Preparation And Characterization Of Geopolymer Foam Concrete Based On Fly Ash-slag

Geopolymer foam concrete（GFC）has attracted extensive research as a new type of building insulation material.Due to its porous structure,GFC has the advantages of light weight,sound insulation,thermal insulation and fire resistance.Existing studies have mainly focused on investigating the effect of raw material ratios on the performance of GFC,while less research has been conducted on its pore characteristics and its effect on the performance of GFC.In this paper,single-factor tests（including Na₂O,fly ash,water-glass modulus,water-cement ratio,aluminium powder and calcium stearate）were conducted to investigate the effects of different factors on the macroscopic properties of GFC（including compressive strength,flow rate,dry density,thermal conductivity and shrinkage properties）using fly ash and GGBS as cementitious materials.On this basis,the microscope was combined with IPP software to analyse the relevant pore structure parameters of GFC for characterisation（including porosity,shape factor,average pore size,pore size distribution）,and finally the link between the fine structure and macroscopic properties of GFC was derived,leading to the following main conclusions.（1）The effects of various factors on the macroscopic properties of GFC were investigated and the results were as follows: 1)With the increase of Na₂O content,the fluidity of the fresh slurry kept increasing,the compressive strength decreased,the dry density and thermal conductivity decreased and the shrinkage kept increasing.2)With the increase of fly ash admixture from 30wt% to 70wt%,the compressive strength of GFC first increased and then decreased,the fluidity of the fresh slurry kept increasing The compressive strength increases and then decreases,the thermal conductivity and dry density increases and then decreases,and the drying shrinkage value is effectively reduced.3)As the water-glass modulus increases from 1.1 to 1.5,the compressive strength increases and then decreases,the flowability of the fresh slurry increases and then decreases,the thermal conductivity and dry density increases and the shrinkage property deteriorates.4)As the water-cement ratio increases from 0.35 to 0.45,the compressive strength increases and then decreases,the fresh slurry.5)With the increase of aluminium powder from 0.1wt% to 0.5wt%,the compressive strength decreases,the flow of new slurry increases,the thermal conductivity and dry density decreases,and the shrinkage performance deteriorates.6)The compressive strength increased and then decreased with As the dosage of calcium stearate increased from0.1wt% to 0.5wt%,the compressive strength firstly increased and then decreased,and the flow of fresh slurry The fluidity of the fresh slurry deteriorated,the thermal conductivity and dry density increased and then decreased,and the drying shrinkage value was effectively reduced.（2）The effect of various factors on the fine structure of GFC was investigated and the results were as follows: 1)A larger increase in the porosity and average pore size of GFC with the increase in Na₂O content,while there was a small deterioration in the shape factor（the more irregular the shape）.2)The percentage of large pores（pore size >600μm）of GFC decreased as the fly ash admixture increased from 30wt%to 70wt%.The shape factor is lowest at 50% fly ash admixture,which in turn makes the macroscopic properties optimal.3)As the water-glass modulus increases from 1.1to 1.5,the proportion of large pores in GFC keeps decreasing,the pore size distribution keeps averaging out and the shape factor keeps decreasing.4)As the water-gel ratio increases from 0.35 to 0.45,the average pore size of GFC keeps decreasing,but the proportion of small pores in GFC（pore size of 0-The pore size of GFC（pore size 0-600μm）is increasing,and the best GFC is recommended to be 0.40,which is a more even distribution of porosity and pore size.5）As the doping of aluminium powder increases from 0.1wt% to 0.5wt%,the pore size of GFC increases,which makes the shape factor deteriorate.6)With the increase of calcium stearate from 0.1wt% to 0.5wt%,the pore size distribution tends to be more even because calcium stearate can enhance the strength of bubbles and prevent the bubbles from fusing with each other to form larger pores,but has little effect on the shape factor.（3）The macroscopic properties of GFC are related to its fine structure: the compressive strength of GFC is not only related to the porosity,but also related to the average pore size and shape factor of its pore structure characteristics.With close porosity,the smaller the average pore size,the lower the thermal conductivity.The larger the average pore size and shape factor,the lower its compressive strength.Figure [82] table [13] reference [97]...