Research On The Mechanical And Thermal Properties Of Alkali Slag Composite With The Structureinsulation Integration

With the deterioration of the global environment and the development of modern building technology,the requirement on the functional and structural properties of building materials are getting higher.For example,the new types of building materials with excellent thermal insulation and high mechanical strength are required to solve the heavy energy consumption of buildings.However,due to the poor mechanical strength and high cost,the traditional thermal insulation materials cannot meet the requirements of the above-mentioned modern building materials.Therefore,the research and application of structural-insulation integration materials have become one of the key directions of research.In this study,expanded polystyrene beads（EPS）were firstly used to replace traditional aggregates and incorporated into alkali slag mortars（EPS-AASMs）to reduce the thermal conductivity,prepare green wall insulation materials and promote the recycling of EPS.At the same time,because the addition of EPS as lightweight aggregates will drastically reduce the mechanical strength of AASMs,therefore,this study also uses the method of incorporating reduced graphene oxide（rGO）as nano-material to improve the mechanical strengths of EPS-AASMs,achieving the goal of structural-insulation integration.In this study,the physical characteristics,mechanical,thermal properties,microstructural performances,life cycle assessment and building information model of alkali activated slag mortars with EPS and rGO（rGO-WEA）were comprehensively investigated.The feasibility and economics of structure-insulation integration are studied.Based on the above research objectives,the conclusions of this study include the following aspects:（1）With the increase of EPS,the results indicate that the dry and wet densities,mechanical strengths and workability of EPS-AASMs reduced.And the porosities of EPS-AASMs increased with the increase of EPS,so that the thermal conductivity of the EPS-AASMs decreased with the EPS content increase.The thermal conductivities of 60EPS,80EPS,and 100EPS were 66.1%,75.2%,and 82.6%lower than 0EPS,respectively.Through the homogenization theory,the effect thermal conductivities of EPS-AASMs were calculated,and the thermal insulation properties of EPS-AASMs can be predicted by the amount of EPS.（2）The dry and wet densities of rGO-WEA decreased with the increase of EPS and slightly increased with the increase of rGO.Meanwhile,incorporating rGO into AASMs with EPS was an effective method to improve mechanical strength.The incorporation of rGO can promote the velocity of reaction,and optimize the interface transition zone（ITZ）between the EPS and alkali activated slag pastes.Meanwhile,it was found that the thermal conductivity of E8-G4 decreased by 74.5%,compared to E0.In terms of compressive strength,thermal conductivity and cost,the efficiency index（EI）of E8-G4 was 798 and increased by 8.7%than E0.It can realize the structure-insulation integration of building materials and achieve good balance among mechanical properties,thermal conductivity and cost.（3）According to the results of life cycle assessment（LCA）,the EE,ECO₂e,and cost of E8-G4 were 3382.27 MJ/m³,190.75kg CO_2e/m³,and 933.75 Yuan/m³,respectively.The ECO₂e of E8-G4 was 16.8%lower than E0 and more environmentally friendly.An office building model made from rGO-WEA was designed using building information modeling（BIM）tools to simulate energy consumption.In the five typical cities（Shenzhen,Beijing,Wuhan,Harbin and Kunming）,a building with the E8-G4 as walls have reduced their total energy consumption by 1.2%,20.5%,11.6%,31.8%and8.0%,respectively,compared with the use of traditional walls.Hence,rGO-WEA can realize the application of structural-insulation integration and also reduce the energy consumption and CO₂ emissions.