CN104860554A - New-style composite base material for reinforcing foundation manufactured via reconstruction of steel slag at normal temperature - Google Patents

Abstract

The invention is a new-style composite base material for reinforcing a foundation manufactured via reconstruction of steel slag at a normal temperature, belonging to the technical field of foundation processing in communication and transportation engineering and civil engineering; the new-style composite base material for reinforcing the foundation manufactured via the reconstruction of the steel slag at the normal temperature is characterized in that: metakaolin and slaked lime are added into the steel slag, and the control indices are respectively: SM is controlled to be between 2-2.4; IM is between 1.2-1.6, and KH is between 0.9-0.94, after the mixture is prepared, a sample is prepared according to water demand, and is put into a standard curing room, and the sample is prepared. After the steel slag is reconstructed according to the ratio of concrete, the ingredients of the steel slag are made up and supplemented, the strength is improved obviously on the basis of early strength, and the cost can be reduced greatly.

Description

The NEW TYPE OF COMPOSITE base material of slag normal temperature reconstruct preparation foundation stabilization

Technical field

The present invention is the NEW TYPE OF COMPOSITE base material of slag normal temperature reconstruct preparation foundation stabilization, that one utilizes metakaolin, white lime, a small amount of composite high-early strength water reducer, excite the composite reactive base material of slag at normal temperatures, belong to the technical field of basement process in Communication and Transportation Engineering and civil engineering work.

Background technology

Cut-off reaches about 8.3 hundred million tons to crude steel output in 2012, accounts for about 50% of Gross World Product.At present, China's slag output accounts for 15 ~ 20% of crude steel output, therefore about has 100,000,000 ~ 1.5 hundred million tons of slags to produce and output along with crude steel every year.But China's steel slag utilization rate is but less than 25%, therefore there is large steel slag to be not used every year, cause soil to be subject to polluting, edaphon suffers the problems such as destruction, body of groundwater pollution.

Slag is a kind of material with potential gelling, mainly CaO, SiO in its slag chemical composition ₂, and a small amount of Al ₂o ₃, Fe ₂o ₃, MnO equal size fluctuating range is larger; Mineralogical composition mainly slag essential mineral composition have tricalcium silicate (C ₃s), Dicalcium Phosphate (Feed Grade) (C ₂s), RO (R represents the Solid solution that formed of oxide compound of magnesium, iron, manganese), free lime (free CaO; F-CaO) etc.Due to C in slag ₂s accounts for 30 ~ 60%, and C ₃s content is but only less than 20%, and therefore slag hydration rate is slower than ordinary Portland cement many, is usually used to do roadbed filling, aggregate, asphalt aggregate use, and often do not used as being gelling material by slag.Its reason mainly slag inner activity is more difficult ejects, its early hydration degree is low, shows as early strength low.

On the other hand, existing slag reconfiguration technique is in slag, add adjustment material (aluminium matter, siliceous and calcareous material), makes it at high temperature chemical reaction occur, and absorbs f-CaO, and generates active mineral C ₂s, C ₃s and C ₃a etc., improve the gelation activity of slag.Existing slag reconfiguration technique mainly comprises: front end reconstruct and rear end reconstruct.Front end reconstruct refers in slag, add modulator under maintenance high temperature, adjusts slag component; Rear end reconstruct refers to mix modulator at normal temperatures, cools, reach the object adjusted slag component after at high temperature calcining for some time subsequently.Two kinds of reconfiguration techniques can make the slag composition after reconstruct similar to cement, but all relate to hot conditions, and cost is higher, not to be directly applied in Communication and Transportation Engineering and civil engineering work in basement process as soil body solidifying agent.Meanwhile, hot conditions reconstruct slag needs to consume a large amount of electric energy, heat energy, consumes mass energy, to environment protection, reduces Carbon emission unfavorable.

From Appropriate application material with given play to material maximum performance angularly under the suitable conditions, need at room temperature to excite making up of activity of steel slag to slag reconfiguration technique.Conventional slag alkali-activator has gypsum, grog, lime and alkali-metal silicate, carbonate or oxyhydroxide etc.Metakaolin is a kind of active geopolymer, is take kaolin as raw material, and (600 DEG C ~ 900 DEG C) are through the anhydrous aluminium silicate (Al of dehydration formation at a proper temperature ₂o ₃2SiO ₂, AS ₂).Metakaolin can be inspired its activity under alkaline environment, i.e. so-called pozzolanic activity, and in kaolin calcined process, the free energy of system raises, and structural stability reduces, and Al-O structure restructuring occurs thus shows activity.In materials'use, often need in material, to add composite additive to meet the actual user demand of material, these admixtures have water reducer, hardening accelerator, air entrapment agent etc. usually.

The present invention is with white lime and metakaolin for raw material for this reason, with composite high-early strength water reducer for admixture, seeks suitable proportioning, forms the compound reconstruct base material that can excite slag under normal temperature.

Summary of the invention

Technical problem: be high-temperature reconstruction technology for current slag reconfiguration technique, cannot in engineering direct applied problem, to be added in slag containing active metakaolin, and add alkali-activator and early strength water-reducing agent wherein, form compound reconstruct base material, reach the difference of chemically composition supplying on slag and ordinary Portland cement, excite the potential gelling of slag, promote slag overall utilization rate, the object of save energy and reduction Carbon emission.

Technical scheme: according to the rate value scope of ordinary Portland cement, add metakaolin and white lime in slag, make the chemical composition of mixture similar in ordinary Portland cement.Con trolling index is respectively:

1. silicon rate (Silica Modulus, SM) SM=SiO ₂/ (Al ₂o ₃+ Fe ₂o ₃)

2. aluminium rate (Iron Modulus, IM) IM=Al ₂o ₃/ Fe ₂o ₃

3. lime saturation factor (Lime Saturation Coefficient, KH)

$\mathrm{KH}=\frac{(\mathrm{CaO}-1.65{\mathrm{Al}}_2{O}_3-0.35{\mathrm{Fe}}_2{O}_3)}{2.8{\mathrm{SiO}}_2}$ (when IM >=0.64)

$\mathrm{KH}=\frac{(\mathrm{CaO}-1.1{\mathrm{Al}}_2{O}_3-0.7{\mathrm{Fe}}_2{O}_3)}{2.8{\mathrm{SiO}}_2}$ (as IM<0.64)

Control SM is between 2 ~ 2.4; IM is between 1.2 ~ 1.6, and KH is between 0.9 ~ 0.94.After configuring mixture, to add water sample preparation according to standard consistency water requirement, at standard curing box.

Beneficial effect: after being reconstructed by slag according to cement proportion, the composition of slag obtains and makes up and supplement, and in early days intensity is significantly improved.Do not add metakaolin, slag 3 days unconfined compression strengths of lime are 0.3MPa, 7 days unconfined compression strengths are 1.6MPa, and 28 days unconfined compression strengths are 18.4MPa; And that slag 3 days unconfined compression strengths after reconstruct is 2.5MPa ~ 5.9MPa, 7 days unconfined compression strengths are 5.4MPa ~ 11.8MPa, and 28 days unconfined compression strengths are 19.6 ~ 25.4MPa.From the change of unconfined compression strength, the early strength reconstructing slag after mixing metakaolin, lime is enhanced, and later strength increase rate is less.Slag after reconstruct can better ensure job schedule and safety.

Due to the difference of steel manufacturing process, pretreatment of slag technique etc., cause slag difference to some extent on composition, the Activiation method of therefore passing by often can not be replicated, and does not have same standard.Employing rate value method, by slag reconstruct, can unify slag normal temperature reconstruct activate formula, be a kind of can by the method promoted.

At present, the price of slag is uneven on the market, and testing slag used is product after wet magnetic separation, and market value is about 50 yuan/ton.In addition white lime market value is about 150 yuan/ton, and metakaolin is about 400 yuan/ton, and cement price is about 450 yuan/ton.The slag gone out according to proportion design accounts for 31%, and lime accounts for 60%, and metakaolin accounts for 9%, so be about 138 yuan/ton with the slag after a ton calculates this reconstruct, although exceed 2.8 times than slag price, be but only 30% of cement price, can reduce costs greatly.

Embodiment

Specific surface area is selected to be 300m ²/ g ~ 500m ²slag between/g, and chemical composition test is carried out to it, utilize test result and cement composition to compare, add metakaolin, lime wherein.Add fashionable, the composition that should control to mix rear material meets the requirement of cement rate value.Control SM is between 2 ~ 2.4; IM is between 1.2 ~ 1.6, and KH is between 0.9 ~ 0.94.The composite early strength water-reducing agent of SEU type selected by early strength water-reducing agent, and its proportioning is in table 2, and the incorporation of early strength water-reducing agent is 2%.

Example: the slag after selecting Jiaxing Area to carry out wet magnetic separation, its chemical composition is listed in table 1:

Table 1 slag chemical composition (massfraction)

CaO	Al 2O 3	SiO 2	Fe 2O 3	MgO
					49.83～55.46	4.77～4.82	28.47～34.28	10.19～14.17	2.17～5.83

The composite early strength water-reducing agent proportioning of table 2 SEU type

Material name	Mass ratio	Material name	Mass ratio
				Anhydrous sodium sulphate	12	Sodium Nitrite	2
NF naphthalene series high-efficiency water-reducing agent	8	Wollastonite powder	29.4
				Trolamine	0.6	Flyash (2 grades)	48

According to the regulation of " steel-making slag powder in cement and concrete " (GB/T20491-2006), by the sieve of slag by 0.9mm, screen over-size is less than 0.5%.Test slag standard consistency water requirement is 0.23, and according to this water requirement sample preparation, put into standard curing room (20 DEG C, 90% ± 4%) maintenance form removal after a day, normal curing, to the length of time, surveys the unconfined compression strength value of its 3 days, 7 days and 28 days.Result is as shown in table 2.Result can significantly improve the early strength of slag, promote slag aquation, also have certain contribution simultaneously to slag later strength after showing to mix metakaolin, lime and a small amount of early strength water-reducing agent.Within 3 days, intensity improves nearly 20 times, and 7 days intensity also improves 7 times, embodies and mixes the rear superiority stimulated slag activation effect.

Table 2 test-results

Claims (3)

1. slag normal temperature reconstruct preparation foundation stabilization NEW TYPE OF COMPOSITE base material, it is characterized in that: in slag, add metakaolin and white lime, Con trolling index respectively:

1. silicon rate SM=SiO ₂/ (Al ₂o ₃+ Fe ₂o ₃)

2. aluminium rate IM=Al ₂o ₃/ Fe ₂o ₃

3. lime saturation factor KH

$\mathrm{KH}=\frac{(\mathrm{CaO}-1.65{\mathrm{Al}}_2{O}_3-0.35{\mathrm{Fe}}_2{O}_3)}{2.8{\mathrm{SiO}}_2}$ (when IM >=0.64)

$\mathrm{KH}=\frac{(\mathrm{CaO}-1.1{\mathrm{Al}}_2{O}_3-0.7{\mathrm{Fe}}_2{O}_3)}{2.8{\mathrm{SiO}}_2}$ (as IM<0.64)

Control SM is between 2 ~ 2.4; IM is between 1.2 ~ 1.6, and KH is between 0.9 ~ 0.94, and mixes the early strength water-reducing agent that mass ratio is 2%, after configuring mixture, according to this water requirement sample preparation, puts into standard curing room, sample preparation finished product.

2. the NEW TYPE OF COMPOSITE base material of slag normal temperature according to claim 1 reconstruct preparation foundation stabilization, is characterized in that described slag be specific surface area is 300m ²/ g ~ 500m ²steel-making slag powder between/g, slag: white lime: the mass ratio of metakaolin is in 26 ~ 36:55 ~ 64:7 ~ 10.

3. the NEW TYPE OF COMPOSITE base material of slag normal temperature reconstruct preparation foundation stabilization according to claim 1, is characterized in that described early strength water-reducing agent proportioning is:

Material name Mass ratio Material name Mass ratio Anhydrous sodium sulphate 12 Sodium Nitrite 2 NF naphthalene series high-efficiency water-reducing agent 8 Wollastonite powder 29.4 Trolamine 0.6 Flyash (2 grades) 48

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