new building material

Autoclaved aerated concrete block is a porous silicate block made of calcareous materials (such as cement and lime) and siliceous materials (such as sand, fly ash and slag), with aluminum powder as air entraining agent, stirred with water, poured, inflated, pre-cured, cut and then cured with high-pressure steam. Air entraining agent, also known as air entraining agent, is the key material for making aerated concrete. Most of the gas generating agents are degreased aluminum powder. The aluminum powder mixed into the slurry produces a chemical reaction under alkaline conditions: the aluminum powder is extremely fine, and the generated hydrogen forms many small bubbles and remains in the rapidly solidified concrete. These uniformly distributed small bubbles make aerated concrete block have many excellent characteristics.

1. 1 Analysis of application advantages of autoclaved aerated concrete block

In China, the production and popularization of autoclaved aerated concrete blocks still have great advantages, mainly in the following aspects:

The stamina of wall material reform is still sufficient. There is still a great market space for the development of new wall materials. At present, all parts of the country have issued policies to restrict the use of clay products, which has won opportunities for the application of new wall materials.

② Autoclaved aerated concrete blocks are rich in raw materials. Generally speaking, aerated concrete blocks are aerated with sand or fly ash. For example, Wuhan is rich in fly ash resources. Using fly ash to make aerated blocks not only treats wastes, but also develops new wall materials. In Shanghai, Shenzhen, Zhejiang and other places, sand resources are abundant, so there are many sand filling factories. All localities can produce aerated blocks according to their own resource advantages.

③ Aerated block itself has incomparable advantages over other new wall materials. As mentioned above, the thermal insulation performance is good, which is beneficial to building energy saving; Large blocks with low density are beneficial to improve the construction progress; Can improve the use area of the building and so on.

Compared with new wall materials such as clay products and new wall materials such as clay products, autoclaved aerated concrete blocks have the following main advantages: large blocks and simple construction; Low density, reducing weight and foundation burden; The thermal conductivity is small, which meets the requirement of building energy saving by 50% and is a good self-insulation material; Good living comfort.

The thermal conductivity of aerated concrete block is close to 1/7 ~ 1/4 of that of solid clay brick, and only about half of that of sintered porous brick. The energy-saving building built with aerated concrete blocks does not need to add other thermal insulation materials or air spacers, which is impossible for any other new wall materials.

Aerated concrete also has good water vapor permeability, which is 17 1. If there is moisture on the wall, it will be discharged, and the wall will maintain its original excellent thermal insulation for a long time, so its living comfort is relatively high.

Main technical performance of 1.2

1, heat preservation, heat insulation

In the production process of aerated concrete products, countless tiny pores are formed inside. These pores form a static air layer in the material, which makes the aerated concrete block have good thermal insulation performance. Its thermal insulation performance is 6 times that of glass, 7 times that of clay brick and 10 times that of ordinary concrete block.

2, fire resistance, flame retardant

Aerated concrete block is an inorganic substance, which will not burn and will not produce harmful gas even at high temperature. At the same time, the thermal conductivity of aerated concrete block is very small, which makes the thermal conductivity slow, and can effectively resist fire and protect its structure from fire.

3. Sound absorption and sound insulation

Aerated concrete blocks are filled with tiny pores, so the sound insulation effect is good, and the noise can be reduced by 30~50 decibels with different thicknesses.

4. Lightweight players

Aerated concrete blocks weigh only 550 ~ 650kg per cubic meter, which is 1/4 of ordinary concrete and 1/3 of clay brick, which is equivalent to wood. The use of aerated concrete blocks in buildings can reduce the building weight, reduce the cross-sectional size of structural members, reduce the foundation cost and reduce the difficulty of soft foundation construction.

5. Machinable by machine tools

Like wood, aerated concrete products can be easily sawed, drilled, nailed and ground.

Table 1.2- 1 drying shrinkage, frost resistance and thermal conductivity

Bulk density grade B03 B04 B05 B06 B07 B08

Standard method for drying shrinkage value (mm/m)≤ 0.50

Rapid method (mm/m) ≤ 0.80

Frost resistance mass loss (%)≤ 5.0

The frozen strength (MPa) of the excellent product (A) is ≥ 0.8.

0.8 1.6

1.6 2.8 4.0 6.0 8.0

Qualified product (B) 2.0 2.8 4.0 6.0

Thermal conductivity (dry state) [W/(m? k)]≤0. 10 0. 12 0. 14 0. 16 0. 18 0.20

A specifies that the drying shrinkage value of block should be determined by standard method and rapid method. If the determination results are inconsistent and cannot be determined, the standard method shall prevail.

Table 1.2-2 Fire resistance and sound insulation performance

Block thickness (mm) fire resistance (h) sound insulation (dB)

75 2.5 38.8

100 3.75 40.6

150 5.75 43.0

200 8.00

Note: 1. The sound insulation performance test is a double-sided plastered wall.

2. Fire resistance is the technical index of aerated concrete wall with bulk density of 500kg/m3.

3. For the specific numerical reference of fire resistance and sound insulation, please refer to the National Architectural Standard Design Atlas 03J 104 "Autoclaved Aerated Concrete Block Building Structure".

Selection point of 1.3

1. It is mainly used for infilled walls and non-load-bearing interior partitions of buildings, and can also be combined with other materials to form a composite wall with thermal insulation function, but it is not suitable for the outermost layer.

2. Autoclaved aerated concrete blocks shall not be used in the following parts without effective measures: the building elevation is below 0.000; Parts that have been immersed in water for a long time and often undergo dry-wet alternation or freeze-thaw cycles; Parts corroded by acid and alkali chemicals and parts with surface temperature higher than 80℃.

3. For details of design and construction, please refer to National Architectural Standard Design Atlas 03J 104 "Autoclaved Aerated Concrete Block Building Structure". The corner of the external wall and the junction of the internal and external walls should be built by biting, and reinforcement or mesh should be prepared in the mortar joint with a height of about 1m along the wall, and each side should go deep into the mortar joint with a height of about 1m along the wall, and long reinforcement should be added in the mortar joint with a height of about 1m along the gables.

4. Non-load-bearing wall, filler wall or the junction of partition wall and external load-bearing wall should be connected with external wall with steel bars along the wall height of 900 ~ 1000mm, and the length of each side going deep into the wall should not be less than 700 mm..

5. Prominent parts of autoclaved aerated concrete external wall, such as moldings, cornices, windowsills, etc. , should be soaked in water to dry, to avoid repeated freeze-thaw cycles after the water flowing into the wall damage to the external wall.

6. At the bottom of the block wall, at the top of the wall, at the entrance of doors and windows, sintered ordinary bricks or perforated bricks should be used locally, and the height should not be less than 200mm.

7. Aerated concrete blocks with different dry densities and strength grades should not be mixed, nor should they be mixed with other bricks and blocks.

8. Masonry mortar should use special mortar with good bonding performance; Aerated concrete plastering should also use special plastering materials or polypropylene fiber plastering anti-crack mortar.