteristics especially when the preparation of such cement-based material is done in hot weather. Studies have shown that the casting or curing conditions influence the performance of concrete. However, there is limited understanding of the combined role of casting temperature and curing conditions, especially for concrete made with unconventional binders. In this study, five supplementary cementitious materials (SCMs) were utilized as the substitute of the ordinary Portland cement (OPC) at different ratios to produce greener concrete and improve its characteristics and sustainability. The influence of four casting temperatures (i.e., 25 °C, 32 °C, 38 °C, and 45 °C) and two curing regimes (i.e., covering of samples using wet burlap and applying curing compound on the surface of samples) on the corresponding compressive strength and drying shrinkage at various ages was studied. The outcomes of this research revealed that the composition of the binders has a substantial impact on the characteristics of concrete. In addition, the casting temperature and curing regimes also have a huge role on the compressive strength of concrete produced with binary binders. For example, the compressive strength at 3 days of concrete made at 25 °C made with binary binders was reduced up to 31% compared to that made with only OPC as the binder when cured using wet burlap. Nonetheless, less than 38 ℃ was suitable to minimize the durability issues in the studied blended cement mixes.

     

Mitigating environmental impact of waste glass materials: review of the existing reclamation options and future outlook

The environmental impact of waste glass (WG) is one of the major challenges crippling sustainable waste management and mitigation. Reclamation of recycled materials from waste glass remains a tedious task amidst complex technological approaches. The challenge as seen in the global containment measures increase the proportion of waste glass and minimize the existing capacity of landfill space. In many works, findings have shown how best to minimize the impact of waste glass as evidenced in their inclusion as building materials such as cement, mortars, concretes and blocks. The concept of this paper is to appraise previous studies carried out on the use of waste glass as key contributing factor in structural building. The scope of this paper will be broaden to include various successes recorded in the evolution of concrete mixtures containing different proportion of recycle glass. Part of the setbacks noted in the inclusion of these recycled materials as matrix, filler or fibre are also reported in this paper. Also discussed is the durability of glass materials in varying conglomerate involving cement in reinforcement of building and structures. Thermal insulating properties of recycled glass are also considered in this work where considerable energy is saved due to their low thermal conductivity. Based on the analysis of various studies and other factors considered in this paper, it is established that recycled glass materials can be accommodated in structural buildings, while continuous research is necessary to adapt waste glass to high pH value of Portland cement.

     

Radiological Program of the Los Angeles County Air Pollution Control District

Abstract

One technology Geld tested under the SITE demonstration program was stabilization-solidification. The HAZCON process was one of those tested. It treats hazardous wastes, consisting of both inorganic and organic contaminants, by mixing it with portland cement, water and a proprietary additive called Chloranan in a modified cement mixer to produce a concrete mass. In evaluating the technology during the demonstration, two major criteria were investigated by using existing laboratory tests. These criteria were mobility of the contaminants before and after treatment and the long-term effect on mobility, and durability of the solidified masses. The former criteria was evaluated using various leaching tests, primarily the Toxicity Characteristic Leaching Procedure (TCLP) and permeability. The durability criteria was determined from weathering tests, wet-dry and freezethaw, unconfined compressive strength, microstructural analyses and sampling the prepared blocks from the demonstration twice at 9-month intervals. This paper describes the results of the field sampling performed 9 and 18 months after the initial field demonstration and relates it to the results obtained during the demonstration.

According to the data, little or no change in the chemical and physical properties of the blocks occurred. The technology is capable of immobilizing heavy metals. The organics were not immobilized and the treated material appears quite durable.     

Strength development of solidified/stabilized organic waste and optimum treatment design

Artificially contaminated (spiked) natural soils were solidified/stabilized using various combinations of commonly used additives, such as lime, cement, fly ash, activated carbon, and silica fume. The effectiveness of the solidification/stabilization (S/S) processes was evaluated based on experimental findings from compaction testing, unconfined compressive shear strength, and X-ray diffraction (XRD). Correlations of limited reliability between unconfined compressive strength and penetrometer and torvane measurements were derived. Results from XRD experiments indicated that certain organic contaminants (i.e., naphthalene and pyrene) might impact the S/S processes for a given combination of additives. The type and amount of organic contaminants also affected the pozzolanic reactions. Specifically, the absence or small peak intensity of pozzolanic product XRD patterns for a given combination of additives was a good indication that the type and the amount of organic contaminant present inhibited pozzolanic reactions. This phenomenon was tested and confirmed for actual field-contaminated samples.