| Insulation material is the material basis of building energy saving.Compared with organic thermal insulation materials,inorganic insulation materials has such advantages as fireproof,good durable,non-toxic and harmless and has a wide application prospect.General portland cement foamed concrete as a common inorganic insulation materials,there are slow condensation hardening,low absolute strength,light-high strength contradictions and other technical defects,its application has been greatly limited.As a new type of cementing material,slag-based geopolymer possesses numerous features such as quick hardening,high early strength,high strength,waste utilization and environmental protection.In view of this,the light-high strength foamed concrete may be prepared by using the slag-based geopolymer as the cementitious material.First,the foaming properties of sodium dodecyl sulfate(K12),sodium alpha-olefin sulfonate(AOS)and sodium alcohol ether sulphate(AES)at different concentrations were tested.The stability of the composite foaming agent in the air and fresh concrete was analyzed by using the silicone resin polyether emulsion(MPS)as the steady bubble component and K12,AOS and AES as the foaming component.The results showed the foaming property was excellent when the mass fraction of K12,AOS and AES were 0.6 wt%,0.4 wt% and 0.8 wt%,respectively.The comprehensive performance of K12 type,AOS type and AES type composite foaming agent is the best,when the concentration of MPS was 0.08 wt%.The foam multiple of the three kinds of composite foaming agents of K12,AOS and AES was 53,37 and 53,respectively.The distance of settlement for 1 h was 5 mm,9 mm and 5 mm,respectively,and the bleeding water for 1 h was 47 %,49 % and 46 %,respectively.The stability of the three kinds of composite foaming agents in fresh concrete were in the descending order AES type,K12 type,AOS type.Secondly,the effects of the ratio of liquid to plastic(ratio of water glass solution to granulated blast furnace slag)and foam content on the properties of foamed concrete were investigated.The results show the dry density and compressive strength of the foamed slag-based geopolymer decrease with the increase of the liquid-to-plastic ratio,when the foam content was 4.00 %.And the dry density and the compressive strength decreases with the increase of the liquid-to-plastic ratio,when the foam content was 8.00 %.The results showed porosity,average pore diameter and roundness increased,when foam content(foam-to-paste mass ratio)increased from 4.45 to 10.70 %.A good negative exponent relationship between foam content and the main properties of the foamed slag-based geopolymer was observed.The dry density,compressive strength and thermal conductivity were in the range of 398~1325 kg/m3,1.12~17.81 MPa,0.0813~0.2211 W/(m·K),respectively,when foam content increased from 4.45 to 12.00 %.The strength and thermal conductivity of the foamed slag-based geopolymer was significantly better than the technical requirements specified in JG/T 266-2011 at the same density level.Finally,the effects of light aggregate and fiber on the dry density,strength and shrinkage properties of foamed slag-based geopolymer were discussed.The results showed the dry density of foamed slag-based geopolymer increased first and then decreased,the compressive strength decreased and the shrinkage decreased with the increasing of the amount of expanded vermiculite.The dry density and strength of the products increased first and then decreased,and the shrinkage value decreased with the increasing of the amount of expanded perlite.The dry density and strength of the products increased first and then decreased,and the shrinkage decreased with the increasing of PVA fiber content.The dry density,compressive strength and shrinkage value of the product were significantly decreased with the increasing of CF fiber content.Compared with PVA fiber,the toughening effect of CF was better than that of PVA fiber. |
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