CN1541968A - Method for preparing ecological concrete using burning fly ash as admixture - Google Patents

Abstract

The present invention is method of utilizing garbage incinerating flyash as admixture to produce ecological concrete. The ecological concrete is produced with cement, active ore slag powder and garbage incinerating flyash as gelatinizing material, supplementary material zeolite and additive including sodium silicate and water reducing agent in certain proportion. The ecological concrete has excellent mechanical performance and excellent penetration resisting performance, and heavy metal and other harmful matter in flyash are adsorbed, held and stabilized effectively with less separation to make the ecological concrete safe. Utilizing garbage incinerating flyash can change waste into useful material.

Description

Utilize the method for flying ash as adulterant preparation eco-concrete

Technical field

The invention belongs to building material technical field, be specifically related to a kind of method of utilizing flying ash as adulterant preparation eco-concrete.

Background technology

Along with the develop rapidly of urban construction, the discharging of China urban waste also sharply increases, and has become the important factor of restriction Economic development.How to administer these rubbish cost-effectively, prevent to pollute, this is a cross-centennial environmental protection hot issue.The effective processing or the regeneration of waste, not only technical requirements is higher, and investment and processing costs are also big.The treatment process of urban waste has direct landfill, compost and burning etc., and China all adopts direct landfill in most of city.Along with the minimizing in available landfill place and the raising of landfill cost, compost be subjected to extensive restriction because of the market reason and compost quality undesirable, the waste incineration method more and more comes into one's own.Garbage incineration technology reduces the volume of rubbish greatly, and can reclaim the energy owing to can destroy organic toxicant effectively, will become China's garbage as resource, innoxious and subtract the important research and the developing direction of appearanceization treatment technology.

But always produce the incineration residue of some amount after the waste incineration.Form and incineration temperature according to rubbish, burn the difference of time, the amount of residue accounts for 5～30% of the preceding gross weight of waste incineration.Simultaneously, burn some chemical ingredients that also will inevitably concentrate, as heavy metal substance.The flying dust that waste incineration produces contains heavy metals such as the lead of higher leaching concentration and cadmium and belongs to the heavy metal Hazardous wastes because of it, must handle through curing/stabilizing earlier before it is carried out ultimate disposal.The incineration technology of China's municipal wastes also is in and gropes and the experience accumulation stage at present, the disposal of the lime-ash of incinerator and the flying dust of smoke duster (being referred to as incineration residue) does not also obtain enough attention, almost all take landfill or solidification treatment, the disposal utilization research of relevant incineration residue is close to blank especially.There is following point in traditional cement solidification technology when handling the heavy metal refuse:

(1) needs to use a large amount of cement, cause the refuse increase-volume bigger, make the rapid increase of solidified expense and lose inexpensive advantage, bring difficulty also for simultaneously follow-up transportation and processing; (2) high porosity of cement solidification matrix body and hypertonicity;

(3) intensity of cured body very low (intensity of 28d is 0.35-0.70MPa only), and the affiliation that adds of some heavy metals (as Cu, Pb, Zn etc.) delays condensing and hardening of cement, heavy metal in the cured body will face the potentially dangerous of transferring in the environment under the erosion of surrounding medium, may cause secondary pollution to environment, and cured body is difficult to problems such as regeneration.Therefore how disposing safely and effectively utilizes flying ash to become environment and the social concern of being badly in need of solution.Meanwhile, we notice that the main chemical compositions in the flying ash is very approaching with concrete admixtures such as the blast-furnace slag of using always at present, flyash, all belong to CaO-SiO ₂-Al ₂O ₃(Fe ₂O ₃) system, so the existing contaminative of flying ash has the utilization of resources again.Disposal to flying ash both at home and abroad focuses on harmless treatment, and the resource that it had is failed to make full use of.Research to flying ash in the document of publishing both at home and abroad is with landfill behind its stable curing mostly about how.

For solving the pollution problem of domestic waste, only two big two little four municipal solid waste incinerators are just built up at present in Shanghai City, and garbage treatment quantity reaches 3000t/d.If generated by 20% lime-ash by burning 1t rubbish, then four factories have the incineration residue generation of 600t every day.So a large amount of lime-ash produces, and directly banks up if it is not carried out suitable processing and utilization and topples over, and not only can waste resource, more seriously will pollute the environment, and the people's production and life caused very big harm.How incineration residue safety being disposed utilization effectively, is the emphasis problem that current people pay close attention to.

Summary of the invention

The objective of the invention is to propose a kind of with the method for incineration of refuse flyash, so that flying ash is carried out recycling as adulterant preparation eco-concrete.

The incineration of refuse flyash that utilizes that the present invention proposes is prepared the method for eco-concrete for adulterant, with cement, active slag micro mist and incineration of refuse flyash as gelling material, and be equipped with subsidiary material zeolite and admixture (water glass, water reducer) etc., wherein, the quality proportioning of each component is as follows:

Gelling material (total amount is 100%):

Cement 30-70%

Slag micropowder 50-20%

Flying ash 20-10%,

Subsidiary material and admixture:

Zeolite 3-8%

Water glass 0.5-2%

Water reducer 0.5-1.5%

The materials mass percent of subsidiary material and admixture is that radix calculates by gelling material.

The flying ash that the present invention utilizes garbage burning factory to produce replaces part cement, and with other adulterant, admixture etc. carry out composite modified, preparation high performance concrete, and guarantee its safe handling.With flying ash as concrete adulterant regeneration, really having accomplished turns waste into wealth, this invention with the development of environment waste treatment and Materials science organically molten be one, be the breakthrough that the flying ash the like waste dispose is utilized, have remarkable social benefit and economic benefit.

Embodiment

Used flying ash is taken from the PVG and is driven bridge garbage burning factory smoke duster, and drying, grinding are controlled its specific surface area and be about 360m ²/ Kg.The main chemical compositions fluctuation range of flying ash sees Table 1.

The main chemical compositions fluctuation range (%) of table 1 flying ash

Title	??SiO 2	??Fe 2O 3	??Al 2O 3	??TiO 2	??CaO	??MgO	??SO 3	??Cl -	????f-CaO	Loss on ignition
											Flying dust	??22.5- ??26.5	??3.0- ??5.0	??6.2- ??8.5	??0.3- ??0.9	??21.3- ??25.5	??2.1- ??3.2	??11.0- ??12.5	??8.5- ??10.0	????0.5- ????1.5	??20.0- ??22.0

Main chemical compositions in the flying ash also is CaO, SiO as can be seen from Table 1 ₂, Al ₂O ₃And Fe ₂O ₃, very approaching with concrete admixtures such as the blast-furnace slag of using always at present, flyash.

But the objectionable impuritiess such as heavy metal that contain higher concentration in the flying ash again, its heavy metal content and leaching toxicity see Table 2.

The leaching toxicity of table 2 flying ash

Heavy metal content (mg/kg) solid waste leaches toxicity in metal title flying ash leach liquor concentration (mg/l) flying ash

Judging standard (mg/l)

Zn??????????54.0-59.0??????????????????????3000-4500????????????????????50

Pb??????????24.0-28.0??????????????????????1200-1850????????????????????3.0

Cu??????????5.5-10.5???????????????????????380-680??????????????????????50

Cd??????????1.2-3.5????????????????????????30.5-43.7????????????????????0.3

Cr??????????1.5-4.3????????????????????????128.0-160.5??????????????????1.5

As can be seen from Table 2, the concentration of Zn, Pb, Cd, Cr all is higher than solid waste leaching toxicity judging standard (GB5085.3-1996) in the flying ash leach liquor, exactly because also flying ash is generally believed is a kind of Hazardous wastes to this point, therefore when finally being utilized, it must handle especially objectionable impuritiess such as heavy metals wherein.

Following table is that the flying ash volume is the influence to cement slurry physicals and mechanical property in 20% o'clock.Flying ash is less to the influence of cement slurry physicals as can be seen from the table, and flying ash still has certain gelling reaction activity simultaneously.

The physics and the mechanical property of table 3 flying ash-cementitious composite gelling system

	Standard consistency water requirement (%)	Time of coagulation		Stability	Activity index (%)	Ultimate compression strength (MPa)
									Initial set (h: min)	Final set (h: min)	??3d	??7d	??28d
		Cement	????27.50			???2∶04	?3∶15	Qualified						??100	??45.4	??56.2	??62.5
Flying ash-cement	????28.75			???1∶50	?2∶43				Qualified	??57	??42.3	??50.0	??54.9

For intensity after overcoming Portland cement curing flying ash is low, defectives such as objectionable impurities leaching yield height, the utility model technology provide a kind of new type of safe to utilize the pattern of flying ash preparation eco-concrete.When utilizing the flying ash concrete batching, should note the problem of two aspects, the one, concrete every performance; The 2nd, guarantee that the leaching of objectionable impurities meets national standard in the concrete.As everyone knows, the main hydration products C-S-H gel of silicate cement has the clay structure of degeneration, have stronger ionic adsorption and exchange capacity, especially after Al replaces part Si, the mechanical property of absorption and exchange capacity and cured body improves than descending with Ca/Si among the C-S-H, and the acidity of Ca/Si and system is inversely proportional among the C-S-H.Make great efforts to reduce liquid phase Ca (OH) ₂Concentration, the system's acidity that improves can improve the ability of solidified cement body delay harmful ion.Admixture active slag micro mist is because its active SiO ₂Ca (OH) with the hydrated cementitious generation ₂Reaction has consumed Ca (OH) ₂And form C-S-H, improve the C-S-H adsorptive power and improved pore structure (newborn C-S-H stops up the density that hole increases system).Add levigate zeolite in concrete, zeolite has strong adsorptivity and ion-exchange absorption on the one hand, thereby can hold and stable harmful heavy metal, and zeolite also has certain gelation activity simultaneously, kills two birds with one stone.By reducing water cement ratio, adding water glass, improve mechanical properties of concrete and weather resistance in addition, and guarantee that heavy metal is difficult for leaching in the flying ash from concrete, thereby guarantee its safe handling as measures such as activity excitants.

The eco-concrete proportioning sees Table 4.Wherein a unit cube concrete cement consumption is 550kg, and slurry collection is than being 35: 65.The maximum particle diameter of coarse aggregate is no more than 20mm, continuous grading.

Table 4 eco-concrete proportioning

Gelling material (100%)			Zeolite	Water glass	High efficiency water reducing agent	Water cement ratio	Sand coarse aggregate ratio
								Cement	Slag	Flying dust
??40-60	??30-40	??10-20									??5％	??1％	??1％	??0.35	??40％

The basic mechanical design feature of eco-concrete sees the following form.

The basic mechanical design feature of table 5 eco-concrete

Mobile ultimate compression strength (MPa) impermeability

The slump (mm) 28d 60d 90d (MPa)

Eco-concrete 175 60.2 65.5 68.7 1.2

As can be seen from the table, eco-concrete has the good mechanical performance, has excellent impermeability simultaneously, illustrates that the eco-concrete density is very high, and the impermeability of its excellence is also highly beneficial to the leaching of its opposing heavy metal.Other endurance quality of concrete is the same substantially with normal concrete.The heavy metal leaching test (GB5086.2-1997) carries out according to " solid waste leach toxicity leaching method horizontal succusion ", and filtrate is analyzed with ICP, and following table has been listed the leaching situation of heavy metal in the eco-concrete in the 28 day length of time.

The leaching of heavy metal (mg/l) in table 6 eco-concrete

Zn???????????Pb???????Cu?????????Cd?????????????Cr

Eco-concrete 0.0221 ND 0.0032 0.0051 ND

Solid waste leaches toxicity judging standard 50 3.0 50 0.3 1.5

As can be seen from the table, the concrete heavy metal leaching amount of mixing 20% flying ash is very low, illustrate flying ash in concrete since dilution effect, gelling material to actings in conjunction such as the physical inclusion of heavy metal and Chemical bond, make heavy metal be able to stable existence in concrete, it leaches well below solid waste and leaches the toxicity judging standard.Therefore use is safe and reliable to flying ash as concrete admixture.

Claims (1)

1, a kind of incineration of refuse flyash that utilizes is as the living penta concrete method of adulterant preparation, it is characterized in that with cement, active slag powder and incineration of refuse flyash as gelling material, and be equipped with subsidiary material zeolite and admixture, wherein, each component folding quality proportioning is as follows:

Gelling material (total amount is 100%):

Cement 30-70%

Slag micropowder 50-20%

Flying ash 20-10%,

Subsidiary material and admixture:

Zeolite 3-8%

Water glass 0.5-2%

Water reducer 0.5-1.5%

The materials mass percent of subsidiary material and admixture is that radix calculates by gelling material.