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Construction industry as one of the pillar industries of the national economy, nearly a hundred years has been the rapid development, which will inevitably produce large amounts of construction waste in the construction, use and demolition of buildings in the process.Currently, the number of construction waste has accounted for 30% to 40% of the total amount of municipal waste. Construction waste emissions have more than 400 million ton, including Beijing, Shanghai and other major cities in emissions are more than 30 million ton.The vast majority of untreated construction waste was shipped directly to the suburbs or the countryside using open dumps or landfills way deal, while piling up and you need to consume a large amount of land landfill, garbage removal and other construction investment, while removal and stacking process or scatter and dust has aggravated environmental pollution.In the modern city toward industrialization and urbanization development today, a lot of construction waste generated is threatening the natural environment for human survival. Developed to address the problem earlier on a series of fruitful research and practice, proven to achieve construction waste recycling is effectively solve the social problems of the recipe.But so far, China's construction waste resource related work is lagging behind, thus to society, the environment and resources to bring a variety of adverse effects. 1.Technical aspects Feasibility of construction waste as a raw material, including sand brick, wood, decorative tiles, soil and other miscellaneous waste any impact on product performance through research and analysis with relevant departments and experts believe that:? First, as long as careful handling of raw materials and strict management, entirely feasible; second, domestic equipment manufacturers can provide specialized equipment and production technology in September 2006 by the provincial scientific and technological achievements, the technology and processes leading domestic level. 2.Product performance Construction waste brick product performance depends on the characteristics of raw materials and forming machinery of the product by the national quality inspection center wall and roof materials testing, its brick and standard bricks conform JC943-2004 "concrete brick" and NY/T671-2003 "ordinary concrete bricks and decorative bricks" standards, and no radioactivity. In addition, the structure of the performance of this product is between sintered products and non-sintered products, bulk density and water absorption than ordinary concrete slabs, shrinkage resistance and thermal conductivity is smaller than the average concrete products. 3.Comprehensive benefits As the main raw material transportation cost is not required, it will be costing a lot in profit margins, plus value-added tax, income tax and maintenance fee relief for businesses, will undoubtedly increase greater market competitiveness, economic benefit. In addition, social and environmental benefits are very obvious. 4.Scale First, determine the market demand for space generation and construction waste, then we can decide the scale of production, construction land. If the construction of small-scale, social, environmental and economic benefits not obvious. Therefore, the project must gain the support of the government and relevant departments, and lay a solid foundation for building applications to achieve better product. 5.production technology 6.Ratio of raw materials (1)Select the cementitious material Initially considered is three materials: cement matrix cement, lime, gypsum. These involve not only the performance of cementitious materials products. Also affects the production costs. Through comprehensive analysis, the final choice of cement. (2)The particle size distribution of raw materials The ratio of raw materials, it is required in the construction waste soil composition (particle diameter of 5mm ~ 10mm) of not more than 3%, of coarse particles (particle diameter of 3mm ~ 5mm) not more than 30% of fine particles (diameter of 0.5mm ~ 3mm) not more than 30%, the powder (particle diameter of 0.5mm or less) not exceeding 30%. If too much powder, it will affect the strength, shrinkage is large, it is not easy molding; If fine particles excessive body of water can not be discharged. (3)Mixing a quantity of fly ash Production of new wall materials of construction waste, the main ingredient is construction waste. In order to improve the strength of the latter products, need some siliceous material, fly ash silica content of about 50%, and the ash is also solid waste. Therefore, fly ash is generally controlled at about 10%. (4)Shaping and molding pressure water In forming the body, the size of the water body and a molding pressure of critical water which affect strength of the molded article is generally 11% to 13% of each block forming a molding pressure to 50, for example, the choice of hydraulic vibration 180kN equipment.

With centralized incineration has become the main way of urban living garbage disposal. Incineration safe disposal and utilization of fly ash has become a scholar of common concern. Due to a variety of environmental factors shaped ring in the landfill process. Heavy metals in waste incineration fly ash migration and transformation may occur. So how to deal with the development of incineration ash society more and more attention. Prior to final disposal incineration ash must be stable, curing, because incineration fly ash contains a higher concentration of the leaching of lead, cadmium and other heavy metals, incineration ash of course also a special hazardous waste destined for landfill. In recent years, many cities are on the incineration ash curing treatment, and achieved good results. The characteristics of waste incineration ash The solid residue after incineration of garbage generated roughly 30% -35% by weight of the garbage, bottom ash which accounted for 25% -30%, the rest is fly ash, accounting for about 5% [2].Fly ash after burning heat recycling system, flue gas purification system to collect the material.Fly ash production and waste type, burning conditions, incinerator and flue gas treatment process related.Less heavy metals in waste incineration bottom ash produced, especially volatile metals such as: Pb, Zn, Hg, Cd less content, mainly because some metals such as lithology pro: Ni, Cr, Cu, etc., are generally considered no poison can be used as raw material for reuse.Such as Denmark, the Netherlands waste incineration bottom ash more than 90% of used car parks, dams, embankment fill material such as asphalt and concrete and aggregates, Germany and France, respectively, 60% and 45% of incineration bottom ash used as roadbed and municipal engineering [3] materials.Analysis showed that: waste incineration ash is not chemically inert substance, which can contain flooding out of Cd, Pb, Zn, Cr and other harmful heavy metals and salts.If direct incineration ash landfill or mishandled, in the natural environment due to the effect of acid rain and other factors, the acidic environment will gradually leaching out heavy metals, re-enter the environment, polluting groundwater and crimes against humanity [4].Meanwhile, the fly ash dioxin is also potentially important environmental pollutants. Since waste incineration fly ash and other heavy metals and dioxins difficult natural degradation, so its impact on the environment very seriously. Results Characteristics of heavy metals in fly ash and abroad show: Heavy metals having a high boiling condensation easily even in the combustion process, thereby forming the core of the fly ash, and volatile heavy metals at high temperature will decrease as the temperature of condensation in the fly ash surface, heavy metals in fly ash with fly ash particle size decreases and increases. Leaching of toxic heavy metals in fly ash and fly ash particle size, surface area, pH value, primarily dependent on the presence of heavy metals in fly ash morphology [5].Table 1 lists the hazardous waste leaching toxic identification standard. Incineration ash solidification processing required to meet the following requirements: (1) Cured after treatment by curing the formed should have excellent resistance to leaching resistance, wet and dry, penetration resistance, frost resistance, and must also have sufficient mechanical strength, the best effect is obtained by curing the curable can be reused as resources. (2)Must take into account the material and energy curing process that requires the use of the energy consumption as low as possible, but also should take into account the capacity increase ratio, Capacity ratio is an important indicator for the evaluation of the curing method, while increasing really depends on the size of the infiltration capacity ratio and an acceptable level of salt curing toxic and harmful substances in the body. (3)Curing process to be as simple and easy to operate, easy to use. (4)Source curing agent should be more widely used, but cheap and easy to get. (5)To lower the cost of curing, so that it can be widely promoted. The current implementation of the stabilization process still has the following three methods: 1.Cement curing technology: cement curing is fly ash, cement by mixing an appropriate amount of water to make a method of curing, the curing mechanism is in the process of hydration of cement, by adsorption, chemical absorption, sedimentation, ion exchange, passivation and other means, the ultimate form of heavy metal hydroxides or hydrated silicate complexes remain in the surface of the cement cures to form CSH gel, while cement is added also provides an alkaline environment of heavy metals, inhibiting heavy metals in the fly ash leachate. Fly ash cement solidification technology is a relatively mature hazardous waste treatment technology has obvious advantages in terms of economics and operational, but the amount of cement is high, resulting in high capacity increase solidified over time, solidified part of the gradual dissolution of toxic substances may be long-term, the existence of a potential threat to the environment. 2.Melting and solidification technology: the melting and solidification technology mainly to small mixing fly ash and glassy, after mixing granulation molding, melting at 1000-1400 ℃ high temperature, usually around 30min (melting time depending on the nature of the fly ash may be) , fly ash upon the physical and chemical state changes, cooling cured to form a cured body of glass, with a dense crystalline structure of the vitreous, to ensure stability of heavy metals. Melting and solidification technology for residue volume reduction rate, curing effect is good, but the fatal flaw is part of the toxic substances will evaporate, exhaust gas treatment measures must be taken. Therefore, the more complex the system, high operating costs. 3.Chemical stabilization techniques: chemical stabilization technology is the use of chemical agents, toxic and hazardous substances by chemical reaction into a low solubility, low migration and low process toxic substances. The stabilizer is commonly used inorganic and organic. Inorganic mainly Na2, S and phosphoric agent, an organic chelating agent primarily polymer material, fly ash insoluble drug is mixed with the complexing group, ash soluble metal (Cd, Pb, etc.) with complexing agents in the radical reaction, the formation of stable complexes, thereby fixing the fly ash, fly ash in order to reduce the possibility of leaching of harmful ingredients. Treatment with these agents ash, generally can achieve good results, this method has a simple process, less investment in equipment, etc., but will produce high concentrations of inorganic waste, the need for further processing. In summary, the use of cement solidification and stabilization combined process chemical treatment, incineration ash is an effective way to present the best practicable, on the basis of the company after years of painstaking experiments and practice, successfully developed the following process technology solutions, products made leachate tests are in line with the national emission standards. Fly ash curing systems Process Description After the fly ash from the incineration plant flue gas treatment systems into the storage bin , quantitative transported to screw conveyor, then chelated by a screw conveyor to the mixing device , cement silo of cement delivered to the screw conveyor is also quantitatively under cement silo machine , the same machine sent by the chelating spiral kneading apparatus , according to the design in the ratio of fly ash and cement mixing device for mixing chelation , and chelating agents diluent pump and water supply systems at the same time start to chelate mixing device chelating agent and water supply . Fly ash , cement, chelating agents and water mixed in a kneading apparatus chelation , heavy metals in fly ash with chelating agents reacted chelate thus be stabilized . Chelation mixing device out of the fly ash and cement slurry is stabilized after delivery device by belt conveyors, pallet conveyor, block making machine, block , made of cement blocks after the last conservation between conservation . Evaporate a lot of water conservation process , and then transported by a special brick car away. Brick carrier transported to designated locations landfill, thereby completing the entire fly ash stabilization solidification process. The ratio of the chelating agent is from 0.5 to 3% . The actual amount to be determined according to the use of fly ash in the final test component ; cement ratio of 10% to 20% ; at 10% design design. Fly ash handling output capacity by 100 tons / day design. technological process

Industrial waste in the production process of unburned brick have aggregate effect. Many industrial waste can be used to produce unburned bricks , including : power plant fly ash , steel plant slag , non-ferrous metal smelters smelting slag , all kinds of mining tailings , copper carbon , chemical waste gypsum , chemical lime , construction waste brick , construction waste etc. Chemical composition , mineral composition, hazardous substances and take advantage of the positive side effects of various industrial wastes are not the same, so when the use of industrial waste produced unburned bricks , after analyzing characteristics of the various waste , formation mechanism based on its strength, to develop a reasonable formula. Some industrial waste, after adding an appropriate amount of curing agent and additives, can be used to make separate unburned bricks : Such as the use of fly ash , add river sand and lime, gypsum, cement and composite admixture to produce 28d strength of 31MPa of industrial waste unburned bricks; Again , after pretreatment lead and zinc tailings, adding the right amount cement and admixture, manufacture of industrial waste is not less than MU10 unburned. And most of the studies is to some industrial waste with each other, or the merits of the complementary strengths to take advantage of synergies: good example now more is to combine the manufacture unburned bricks of fly ash and slag , the active ingredient in the fly ash and slag is excitated under the effect of a curing agent and admixture , bricks are met strength requirements. Ash material diameter is relatively small, single brick aggregate effect of the lack of large particles.The slag has a larger particle size distribution, to meet this condition, thereby producing the unburned better performance, such as the use of fly ash and slag Steel manufactured MU10-MU15 of unburned. In determining the industrial waste unburned formula, only to waste as much as possible to improve the content, but should be possible to use a variety of waste itself is conducive to the production of unburned features to reduce as much as possible agents and admixtures an amount, effective to reduce the production cost of the bricks. The main chemical production of industrial waste residue of unburned more common minerals. In addition, some industrial waste due to radioactive, or should not be used in a lot of brick, its use should be preceded by radioactive detection. Some industrial waste such as fly ash, must be pretreated before use, remove roots and debris, and some also need to need to use abrasive material diameter rear; Again converter steel slag discharged, you must first go through magnetic separation, excluding the massive steel block, then by wet milling grinding to the desired particle size. Waste particle size determines whether the production of industrial waste unburned add an additional aggregate. In the batch of industrial waste unburned, mixing with the appropriate amount of aggregate particle size prevents brick layers, reduce shrinkage, improve performance exhaust brick molding, increasing density, thereby increasing the strength of brick and durability, and can save the amount of binder, and reduce costs. There are river sand as an aggregate of sand, sand and sand hill three kinds. Due to the mountain of sand with sharp edges, can better integrate and cement, leaving the brick has a high strength to listen to, so choose a good mountain sand. But most of the sand can be used in building materials, can be used for the production of industrial waste unburned. In fact, some waste itself has a role in the aggregate, such as steel mills produced steel slag, coal gangue, tailings and other mining. 1.2 Curing agent Industrial waste unburned curing agent is the cementing material can form a variety of materials dispersed in the role of physics, chemistry, solid form with a certain intensity, such as cement, lime, gypsum, etc. 1.2.1 Cement Cement in the production of industrial waste unburned, both cementing agent, but also activators. The initial strength of the brick-and post-effective three-dicalcium silicate and calcium silicate component contributed greatly. Generally used in high alkalinity 32.5 ordinary portland cement. The more amount of cement, the more beneficial to industrial waste unburned durability; But with the increasing amount of cement, the cost will increase as bricks. To reduce costs, many manufacturers try to use proper industrial waste or by the action of admixture with each other, under the premise to ensure the strength of the brick, as little as possible so as not to add to the cement. As in the use of red mud and fly ash manufacturing unburned just add some alkaline activator and sulfate activator, the strength of the brick can reach MU15 more. 1.2.2 lime Lime slaking calcium hydroxide, early strength cement and late strength has an important role, it is also industrial waste unburned forming binders binders and alkaline activator. But some technology, especially in the late steam curing requires the use of industrial waste unburned, the use of hydrated lime can simplify the process and reduce the time spent in the factory brick, brick shorten turnaround time and capital. 1.2.3 gypsum Gypsum is the production of industrial waste unburned sulfate activator, while its ability to synergies and lime, plays a role in promoting agent, on the strength of industrial waste unburned plays the role of direct and indirect. General use of natural gypsum better, of course, in order to reduce costs, you can also use industrial chemical gypsum, such as industrial phosphogypsum. In the industrial production of unburned waste, the curing agents may be used, such as cement. And in most cases, as the case may be used in combination of several curing agents, such as the use of a combination of lime and gypsum, or gypsum, lime and cement used together, the effect is good. Of course, the application of industrial waste unburned curing agent is far more than the above three kinds, and some sulfate and the like. Meanwhile, some industrial waste (such as caustic sludge, etc.) may also be in the batch of bricks, act as agents to stimulate action. 1.3 Admixture Pastes can make use of industrial waste outside agent to improve strength, improve performance, quality and stability. There are many additives for industrial waste unburned are: plasticizers ( ie water reducer ) , early strength agent, antifreeze agents. Unburned material mixed with industrial waste uniformity will directly affect the ultimate strength of brick. Generally, in order to improve mixing of the batch , in addition to strengthening the stirring , the added reducing agent effective to increase the fluidity of the material with substantial reduction of mixing water , so as to improve the density of brick , strength, frost , impermeability , etc. there is also a result of improved ; the other hand, due to the dispersion of water-reducing agent , such that each material contact surface area increases, thus contributing to improve the reaction probability. The production of industrial waste unburned , incorporated superplasticizer mostly hydrophilic surface active substances , commonly used lignin , such as calcium lignosulfonate . Early strength agent is to improve the early strength admixture products , whether inorganic salts, organic salts, or inorganic - organic compound early strength agent , they have to rely on speed to accelerate batch of hydration to improve the early strength of brick. Use more early strength agent sodium chloride , calcium chloride , triethanolamine, sulfur acid amine salt compound early strength agent. 2.Unburned brick production process of industrial waste Precautions production as follows: (1) If you are using a dry material, the amount of water to be added in the grinding wheel; If the compound itself contains water, as the case may add less water. (2) aging or not, as the case may be, the general use of lime as a curing agent needs to aging, but you can avoid the use of hydrated lime aging process. (3) if necessary, add water and cement should be added before molding. Impact. (4) the amount of water, pressure molding process parameters on the brick strength is relatively large, the corresponding parameters are determined through testing.