Compound Effect of Dihydrate Gypsum and Silica Fume on Strength of Steel Slag-Cement Binding Materials

By adding small amount of dihydrate gypsum (CaSO4·2H2O) and silica fume in steel slag-cement system, steel slag-cement binding materials were prepared. And the dosage of CaSO4·2H2O and silica fume on the properties of steel slag-cement binding materials was studied. Hydration properties and paste structure were investigated by SEM and XRD. The results show that both CaSO4·2H2O and silica fume can improve the strength of steel slag-cement binding materials. Compared with single-doped, compound of CaSO4·2H2O and silica fume has much better effect on strength of steel slag-cement binding materials. The optimum proportion of CaSO4·2H2O and silica fume are 1% and 4%, respectively. The 3 d compressive strength is increased by 59.0%, and the 28 d compressive strength is increased by 36.5%. No matter adding CaSO4·2H2O and silica fume or not, the steel slag-cement binding materials have the same hydration products. However, the content of C-S-H gel and AFt crystals is higher, and the content of Ca(OH)2 crystals is lower in steel slag-cement binding materials containing CaSO4·2H2O and silica fume than those in steel slag-cement binding materials without CaSO4·2H2O and silica fume.     

脱硫石膏对乔木树种抗盐生理特性影响的研究

为了研究脱硫石膏提供的外源钙化合物对乔木树种耐盐性生理影响,本试验利用新疆阜康电厂脱硫石膏,研究外源钙化合物对4个树种(长枝榆、白榆、大叶白蜡、紫穗槐)的耐盐性、植物生理特性的影响。结果表明:施用脱硫石膏后,加快了林木生长,提高了林木的存活率、耐盐指数;增加了叶片中叶绿素a、叶绿素b、脯氨酸的含量和K+离子的吸收能力,但是却降低Na+离子的吸收。因此推测,外源钙化合物通过影响植物叶绿素和脯氨酸含量、调节植物体内K~+/Na~+的平衡,增加植物的抗盐性。     

Impacts of Wetting Fly Ash on the Properties of Concrete

Two types of wetting low calcium fly ash were made for studying the performance under different storage time (1 to 60 months). The surface morphology, granule size distribution of the wetting fly ashes and their properties as supplementary cementitious materials in concrete were investigated. Although the granule size increased and there appeared considerable erosion on the surface, the surface morphology of wetting fly ash kept mostly unchangeable. The water reducing effect resulted from mineral properties of fly ash decreased much due to wetting. Compared with a parallel concrete with dry fly ash, slump of concretes with fly ash of 20~40% wetting for 3 months decreased by 20~40 mm while bleeding and permeability and carbonation had no change. The compressive strength of concrete in 28 day and 60 days with fly ash of 30% wetting for 3 months decreased by 5.8% and 3.7% respectively. However, the specific compressive strength of concrete in 56 days with fly ash of 20% wetting for 36 months still reached at 85% and there was no visible strength discrepancy of fly ash concrete wetting for 3 and 5 years. It was concluded that a wetting low calcium fly ash could be used as supplementary cementitious material in some important concretes.      

Influence of Macromolecule-type Retarders on the Hydration and Microstructure of Hardened Paste

Influence of one macromolecule-type retarder bone glue on the setting time, strength, ion concentration in liquid phase and supersaturation degree, crystal morphology of dehydrate and microstructure of hardened paste of building gypsum is investigated. Furthermore, internal cause of strength loss of building gypsum with addition of retarder is analyzed, The results indicate that bone glue could retard the hydration of building gypsum markedly, but its negative influence on the strength of building gypsum is far lower than that of low molecule-type retarders. Bone glue has a minor effect on crystal morphology of dehydrate and porosity of hardened paste, but it causes the large crystal size and coarsening of pore size distribution of hardened gypsum paste, which is the very intrinsic reason of strength loss of building gypsum.     

Modification and Application of Fly Ashfor the Stabilization of Sludge

Under the microwave irradiation, a highly effective adsorptive material zeolitized fly ash (FZ) was made by adding a certain amount of mineralizer in the raw material of the limestone and fly ash. The structure of zeolite and the mechanism of modification were investigated by the analysis of XRD and SEM.The stabilization mechanism was analyzed and the variation of heavy metals and nutrient contents in sewage sludge were investigated through the sludge stabilization experiment by mixing zeolitized fly ash in the municipal sewage sludge. It was indicated that the zeolitized fly ash had obvious stabilization effect to heavy metals (Zn、Cu、Mn) and had apparent retention ability to the nutrients contents of N、P of the municipal sewage sludge. The heavy metals contents of Zn, Cu and Mn were all significant lower than those in the national control standards for pollutants in sludges from Agricultural. After the stabilization treatment of the municipal sewage sludge, the total content of N was lower than that in the national surface water environmental quality standards (10 mg/L), the total content of P was lower than that in Quality Standard of the Sewage discharged into the city sewer system(1 mg/L).     

Research and Production of Non-Fired and Non-Steam-Cured Clinker_Free Fly Ash Bricks

A fly ash brick is developed by using fly ash-lime-sulphate system as the binding material, added with certain quantities of aggregates and moulded by press, which can yield 28-day compressive strength up to 20 MPa under normal curing conditions. The factors affecting the strength of product are analyzed.     

Properties and Disposal of Municipal Solid Waste Incineration Fly Ash

Incineration has been used to dispose municipal solid waste(MSW) in the world.Attention is paid to the secondary pollution from municipal solid waste incineration(MSWI).Especially the safe and effective disposal of MSWI fly ash becomes an environmental and social problem which should be urgently resolved.The paper focuseds on the properties of MSW fly ash.The different kinds of technology of MSW fly ash are analysed in details.The main disposals of MSWI fly ash are filling,solidification and stabilization,and distilling heavy metals.The innocuous disposal of MSW fly ash which is compatible in China is impoldering advanced incinerator controlling the MSW and research effective and inexpensive stabilization chemicals and effective technique of distilling heavy metals to reduce the secondary pollution caused by the heavy metal of MSWI fly ash.     

Technology of Mixing High Property Concrete with Large Dosage Fly Ash

Being the largest mass of man-maded material, concrete demands much to resource and energy as well as affects much to environment. Whether concrete can be the dominating constructive material, the key is whether it can become green material and protect the environment at the same time. The important approach of developing is using industrial castoff largely in concrete. The tests note, that high performance concrete used of large mass of fly ash is doable. By grinding fly ash and adding high-efficient water reducer, when the dosage of cement clinker is only 25% and the dosage of fly ash is 70%, concrete with a good workability that 3 day and 28 day strength are bigger than 20 MPa and 50 MPa respectively can be achieved, which later strength develop very well. The large mass of fly ash concrete can utilize fly ash largely and reduce the dosage of clinker, that is very advantageous to protect environmental.     

盐碱土壤上石膏与有机物料组合对作物产量与籽粒养分含量的影响

为了研究不同改良物料（脱硫石膏、草碳、腐殖酸）单一施用与不同配比在盐碱土壤上对作物产量与土壤理化性质的短期改良效果,于2014—2015 年在山东乐陵地区进行了8 处理3 重复的随机区组试验。结果表明：第一季小麦相比未改良处理,脱硫石膏、有机物料单一施用及不同配比均没有显著增加小麦产量。玉米季时,脱硫石膏与腐殖酸单一施用与其1:2 组合与未改良处理在玉米产量上没有显著性差异,但脱硫石膏与腐殖酸1:1 组合实现玉米增产40%。改良物料1:1 组合措施显著提高了玉米籽粒的氮与钾浓度,同时降低土壤pH 0.5 个单位。土壤中的速效钾含量显著提高,交换性钠的含量显著降低,维持了土壤溶液中钾钠比的平衡。因此,盐碱土短期的改良过程中,脱硫石膏与腐殖酸1:1 组合施用,对于改良土壤盐碱具有一定的应用前景。     

Using Garbage Incinerator in Recycling Disposal of Fly Ash Technology Research

The technology of incinerator fly ash as the main material and the core carbonaceous reducing agent, and the necessary absorption of chlorine and catalyst made of composite pellets, Into the garbage incineration furnace temperature reduction decomposition of dioxin, heavy metal forming glassy slag. The fly ash harmless treatment, fly ash in the incineration plant in their complete closed circulation waste disposal to achieve, Provides the optimum technical route for the treatment of MSW fly ash.     

Study on Deep Treatment of Phosphorus in Secondary Effluent by Coal Fly Ash

In order to explore the best adsorbent and new way of removing phosphorus, this trial uses coal fly ash with PFS and alkali modified coal fly ash to deal with phosphorus in Secondary Effluent. The results: using the coal fly ash with PFS to deal with the model wastewater of 3mg/L, the removing rate can reach 72%. The combination of coal fly ash and PFS can make adsorption and coagulation express synergistic effect, and strengthen the Coagulation Effect. Using the NaOH modified coal fly ash to deal with phosphorus in Secondary Effluent, when dosage is 8g and stirs for 5min in 30r/min, the removing rate can reach 90%. After modified, coal fly ash expresses the adsorption, at the same time coal fly ash and phosphoric acid root ion settles, and strengths the treatment effect. Comparative analysis of the two methods, the NaOH modified coal fly ash can remove phosphorus effective and realize spate separation. This method can reduce the cost, and the metod is easy. It is worth to extensive application.     

三色堇对粉煤灰-醋糟基质的适应性探究

为了研究粉煤灰醋糟基质中的养分对植物生长的影响,对植物出苗期、幼苗期的N、P、K需求量进行研究,进而为基质配置中的养分调节提供理论依据,以三色堇为试材,在粉煤灰醋糟基质中配施以不同比例的N、P、K营养液,以德国泥炭、普通土壤为对照,综合分析植株的成活率、叶面积、茎粗、株高、鲜重、干物重、壮苗指数、水分散失状况等各项指标。结果表明,对三色堇生长影响最大的养分为P,尤其表现在幼苗期;不同养分配比之间具有明显差异,其中,N、P配比对三色堇的幼苗的壮苗指数影响较大,而N、K配比对植物生长无显著影响,以低N、高P、配合适宜的K含量为粉煤灰醋糟基质中三色堇生长的最佳养分配比;同时,基质的养分供应依赖于水分供应,调节基质的水分散失曲线是养分供应的基础。因此,在粉煤灰醋糟基质配置中,应首先针对不同的修复植物添加相应的养分;其次,通过调节基质配比来改善其水分供应状况,才能使植物修复粉煤灰污染的过程顺利进行。     

Influence of Cement Fineness and Components on Temperature Rise of Concrete

Adiabatic temperature rise of mass concrete is effected by many factors. Among those factors, the analysis of cement fineness and components is lacking. Influences of cement fineness, alkali content, replacement of fly ash, and gypsum content on temperature rise of concrete were investigated. The test results show that, temperature rise and temperature rise rate are improved with the increment of specific surface area of cement. When alkali content is ranging from 0.4% to 1.2%, the maximum temperature is reduced with the increment of alkali content, and the temperature-time will be extended whether too high or too low alkali content in cement. The increment of replacement of fly ash and gypsum content is good for reducing temperature rise of concrete.     

Crystallization Behavior of Glass-ceramics from Arc-melting Slag of Waste Incineration Fly Ash

To deal with the issue of municipal solid waste incineration fly ash, are melting treatment technology was developed in combination with electric arc furnace metallurgical processes. Glass-ceramics was made of arc-melting slag from waste incineration fly ash and additional glass cullet through crushing, pressing and sintering at temperature between 750 ℃ and 1050 ℃. The crystallization behaviours of the glass-ceramics were examined by differential thermal analysis (DTA), X-ray diffractometry (XRD) and scanning electron microscopy (SEM). It is shown that main crystalline phase of the glass-ceramics are wollastonite (CaSiO3) and diopside (Ca(Mg,Al)(Si,Al)2O6), and the diffraction peaks become more intensive at higher temperature. It is found that the glass-ceramics sintered at 850 ℃ has the optimal physical, mechanical and chemical characteristics, and it has density of 262 g/cm 3, bending strength of 5496 MPa, chemical resistance of 27% and 0.9% in acid and alkali solution respectively. Furthermore, the leaching concentration of heavy metals is very low.     

Strength and Microstructure of Sulphoaluminate Cement Containing Ultra- Fine CaCO3

The existence of ettringite in sulphoaluminate cement hardened paste is mainly in the form of pole-like crystal,which causes unfavorable effect on the cement.In this paper the strength and microstructure of the sulphoaluminate cement containing ultra-fine CaCO_3 weze discussed.Experimet results show that the strength of sulphoaluminate cement was obviously improved by adding 3% of ultra-fine CaCO_3.After curing for 28d,the compressive strength of cement paste and mortar is 100.6MPa and 94.1MPa respectively,and the bending strength of the mortar reached 12.5MPa.SEM study on hardened paste of sulphoaluminate cement containing ultra-fine CaCO_3 showed that its structure was dense and homogeneous,there was hardly any massive crystall detected.     

Characteristics of Hydration Products and Pore Structure of Super Sulphated Cement

The mechanical properties, hydration products, and pore structure of SSC(super sulphated cement) were tested with universal test machine,XRD(X-ray diffraction), SEM(scanning electron microscope) and MIP(mercury intrusion porosimetry), which were compared with P·O 42.5 and slag cement. Results show that the main hydration products of SSC are ettringite, C-S-H gel and little gypsum crystals, while without calcium hydroxide; SSC hardened paste has smaller threshold pore diameter, the most probable pore diameter, middle pore diameter and average pore diameter, and has lower porosity and higher density, which can effectively promote the 90-day strength increase of SSC paste.     

Effects of a New Retarder on Building Gypsum and Its Mechanism

We studied the effect of a new kind of retarder, hydroxy carboxyl compound (KH PT), on setting time and 28 d strength of building gypsum. We used a non contacting electrical resistance device and a scanning electric microscope to study the change of the hydration process and the crystal morphology of the gypsum. The results indicate the following: With increasing addition of new retarder, gypsum setting time extends. A new retarder content of 0.05% not only affects gypsum setting but also enhances gypsum strength. At a retarder content of 0.10%, the retarding effect is quite good with the setting time nearly reaching 1 hour. With increased new retarder content, the abrupt change stage of hydration resistivity of building gypsum is delayed, the resistivity stabilization stage decreases, the crystal enlarges, and the ratio of length to diameter decreases.     

Experimental Analysis High calcium Fly Ash Geopolymers Solidification/Stablization of Heavy Metals

Utilization of high calcium fly ash geopolymer to solidify/stabilize heavy metals was explored. The solidification/stabilization effectiveness of heavy metals was studied using static and dynamic leaching experiments. Additionally, transferring mechanism and long term safety of heavy metals in geopolymer were also investigated. The results show that the leaching concentrations of heavy metals from the solidified/stabilized matrix were far lower than the limit values, and all the solidified/stabilized ratios of heavy metals reached 98% when the geopolymer solidified/stabilized 0.025% Pb(II), 0.025% Cr(VI), and 0.01% Hg(II), respectively. The results Dynamic leaching experiment show that real time leaching concentrations of heavy metals were lower than allowable maximum values, and the accumulated leaching concentrations became stable after 72 h. After dynamic leaching experiment, the radial distributions of heavy metals in geopolymer specimens were similar. Effective diffusion coefficient and dynamic leaching ratios of heavy metals from geopolymer were very low, and this geopolymer has a good long term safety.