Research On The Self-insulation Solf Wall Of The Auoclaved Aerrated Concrete Blocks

Building is the most basic material conditions for the human being survival, living and development of society. According to statistics, China’s total building energy consumption accounts for roughly20.7%of the terminal energy consumption of the whole society. And wall materials are the important parts of building materials, and wall materials consumption accounts for50%of building materials consumption. Cost is around30%of the cost of building, energy consumption accounts for50%of building energy consumption. So it gets necessary to make great efforts in research of the extensive use of energy-efficient building materials.The most important of implement building energy efficiency is that we must carry on the transformation and upgrading of building wall energy saving technology, the main way is to try to develop exterior wall thermal insulation technology and new energy-saving materials. So far, however, the existing external insulation system has technical limitations more or less, and there are some potential safety hazards. So studying the building structure and building energy-saving integration is the development direction which construction industry constantly explores and pursuits.After a lot of research and practice, a new structural system, such as cast-in-place reinforced concrete sandwich energy structure, block insulation sandwich structure, light steel frame reinforced concrete insulation sandwich panels, within the pouring plug sandwich panels, developed rapidly, and that becomes the main force of the integration of building energy efficiency and structure. However, as a new structural system, there are still certain problems in systematization and standardization of the material production technology development, and large scale popularization and application.As a kind of new wall materials, light pressure sand aerated concrete block, on one hand, has the very good heat preservation and heat insulation performance, on the other hand, has the very good bearing capability. according to the country’s current energy requirements it can only be done to save material energy by50%when aerated concrete is used as single-wall materials, now it is only one single wall materials that can meet the different efficiency targets.The light pressure sand aerated concrete block makes calcium materials and siliceous materials as the main raw material, using gas agent and its components in the slurry chemical reaction and gas generation, through mixing, pouring and quiet park, pin cutting, pressure maintenance and the kettle technology, thus forming a lightweight porous structure of silicate products.Sand aerated concrete block is primarily composed of inorganic material, the material density is small, low heat transfer coefficient, water absorption and wet slowly, according to certain technology and technical measures, the preparation of a lightweight porous structure is formed within larger volume of silicate products, because of its structure, material properties and product structure makes it have the following advantages:light fire prevention, sound insulation heat preservation, anti seismic, environmental protection and energy saving, durable, fast construction and economic and applicable.Many scholars at home and abroad have started to study how to save energy of buildings, from the structure of the material properties, structure, etc, and some research has made certain achievements. Aerated concrete was born in1898abroad, but it wasn’t truly developed until1927, when Sweden adopted after the success of the curing reaction caldron in the aero concrete. After decades of development, in Sweden, Denmark, Germany, Poland, the Netherlands and other countries six major production process has formed, based on which, through introduction, absorption and development,each country gradually forms its own unique production technology, the number of production countries gets to more than100, changing from only Europe countries who can produce the materials earlier. At present, in the United States and Japan, the aerated concrete has become the main wall materials, accounting for about35%of the wall materials, the dosage of the aerated concrete in European countries accounts for between10%and30%of wall materials. In1931, China built factories to produce aerated concrete block in Shanghai, and built a20floors building, which was then the highest in China. In the60s, Beijing introduced Sweden technology to build in production line, in1976national reinforced reform in wall building, thus, aerated concrete industry developed rapidly in our country. But so far, the extent of the aerated concrete applied in the construction and function of heat preservation and heat insulation is far from proper level. Considering its main reasons, one is aerated concrete block masonry characteristics and production process needs further research and optimization; the other is that most study is about the single structure, without constructing a whole theory research and practice research.On the basis of predecessors’ work, through the investigation and study, laboratory test, field test and numerical analysis, with the aid of modern testing techniques and methods, this paper researches sand aerated concrete block (AAC), the relationship between structure and properties, using compound excitation activated slurry technology to optimize mixture ratio design, through the control of the production process parameters, the production conforms to the autoclaved aerated concrete block (GB11968-2006) standard requirements of the product. By studying the AAC and masonry structure performance, put forward suggestions to prevent or control wall cracks and concrete empty drum. Research USES the thermal performance of AAC itself eventually supplemented by special (inorganic) masonry, plastering and anti-cracking mortar, through the construction of local thermal bridge area heat preservation and heat insulation measures, establishes different building energy conservation goal of sand aerated concrete block for the wall thermal insulation system.The specific work was carried out by the following aspects:(1) Sand aerated concrete block and masonry structure characteristic is researched. Research the chemical reaction mechanism in the sand aerated concrete block autoclave curing and curing process. Through a large number of laboratory studies, at the same time, combining with the production test of various mixing ratio, according to the performance characteristics of raw materials mixing proportion of sand autoclaved aerated concrete block, the optimal mixture ratio of local material production of AAC block is developed, providing technical support for the factory to produce high quality AAC block. By observing macro porosity of sand aerated concrete block, analyzing macro porosity distribution, and the water permeability tests which are carried out at the same time, to find out the relationship between water absorption and water absorption time(2) Special mortar about sand aerated concrete block wall is researched. this paper will develop sand aerated concrete block dedicated plaster anti-cracking mortar by analysis the raw materials composing of sand aerated concrete block wall dedicated mortar, through mix proportion optimization design, and the orthogonal experiment to optimize formula design, the finally, we get series of thermal insulation mortar of special sand aerated concrete block, masonry binder, metope interface agent, special thermal insulation coating and polymer cement mortar anti-cracking mortar, etc. this is of great engineering and realistic significance.(3) Simulate Sand aerated concrete block insulation exterior wall systems. Conduct a study of mechanical properties and thermal simulation, on the overall composed of sand and special mortar for aerated concrete block wall, identify where are prone to cracking about the parts of the system, verify the rationality of self thermal insulation system in theory.(4) The conditions of insulation system, for exterior wall made of Sand autoclaved aerated concrete block, researched. based on the analysis of sand aerated concrete block thermal indicators, the influence of moisture content on the coefficient of thermal conductivity, the thermal insulation masonry mortar joint effect coefficient, the heat preservation exterior wall thermal performance calculation and the wet heat preservation exterior wall system, the conditions of insulation system, for exterior wall made of Sand autoclaved aerated concrete block, is proposed, etc.(5) The engineering application is researched. Selecting an engineering project using the study of special sand aerated concrete block and mortar, respectively calculating and analyzing construction practices and the performance parameters of the main structure including roofing, external wall, ground, outside the window, and judging from building thermal performance, the wall thermal insulation system made from the sand aerated concrete block is further verified.This article innovation lies in the following aspects:(1)Through comparative research about the block characteristics, optimization and mortar, the masonry mechanical stability and thermodynamic stability problem is solved. The establishment of autoclaved aerated concrete block wall insulation technology is proposed, to build exterior wall structure system and achieve different building energy-saving targets.(2) A special plaster mortar and a series of special series of insulation mortar, including masonry walls, special adhesive for interface agents, special insulation plastering mortar and cement mortar, polymer, is developed.(3) Using Msc.Marc and Midas/Civil software to simulate the "unit wall ", the rationality of autoclaved aerated concrete block from the external wall insulation system is further verified.