The concept of building thermal insulation and structure integration technology

The concept of building thermal insulation and structure integration technology and brief introduction of existing integration technology

1、 Technical concept of integration of thermal insulation and structure

Building thermal insulation and structure integration technology is a building energy-saving technology that integrates the functions of thermal insulation and enclosure structure. The wall can meet the requirements of the current building energy-saving standards without taking additional thermal insulation measures, and realize the same service life of thermal insulation and wall.

Building thermal insulation and structure integration technology has the performance of structural thermal insulation and structural fire prevention. It can effectively realize the same life of building thermal insulation and wall. The implementation of integration technology is in line with the national industrial policy of energy conservation and emission reduction. It is an effective way to do a good job in building energy conservation and develop green buildings and prefabricated buildings.

2、 Meet the conditions of thermal insulation and structure integration technology

Defining the concept of integrated technology should meet three conditions:

1. The thermal insulation of the building wall shall be constructed simultaneously with the structure, and there shall be a protective layer of concrete or other inorganic materials with sufficient thickness outside the thermal insulation layer;

2. After construction, the structural insulation wall can meet the requirements of the current energy-saving standard without further insulation;

3. It can realize the same service life of building insulation and wall. Only when the above conditions are met can it be the integrated technology of building energy conservation and structure.

3、 Advantages and characteristics of thermal insulation and structure integration technology

(1) Thermal insulation has the same service life as the whole building. The external enclosure wall of the self insulation system is filled with composite self insulation blocks, and the beam, column and other thermal bridge parts are cast on site with permanent composite insulation external formwork, which can ensure the whole life cycle of the building without maintenance and repair of the insulation layer, and solve the problem of later maintenance of external insulation; The purpose of building thermal insulation and the same service life of the whole structure is realized.

(2) Excellent fireproof performance solves the problem of external wall insulation and meets the requirements of fire protection specifications. The exterior of the composite shear wall structure is a concrete protective layer with a thickness of 50mm or more, and there are many flame-retardant insulation boards (polystyrene board, extruded board, graphite polystyrene board and graphite extruded board, because these insulation boards have the characteristics of excellent insulation effect, high strength and excellent cost performance). The interior is the main structural layer, with flame retardant grade B1, excellent fire resistance and no hidden dangers such as fire falling off.

(3) Factory assembly avoids on-site cutting waste, saves materials and improves construction quality.

(4) The construction process is simple and easy to be popularized and applied. The built-in thermal insulation cast-in-situ concrete composite shear wall structure has the industry standard JGJ / t451-2018, which has been implemented on April 1, 2019. The production, design and construction of reinforced grid plate can meet the standard requirements of building energy-saving design. The construction process is simple and easy to be popularized and applied.

(5) The project cost is reduced. The insulation life of the built-in insulation cast-in-situ concrete composite shear wall structure is the same as that of the building. There is no need to replace and maintain in the middle, which reduces the maintenance cost. It is constructed at the same time with the main structure, shortens the construction period and reduces the project cost.

(6) Solve the hidden dangers such as cracks, hollowing, leakage and falling off easily caused by the current external wall pasting and external insulation layer technology;

(7) Provide conditions for the diversification of exterior wall decoration surface.

4、 Developing the integrated technology of building insulation and structure -- the inevitability of building energy conservation and green building development

The promotion and application conditions of building thermal insulation and structure integration technology are improved from the basic supporting facilities such as government policies, technical regulations and standard atlas, and are constantly recognized and accepted by the construction unit, design unit and construction unit. With obvious technical advantages, it will become the choice of building exterior wall thermal insulation in the future.

With the in-depth development of building energy conservation, it is urgent to implement the green building action, promote the modernization of the construction industry, meet the fire protection requirements of the code for fire protection design of buildings (gb50016-2014) for building insulation system, and comprehensively improve the quality and safety performance of building energy conservation projects. The integrated technology of building thermal insulation and structure can effectively realize the same service life of building thermal insulation and structural wall, and improve the thermal insulation and structural fire protection performance of building engineering structure, which will produce good social benefits.

5、 Brief introduction of domestic building insulation and structure integration technology types

The integration of building structure and thermal insulation can be roughly divided into the following types of thermal insulation systems according to the type:

1. Steel wire grid type built-in thermal insulation integrated system:

The composite shear wall system (including infilled wall) is composed of steel wire grid sandwich plate and main structure through effective connection and fixation and double-sided cast-in-situ concrete. Construction model of shear wall and infilled wall of point connected built-in thermal insulation cast-in-situ composite wall

2. Steel wire mesh frame cement external formwork insulation system (formwork free):

The rigid external formwork is composed of composite cement mortar on both sides of the organic insulation board, which is connected with the cast-in-situ concrete wall through the anchor. 3. EPS cavity modular insulation system:

The EPS cavity module is heated by foaming with flame retardant polystyrene particles, and is heated by a EPS particle in the mold. The mold has a cross or rectangular type socket and a polystyrene foam profile with a swallow tail groove inside and outside.

4. Wall self insulation system:

The EPS insulation wall is made of self insulation block, autoclaved aerated concrete block, foam concrete block, composite insulation concrete block, sintering insulation block and so on.

5. foam concrete insulation system

The main features of foam concrete cast-in-place walls are:

(1) Mechanized and efficient construction: foaming, mixing and transportation are integrated. The vertical transportation is 120m and the horizontal transportation is 800m. The general building only needs one or two working points to complete the pouring project of the whole building. The pouring capacity of 25 cubic meters per hour makes the wall pouring work efficiency amazing. Taking the partition wall thickness of 120mm as an example, it is equivalent to completing the wall pouring of 200 square meters per hour, calculated as 10 hours per day, The wall pouring of nearly 2000 square meters can be completed every day.

(2) Non dismantling formwork technology the non dismantling formwork technology eliminates the cumbersome formwork erection and removal process and improves the flatness of the wall surface. After pouring, the wall keel and wall panel are connected by pouring foamed concrete. The overall effect and wall surface quality are excellent. The wall plastering process is omitted, and the wall surface decoration treatment such as white scraping and ceramic tile pasting can be directly carried out.

(3) Light weight: traditional buildings have thick walls, fat beams and self weight. The dry bulk density of foam concrete is 200-700kg/m3, which is equivalent to about 1/3-1/10 of clay brick. About 1 / 5-1 / 10 of ordinary concrete, so using foamed concrete as wall material can greatly reduce the self weight of the building, increase the floor height and reduce the foundation cost by about 10%.

(4) good insulation performance, thin wall reduction, and saving area of 10%. Because foam concrete contains large amount of bubbles and pores, it has good thermal insulation. The thermal conductivity is usually 0.09-0.17W/ (m.K), its thermal insulation effect is several times higher than that of ordinary concrete, and the 20cm thick foam concrete exterior wall has the same thermal insulation effect as the 49cm clay brick external wall. There is no large-scale application to external wall insulation, and it is widely used in roof insulation and floor heating leveling insulation houses.

6、 Characteristics and application of integrated thermal insulation and structure technology system of various buildings

（1） Technical system of built-in thermal insulation cast-in-situ concrete composite shear wall with integrated technology of building thermal insulation and structure

1. Technical system of built-in thermal insulation cast-in-situ concrete composite shear wall

2. Technical characteristics of cast-in-situ concrete built-in thermal insulation system

Grade B1 \ B2 thermal insulation materials can be applied in the built-in thermal insulation technology system. According to the provisions of 6.7.3 of code for fire protection design of buildings gb50016-2014 implemented on May 1, 2015, when the thickness of protective layer reaches 50mm, thermal insulation materials with fire resistance rating of B1 and B2 can be used. When the building height of residential buildings is not more than 100m, a protective layer of non combustible materials with thickness of not less than 50mm shall be set outside the thermal insulation layer with flame retardant rating of B1 to make the structural wall, thermal insulation materials and protective layer form a composite wall without cavity, It can still meet the requirements of code for fire protection design of buildings bd50016-2014, without fire windows and fire isolation belts. It solves the problem of selecting class a materials for exterior walls. The concrete protective layer of 50mm outside the insulation board was burned continuously for four hours, and the average temperature rise of the back fire side was 30.9 ℃, without collapse. It has won valuable time for rescuing lives and property in case of fire emergencies.

The concept of composite wall is a new idea for the application of thermal insulation materials with excellent thermal insulation properties, such as polystyrene foam plastics (EPS, XPS, GXPS), PU and other insulation materials, which are of B1/B2 grade in building energy efficiency projects. The insulation layer of the built-in insulation composite shear wall system is reinforced concrete with certain strength and durability.

The connection between the protective layer and the main structure adopts professional connectors, which connect the concrete protective layer, thermal insulation layer and the main structure as a whole; Reinforcement and section steel are generally used for connectors; The connector bears the vertical action of protective layer and thermal insulation layer, wind load and earthquake load.

3. Performance characteristics and advantages of built-in thermal insulation cast-in-situ concrete system

（1）. Thermal insulation performance

It can meet the national energy-saving standard of 75% or higher. The concrete on both sides of the wall can play a good role in protecting the insulation board, so that the insulation board has the same service life as the building, avoiding or reducing the maintenance or replacement of the insulation system during use.

（2）. Fire performance

As the insulation board is sandwiched between the inner and outer layers of concrete, it can not contact the open fire, and the overall construction method of the wall can reach the fire resistance limit of 4 hours.

According to article 6.7.3 of code for fire protection design of buildings gb50016-2014, when the combustion performance of thermal insulation materials is grade B1 and B2, the wall of thermal insulation materials shall be non combustible materials and the thickness shall not be less than 50mm. Article 6.7.7 in addition to the provisions of article 6.7.3, when the external wall insulation system of the building adopts thermal insulation materials with flame retardant properties of B1 and B2, a horizontal fire isolation belt shall be set on each floor of the insulation system. A 50 ~ 60mm thick concrete layer is set outside the insulation layer of the built-in insulation cast-in-situ concrete composite wall. The B1 / B2 EPS, XPS and PU (PIR) are used as insulation materials, which can meet the requirements of gb50016-2014. There is no need to set fire isolation belt within the specified range.

（3）. Good seismic performance

The outer concrete is connected with the concrete of the main structure through the reinforcement grid, which improves the lateral force stiffness of the wall and enhances the ability to resist the horizontal force of earthquake.

(4) Fast construction progress

As the reinforcement mesh and thermal insulation board of the wall are produced in the factory, the thermal insulation layer is set during the construction of the composite wall, which reduces the construction process of external thermal insulation of the external wall, improves the overall construction progress and shortens the overall construction period.

(5) A concrete layer of 50 ~ 60mm is set outside the insulation layer, which can meet the requirements of external wall facing bricks

(6) Comply with the new wall material policy and the prefabricated building strongly advocated by the state.

(7) Comply with the industrial policy of building modernization and reduce on-site operation and environmental protection

4. Design points of built-in thermal insulation cast-in-situ concrete composite wall system

The structural design of the built-in thermal insulation concrete wall building shall be carried out in accordance with the requirements of the current national codes and standards. In the design, the outer concrete and reinforcement welded grid are considered as the load on the inner concrete wall. The inner concrete wall is involved in the calculation of the main structure, and the outer concrete is not involved in the calculation of the main structure.

The building energy-saving design of built-in thermal insulation concrete wall shall comply with the design standards for building energy efficiency of all provinces in China and adapt to the regional climate, meet the design requirements of thermal insulation in winter and summer, and meet the requirements of thermal insulation and energy-saving standards of external enclosure wall in different thermal zones in China.

5. Construction points of built-in thermal insulation cast-in-situ concrete composite wall system

How to ensure the position of thermal insulation layer and the pouring quality of outer concrete in the construction stage of built-in thermal insulation cast-in-situ concrete composite wall system is the key for its technical system to achieve the expected goal.

The technical system of point connected built-in thermal insulation cast-in-situ concrete composite wall is composed of concrete protective layer, thermal insulation layer and concrete layer of the main structure. The concrete protective layer and thermal insulation layer are connected and fixed on the main structure through reinforcement ties and transmitted to the main structure as load, realizing the same service life of thermal insulation and structure, and the integration of thermal insulation and structure; As for the intermediate protection between the concrete protective layer and the concrete layer of the main structure, the thermal insulation layer can improve the fire resistance of the wall insulation. When the thermal insulation materials with combustion performance of B1 and B2 are used, there is no need to set additional fire isolation belt and fire window, which can meet the requirements of code for fire protection design of buildings gb50016-2014; It provides a variety of decorative surface choices for exterior wall finishes.

（2） Detachable composite insulation formwork system

The application technology of the detachable composite formwork system adopts grade B1 thermal insulation material with a thin protective layer outside. With the promulgation and implementation of the national standard code for fire protection design of buildings gb50016-2014.

Class B1 thermal insulation material is adopted, and the requirements of code for fire protection design of buildings (gb50016-2014) can be met by setting a thicker protective layer and appropriate structural measures outside the thermal insulation layer. It is applicable to housing projects with seismic fortification intensity of 8 degrees and below in all provinces of China, and the building height of which shall not exceed 100m.

The detachable composite thermal insulation formwork is a composite plate prefabricated in the factory by the thermal insulation layer and surface layer. The thermal insulation layer and surface layer can be made by bonding or covering as cast-in-situ concrete components, facing the formwork and making the components meet the thermal insulation requirements.

The surface layer is bonded with the thermal insulation board or directly coated on the thermal insulation layer to form a detachable composite thermal insulation formwork, which can not only enhance the thermal insulation formwork and flexural strength of the detachable composite formwork, but also serve as the external protective layer of the thermal insulation layer.

In order to meet the fire protection requirements of different buildings and places, the surface layer can choose thin surface layer or thick surface layer plate according to the needs. The thin surface course is made of various mortar materials such as cement board, calcium silicate board or polymer cement mortar; The thick surface layer is made of light concrete with reinforcement mesh inside, and the concrete strength grade is not less than C20. The thermal insulation layer is composed of XPS board, EPS board and PIR. The composite thermal insulation layer is composed of class a thermal insulation materials such as glass wool and Class B1 thermal insulation materials such as XPS board, EPS board and PIR.

The removable composite insulation formwork is firmly connected with the concrete components through the connector when pouring concrete. The connector of the external wall insulation system is the split bolt used as the formwork system when pouring concrete, and the external protective layer is firmly connected with the concrete components in the later stage.

（4） EPS cavity modular insulation system:

The EPS cavity module is heated by foaming with flame retardant polystyrene particles, and is heated by a EPS particle in the mold. The mold has peripheral or one-piece rectangular socket and the polystyrene foam profile with a dovetail groove inside and outside the surface, which achieves more than 65% building energy efficiency standards. It not only provides an effective way of building exterior wall insulation in cold areas, but also solves the problems of cavity and falling off of exterior wall bonding surface; It can be used not only for new buildings, but also for wall insulation transformation of existing buildings.

(1) The pasting method between the surface of module board and the surface of wall has been fundamentally improved. EPS module thermal insulation building exterior wall abandons the tradition of cavity pasting of smooth thermal insulation board