0 Introduction The thermal insulation performance of building envelopes is the main factor affecting building energy consumption. In the heat transfer heat loss of the building envelope, the roof is about 9%, so the building energy saving must improve the thermal insulation performance of the roof. Residential buildings generally use inorganic thermal insulation materials, such as expanded perlite, porous concrete and other organic insulation materials, such as fiberboard, foam and other reinforced roof insulation performance, reduce building energy consumption and improve the thermal environment of the building. However, common roof insulation materials need to consume a large amount of mineral resources and energy in the production process and cause certain environmental pollution. In this paper, the grading-optimized waste expanded polystyrene particles are used as the thermal insulation aggregate with Portland cement as the main cementitious material, and the project is added by adding appropriate amount of fiber and adding funds: National Natural Science Foundation of China (50638040) Research on building materials. The agent is modified to prepare an energy-saving and waste-type roofing insulation material with excellent heat preservation performance, small water absorption rate and good construction property. The developed thermal insulation material not only has good insulation performance, low cost, can be cast on site and helps to save resources and reduce the white pollution caused by waste polystyrene to the environment.
1 Experimental part 11 raw material cementing material: 42.5 grade ordinary Portland cement with 3d, 8d compression; d, 8d flexural strength is 5.3, 7.6MPa initial setting time final setting time 248min. Lightweight aggregate waste expansion polymerization The particle size of EPS particles obtained by crushing styrene (EPS) plate is 2 4mm. Bulk density is 8 40kg/m3. The particle size distribution of closed-cell expanded perlite bulk density 70kg/m3 is shown in Table 1. Table 1 Particle size distribution of expanded perlite Diameter range / mm mass percent /% reinforcing fiber chopped fiber, length 9 mm. Thickener.
Modifier: Self-made to improve the affinity of EPS and inorganic materials.
Water-repellent agent A water-soluble polymer having a small molecular weight reacts with CO2 in the air to form a water-repellent substance.
1.2 Experimental technology route) EPS particle size distribution range is small, gradation is not ideal, need to be combined with expanded perlite to obtain the best gradation, thereby reducing the amount of cementitious materials to improve the pore structure of insulation materials, low insulation materials Thermal conductivity.
The thermal insulation material has a large porosity and the strength of the thermal insulation aggregate is low. Therefore, an appropriate amount of Portland cement is used as a bonding material to obtain the necessary mechanical properties of the thermal insulation material.
The density difference between the heat-insulating aggregate and the cement slurry is large, and it is easy to cause delamination when mixing. Therefore, it is necessary to select a suitable additive to modify the cement slurry to obtain the desired workability.
The high porosity of the thermal insulation material is likely to reduce the durability of the material due to the influence of water absorption on the thermal insulation property of the material. Therefore, it is necessary to improve the pore structure of the material, and to connect the water-repellent agent to reduce the water absorption rate of the material.
13 Experimental method Experimental specimens Forming amine setting ratio The mixing material and water were uniformly stirred in a cement mortar mixer (mixing time 2 mm), so that the consistency of the slurry reached 64 cm, and then poured into a standard mold to be cured as required.
Data test dry apparent density, water absorption, compressive strength test specimens dried to constant weight according to GB5486 test thermal conductivity according to GB10294 test line shrinkage test specimens after demolding according to GB/T17369 determination of water-repellent rate amine GB10299 test.
14 Insulation material preparation 141 Insulation aggregate grading optimization EPS particles are ideal for heat preservation aggregate, but the particle size range is small (2 grades. The use of polystyrene alone as insulation particles will have a larger If there are voids, it is not conducive to reducing the thermal conductivity of the thermal insulation material. However, if the amount of cementing material is reduced, the internal pore structure of the thermal insulation material is difficult to control, and the open pores which are easy to form a connection affect the thermal insulation material. The thermal performance and mechanical properties. Therefore, this paper uses the expanded perlite to optimize the EPS particles to reduce the porosity of the insulating aggregate.
More than 90% of the selected expanded perlite particles are smaller than the minimum particle size of the EPS particles. Therefore, it is assumed that the voids of the EPS particles in the natural accumulation state are all filled with expanded perlite, and the expanded perlite is calculated by the formula (1) in the thermal insulation aggregate. The best mass percentage (the loose bulk density of IU Poz expanded perlite, g/m3; the loose bulk density of Poe polystyrene particles, g/m3; the loose bulk volume of expanded perlite in V unit volume insulation) M3; Voe unit volume of loose bulk volume of polystyrene particles in thermal insulation material m3; (1-i) X100% = 40% (tested, apparent density of polystyrene particles P The best ratio calculated above is After the EPS particles are mixed with the expanded perlite, the accumulation volume does not change, and the gradation of the expanded perlite does not change under the mixing process. However, these factors may occur in the actual production process. Changes, especially the expanded perlite, will break under mechanical mixing. For this reason, according to the selected raw materials, the reasonable proportion of the thermal insulation aggregate is corrected by experiment to determine the expansion The optimum mass ratio of rock to EPS particles is 3.51. 142 Insulation material mix ratio Through the comprehensive experiment of optimized insulation aggregate, cement, fiber and additives, the ratio of roof insulation material is 10~12kg of polystyrene particles. Perlite 35~42kg, chopped fiber 0.85~1.0kg, cementitious material 130~160kg thickener 1.0~1.2kg it 2~3kg. 2 Experimental results and analysis 2.1 Relationship between dry density and thermal conductivity of thermal insulation material Roof insulation material is a multi-porous composite system composed of various materials, not only its dry density is related to thermal conductivity, but also the pore structure and shape inside the material also affects the thermal conductivity of the material. Test data of dry density and thermal conductivity of thermal insulation material See Table 2. Table 2 Relationship between Thermal Conductivity and Dry Density of Insulation Material Dry Density Thermal Conductivity As can be seen from Table 2, when the dry density of the thermal insulation material is greater than 200 kg/m3, the thermal conductivity increases as the density increases; Less than 200kg/m3 decreases with the decrease of dry density. The reason for the increase in thermal conductivity is that the porosity of the insulation material is too large, and the cementitious material in the system is relatively insufficient, so that the internal pores are connected to each other.
2.2 The relationship between the amount of heat-insulating aggregate and the strength of the material The heat-insulating aggregate is bonded to each other by a cementitious material to form a uniform porous composite system. The hardened gelling material forms a continuous mesh skeleton within the insulating material to impart the necessary strength to the insulating material. The amount of insulating aggregate (the percentage of mass of the insulating aggregate in the insulating material) is closely related to the strength of the insulating material (see 圄 1).
It can be seen from 圄1 that the compressive strength and bond strength of the thermal insulation material decrease as the amount of the retained aggregate increases. The reason is that the amount of the heat-insulating aggregate increases, the specific surface area of ​​the aggregate increases, and the amount of the cementing material which is filled and bonded is relatively reduced. The hydration product of the cementitious material in the heat-insulating material has a weakening effect even Can not form a sturdy grid structure. If you continue to increase the amount of insulation aggregate, even the composite insulation material will appear loose. The state will result in loss of strength and can not be used. In practical applications, the strength of engineering design can be obtained by adjusting the amount of insulation aggregate.
2.3 The effect of fiber on the performance of thermal insulation material Adding chopped reinforcing fiber to the thermal insulation material and uniformly dispersing it by mechanical agitation to form a spatial fiber network structure can effectively prevent the thermal insulation aggregate from floating up and separating when adding water to improve the thermal insulation material. Uniformity, small bleeding, barely construction operability. On the other hand, the short-cut reinforcing fiber can effectively suppress the expansion of the shrinkage crack of the mortar by the mixing of the space fiber network formed by the dispersion in the hardened heat-insulating material, and the maximum deformation amount when the heat-insulating material is broken is large. The range is increased.
The roof insulation material developed by the water-repellent material of the thermal insulation material belongs to the lightweight porous material, and the water service rate is high. In engineering applications, the thermal performance and service life of the material are easily reduced by water absorption.
Therefore, this paper uses a water repellent to improve the hydrophobic properties of the material. The water repellent used is a water-soluble polymer having a relatively small molecular weight, which can form a water-insoluble methyl silicate under the action of CO 2 in water and air, and further form a methyl silicone waterproofing membrane with water repellency. Features. The waterproof membrane is attached to the capillary wall of the new building material part of the thermal insulation material, which effectively reduces the water absorption rate of the material.
3 Cement polystyrene granule roof insulation material production mix ratio design method Through the experimental design method, single factor experiment and orthogonal experimental data and the interaction law of each component, the cement polystyrene granule roof insulation material studied will be studied. The design method of production mix ratio is as follows: 450kg/m3 roof insulation material (the technical parameters of the insulation aggregate used are polyphenylene particles with a bulk density of 842kg/m3, and the maximum particle size of less than 5mm. 6040kg/m3, good gradation, 5mm sieve residue is less than 15%), the mixing ratio parameter is the amount of polystyrene particles in the mixture, the volume of expanded perlite, the amount of cementing material, Fiber content, additive dosage, water consumption, and the like. The specific design steps are as follows: the bulk volume of the polystyrene particles is: Ve-the bulk volume of the desired polyphenyl particles m3. The bulk volume of the heat insulating material is 1.1 of the bulk volume of the polystyrene particles, according to the apparent density and looseness of the polyphenyl particles. The porosity is calculated by parameters such as density. The void volume is considered to be the volume of the expanded perlite.
Determination of the amount of cementitious material. According to the correlation between the amount of cementing material and compressive strength and thermal conductivity, the amount of cementing material is determined by the demand index. See Table 3. Table 3 Relationship between the amount of cementing material and the main properties of the insulating material. Item Cementing Material/% Thermal Conductivity /Compressive strength value / MPa fiber content The amount of fiber used per cubic roof insulation material (dry mixed loose state) is 0.84.2 kg. The amount of water required for mixing the water mixture mixture to 80 mm.
The amount of the admixture depends on the specific performance requirements depending on the amount of the gelling material.
According to the above steps, several sets of mixing ratios were calculated and tested, and the performance indexes such as workability, thermal conductivity and compressive strength were evaluated to select the suitable ratios for design requirements.
4 Conclusion Using the expanded perlite to optimize the EPS particles, the EPS particle size distribution range is small, the gradation is poor, and the pore structure of the thermal insulation material is difficult to control. The energy-saving concrete porous brick hole design and thermal analysis of the Chinese Chinese children's journal are difficult to control. Wang Zhi, Qian Jue Shi 12, Wang Yifang 34, Shi Liang 2 (1. College of Chemistry and Chemical Engineering, Chongqing University, Chongqing 400044; 2. School of Materials Science and Engineering, Chongqing University, Chongqing 400045; 3. Changzhou Construction Engineering Quality Inspection Center, Changzhou, Jiangsu 213015) Effective design.
With the continuous improvement of wall materials and the continuous improvement of building energy-saving level, new high-efficiency insulation materials have gradually received attention. The external wall self-insulation technology has become a major trend in the development of wall materials. Concrete perforated bricks have the characteristics of profit-saving and high-efficiency, and have become the ideal wall material to replace clay bricks. However, how to ensure that concrete perforated bricks have good thermal insulation performance while bearing weight is worthy of further discussion and research. This paper mainly discusses the relationship between the pore shape of concrete porous brick and its thermal resistance.
1Requirement for thermal performance of concrete porous brick wall in summer hot and cold winter area According to the energy-saving design standard of residential building in G134-2001 summer hot winter cold area, it is necessary to carry out thermal design of energy-saving building envelope structure in hot summer and cold winter area. To meet the winter insulation and to meet the summer heat insulation, the average heat transfer coefficient of the outer wall of the building envelope should not exceed 1.5W/(m4K). As a new type
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