Study On The Preparation And Properties Of Novel Alkali Slag Composite Block Including Form Stable Phase Change Material

Energy saving,consumption reduction and functionalization is a key development direction of new building wall materials.Compound the phase change material with large latent heat and alkali slag cementitious material at room temperature to prepare wall material,which can make the indoor temperature relatively stable when the external environment temperature changes greatly,thus improving the comfort of the house and achieving the goal of building energy saving and emission reduction.In this paper,typical inorganic phase change material CaCl₂·6H₂O and organic phase change material paraffin were selected as the research objects.Two kinds of form stable phase change materials?FSPCM?,CEV and PEV,were prepared by mixing CaCl₂·6H₂O or paraffin with porous carrier expanded vermiculite?EV?respectively.Then they were compounded with energy-saving and environmental-friendly alkali slag to prepare energy storage block,which was a new building material with heat storage and temperature regulation.The performances of FSPCM were characterized by analysis and test methods of anti-leakage test,thermal cycle test,SEM,DSC,TGA,XRD and FI-IR.The results shown that EV was an excellent support material,and medium-sized?30-60 mesh?EV had the largest adsorption capacity for CaCl₂·6H₂O.The latent heat loss rate of the phase change materials after 200 thermal cycles decreased with the smaller the particle size.CaCl₂·6H₂O and paraffin can be well adsorbed in lamellar gap of the EV;the latent heat of FSPCM increased with the increase of CaCl₂·6H₂O or paraffin content;the optimum content of CaCl₂·6H₂O in the CEV prepared by atmospheric pressure impregnation was 60wt%,and the phase change temperature and latent heat were 28.27?and 105.06 J·g^-1,respectively;The optimum content of paraffin in PEV prepared by vacuum impregnation method was 50wt%,the phase change temperature and latent heat were 23.72?and 95.51 J·g^-1,respectively.With the increase of phase change materials and thermal cycles,the latent heat loss rate of FSPCM also increased.CaCl₂·6H₂O and paraffin paraffin were only physically adsorbed with EV and had good chemical compatibility.From the SEM images of the two kinds of composite blocks,it was observed that a large number of hydrated products of slag were well coated with the FSPCM.With the increase of the content of the FSCPM,the compressive strength and flexural strength of the energy storage composite blocks gradually decreased.The 28-day compressive strength of SCEV-90with the largest content of CEV2-60 was still 10.5 MPa,and the 28-day compressive strength of SPEV-100 with the largest content of PEV2-50 was 14.57 MPa.The test results of two kinds of composite blocks by volume density tester and thermal conductivity tester shown that the volume densities and thermal conductivities of energy storage composite blocks decreased significantly with the increase of the content of phase change materials;The temperature regulation performance of energy storage composite blocks were studied by stablishing phase change simulation room.The results shown that the energy storage composite block can significantly reduce the temperature fluctuation in the simulation room and maintain indoor comfortable environment.Compared with the highest ambient temperature,the peak temperatures of energy storage composite block SCEV-90 and SPEV-100 in the central position of the simulated room were reduced by 5?C and 6.2?,respectively.These results shown that the composite block was a new building material with excellent heat storage and temperature regulation performance.By comparing the properties of two kinds of FSPCM and composite blocks,it was found that the normal pressure impregnation method was suitable for the CEV,while the vacuum impregnation method was suitable for the PEV;the phase change temperature and latent heat of the CEV-60 were higher than that of PEV-50,but the thermal cycle stability was lower than that of PEV-50;the comparison of TGA shown that the thermal stability of the CEV was better than that of the PEV-50;The temperature regulation performance of PEV was better than that of SCEV,and the effect of temperature regulation was more obvious with the increase of the amount of phase change materials.Among them,the peak temperature of SPEV-100 simulation room was 1.2?lower than that of SCEV-90,and the time of SPEV-100 staying in the range of 20-28?was 170.1 min longer than that of SCEV-90.