CN102584070A

CN102584070A - Concrete expanding agent

Info

Publication number: CN102584070A
Application number: CN201210033574XA
Authority: CN
Inventors: 万建东; 刘小全; 王彦梅; 徐红英; 林清芳; 唐修仁
Original assignee: ZHEJIANG EFFUL NEW MATERIAL SCIENCE AND TECHNOLOGY Co Ltd
Current assignee: ZHEJIANG EFFUL NEW MATERIAL SCIENCE AND TECHNOLOGY Co Ltd
Priority date: 2012-02-15
Filing date: 2012-02-15
Publication date: 2012-07-18

Abstract

The invention discloses a concrete expanding agent, which comprises II-type anhydrite and fly ash, namely comprises 0 to 50 mass percent of fly ash and the balance of II-type anhydrite. The II-type anhydrite can be natural anhydrite, and can also be formed by calcining natural dihydrate gypsum or chemical gypsum at the temperature of between 500 and 1,000 DEG C. According to the expanding principle, after the expanding agent is added into concrete, the anhydrite is hydrated to form the dihydrate gypsum, and then volume is enlarged, and the dihydrate gypsum is reacted with the material in the concrete to generate more expandable ettringite. The substance for expanding does not comprise an alkali material, so alkali aggregate reaction is not produced. The chemical gypsum and the fly ash are industrial solid wastes, so that the wastes are changed into valuable, and the concrete expanding agent has remarkable economic and social benefits.

Description

A kind of cement expansive material

Technical field

The present invention relates to a kind of concrete admixture, particularly cement expansive material.

Background technology

The swelling agent that is used for cement concrete and mortar at present mainly contains four kinds: the quicklime aquation generates calcium hydroxide, and the Natural manganese dioxide aquation generates Marinco H, and the red stone aquation generates ironic hydroxide, and by Al ³⁺, SO ₄ ^2-And Ca (OH) ₂Generate the aquation calcium sulphoaluminate and have another name called ettringite (3CaOAl ₂O ₃3CaSO ₄32H ₂O).Because the hydration reaction of first three is very responsive to the physical and chemical performance of hydration temperature and swelling agent, therefore use lessly, having only the generation ettringite at present is that the material of expansion sources is widely used in the production swelling agent.Like alumite plumping agent, its reaction formula is: 2KAl ₃(SO ₄) ₂(OH) ₆+ 13Ca (OH) ₂+ 5CaSO ₄+ 78H ₂O → 3 (3CaOAl ₂O ₃3CaSO ₄32H ₂O)+2KOH.Except that generating the ettringite expansion sources, also generate KOH simultaneously, this just increases the possibility that alkali-aggregate reaction takes place.

Summary of the invention

Problem to be solved by this invention is: a kind of controlled new concrete swelling agent of basic material, low price, wide material sources and performance that do not comprise is provided.

For addressing the above problem, the scheme that the present invention adopts is:

A kind of cement expansive material comprises II type anhydrite and flyash, and flyash content is 0-50% by mass percentage, and surplus is an II type anhydrite.Above-mentioned II type anhydrite can be a natural anhydrite, is perhaps formed through 500～1000 ℃ of calcinings by natural dihydrate gypsum or chemical gypsum.Chemical gypsum wherein can be phosphogypsum, desulfurated plaster, salt gypsum etc.

Expansion principle of the present invention is: volume will increase 1.4 times when pure anhydrite hydration became dihydrate gypsum, Theoretical Calculation such as table 1.

Table 1. anhydrite hydration becomes the theoretical value of dihydrate gypsum volumetric expansion

Anhydrite except that self hydration swelling, also will with the calcium aluminate C of hydrated cementitious product ₃AH ₆And the calcium sulphoaluminate 3CaOAl of single sulphur type ₂O ₃CaSO ₄12H ₂O (AFm) reaction generates ettringite 3CaOAl ₂O ₃3CaSO ₄32H ₂O (AFt) needle-like crystal and produce volumetric expansion, its Theoretical Calculation such as table 2 and table 3.

Table 2. drated calcium aluminate C ₃AH ₆With volumetric expansion theoretical value behind the anhydrite hydration

Volumetric expansion theoretical value behind table 3. AFm and the anhydrite hydration

In order to generate more ettringite, can mix an amount of flyash, because the aluminum content in the flyash is higher, generally about 20%.At cement concrete (mortar) if in Al is arranged ³⁺, SO ₄ ^2-And Ca (OH) ₂Just can generate aquation calcium sulphoaluminate (ettringite).

The consumption of anhydrite swelling agent of the present invention in the cement concrete mortar can change between 8～20% according to request for utilization.Use between being preferably in 10～15%.In addition, late have much relations with the hydrating capacity of II type anhydrite the morning of expansion effect, and natural anhydrite forms under underground HTHP, the particle densification, so hydration rate is very slow, and the anhydrite hydration speed that is sintered into dihydrate gypsum is very fast relatively.Calcining temperature also has very big influence to anhydrite, and after calcining surpassed 500 ℃, the high more hydration rate of temperature was slow relatively more.

The invention has the beneficial effects as follows: the main raw material of cement expansive material of the present invention is waste desulfurized gypsum residue and flyash; Be industrial solid castoff; Replace this Nonrenewable resources of the plaster of paris to be used for cement expansive material with them; Reduced the stacking of industrial solid castoff, turned waste into wealth, remarkable economical and social benefit have been arranged; The present invention is used for the expansible material and does not comprise basic material, can not cause alkali-aggregate reaction.Calcining temperature is different, and the aquation rate that produces anhydrite is different, and the swell increment that causes thus is different, and the amount difference that adds flyash in addition also can influence concrete swell increment, therefore can be according to the swelling agent of engineering specific requirement different choice different composite degree.

Description of drawings

Fig. 1 is that the anhydrite of natural anhydrite, 500 ℃, 700 ℃ and 900 ℃ of calcining desulfurated plasters is mixed 12% expansion effect figure in swelling agent is in 1: 2 sand-cement slurry.Among the figure, 1. be the anhydrite of 500 ℃ of calcining desulfurated plasters; 2. be the anhydrite of 700 ℃ of calcining desulfurated plasters; 3. be the anhydrite of 900 ℃ of calcining desulfurated plasters; 4. be natural anhydrite.

Fig. 2 is anhydrite and the flyash composite expanding agent expansion effect figure in 1: 2 sand-cement slurry of different performance.Among the figure, 1. be natural anhydrite 50% and flyash 50% composite expanding agent, in mix 20%; 2. be the anhydrite 50% and flyash 50% composite expanding agent of 900 degree calcining desulfurated plasters, in mix 12%; 3. be the anhydrite 70% and flyash 30% composite expanding agent of 900 degree calcined phosphogypsums, in mix 16%; 4. be the anhydrite 70% and flyash 30% composite expanding agent of 700 degree calcining desulfurated plasters, in mix 12%.

Embodiment

Below in conjunction with accompanying drawing and specific examples the technical characterictic of a kind of anhydrite cement expansive material of the present invention and preparation method thereof is done further to set forth.

The anhydrite swelling agent effect of different performance such as Fig. 1, shown in Figure 2.

Natural anhydrite among Fig. 1 and Fig. 2 and desulfurated plaster, and the chemical ingredients of used natural dihydrate gypsum, desulfurated plaster, phosphogypsum, salt gypsum and flyash is as shown in table 4 among the following embodiment.Used cement is 42.5 ordinary Portland cements among the embodiment.

Table 4 starting material chemical ingredients (%)

Title	Loss on ignition	SiO ₂	CaO	SO ₃	MgO	Al ₂O ₃	Fe ₂O ₃	K ₂O	Na ₂O
										Natural dihydrate gypsum	20.12	-	26.31	40.56	1.44	1.27	0.46	0.02	0.08
Natural anhydrite	0.25	-	40.52	54.12	1.24	0.03	0.03	0.015	0.027
										Desulfurated plaster	19.88	-	30.93	44.19	-	-	-	-	-
Phosphogypsum	15.31	2.31	24.72	38.33	2.11	3.75	0.24	0.21	2.33
										The salt gypsum	16.47	-	22.17	36.25	3.15	0.08	0.05	2.73	5.32
Flyash	8.5	45.4	3.5	-	0.5	25.3	15.4	-	-

Specific embodiment is following:

Embodiment 1

Take by weighing 60g natural anhydrite powder as expansive agent for cement slurry; Detect according to national standard; Swelling agent in the 1:2 sand-cement slurry in volume be 12% o'clock; 7 days limited expansion rates of maintenance are 0.035% in the water, and 28 days limited expansion rates of maintenance are 0.089% in the water, meet " cement expansive material " JC476-2001 standard-required.

Embodiment 2

Waste desulfurized gypsum residue is calcined 2h down for 700 ℃, and grinding becomes 300 order powder.Take by weighing the above-mentioned powder of 60g as expansive agent for cement slurry; Detect according to national standard; Swelling agent in the 1:2 sand-cement slurry in volume be 12% o'clock; 7 days limited expansion rates of maintenance are 0.072% in the water, and 28 days limited expansion rates of maintenance are 0.098% in the water, meet " cement expansive material " JC476-2001 standard-required.

Embodiment 3

At 900 ℃ of calcining 2h, grinding becomes 300 order powder with the phosphogypsum slag.Take by weighing the above-mentioned powder of 30g, the levigate cement concrete swelling agent of processing of 30g flyash mixing; Detect according to national standard; Swelling agent in the 1:2 sand-cement slurry in volume be 12% o'clock; 7 days limited expansion rates of maintenance are 0.051% in the water, and 28 days limited expansion rates of maintenance are 0.090% in the water, meet " cement expansive material " JC476-2001 standard-required.

Embodiment 4

The salt gypsum tailings is calcined 2h in 700 ℃ of scopes, grinding becomes 300 order powder.Take by weighing the above-mentioned powder of 28g, the levigate cement concrete swelling agent of processing of 12g flyash mixing; Detect according to national standard; Swelling agent in the 1:2 sand-cement slurry in volume be 12% o'clock; 7 days limited expansion rates of maintenance are 0.071% in the water, and 28 days limited expansion rates of maintenance are 0.083% in the water, meet " cement expansive material " JC476-2001 standard-required.

Embodiment 5

Natural dihydrate gypsum is calcined 2h in 500 ℃ of scopes, grinding becomes 300 order powder.Take by weighing the above-mentioned powder of 50g, the levigate cement concrete swelling agent of processing of 10g flyash mixing; Detect according to national standard; Swelling agent in the 1:2 sand-cement slurry in volume be 12% o'clock; 7 days limited expansion rates of maintenance are 0.064% in the water, and 28 days limited expansion rates of maintenance are 0.088% in the water, meet " cement expansive material " JC476-2001 standard-required.

Embodiment 6

Natural dihydrate gypsum is calcined 2h in 1000 ℃ of scopes, grinding becomes 300 order powder.Take by weighing the levigate cement concrete swelling agent of processing of the above-mentioned powder of 60g; Detect according to national standard; Swelling agent in the 1:2 sand-cement slurry in volume be 12% o'clock; 7 days limited expansion rates of maintenance are 0.062% in the water, and 28 days limited expansion rates of maintenance are 0.086% in the water, meet " cement expansive material " JC476-2001 standard-required.

Claims

1. a cement expansive material is characterized in that, comprises II type anhydrite and flyash, and flyash content is 0-50% by mass percentage, and surplus is an II type anhydrite.

2. cement expansive material according to claim 1 is characterized in that, described II type anhydrite is a natural anhydrite, or natural dihydrate gypsum or chemical gypsum form through 500～1000 ℃ of calcinings.

3. cement expansive material according to claim 2 is characterized in that, described chemical gypsum is phosphogypsum, desulfurated plaster, salt gypsum.