CN104671694B - Modified calcium oxide expanding agent for compensating concrete temperature shrinkage and preparation method thereof - Google Patents
Modified calcium oxide expanding agent for compensating concrete temperature shrinkage and preparation method thereof Download PDFInfo
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- CN104671694B CN104671694B CN201510061626.8A CN201510061626A CN104671694B CN 104671694 B CN104671694 B CN 104671694B CN 201510061626 A CN201510061626 A CN 201510061626A CN 104671694 B CN104671694 B CN 104671694B
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- extender
- calcium oxide
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- temperature shrinkage
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Abstract
The invention provides a modified calcium oxide expanding agent for compensating concrete temperature shrinkage and a preparation method thereof. The modified calcium oxide expanding agent for compensating concrete temperature shrinkage is composed of a core layer and a wrapping layer, wherein the core layer is made of an expanding material, and the wrapping layer is made of a phase-change material; and the weight of the phase-change material accounts for 6-10% of the total weight of the expanding agent. The modified calcium oxide expanding agent provided by the invention has the characteristics such as simple preparation technology, wide-source and cheap and easily-available raw materials and good compensation effect on concrete temperature shrinkage, is suitable for compensating large-volume concrete temperature shrinkage and is of remarkable social and economic significance.
Description
Technical field
The present invention relates to a kind of cement expansive material is and in particular to a kind of modified oxygen for compensating concrete temperature shrinkage
Change calcium extender and preparation method thereof.
Background technology
Cement concrete is a kind of hydraulic cementing materials, certainly pours the cement that molding starts and be in natural environment and mixes
Xtah Crude Clay structure, in the whole process of its hydration and hardening, due to itself hydration reaction and the dehydration to surrounding medium
Process, has dry shrinkage, self-desiccation shrinkage and temperature drop and shrinks, the contraction under constraints causes concrete cracking, is to make
Become the main cause of accident resulting from poor quality of projects.Adding extender in cement concrete material is to improve cement concrete volume stability
Property and the common method of crack resistance.
Dry shrinkage refers to that cement concrete material is exposed in natural environment, because ambient humidity is internal wet less than it
Degree, the dehydration shrinkage that internal moisture is evaporated and caused, is that the conventional concrete being characterized with high water-cement ratio and high cement consumption is sent out
The main cause of raw cracking；
Self-desiccation shrinkage is because chemical shrinkage consumes internal moisture, the internal relative humidity causing under conditions of waterproof
Decline caused contraction, be the contemporary high performance concrete being characterized with low water binder ratio and high content mineral admixtures in early days
The main cause of cracking；
Temperature drop shrinks and refers to cement concrete under ambient temperature conditions, because cement early hydration heat release, causes inside
Temperature raises, and is increased to the shrinkage that causes of temperature drop after to a certain degree, is cause mass concrete cracking mainly former
Cause.
At present, existing cement expansive material patent and kind are more both at home and abroad, divide by expansion sources, mainly have entringite
Type, calcium oxide type and oxidation magnesium types.Entringite type extender and calcium oxide extender mainly pass through early moist curing and mix in reinforcing bar
Set up compressive pre-stress in solidifying soil, by compressive pre-stress compensating concrete later stage dry shrinkage and self-desiccation shrinkage, improve concrete
Crack resistance.But, the dilatancy of entringite type extender and calcium oxide extender is respectively provided with stronger temperature sensitivity, temperature
Raise, speed of expansion is drastically accelerated, expand and terminate time advance, work is no substantially compensated to the temperature shrinkage of mass concrete
With.Oxidation magnesium types extender has delayed expansion effect, can compensate for the temperature shrinkage of mass concrete, but oxidation magnesium types is swollen
There is significant limitation in the distribution of China in swollen dose of raw material magnesite, be substantially distributed in Liaodong Peninsula and northern Shandong
The peninsula, and hydroelectric project focuses mostly in southwest, has that expanding material long-distance transportation, cost of transportation be very high, expanding material
The problems such as activity is easily lost, needs to carry out the expanding material that the production of universality raw material can compensate temperature shrinkage of mass concrete
Research.
Calcium oxide extender possesses that aquation water requirement is few, expansion performance is high, to working performance of concrete and mechanical property shadow
Ring little, the low excellent properties of moisture sensitivity, scientific research and engineering practice occupy increasingly consequence.Produce oxygen
The main raw material(s) limestone changing calcium extender is widely distributed in China, and reserves enriches.If passing through technological means
Realize the regulation and control that calcium oxide extender expands course, delay calcium oxide extender in the expansion of temperature rise period, increase calcium oxide swollen
The swollen dose of expansion in the concrete cooling stage, to realize the effective compensation that concrete temperature is shunk, will in water power etc. substantially
It is widely used in long-pending concrete works, there is significant social and economic significance.
Content of the invention
Dilatancy for existing entringite type extender and calcium oxide extender is respectively provided with stronger temperature sensitivity,
Temperature raises, and speed of expansion is drastically accelerated, and expands and terminates time advance, the temperature shrinkage of mass concrete is no substantially compensated
The problem of effect, and the hydration process of existing calcium oxide extender is too fast, the few problem of effective expansion energy；A kind of using is provided
Modified oxidized calcium extender in compensating concrete temperature shrinkage and preparation method thereof.
The know-why that the present invention is taken：Calcium oxide extender is wrapped up using the paraffin surface that fusing point is 40 DEG C ~ 45 DEG C,
Obtain modified oxidized calcium extender, its surface is one layer of fine and close paraffin membrane waterproofing, be less than 40 DEG C in concrete internal temperature
Before, paraffin membrane waterproofing keeps solid phase to stop calcium oxide extender from contacting with water, effectively reduces calcium oxide extender in coagulation
The expansion of native temperature rise period, when concrete internal temperature is more than 40 DEG C, paraffin membrane waterproofing starts to melt, and gradually becomes from solid-state
Become liquid, discharge wrapped calcium oxide extender granule, calcium oxide extender is started with the contact with moisture of inside concrete
Aquation produces and expands.
Existing documents and materials show, mass concrete internal temperature typically reaches highest pouring in 3 ~ 5d（45℃~
50 DEG C about）, afterwards concrete internal temperature start to be gradually reduced, until identical with ambient temperature.It can be seen that, change through parafilm wrap
The time that the modified oxidized calcium extender expansion start time of property starts to occur temperature drop with mass concrete matches, this
When calcium oxide extender aquation produce expansion can effective compensation mass concrete temperature shrinkage.
Modified oxidized calcium extender for compensating concrete temperature shrinkage of the present invention is by core layer and integument group
Become, wherein said core layer is calcium oxide extender；Described integument is phase-change material, and the fusing point of described phase-change material is 45 DEG C
~ 50 DEG C about；The weight of phase-change material accounts for the described modified oxidized calcium extender gross weight for compensating concrete temperature shrinkage
6% ~ 10%.
Described expanding material is calcium oxide extender, commercially available.
As preferred；F-CaO content >=60% in calcium oxide extender.
Described phase-change material is modified paraffin, and described modified paraffin is mixed to prepare by 52# paraffin and carbamide, 52# paraffin
Mass ratio with carbamide is 85:15~95:5, fusing point is adjustable between 40 DEG C ~ 45 DEG C.
52# paraffin is minimum one kind of fusing point in hard paraffin, typically it is believed that 52# melting point of paraffin wax is 52 DEG C.
Can adjust the phase transition temperature of modified paraffin by the ratio adjusting paraffin and carbamide, carbamide proportion is more, changes
Paraffin melting point after property is lower.
Specifically method of modifying is：First 52# heating paraffin is melted, be then proportionally added into carbamide mixing, obtain final product after cooling
The modified paraffin reducing to fusing point.
The preparation method of the modified oxidized calcium extender for compensating concrete temperature shrinkage of the present invention, has as follows
Processing step：
1）By above-mentioned mass ratio, powdery calcium oxide extender is placed in the coating pan of seed-coating machine, in mass ratio by modified stone
Wax is placed in the charging bucket of seed-coating machine, and heating charging bucket makes modified paraffin be fused into liquid；
2）Open the modified paraffin that lance ejection is fused into liquid, powdery calcium oxide extender is made in pot by pot rotation
Interior rolling, makes modified paraffin be uniformly distributed in calcium oxide extender particle surface；
3）When powder body calcium oxide extender surfaces of tacky, stop injection, until powder body calcium oxide extender surface is done
Dry；It is again turned on the modified paraffin that lance ejection is fused into liquid, carry out a new wheel reaction coating circulation, and so on, directly
Sprayed to the desired amount of liquid modified paraffin, powder body calcium oxide extender dry tack free.Thus being used for described in obtaining mending
Repay the modified oxidized calcium extender of concrete temperature contraction.
Seed-coating machine of the present invention refers to by rotary coating pot, high-pressure spray gun, heating system, air-supply and exhaust system
Deng the common of composition or programmable instrument equipment.
Compared with existing extender product, after mixing concrete, early expansion deformation is subject to concrete hydrating temperature rise to the present invention
Impact less, the concrete temperature drop stage start produce expand, to concrete temperature shrink have preferable compensating action.Calcium oxide
The raw material sources such as extender and paraffin are extensive, cheap and easy to get, the modified preparation process is simple of parcel, can effective compensation large volume mix
The temperature shrinkage of solidifying soil, is therefore highly suitable for mass concrete, has significant economic results in society.
Brief description
Fig. 1 is the alternating temperature curing temperature course figure of simulation mass concrete temperature change.
Fig. 2 is not mix the normal concrete of extender, mix the concrete of 8% embodiment of the present invention 1-3 and mix 8% comparative example
Autogenous volumetric deformation curve chart under alternating temperature curing condition for the concrete of extender.
Specific embodiment
Below by specific embodiment, the present invention is described in further detail.
The source of calcium oxide extender is that market is commercially available, domestic also several manufacturers, oxidation used in the present invention
Calcium extender is the HME of Jiangsu Subotexin Material Co., Ltd.
Embodiment 1
920g powdery calcium oxide extender is taken to be placed in the coating pan of seed-coating machine, adjustment rotating speed is at 300 revs/min about.
80g modified paraffin is placed in the charging bucket of seed-coating machine, heat modification paraffin makes it be fused into liquid, opens lance ejection fusing
Become the modified paraffin of liquid, so that powdery calcium oxide extender is rolled in pot by pot rotation, so that paraffin is expanded in calcium oxide
Agent particle surface is uniformly distributed.
When powder body calcium oxide extender surfaces of tacky, stop injection until powder body calcium oxide extender dry tack free is
Only.Now it is again turned on the modified paraffin that lance ejection is fused into liquid, carry out a new wheel reaction coating circulation.So past
Multiple, until the desired amount of modified paraffin sprayed, till powder body calcium oxide extender dry tack free, the modified paraffin of formation wraps up
Layer accounts for the 8% of described modified expanded dose of gross mass, that is, obtain the modification for compensating concrete temperature shrinkage of the present invention
Calcium oxide extender.
Embodiment 2
900g powdery calcium oxide extender is taken to be placed in the coating pan of seed-coating machine, adjustment rotating speed is at 300 revs/min about.
100g modified paraffin is placed in the charging bucket of seed-coating machine, heat modification paraffin makes it be fused into liquid, opens lance ejection and melt
The modified paraffin of chemical conversion liquid, makes powdery calcium oxide extender roll in pot by pot rotation, makes paraffin swollen in calcium oxide
Swollen dose of particle surface is uniformly distributed.
When powder body calcium oxide extender surfaces of tacky, stop injection until powder body calcium oxide extender dry tack free is
Only.Now it is again turned on the modified paraffin that lance ejection is fused into liquid, carry out a new wheel reaction coating circulation.So past
Multiple, until the desired amount of modified paraffin sprayed, till powder body calcium oxide extender dry tack free, the modified paraffin of formation wraps up
Layer accounts for the 10% of described modified expanded dose of gross mass, that is, obtain changing for compensating concrete temperature shrinkage of the present invention
Property calcium oxide extender.
Embodiment 3
940g powdery calcium oxide extender is taken to be placed in the coating pan of seed-coating machine, adjustment rotating speed is at 300 revs/min about.
60g modified paraffin is placed in the charging bucket of seed-coating machine, heat modification paraffin makes it be fused into liquid, opens lance ejection fusing
Become the modified paraffin of liquid, so that powdery calcium oxide extender is rolled in pot by pot rotation, so that paraffin is expanded in calcium oxide
Agent particle surface is uniformly distributed.
When powder body calcium oxide extender surfaces of tacky, stop injection until powder body calcium oxide extender dry tack free is
Only.Now it is again turned on the modified paraffin that lance ejection is fused into liquid, carry out a new wheel reaction coating circulation.So past
Multiple, until the desired amount of modified paraffin sprayed, till powder body calcium oxide extender dry tack free, the modified paraffin of formation wraps up
Layer accounts for the 6% of described modified expanded dose of gross mass, that is, obtain the modification for compensating concrete temperature shrinkage of the present invention
Calcium oxide extender.
Comparative example 1：Unmodified calcium oxide extender used by embodiment 1-3.
P II 52.5 portland cement being produced using the south of the River- little Ye field Cement Co., Ltd, mixes outward 35% I level fine coal
Ash, water-cement ratio is fixed as 0.41, unit consumption of water 124kg/m3, sand coarse aggregate ratio 33%,
The mass substitution gelling such as respectively of the modified oxidized calcium extender of embodiment 1-3 gained of the present invention and comparative example 1
Total amount of material 8%, the coagulation soil sample of prepared embodiment 1-3, and the coagulation soil sample of comparative example 1；Do not mix the coagulation soil matrix of extender
Quasi- sample is blank sample.
Test pours the concrete cylindrical of molding φ 150 × 500mm, buries strain gauge in test specimen, sealed maintenance in
In environmental test chamber, the alternating temperature course of environmental test chamber is shown in Fig. 1.With concrete final setting time for starting the initial time measuring,
Autogenous volumetric deformation curve under alternating temperature curing condition for the concrete is shown in Fig. 2.
Result shows：Temperature rise period, mix and all produce obvious autogenous volume dilatancy with the concrete not mixing extender,
The autogenous volume dilatancy wherein mixing the concrete generation of the calcium oxide extender of comparative example 1 is bigger, mixes the embodiment of the present invention 1
Concrete essentially identical with the normal concrete autogenous volume dilatancy not mixing extender；Temperature-fall period, mix with do not mix swollen
The autogenous volumetric deformation of swollen dose of concrete all produces contraction distortion with the decline of temperature, wherein mixes the mixed of the embodiment of the present invention 1
Solidifying soil is less in the contraction distortion of temperature-fall period, and the concrete mixing comparative example 1 and the normal concrete not mixing extender are in cooling
The contraction distortion in stage is all larger, shrinks development speed essentially identical.
It can be seen that, the expansion performance of the unmodified calcium oxide extender of comparative example 1 occurs mainly in concrete hydrating temperature rise
Stage, weaker to the contraction distortion compensating action in concrete temperature drop stage, the embodiment of the present invention 1 for compensating concrete temperature
The expansion performance of the modified oxidized calcium extender shrinking is mainly the temperature drop stage of concrete, concrete temperature drop is shunk and mends
The effect of repaying is preferably.
Claims (4)
1. a kind of modified oxidized calcium extender for compensating concrete temperature shrinkage is it is characterised in that by core layer and parcel
Layer composition, wherein said core layer is calcium oxide extender；Described integument is phase-change material, and the weight of phase-change material accounts for described
For the modified oxidized calcium extender gross weight of compensating concrete temperature shrinkage 6%～10%；
Described phase-change material is modified paraffin, and described modified paraffin is mixed to prepare by 52# paraffin and carbamide, 52# paraffin and urine
The mass ratio of element is 85:15～95:5, fusing point is adjustable between 40 DEG C～45 DEG C.
2. the modified oxidized calcium extender for compensating concrete temperature shrinkage according to claim 1 it is characterised in that
F-CaO content >=60% in described calcium oxide extender.
3. the modified oxidized calcium extender for compensating concrete temperature shrinkage according to claim 2 it is characterised in that
The preparation method of described modified paraffin is：First 52# heating paraffin is melted, be then proportionally added into carbamide mixing, after cooling i.e.
Obtain the modified paraffin that fusing point reduces.
4. the system of the modified oxidized calcium extender for compensating concrete temperature shrinkage described in any one of claim 1-3
Preparation Method is it is characterised in that have following processing step：
1) by above-mentioned mass ratio, powdery calcium oxide extender is placed in the coating pan of seed-coating machine, in mass ratio modified paraffin is put
In the charging bucket of seed-coating machine, heating charging bucket makes modified paraffin be fused into liquid；
2) open the modified paraffin that lance ejection is fused into liquid, powdery calcium oxide extender is made in pot varus by pot rotation
Rolling, makes modified paraffin be uniformly distributed in calcium oxide extender particle surface；
3) when when powder body calcium oxide extender surfaces of tacky, stop injection, until powder body calcium oxide extender dry tack free；Again
Secondary open the modified paraffin that lance ejection is fused into liquid, carry out a new wheel reaction coating circulation, and so on, until required
The liquid modified paraffin of amount has sprayed, till powder body calcium oxide extender dry tack free.Thus being used for described in obtaining compensating coagulation
The modified oxidized calcium extender of native temperature shrinkage.
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| CN109796150B (en) * | 2019-03-27 | 2021-06-08 | 常熟京常智能科技有限公司 | Temperature shrinkage expanding agent for intelligent transportation equipment installation wall and preparation method thereof |
| CN110655344B (en) * | 2019-10-18 | 2023-01-03 | 江苏苏博特新材料股份有限公司 | Anti-cracking additive suitable for strong-constraint superimposed wall lining concrete |
| CN112649463A (en) * | 2020-12-17 | 2021-04-13 | 武汉大学 | Self-generating volume deformation testing equipment based on concrete heat insulation and temperature rise |
| CN113620671B (en) * | 2021-09-08 | 2022-10-14 | 中国水利水电第十二工程局有限公司 | Preparation method of shrinkage-compensating concrete and shrinkage-compensating concrete |
| CN117285273B (en) * | 2023-11-27 | 2024-02-02 | 内蒙古工业大学 | Soybean wax coated carbide slag micro-expanding agent and preparation method and application thereof |
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| CN1059750A (en) * | 1990-09-10 | 1992-03-25 | 郑亢三 | Water-proofing powder and manufacture method thereof |
| JP2965896B2 (en) * | 1995-10-13 | 1999-10-18 | 田口 ひろみ | Processing material for oil containing polychlorinated biphenyl |
| CN101774777B (en) * | 2010-01-26 | 2012-08-29 | 江苏博特新材料有限公司 | Preparation method of calcium oxide expansion agents |
| CN101805002B (en) * | 2010-04-16 | 2012-01-11 | 西安石油大学 | Preparation method of surface modification calcium oxide |
| CN102008393B (en) * | 2010-11-12 | 2012-11-28 | 罗彦凤 | Dry method coating device |
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