| Foam concrete is a new kind of light building material which has s series of good properties such as heat-insulation,sound-insulation,fire-resistance and anti-seismic property.It is suitable for producing partition wall and filling material,and it has been used widely in construction production.With the rapid development of prefabricated building industry,it has great development potential to use medium-density foam concrete which is manufactured with low-cost cement-based materials to prefabricate large building partition walls in factory.And coal gangue is a kind of industrial solid residues in coal field which has caused more and more serious environmental problems for it occupies lots of land.Now it is necessary to find new ways to recycle coal gangue and minimize its pollution.So this study has important social and environmental benefits through adding calcined coal gangue powder to get medium-density foam concrete.This study used cement mortar to produce foam concretes with different densities,and has studied the influence of the rheological property of the paste to the stability of foam and the relationship between the volume density and compressive strength.The result shows that the flowability of foam concrete grows with the content of water reducer increasing;and with the same cement-sand ratio and water-cement ratio.The volume density of foam concrete decreases linearly with the volume quantities of foam increasing.When the sand-cement ratio is 1:2,1:1.5and 1:1,we can get foam concrete with the density between 1000kg/m3 and 1200kg/m3 when the volume quantities of foam ranges between 48%~57%,46%~54% and 48%~55% respectively.With the volume density of foam concrete grows,the compressive strength increases in exponential type when the cement-sand ratio is 1:2 and 1:1.5,and increases linearly when the cement-sand ratio is 1:1.At the basic of foam concrete with cement mortar,it got coal gangue powder with different fitness and studied the influence of different content of coal gangue powder to the properties of foam concrete.The result shows,the fitness of the coal gangue powder which is grinding for 45 min is the same as the cement.And when the content of coal gangue powder increases,the flowability of foam concrete decreases,but it can increase the stability of sand and bubble.With the content of coal gangue powder increases,the volume density of foam concrete decreases,and the compressive strength decreases observably.And the compressive increases as the activity of coal gangue powder grows.At last,it studied the influence of steam curing to the compressive strength of foam concrete with coal gangue,and analyzed the hydration products with XRD.The result shows that the suitable temperature for foam concrete with coal gangue which is procuring for 8h is 40 oC.And steam curing and increase the 1d compressive strength obviously,and the 1d compressive strength which is steam cured for 18 h is 3Mpa,but steam curing has no obvious influence to the 7d and 28 d strength.Compared with natural curing,the sample of 1d age has more Ca(OH)2 and little SiO2,which shows steam-curing can accelerate the progress of cement hydration and pozzolanic reaction.The foam concrete with coal gangue whose age is 28 d has few Ca(OH)2 but more CaCO3,and this shows that there are more pozzolanic reaction and carbonation reaction progress take place by this time.And the pozzolanic reaction with low-activity coal gangue powder goes slowly,for there has more Ca(OH)2 in the sample of 28 d age. |
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