CN114470882A - Solid degassing agent for concrete and preparation method thereof - Google Patents

Abstract

The application discloses a solid degassing agent for concrete and a preparation method thereof, wherein the degassing agent comprises 40-60% of a carrier, 10-30% of fatty alcohol polyoxyethylene polyoxypropylene ether fatty acid ester, 10-30% of polyether modified polysiloxane and 5-15% of fatty alcohol polyoxyethylene polyoxypropylene ether carboxylate. According to the application, fatty alcohol polyoxyethylene polyoxypropylene ether fatty acid ester and polyether modified polysiloxane are used as defoaming substances, fatty alcohol polyoxyethylene polyoxypropylene ether carboxylate with a specific structure is introduced, so that the defoaming agent has a defoaming enhancement effect in concrete, meanwhile, the compatibility between two defoaming substances of the fatty alcohol polyoxyethylene polyoxypropylene ether fatty acid ester and the polyether modified polysiloxane and other additives of the concrete can be improved, and the product has excellent compatibility and defoaming performance.

Description

Solid degassing agent for concrete and preparation method thereof

Technical Field

The invention belongs to the technical field of additives for concrete, and relates to a solid degassing agent for concrete and a preparation method thereof.

Background

In order to improve the quality of concrete, various cement additives, such as air-entraining agents and water-reducing agents, are often used. The air entraining agent is used to improve the fluidity of unhardened concrete by introducing air bubbles into the concrete, and to improve the workability during construction and the frost resistance of hardened concrete. The water reducing agent can improve the fluidity of concrete and reduce the water content of the concrete, and the reduction of the water content can improve the strength of the concrete. However, if the amount of air introduced into the concrete is increased, coarse air bubbles are easily generated, resulting in uneven filling and a decrease in the strength of the concrete, and voids are formed on the surface of the hardened concrete, which deteriorates the appearance. Air release agents or defoamers are therefore typically added to the concrete to reduce internal air bubbles in the concrete.

The air-entraining agent is often insoluble in water, while other additives in the concrete, such as air-entraining agents and water-reducing agents, are soluble in water, so that the air-entraining agent separates over time, resulting in fluctuations in the air content inside the concrete. While compatibility in concrete can be improved by increasing the hydrophilicity of the air release agent, the ability to eliminate coarse air bubbles is diminished.

CN201980024049 discloses a defoaming agent composed of a polyoxyalkylene compound and a phosphate compound, which can achieve both defoaming property and compatibility in concrete, and can produce concrete with less coarse bubbles on the surface and beautiful surface. There is still room for improvement in defoaming performance.

CN108164181A discloses a concrete defoamer, which is composed of fatty alcohol polyoxyethylene ether phosphate, random polyether, an emulsifier, a wetting agent, a thickening agent, a compounding agent and water, wherein the chemical stability of the defoamer is improved by introducing the fatty alcohol polyoxyethylene ether phosphate. There is still room for improvement in defoaming performance.

CN110272222B discloses a solid defoaming agent for self-leveling mortar, which utilizes high-carbon alcohol to carry out high-temperature treatment on white carbon black, improves the foam breaking capability of the defoaming agent on the surface of a self-leveling mortar system, utilizes the high-carbon alcohol to spray a carrier, improves the storage stability of the defoaming agent, and increases the degassing performance of the defoaming agent. The preparation process is complex.

CN107117851B discloses an oil well cement powder defoaming agent, which is composed of hydrophilic white carbon black, hydrophobic white carbon black, a polar solvent, polyether and mineral oil, and the preparation method comprises the following steps: (1) mixing the first part of hydrophobic white carbon black with mineral oil to obtain an intermediate E; (2) mixing the second part of hydrophobic white carbon black with polyether to obtain an intermediate F; (3) mixing the intermediate E with hydrophilic white carbon black to obtain a mixture G; (4) adding a polar solvent into the mixture G, and uniformly mixing to obtain a mixture H; (5) and adding the intermediate F into the mixture H, mixing to obtain a mixture I, and finally screening the mixture I to obtain the powder defoaming agent. The preparation process is complex.

CN103172297B discloses a water soluble silicone having at least two different polyalkyleneoxy moieties, which has good compatibility with superplasticizers for concrete and good defoaming properties. The compatibility with other additives of concrete is improved by increasing the water solubility of the polysiloxane, and the defoaming performance of the polysiloxane is usually insufficient.

CN102961896B discloses a powder defoaming agent using fly ash hollow glass beads as a filler, wherein defoaming active substances are organic siloxane and hydrophobic white carbon black, an emulsifier is a nonionic silicon polyether emulsifier, and the filler is the fly ash hollow glass beads. The preparation method comprises the steps of preparing silicone grease from the organopolysiloxane and the hydrophobic white carbon black at a high temperature, and uniformly stirring and mixing the obtained silicone grease with the emulsifier and the fly ash hollow glass beads to prepare the powder defoaming agent. The defoaming agent can be applied to concrete defoaming. The product of the invention has simple preparation process and excellent defoaming performance, but the compatibility of polysiloxane and concrete is poor.

Disclosure of Invention

Aiming at the defects in the prior art, the technical problem to be solved by the application is to provide the solid degassing agent for the concrete, which has a defoaming enhancement effect in the concrete and can improve the compatibility with other additives. The invention also provides a preparation method of the solid degassing agent for concrete.

In order to solve the technical problem, the technical scheme adopted by the application is as follows:

a solid degassing agent for concrete comprises 40-60% of a carrier, 10-30% of fatty alcohol polyoxyethylene polyoxypropylene ether fatty acid ester, 10-30% of polyether modified polysiloxane and 5-15% of fatty alcohol polyoxyethylene polyoxypropylene ether carboxylate.

In the components of the solid degasifier for concrete, fatty alcohol polyoxyethylene polyoxypropylene ether fatty acid ester and polyether modified polysiloxane are main defoaming substances, and fatty alcohol polyoxyethylene polyoxypropylene ether carboxylate can enhance the defoaming performance of the fatty alcohol polyoxyethylene polyoxypropylene ether fatty acid ester and the polyether modified polysiloxane and improve the compatibility of the fatty alcohol polyoxyethylene polyoxypropylene ether fatty acid ester and the polyether modified polysiloxane with other additives of concrete.

The carrier is selected from one or more of sodium sulfate, sodium silicate, sodium carbonate, sodium bicarbonate, calcium carbonate, zeolite, diatomite, bentonite and silicon dioxide.

The fatty alcohol polyoxyethylene polyoxypropylene ether fatty acid ester has a structural general formula of { R¹O(EO)_m(PO)_nCOR²}_pWherein R is¹Is an alkyl group having 1 to 22 carbon atoms; m is an integer of 1 to 10, n is an integer of 20 to 40, R²Is an alkyl group having 12 to 22 carbon atoms, and p is 1, 2 or 3.

The polyether modified polysiloxane has a structural general formula as follows: r³ ₃SiO(Me₂SiO)_a(MeSiR⁴O)_bSiR³ ₃Wherein R is³Is methyl, ethyl, propyl or butyl, a is an integer of 1 to 200, b is an integer of 10 to 100, R⁴Is (CH2)_cO(EO)_d(PO)_eR⁵C is an integer of 3 to 6, d and e are integers of 1 to 50, and R5 is a hydrogen atom, methyl, ethyl, propyl or butyl.

The fatty alcohol polyoxyethylene polyoxypropylene ether carboxylate has a structural general formula of { R⁶O(EO)_x(PO)_yCH2COO}_zM, wherein R6 is alkyl with 1-22 carbon atoms, x is an integer of 1-10, y is an integer of 20-40, z is 1, 2 or 3, and M is selected from hydrogen, sodium, magnesium, calcium and aluminum.

The preparation method of the solid degassing agent for concrete comprises the following steps:

1) stirring and mixing fatty alcohol polyoxyethylene polyoxypropylene ether fatty acid ester, polyether modified polysiloxane and fatty alcohol polyoxyethylene polyoxypropylene ether carboxylate uniformly to obtain a mixture;

2) and (2) uniformly stirring and mixing the mixture obtained in the step (1) and a carrier to obtain the solid degassing agent.

The solid degassing agent for concrete is applied to concrete.

Has the advantages that: compared with the prior art, the method has the following advantages:

1) the application provides a solid degassing agent for concrete, fatty alcohol polyoxyethylene polyoxypropylene ether fatty acid ester and polyether modified polysiloxane are used as defoaming substances, fatty alcohol polyoxyethylene polyoxypropylene ether carboxylate with a specific structure is introduced, so that the fatty alcohol polyoxyethylene polyoxypropylene ether carboxylate has a defoaming enhancement effect in concrete, meanwhile, the compatibility between two defoaming substances of the fatty alcohol polyoxyethylene polyoxypropylene ether fatty acid ester and the polyether modified polysiloxane and other additives of the concrete can be improved, and the product has excellent compatibility and defoaming performance.

2) The preparation process is simple, and the target product can be obtained by uniformly mixing the defoaming substance and the fatty alcohol polyoxyethylene polyoxypropylene carboxylate and then uniformly mixing the defoaming substance and the carrier.

Detailed Description

The present invention will be further described with reference to the following specific examples.

In the following examples and comparative examples, starting material A was used: fatty alcohol polyoxyethylene polyoxypropylene ether fatty acid ester with a structural general formula of { R¹O(EO)_m(PO)_nCOR²}_pWherein R is¹Is an alkyl group having 1 to 22 carbon atoms; m is an integer of 1 to 10, n is an integer of 20 to 40, R²Is an alkyl group having 12 to 22 carbon atoms, and p is 1, 2 or 3. A typical structure is shown in table 1.

Table 1: typical fatty alcohol polyoxyethylene polyoxypropylene ether fatty acid ester

Name (R)	R1	m	n	R2	p
						A1	Propyl radical	5	40	Dodecyl radical	3
A2	Octadecyl radical	10	20	Octadecyl radical	1
						A3	Propyl radical	1	30	Docosyl	2
A4	Propyl radical	20	40	Dodecyl radical	3

Raw material B used: polyether modified polyorganosiloxane with the structural general formula: r³ ₃SiO(Me₂SiO)_a(MeSiR⁴O)_bSiR³ ₃Wherein R3 is methyl, ethyl, propyl or butyl, a is an integer of 1-200, b is an integer of 10-100, R⁴Is (CH)₂)_cO(EO)_d(PO)_eR⁵C is an integer of 3 to 6, d and e are integers of 1 to 50, R⁵Is hydrogen atom, methyl, ethyl, propyl or butyl. A typical structure is shown in table 2.

Table 2: typical polyether modified polyorganosiloxanes

Name (R)	R3	a	b	c	d	e	R5
								B1	Methyl radical	200	50	3	20	20	Hydrogen atom
B2	Ethyl radical	100	100	4	5	50	Methyl radical
								B3	Methyl radical	10	10	3	50	10	Butyl radical

Raw material C used: the fatty alcohol polyoxyethylene polyoxypropylene ether carboxylate has a structural general formula as follows: { R⁶O(EO)_x(PO)_yCH₂COO}_zM, wherein R⁶And the above R¹The same applies to x, y, z and M, wherein x is the same as M, y is the same as n, z is the same as p, and M is any one ion selected from hydrogen, sodium, magnesium, calcium and aluminum. The usage amount of the fatty alcohol polyoxyethylene polyoxypropylene ether carboxylate accounts for 5-15% of the total amount of the degassing agent. A typical structure is shown in table 3.

Table 3: typical fatty alcohol polyoxyethylene polyoxypropylene ether carboxylates

Name (R)	R6	x	y	z	M
						C1	Propyl radical	5	40	3	Hydrogen
C2	Octadecyl radical	10	20	1	Sodium salt
						C3	Propyl radical	1	30	2	Magnesium alloy
C4	Dodecyl radical	10	40	1	Hydrogen
						C5	Propyl radical	20	40	3	Hydrogen

Example 1

Typical compositions of the degassing agents (D1-D4) and of the comparative products (F1-F5) are shown in Table 4, prepared in the same way and are: uniformly stirring and mixing the component A, the component B and the component C with designed dosage to obtain a mixture E1-E4 and a comparison mixture H1-H5, then adding the mixture into a carrier with designed dosage, and uniformly stirring and mixing to obtain various degasifier products (D1-D4) and comparison products (F1-F5).

Table 4: typical composition of degassing agent D

Name (R)	A	B	C	Carrier
					D1	20 parts of A1	20 parts of B1	15 parts of C1	45 parts of sodium sulfate
D2	30 parts of A2	10 parts of B2	5 parts of C2	55 parts of calcium carbonate
					D3	10 parts of A3	30 parts of B3	10 parts of C3	50 parts of zeolite
D4	20 parts of A1	20 parts of B2	10 parts of C4	50 parts of silicon dioxide
					F1	20 parts of A4	20 parts of B1	15 parts of C1	45 parts of sodium sulfate
F2	30 parts of A2	10 parts of B2	5 parts of C5	55 parts of calcium carbonate
					F3	20 parts of A3	30 parts of B3	/	50 parts of zeolite
F4	40 parts of A1	/	10 parts of C4	50 parts of silicon dioxide
					F5	/	40 parts of B3,	10 parts of C3	50 parts of zeolite

The product is subjected to performance test, and the specific method is as follows:

1. compatibility testing

The liquid mixture of each product (E1-E4, H1-H5) was added to the water reducing agent in an amount of 0.2%, left at 25 ℃ for 30 days, and the compatibility was visually observed.

2. Defoaming Performance test

According to the water: river sand: cement (in accordance with GB 175): water reducing agent (polycarboxylic acid water reducing agent): the concrete is prepared by the concrete with the degasifier mass ratio of 150: 300: 3: 1.5, and river sand, cement, water reducer, degasifier and water are firstly stirred at low speed for 60s, then are stood still for 30s and then are stirred at high speed for 60s by using a planetary cement mortar stirrer. And pouring the stirred mortar into a measuring range, recording the volume corresponding to the mass of the mortar, and calculating the density. Density is the mass of mortar/volume of mortar. The defoaming performance is expressed in terms of density, and the higher the density, the better the defoaming performance is.

3. The test results are shown in Table 5

Table 5: test results

Product(s)	Compatibility	Product(s)	Density (g/mL)
				E1	◎	D1	2.03
E2	◎	D2	2.01
				E3	◎	D3	2.01
E4	◎	D4	2.00
				H1	×	F1	1.87
H2	×	F2	1.78
				H3	×	F3	1.70
H4	◎	F4	1.88
				H5	◎	F5	1.75

In table 5 ∈ indicates that the product has good compatibility with the water reducing agent and no separation or adhesion occurred, and ×. indicates that the product has poor compatibility with the water reducing agent and separation or adhesion occurred to the wall surface of the container.

The test result shows that compared with a comparative product, the defoaming agent prepared by the method has good compatibility with the additive water reducing agent of concrete in the presence of fatty alcohol polyoxyethylene polyoxypropylene ether carboxylate, and the prepared degassing agent has good defoaming performance.

Claims (7)

1. The solid degassing agent for concrete is characterized by comprising 40-60% of a carrier, 10-30% of fatty alcohol polyoxyethylene polyoxypropylene ether fatty acid ester, 10-30% of polyether modified polysiloxane and 5-15% of fatty alcohol polyoxyethylene polyoxypropylene ether carboxylate.

2. The solid degassing agent for concrete according to claim 1, wherein the carrier is one or more selected from the group consisting of sodium sulfate, sodium silicate, sodium carbonate, sodium bicarbonate, calcium carbonate, zeolite, diatomaceous earth, bentonite, and silica.

3. The solid degassing agent for concrete according to claim 1, wherein said fatty alcohol-based polymerThe structural general formula of the polyoxyethylene polyoxypropylene ether fatty acid ester is { R¹O(EO)_m(PO)_nCOR²}_pWherein R is¹Is an alkyl group having 1 to 22 carbon atoms; m is an integer of 1 to 10, n is an integer of 20 to 40, R²Is an alkyl group having 12 to 22 carbon atoms, and p is 1, 2 or 3.

4. The solid degassing agent for concrete according to claim 1, wherein the polyether-modified polyorganosiloxane has a general structural formula: r³ ₃SiO(Me₂SiO)_a(MeSiR⁴O)_bSiR³ ₃Wherein R is³Is methyl, ethyl, propyl or butyl, a is an integer of 1 to 200, b is an integer of 10 to 100, R⁴Is (CH2)_cO(EO)_d(PO)_eR⁵C is an integer of 3 to 6, d and e are integers of 1 to 50, R⁵Is hydrogen atom, methyl, ethyl, propyl or butyl.

5. The solid degassing agent for concrete according to claim 1, wherein said fatty alcohol polyoxyethylene polyoxypropylene ether carboxylate has a general structural formula of { R } [ ((R) ])⁶O(EO)_x(PO)_yCH2COO}_zM, wherein R⁶Is alkyl with 1-22 carbon atoms, x is an integer of 1-10, y is an integer of 20-40, z is 1, 2 or 3, and M is selected from hydrogen, sodium, magnesium, calcium and aluminum.

6. The method for preparing a solid degassing agent for concrete according to claim 1, comprising the steps of:

1) stirring and mixing fatty alcohol polyoxyethylene polyoxypropylene ether fatty acid ester, polyether modified polysiloxane and fatty alcohol polyoxyethylene polyoxypropylene ether carboxylate uniformly to obtain a mixture;

2) and (2) uniformly stirring and mixing the mixture obtained in the step (1) and a carrier to obtain the solid degassing agent.

7. Use of the solid air release agent for concrete according to claim 1 in concrete.