CN109095802B

CN109095802B - Expansive agent for concrete, concrete and preparation method thereof

Info

Publication number: CN109095802B
Application number: CN201810978402.7A
Authority: CN
Inventors: 不公告发明人
Original assignee: Guangdong Ruizhu Residential Technology Co ltd
Current assignee: Guangdong Remac Equipment Information Technology Co Ltd
Priority date: 2018-08-27
Filing date: 2018-08-27
Publication date: 2021-11-09
Anticipated expiration: 2038-08-27
Also published as: CN109095802A

Abstract

The invention discloses an expanding agent for concrete, concrete and a preparation method thereof, wherein the expanding agent for concrete comprises an expanding agent base material and an additive, the additive is meta-aluminate, and the mass ratio of the meta-aluminate to the expanding agent base material is 1.0-3.0%. The concrete contains the following components in parts by mass per cubic meter: cement, 240 and 300 parts; 15-63 parts of an expanding agent for concrete; sand, 920 and 1110 parts; 810 and 1000 parts of stone; 2.1-3.6 parts of a water reducing agent; and water, 160-. According to the technical scheme, the expansion amount of the concrete can be increased, uniform expansion is realized, and the compactness of the concrete is enhanced.

Description

Expansive agent for concrete, concrete and preparation method thereof

Technical Field

The invention relates to the technical field of concrete, in particular to an expanding agent for concrete, concrete and a preparation method thereof.

Background

The prefabricated building is the main trend of the building industry, and the main structural form of the prefabricated building is a prefabricated concrete structure. The connection between the prefabricated components in the precast concrete structure can bring a large amount of post-cast concretes, and after the common concretes are poured, the shrinkage is inevitable, the cracks are seriously caused, and the structure safety is influenced. The expansion agent is added into the concrete, and the expansion effect generated by the expansion agent is utilized to compensate the shrinkage of the concrete to prepare the shrinkage-compensated concrete with good volume stability, which is a common economic, effective and practical method.

After the expanding agent is added into the concrete, the expanding agent is hydrated, so that not only water or hydration products of other cementing materials are consumed, but also new substances are generated, and the generated expansion stress also has important influence on the concrete structure. According to different chemical compositions, the expanding agents mainly comprise calcium sulphoaluminate expanding agents, calcium oxide expanding agents, calcium sulphoaluminate-calcium oxide expanding agents and magnesium oxide expanding agents, and the expanding agents affect hydration of mineral admixtures in concrete, carbonization resistance of the concrete, sulfate corrosion resistance of the concrete and the like.

The expansion agent can reduce the fluidity of the fresh concrete, and the reduction effect is more obvious along with the increase of the mixing amount. This is because the swelling agent hydration usually occurs early, resulting in a reduction in free water in the concrete; the needle-shaped or columnar ettringite and the plate-shaped calcium hydroxide generated by hydration obviously increase the viscosity and the yield shear stress of the cement paste, thereby reducing the fluidity of the fresh concrete. The expanding agent has important influence on the compactness and hydration products of the concrete, the expansion of a plurality of expanding agents is difficult to control at present, the stress generated during the expansion is overlarge, the compactness of the concrete is reduced, and the durability of the concrete cannot be ensured.

Disclosure of Invention

The invention mainly aims to provide an expanding agent for concrete, aiming at improving the expansion amount of the concrete, realizing uniform expansion and enhancing the compactness of the concrete.

In order to achieve the purpose, the concrete expanding agent provided by the invention comprises an expanding agent base material and an additive, wherein the additive is meta-aluminate, and the mass ratio of the meta-aluminate to the expanding agent base material is 1.0-3.0%.

Optionally, the expander base is a calcium sulfoaluminate expander.

Optionally, the metaaluminate is at least one of sodium metaaluminate and potassium metaaluminate.

The invention also provides concrete, wherein each cubic meter of the concrete comprises the following components in parts by mass:

cement, 240 and 300 parts;

15-63 parts of the expansion agent for concrete;

sand, 920 and 1110 parts;

810 and 1000 parts of stone;

2.1-3.6 parts of a water reducing agent; and

water, 160 and 175 portions.

Optionally, the cement is portland cement or ordinary portland cement of strength grade 42.5; and/or the water reducing agent is a polycarboxylic acid high-performance water reducing agent.

Optionally, the sand is machine-made sand or river sand, and the fineness modulus is 2.3-2.8; and/or the stones are continuous graded broken stones, and the particle size is 5mm-20 mm.

Optionally, the concrete also contains 60-120 parts of active admixture per cubic meter by mass.

Optionally, the active admixture is at least one of fly ash and zeolite powder.

The invention also provides a preparation method of the concrete, which comprises the following steps:

providing 15-63 parts by mass of an expanding agent for concrete, 300 parts by mass of cement, 1110 parts by mass of sand for 920-;

mixing the expanding agent for concrete, the cement, the sand and the stone to obtain a mixed base material;

mixing the water reducing agent and the water to obtain a water reducing agent solution;

and adding the water reducing agent solution into the mixed base material, and stirring and mixing to obtain the concrete.

Optionally, 60-120 parts of active admixture is added in the step of obtaining the mixed base material.

Compared with the prior art, the technical scheme of the invention has the following beneficial effects: the expanding agent for concrete contains an expanding agent base material and an additive, wherein the additive is meta-aluminate, and the proportion of the meta-aluminate to the expanding agent base material is reasonably adjusted, so that the additive and the expanding agent base material can well play a synergistic effect, the generation rate of an expanding agent base material hydration product ettringite is effectively adjusted, the expansion amount of the ettringite is improved, and therefore, the uniform expansion is realized, and meanwhile, when the expanding agent for concrete disclosed by the invention is applied to concrete, the compactness of the concrete can be effectively enhanced.

Detailed Description

The technical solutions in the embodiments of the present invention will be described clearly and completely below, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

In addition, technical solutions between various embodiments may be combined with each other, but must be realized by a person skilled in the art, and when the technical solutions are contradictory or cannot be realized, such a combination should not be considered to exist, and is not within the protection scope of the present invention.

The invention provides an expanding agent for concrete, which comprises an expanding agent base material and an additive, wherein the additive is meta-aluminate, and the mass ratio of the meta-aluminate to the expanding agent base material is 1.0-3.0%.

The base material of the expanding agent is used as the main component of the expanding agent, so that the expanding agent has better expansion performance, and the expansion effect generated by the expanding agent can be used for compensating the shrinkage of the concrete after the expanding agent is added into the concrete, so as to prepare the shrinkage-compensated concrete with good volume stability. According to different chemical compositions, the expanding agent base materials are divided into calcium sulphoaluminate expanding agent base materials, calcium oxide expanding agent base materials, calcium sulphoaluminate-calcium oxide expanding agent base materials and magnesium oxide expanding agent base materials. The main active components of the expanding agent base material are alumina and calcium oxide, and when the expanding agent base material is used for concrete, the expanding agent base material is usually hydrated in the early stage to produce needle-shaped or columnar ettringite and platy calcium hydroxide. The metaaluminate is used as an additive, and after being added, the metaaluminate can play a synergistic role with the expanding agent base material in the mixture, promote the hydration reaction of the expanding agent base material, and can promote the generation rate of hydration products, namely ettringite, so as to promote the expansion amount, thereby realizing uniform expansion and simultaneously enhancing the compactness of concrete.

In the concrete expanding agent, the proportion of the meta-aluminate and the expanding agent base material is proper, the mass ratio of the meta-aluminate to the expanding agent base material is 1.0-3.0%, for example, the mass ratio of the meta-aluminate to the expanding agent base material is 1%, or 2%, or 3%. If the consumption of the metaaluminate is less than 1 percent, the metaaluminate can not play a synergistic role with all the expanding agent base materials, and finally the expansion amount is not obviously improved, and the expansion uniformity and the closed cell property of the concrete are not obviously improved; if the amount of the meta-aluminate is more than 3%, part of the meta-aluminate cannot play its role, which results in resource waste.

Therefore, compared with the prior art, the technical scheme of the invention has the following beneficial effects: the expanding agent for concrete contains an expanding agent base material and an additive, wherein the additive is meta-aluminate, and the proportion of the meta-aluminate to the expanding agent base material is reasonably adjusted, so that the additive and the expanding agent base material can well play a synergistic effect, the generation rate of an expanding agent base material hydration product ettringite is effectively adjusted, the expansion amount of the ettringite is improved, and therefore, the uniform expansion is realized, and meanwhile, when the expanding agent for concrete disclosed by the invention is applied to concrete, the compactness of the concrete can be effectively enhanced.

Preferably, the expander base is a calcium sulfoaluminate expander. The calcium sulphoaluminate expanding agent is a high-performance expanding agent, the main component of the expanding agent is calcium sulphoaluminate, and when the expanding agent is added into concrete, the calcium sulphoaluminate expanding agent can generate an expansion effect to compensate the shrinkage of the concrete so as to prepare the shrinkage-compensating concrete with good volume stability.

Optionally, the metaaluminate is at least one of sodium metaaluminate and potassium metaaluminate. The sodium metaaluminate and the potassium metaaluminate are used as metaaluminates, and after the metaaluminates are added, the hydration reaction of the base material of the expanding agent can be effectively promoted, the generation rate of hydrate ettringite is increased, and the expansion amount of the base material is increased. In one embodiment of the invention, sodium metaaluminate, or potassium metaaluminate, or a combination of both, is used.

The invention also provides concrete, wherein each cubic meter of the concrete comprises the following components in parts by mass: cement, 240 and 300 parts; 15-63 parts of an expanding agent for concrete; sand, 920 and 1110 parts; 810 and 1000 parts of stone; 2.1-3.6 parts of a water reducing agent; and water, 160-.

The concrete expanding agent is added, wherein the active component alumina can react with a cement hydration product to form hydrated tricalcium aluminate, so that the concrete has better strength and compactness. In order to ensure better workability of concrete, a water reducing agent needs to be added. The water reducing agent can produce strong dispersion to the cement granule wherein, the absorption of water reducing agent at cement granule interface and the electric double layer that forms can make and produce static between the cement granule and repel stress, break apart its flocculation structure to make the yield shear stress that the concrete begins to flow reduce, obtain high flow property, can control the quantity of concrete effectively simultaneously, with the requirement of assurance mechanics and durability.

The concrete of the invention has appropriate dosage of raw materials, so that the finally prepared concrete has better performance. Wherein, the dosage of the cement is 240 portions, or 260 portions, or 300 portions, for example, 240 portions, or 300 portions, per cubic meter of concrete; the amount of the expanding agent for concrete is 15-63 parts, which is 5% -15% of the cementing material in the concrete, such as 15 parts, 30 parts, 50 parts or 63 parts; the amount of the sand is 920-1110 parts, for example, 920 parts, 1000 parts or 1110 parts; the dosage of the stone is 810-1000 parts, for example, 810 parts, 900 parts or 1000 parts respectively; the amount of the water reducing agent is 2.1-3.6 parts, such as 2.1 parts, 3.0 parts or 3.6 parts; the amount of water is 160-175 parts, such as 160 parts, 170 parts, or 175 parts.

Alternatively, the cement is portland cement or portland cement of strength grade 42.5. The invention selects cement as Portland cement or ordinary Portland cement with the strength grade of 42.5; of course, other types of cement may be used, such as 32.5 portland cement, 52.5 portland cement, 62.5 portland cement, aluminate cement, sulphoaluminate cement, ferro-aluminate cement, fluoroaluminate cement, phosphate cement, or special cement.

Optionally, the water reducer is a polycarboxylic acid water reducer. The polycarboxylate superplasticizer has extremely strong water reducing performance, low chloride ion content and high alkali content, and is beneficial to the durability of concrete. After the concrete is added, the early and later strength of the concrete can be greatly improved. Meanwhile, the polycarboxylic acid high-performance water reducing agent has good compatibility with cement of concrete, so that the slump retention performance of the concrete is good, and the construction time of the concrete can be prolonged.

Optionally, the sand is machine-made sand or natural river sand, with a fineness modulus of 2.3-2.8. Machine-made sand and natural river sand, which are one type of sand, are granular loose materials, which are generally used for concrete, and serve as a framework or a filling. The fineness modulus of the selected sand is 2.3-2.8, the effect is better, and the uniformity of the prepared concrete is better. For example, sand having a fineness modulus of 2.3, or 2.5, or 2.8 is used.

Optionally, the stone is a continuous graded crushed stone with a particle size of 5mm-20 mm. The continuous graded broken stone is adopted, so that the strength and the workability of concrete can be improved, the size of slurry is reduced, and the volume stability is improved. The continuous graded crushed stone preferably has a particle size of 5mm to 20mm, such as a particle size of 5mm, or 10mm, or 15mm, or 20 mm. If the particle size is less than 5mm, the effect of improving the strength of the concrete is not obvious; if the particle size is larger than 20mm, the size of the slurry cannot be effectively reduced, and the uniformity of the concrete is not obvious.

Furthermore, the concrete also contains 60 to 120 parts of active admixture per cubic meter by mass. The active admixture is used as a cementing material, and after the active admixture is added, the performance of the concrete can be improved, water can be saved, and the strength grade of the concrete can be adjusted. The active admixture does not harden itself or its hardening speed is very slow, but it can react with the hydration of cement to form calcium oxide, forming a hydration product with gelling ability. In addition, the fluidity, the cohesiveness and the water-retaining property of the concrete can be improved in the presence of the water reducing agent; improving the pumpability of the concrete; while improving the strength and durability of the hardened concrete. Although the amount of the active admixture is appropriate, the present invention selects the addition of 60-120 parts of the active admixture per cubic meter of concrete, for example, 60 parts of the active admixture, or 100 parts of the active admixture, or 120 parts of the active admixture. If the content of the added active admixture is less than 60 parts, the performance of the concrete is improved less obviously; if the content of the added active admixture is more than 120 parts, part of the active admixture cannot fully exert the function thereof, and resource waste is caused.

It should be noted that the commonly used active admixtures are fly ash, granulated blast furnace slag powder, zeolite powder, and silica fume.

Optionally, the active admixture is at least one of fly ash and zeolite powder. The active admixture of the invention is selected from fly ash, zeolite powder or a compound of the fly ash and the zeolite powder. Preferably, the active admixture is a composite mineral admixture composed of fly ash and zeolite powder, and after the active admixture is added, the performance of concrete can be effectively improved, water is saved, and the strength grade of the concrete is adjusted.

mixing an expanding agent for concrete, cement, sand and stone to obtain a mixed base material;

mixing a water reducing agent and water to obtain a water reducing agent solution;

Specifically, firstly, weighing 15-63 parts of an expanding agent for concrete, 300 parts of cement in 240-; then sequentially adding the expanding agent for concrete, cement, sand and stone into the stirrer, and stirring for 2-4min at room temperature to obtain a uniformly mixed base material. And adding the water reducing agent and water into another stirrer, and stirring and mixing to obtain a uniform water reducing agent solution. And finally, slowly adding the prepared water reducing agent solution into the mixed base material, and continuously stirring until the uniformly mixed concrete is obtained. In the invention, the water reducing agent is added in the form of solution and can be better dispersed into the mixed base material, so that the performance of the water reducing agent is fully exerted, and the finally prepared concrete has better flow property.

It should be noted that, in the preparation process, the steps of preparing the mixed base material and the steps of preparing the water reducing agent solution can be switched in order.

Further, in the step of obtaining the mixed base material, 60-120 parts of active admixture is also added. The addition of the active admixture can improve the performance of the concrete, save water and adjust the strength grade of the concrete.

The concrete expansive agent, the concrete and the method for producing the concrete of the present invention will be described below with reference to specific examples.

Example one

The concrete comprises the following components in parts by mass per cubic meter: 300 parts of cement, 31.465 parts of concrete expanding agent, 60 parts of active admixture, 970 parts of sand, 950 parts of stone, 165 parts of water and 3.6 parts of water reducing agent; wherein, 31.465 parts of the expanding agent for concrete contains 31 parts of calcium sulphoaluminate expanding agent, 0.31 part of sodium metaaluminate and 0.155 part of potassium metaaluminate; 60 parts of active admixture comprises 30 parts of fly ash and 30 parts of zeolite powder.

The preparation method of the concrete comprises the following steps:

sequentially adding cement, an expanding agent for concrete, an active admixture, sand and stone into a stirrer, and stirring for 2min at normal temperature to obtain a mixed base material;

adding the water reducing agent and water into a stirrer in sequence, and stirring uniformly to prepare a water reducing agent solution;

and slowly adding the prepared water reducing agent solution into a stirrer filled with the mixed base material, and uniformly stirring to obtain the concrete.

And pouring the stirred concrete into a mold, and performing performance test on the concrete in the pouring and forming process, wherein the performance test results are shown in table 1.

Example two

The concrete comprises the following components in parts by mass per cubic meter: 240 parts of cement, 28.28 parts of concrete expanding agent, 120 parts of active admixture, 920 parts of sand, 1000 parts of stone, 170 parts of water and 3.4 parts of water reducing agent; wherein, 28.28 parts of the concrete expanding agent comprises 28 parts of calcium sulphoaluminate expanding agent and 0.28 part of sodium metaaluminate; 120 parts of active admixture comprises 40 parts of fly ash and 80 parts of zeolite powder.

The preparation method of the concrete in this embodiment refers to the preparation method described in the first embodiment, and details are not repeated here.

The concrete stirred in the embodiment is poured into a mold, and the performance test is carried out on the concrete in the pouring and forming process, and the performance test result is shown in table 1.

EXAMPLE III

The concrete comprises the following components in parts by mass per cubic meter: 280 parts of cement, 34.816 parts of an expanding agent for concrete, 80 parts of an active admixture, 1110 parts of sand, 810 parts of stone, 175 parts of water and 3.2 parts of a water reducing agent; wherein 34.816 parts of concrete expanding agent contains 34 parts of calcium sulphoaluminate expanding agent and 0.816 part of potassium metaaluminate; 80 parts of active admixture comprises 10 parts of fly ash and 70 parts of zeolite powder.

Example four

The concrete comprises the following components in parts by mass per cubic meter: 290 parts of cement, 32.96 parts of concrete expanding agent, 70 parts of active admixture, 920 parts of sand, 1000 parts of stone, 160 parts of water and 3.6 parts of water reducing agent; wherein, 32.96 parts of the expanding agent for concrete contains 32 parts of calcium sulphoaluminate expanding agent, 0.48 part of sodium metaaluminate and 0.48 part of potassium metaaluminate; 70 parts of active admixture containing 30 parts of fly ash and 40 parts of zeolite powder.

Table 1 table of concrete performance test results in the casting process of each example

As can be seen from Table 1, the concrete finally prepared in the first to fourth examples is not slushing, is easy to compact, has high compressive strength and has no obvious defects on the surface. In addition, the slump flow stability of the concrete in each example is better, which indicates that the working performance of the concrete is better.

The above description is only a preferred embodiment of the present invention, and not intended to limit the scope of the present invention, and all modifications and equivalents of the present invention, which are made by the present specification and directly/indirectly applied to other related technical fields within the spirit of the present invention are included in the scope of the present invention.

Claims

1. The concrete expanding agent is characterized by comprising an expanding agent base material and an additive, wherein the additive is meta-aluminate, and the mass ratio of the meta-aluminate to the expanding agent base material is 1.0-3.0%; the expanding agent base material is a calcium sulphoaluminate expanding agent; the metaaluminate is at least one of sodium metaaluminate and potassium metaaluminate.

2. Concrete, characterized in that it contains, per cubic meter, in parts by mass:

cement, 240 and 300 parts;

15-63 parts of the expanding agent for concrete according to claim 1;

sand, 920 and 1110 parts;

810 and 1000 parts of stone;

2.1-3.6 parts of a water reducing agent; and

water, 160 and 175 portions.

3. The concrete of claim 2, wherein the cement is a 42.5 strength grade portland cement or ordinary portland cement; and/or the presence of a gas in the gas,

the water reducing agent is a polycarboxylic acid water reducing agent.

4. The concrete according to claim 2, wherein the sand is machine-made sand or river sand, and has a fineness modulus of 2.3 to 2.8; and/or the presence of a gas in the gas,

the stone is continuous graded broken stone with the grain diameter of 5mm-20 mm.

5. The concrete according to any one of claims 2 to 4, further comprising 60 to 120 parts by mass of an active admixture per cubic meter of the concrete.

6. The concrete of claim 5, wherein the active admixture is at least one of fly ash and zeolite powder.

7. The method of preparing concrete according to claim 2, comprising the steps of:

providing 15-63 parts by mass of the expanding agent for concrete as defined in claim 1, 300 parts by mass of cement as defined in claim 1, 1110 parts by mass of sand as defined in claim 920, 1000 parts by mass of stone as defined in claim 810, 2.1-3.6 parts by mass of water reducing agent and 175 parts by mass of water as defined in claim 160;

8. The method of claim 7, wherein the step of obtaining the blended base further comprises adding 60 to 120 parts of an active admixture.