CN101538167A - Porous concrete mixture and products and preparation method thereof - Google Patents

Abstract

A method for preparing porous concrete mixture and its products in the technical field of building materials. The composition and weight percentage of the mixture are: ammonium dihydrogen phosphate 7.5%-30%, magnesium oxide powder 2.45%-9.8%, powder 60% to 90% of coal ash, 0.05% to 0.2% of the setting material; the preparation method of the concrete product formed by the mixture comprises the following steps: putting the porous concrete mixture into a mixer and stirring evenly, adding a weight of porous concrete The concrete mixture is mixed with 25% to 50% of mixing water, fully stirred to form a slurry, and then the slurry is poured into the mold to form, after curing, demoulding and cutting into lightweight concrete products of required size. The present invention can be used in factories to produce lightweight porous concrete products, and can also be used for direct pouring on construction sites to form heat-insulating wallboards, roof insulation panels, etc. The porous concrete prepared by the present invention has high early strength, uniform distribution of internal pores and a The advantages of being closed and not connected to each other.

Description

Preparation method of porous concrete mixture and its products

technical field

The invention relates to a preparation method of concrete and its products in the technical field of building materials, in particular to a preparation method of a porous concrete mixture and its products.

Background technique

Porous concrete, as a lightweight, thermal insulation material, has been paid attention to in recent years with the advancement of building energy-saving technology. Porous concrete refers to those concretes that contain a large number of uniformly distributed closed pores with a diameter of less than 2 mm. At present, there are two main types of porous concrete: one is foam concrete, and the other is air-entrained concrete. Foamed concrete is a porous lightweight material that is hardened after mixing cement or slurry made of mixed materials and water with foam made of foaming agent. Air-entrained concrete is made by using chemical methods to generate gas in the mud. The methods of generating gas include adding metal powder, reacting with acid to generate hydrogen or carbon dioxide, and adding water to calcium carbonate to generate acetylene. These two types of traditional porous materials usually have very low strength, usually less than 1 MPa, and can only be used for some partition wall filling materials, and there are defects such as relatively large drying shrinkage.

In recent years, researchers have carried out a lot of research work in this area and developed a variety of high-performance porous concrete. Chinese patent CN03104729.7 (publication number: CN1443727, publication date: 2003.09.24) describes the method of using composite cementitious materials and various additives and fiber composites to prepare high-strength porous concrete with a strength of 15-30MPa; another example Chinese patent CN200810021256.5 (publication number: CN101328041, publication date: 2008.12.24) describes the use of fly ash, lime, cement, desulfurized gypsum and aluminum powder paste as raw materials, and a special process to prepare high Performance porous concrete; Chinese patent CN200610085717.6 (publication number: CN1884181A, publication date: 2006.12.27) describes cost reduction by using a certain proportion of hydrogen peroxide liquid as beating agent and gas generating agent to replace aluminum powder. However, from the current various types of porous concrete, the cementitious materials used are basically Portland cement, and at the same time, specific air-entraining agents or air-entraining agents are used to achieve porosity inside the concrete, so to a certain extent The cost of porous concrete is increased; in terms of performance, there are defects such as relatively large shrinkage rate, low early strength and deviation in durability.

Contents of the invention

The purpose of the present invention is to overcome the deficiencies of the prior art and provide a preparation method of porous concrete mixture and its products. The invention can be used to produce lightweight porous concrete products in factories, and can also be used to directly pour heat-insulating wall panels, roof insulation panels, etc. at the construction site. The porous concrete prepared by the invention has high early strength, smooth surface, hard, It has the advantages of shrinkage, no deformation, waterproof, high temperature resistance, uniform distribution of internal pores and is closed and not connected to each other.

The present invention is achieved through the following technical solutions:

The porous concrete mixture that the present invention relates to, its component and weight percent are:

Ammonium dihydrogen phosphate 7.5%～30%

Magnesium Oxide Powder 2.45%～9.8%

Fly ash 60%～90%

Coagulation adjusting material 0.05% to 0.2%.

The ammonium dihydrogen phosphate is a powder crystal, and its particle size is less than 100um.

The magnesium oxide powder is overburned magnesium oxide, the purity of which is greater than 80%, and the particle diameter ranges from 2um to 100um.

The fly ash is one of class II fly ash, class III fly ash or high calcium fly ash.

The setting adjusting material is one of boric acid, borax or citric acid.

The setting adjusting material is borax.

The preparation method of the porous concrete mixture product involved in the present invention,

Including the following steps:

①Put the porous concrete mixture into the mixer and stir evenly;

② Add mixing water whose weight is 25% to 50% of the porous concrete mixture, and fully stir to form a slurry;

③Then pour the slurry into the mold for molding, demould after curing and cut into lightweight concrete products of required size.

The slurry can be directly poured into the roof floor of the building, and becomes a lightweight porous concrete roof insulation board after solidification.

The slurry can be poured into the concrete slab mold on which steel supports have been placed, and after curing, the slurry can be demoulded to form a lightweight porous concrete wall panel prefabricated part.

The invention utilizes the rapid chemical reaction of the ammonium dihydrogen phosphate, magnesium oxide and fly ash to produce fine air bubbles that are evenly distributed inside the concrete. When used at the construction site, according to the strength and apparent density of the prepared porous concrete, add mixing water with a weight of 25% to 50% of the dry powder, fully stir to form a uniform slurry, and then pour the slurry into the mold to form it. Lightweight concrete products molded and cut to size.

The invention breaks the limitation that porous lightweight concrete can only be produced and poured in factories and requires specific production equipment and process requirements, and can be poured and constructed under any conditions and environments. The form of products can include blocks, wallboard prefabricated parts, Roof insulation boards, etc.; the porous lightweight concrete of the present invention has rapid demoulding, and the demoulding time can be completed within 30 minutes. It has high strength, high hardness, uniform pore distribution, high temperature resistance, no deformation, no shrinkage and good durability, etc. Excellent performance.

Detailed ways

The embodiments of the present invention are described in detail below: the present embodiment is implemented under the premise of the technical solution of the present invention, and detailed implementation and specific operation process are provided, but the protection scope of the present invention is not limited to the following implementation example.

Example 1

Weigh the components of the porous concrete mixture by weight, including 7.5% ammonium dihydrogen phosphate, 2.45% magnesium oxide, 90% grade III fly ash, and 0.05% borax, and put the mixture into a mixer to fully stir. Add water with a weight of 30% of the mixture, stir for 2 minutes to form a uniform and flowable slurry, pour the uniform slurry into the mold for molding, remove the mold after 30 minutes of curing and cut it into the required size, and then place After curing for 3 days at room temperature, a lightweight porous concrete block can be made. The ^lightweight concrete block is measured according to the standard of GB/T11968-1997 "Autoclaved Aerated Concrete Block". The coefficient is 0.17W/m·k, in line with relevant standards.

Example 2

Weigh the components of the porous concrete mixture by weight, including 30% ammonium dihydrogen phosphate, 9.8% magnesium oxide, 60% grade III fly ash, and 1.2% boric acid, and put the mixture into a mixer to fully stir. Add water with a weight of 45% of the mixture, stir for 3 minutes to form a uniform and flowable slurry, pour the slurry directly into the roof floor of the building, and become a lightweight concrete roof insulation board after curing. After testing, it meets the industry standard requirements for light weight, strength and heat transfer coefficient.

Example 3

Weigh 18.75% of ammonium dihydrogen phosphate, 6.125% of magnesium oxide, 75% of grade III fly ash, and 0.125% of borax by weight, put the mixture into a mixer and stir well, and add 25% of the mixture by water , Stir for 2 minutes to form a uniform and flowable slurry, pour the slurry directly into the concrete mold where the steel supports have been placed, and solidify and demould within 35 minutes to form a lightweight concrete wall panel prefabricated part. After testing, it meets the standard light weight and strength of GB 15762-1995 "Autoclaved Aerated Concrete Slab".

Example 4

Weigh 15% of ammonium dihydrogen phosphate, 4.9% of magnesium oxide, 80% of grade III fly ash, and 0.1% of borax by weight, put the mixture into a mixer and stir it fully, and add 50% of the mixture by water , stirred for 3 minutes to form a uniform and flowable slurry, poured the uniform slurry into the mold for molding, after 45 minutes of curing, demoulded and cut into the required size, and then placed at room temperature for 3 days to make lightweight Porous concrete blocks. The ^lightweight concrete block is measured according to the standard of GB/T11968-1997 "Autoclaved Aerated Concrete Block". The coefficient is 0.08W/m·k, in line with relevant standards.

Claims (9)

1, a kind of porous concrete mixture, is characterized in that, component and weight percent are: Ammonium dihydrogen phosphate 7.5%～30% Magnesium oxide powder 2.45%～9.8% Fly ash 60%～90% Coagulation adjusting material 0.05% to 0.2%. 2. The porous concrete mixture according to claim 1, characterized in that the ammonium dihydrogen phosphate is a powder crystal, and its particle size is less than 100um. 3. The porous concrete mixture according to claim 1, characterized in that the magnesium oxide powder is perburned magnesium oxide, the purity of which is greater than 80%, and the particle size ranges from 2um to 100um. 4. The porous concrete mixture according to claim 1, wherein the fly ash is one of class II fly ash, class III fly ash or high calcium fly ash. 5. The porous concrete mixture according to claim 1, characterized in that, the setting regulating material is one of boric acid, borax or citric acid. 6. The porous concrete mixture according to claim 5, characterized in that the setting regulating material is borax. 7. A method for preparing a porous concrete mixture product as claimed in claim 1, comprising the steps of: ①Put the porous concrete mixture into the mixer and stir evenly; ② Add mixing water whose weight is 25% to 50% of the porous concrete mixture, and fully stir to form a slurry; ③Then pour the slurry into the mold for molding, demould after curing and cut into lightweight concrete products of required size. 8. The method for preparing porous concrete mixture products according to claim 7, characterized in that the slurry can be directly poured into the roof floor of the building, and after curing, it becomes a lightweight porous concrete roof insulation board. 9. The method for preparing porous concrete mixture products according to claim 7, characterized in that the slurry can be poured into a concrete slab mold with steel supports placed therein, and then demoulded after solidification to make lightweight porous concrete Prefabricated wall panels.