Preparation And Thermal Storage Performance Of Phase Change Ceramsite Sand And Concrete

With the development of society,more attention was paid to the efficiency of energy utilization.In the field of construction,the application of phase change materials(PCM)has made a great contribution in building energy conservation,and become a research hotspot related to it.However,the introduction of a large number of PCM will also have a negative impact on the strength of building materials.Therefore,in the current research,the selection of suitable carriers to balance the strength of building material and the amount of PCM is the current technical point of urgent need to break through.In this paper,different size of porous ceramsite with high porosity and specific surface was prepared by using light porous material as filler.The phase change material was adsorbed by its high porosity and adsorption performance to prepare form stable phase change material(FSPCM)and coated,which finally was applied to lightweight concrete as coarse and fine aggregate.BET,SEM,XRD,FT-IR,DSC were taken to characterize the microscopic,thermophysical and chemical properties of PCM and FSPCM,respectively.The mechanical properties,thermal performance of the lightweight concrete was tested and analyzed.Firstly,diatomite(DI)and expanded perlite(EP)were taken as light fillers to prepare ceramsite,respectively.The orthogonal experiment method was used to analyze the influence of raw material on the porosity and bulk density of the materials.The experimental formula was optimized with the porosity as the main evaluation index.When diatomite is chosen as the light filler,the best formula is cement:diatomite:aluminum powder:quick lime:fly ash=10:40:0.5:10:40.When it comes to EP,the best ratio is cement:EP:aluminum powder:quick lime:fly ash=5:30:0.5:5:60.The results illustrated that the introduction of light materials can effectively improve the porosity and specific surface area of ceramsite,and the performance of DI based ceramsite,EP based ceramsite and commercially available ceramsite were compared.Then,the self-made ceramsite was used to adsorb the PCM to prepare phase change aggregate.The adsorption rate and thermal property was compared and analyzed.The study shows that the EP based ceramsite has the highest absorption rate(42.75wt%)under vacuum impregnation conditions,which is better than that of DI based ceramsite(38.68wt%)and commercially available ceramsite(16.18wt%).The melting enthalpy of EP based ceramsite/PCM is 44.38 J/g,which show good thermal storage performance.Finally,cement was chosen as shell material to coat the prepared FSPCM.The influence of shell-core size ratio(Rs:Rc)to core material mass ratio is studied.And the ceramsite with shell-core size ratio of about 0.1~0.2 were obtained when the shell material mass ratio was 1.5:1 and 1.5 min coating time.The self-made ceramsite with different diameter size were chosen as the light fine(1~5mm)and coarse(>5mm)aggregate to prepare the concrete.The fine and coarse aggregate is replaced by the corresponding phase change aggregate to introduce the phase change material and preparation construction material.It is found that when the fine aggregate is all replaced by the corresponding phase change fine aggregate,and half of the coarse aggregate volume ratio is replaced by the phase change coarse aggregate,the strength and dry density of lightweight thermal storage concrete are 21.7 MPa and 1491.2 kg/m~3,respectively.It meets the requirements of LC15 lightweight concrete in JGJ51-2002Technical Regulations for Lightweight Aggregate Concrete(21.58 MPa,1400-1900kg/m~3),and has good temperature-control property.