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Research and Application of Self-insulation System of Fired-shale Hollow Brick

Author XieHouLi
Tutor PengJiaHui
School Chongqing University
Course Materials Science and Engineering
Keywords fired-shale hollow brick self-thermal insulation system optimization of hole types foam concrete pore-forming agent application
CLC TU522.12
Type PhD thesis
Year 2012
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Thermal-insulation exterior wall system contains exterior insulation wall system,interior insulation wall system, self-insulation wall system nowadays while exteriorinsulation wall is widely used at home and abroad, whereas it has some disadvantages,namely, complex and long construction process, shorter longevity compared with mainstructure, low engineering quality, high cost, easy peeling of decorative materials,content of combustible organic materials etc.. However, self-thermal insulation wallsystem has superior properties to a certain extent, it is apparent that the weatherabilityand durability are greater compared with other insulation wall systems, and its longevityis more or less the same with the building structure, moreover, it has some excellentproperties of fireproof performance, shock resistance, easy construction process and lowcost, thus the investigation of self-insulation wall system impede the development andapplication of building energy saving.The thermal bridge to exterior wall ratio and the relationship between wallmaterials and average heat-transfer coefficient of walls are lack of basic researches. Theeffect of thermal bridge to exterior wall ratio on average heat-transfer coefficient of wallwas analyzed in this investigation. The results demonstrate that the average heat-transfercoefficient of wall is less than1.5W/(m~2·K) with the insulation treatment of thermalbridge while thermal bridge to exterior wall ratio is equal to0.172. The survey showsthe minimum thermal bridge to exterior wall ratio of frame structure or frame-shear wallstructure is0.25in Chongqing, therefore, the masonry is mainly studied in the research.Through the test, it presents the effect of equipped of brick and masonry mortar onthermal performance is significant. The thermal conductivity of masonry composedwith hollow brick, solid equipped of brick and ordinary masonry mortar is less than orequal to1.2W/(m~2·K), whereas it is less than or equal to1.0W/(m~2·K) when themasonry is composed with hollow brick, multi-hole equipped of brick and masonrymortar, while the thermal conductivity of hollow brick is equal to0.25W/(m~2·K).Therefore, the reasonably thermal conductivity is less than0.25W/(m~2·K).The early research shows it is unreasonable for hole type of hollow brick of whichthe thermal performance is not suitable enough without using of pore-forming agent.The equivalent thermal conductivities of fired-shale hollow bricks with varied holetypes were tested by using of simulation software FLUENT in the investigation. It reveals the effects of hole type, length-width ratio, arrangement type and quantity ofholes, hole ratio on thermal performance of hollow brick. According to the result thethermal performance is improved when the longer edge of the rectangular holeperpendicular to the thermal flow direction with a suitable length-width ratio rangingfrom3/1to6/1. It is reasonable for a value of the hole width equal to10mm as theincreasing of quantity of lateral holes with the same hole ratio of brick, i. e. the thermalconductivity of hollow brick decreases considerably and the thermal conductivity of airin holes is more or less the same with that of stationary air while the width of hole isequal to10mm. Besides, the thermal conductivity of hollow brick with increasing ofquantity of longitudinal holes reduces5%compared with ordinary hollow brick.Moreover, stagger arrangement of varied types of holes is gainful for improving thethermal performance of brick.The influence of sawdust, paper sludge, coal gangue on plasticity index of mixtureand the influence of dosage of pore-forming agent on property of hollow brick werediscussed in the research. It presents the volume densities and the compressive strengthsof bricks lose with the increasing dosages of sawdust, paper sludge, coal gangue,whereas the porosities and water absorption rates improve gradually while the dosagesof sawdust and paper sludge are6%and7%respectively. The suitable value ofequivalent thermal conductivity should be less than0.25W/(m~2·K) to satisfy the needsof building energy saving according to optimizing the hole type of hollow brick with9holes.Furthermore, the thermal performance of hollow brick filled with foam concrete asthe insulation material is improved of which the dry apparent density is224kg/m~3,thermal conductivity is0.063W/(m~2·K) and the water absorption ratio is equal to11.02%. Moreover, the compound hollow brick is prepared according to optimizing thehole type, of which the dry apparent density is867kg/m~3, thermal conductivity is0.21W/(m~2·K), the water absorption ratio is equal to18%and the compressive strength is5.35MPa.The effects of masonry and equipped of brick on thermal performance ofself-thermal insulation hollow brick were tested in order to obtain the heat-transfercoefficient of hollow brick and the surface temperature of interior wall. It presents theheat-transfer coefficient of insulation masonry decreases13%compared with which ofordinary masonry whereas the heat-transfer coefficient of fired-shale hollow brickreduces12%in comparison with that of compound hollow brick, and the surface temperature of interior wall of multi-hole equipped of brick is about0.5℃highercompared with that of solid brick whereas the temperature of insulation masonry mortaris about0.4℃higher compared with that of cement mortar. According to the result, thethermal conductivity of hollow brick wall built with glazed hollow bead mortar loses20%compared with which built with cement mortar, meanwhile, it reduces8%whenequipped of brick of12holes is used instead of solid brick. The thermal performanceand building energy consumption of varied types of hollow brick masonry, masonrymortar and multi-hole brick were tested in the investigation. It demonstrates theequivalent thermal conductivities of hollow brick wall and compound hollow brick wallare0.32W/(m~2·K) and0.31W/(m~2·K) respectively, and it suits the65%of energysaving design.

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