| Improving the thermal insulation of building walls was the most effective way to achieve energy saving in buildings.Foamed concrete was the most common building energy-saving and environmentally friendly material.It has small density,excellent thermal conductivity,absorbing sound insulation,obvious anti-seismic effect and fire resistance.Good advantages,are widely used in various types of construction projects.However,the research and application of foam concrete have the disadvantages of large thermal conductivity and low strength.Lightweight foam concrete was also difficult to form due to excessive foam content.A new type of ultra-light fiber aerogel foam concrete was prepared by mechanical foaming method with aerogel with low thermal conductivity,high porosity and low density as the filling material and chopped glass fiber as the reinforcement.The properties of the new foam concrete,such as density,thermal conductivity and compressive strength,were tested.The results show that the aerogel blending greatly reduces the self-weight and thermal conductivity of foam concrete.When the aerogel content was 20%(volume ratio),the foam concrete density reduction rate was 39.4%,and the thermal conductivity reduction rate was 35.8%,although the compressive strength was reduced,it still meets the strength requirements of foam concrete JG/T266-2011;the incorporation of glass fiber not only increases the formability of foam concrete,but also enhances the compressive strength of foam concrete.Compared with gel foam concrete,its compressive strength increased by 12.1%.The control variable method was used to study the effects of water-binder ratio,foam content,glass fiber content and water-repellent agent on the basic physical properties(density,thermal conductivity,compressive strength and water absorption)of ultra-light foam concrete.The results show that: The aerogel content was 12%(mass ratio,the same as below,the equivalent volume ratio was 20%),the foam content was 75%(volume ratio),the water-tobinder ratio was 0.70,the glass fiber ratio was 0.9%,and the water repellent ratio was 2.0.The foam concrete prepared by the experiment has the best performance,the density was 195 kg/m3,the thermal conductivity was 0.056 W/(m·K),the compressive strength was 0.31 MPa,and the mass water absorption was 9.4%.Three kinds of thermal insulation boxes such as polystyrene(EPS),ordinary concrete and fiber aerogel foam concrete were tested under the condition of constant temperature outside the box of 35? and initial temperature of 25? in the box.Thermal insulation performance under heating conditions.The results show that the temperature in the polystyrene(EPS)box was stable at about 5 h,and the temperature in the ordinary concrete box was stable at about 4.5 h,while the temperature in the fiber aerogel foam concrete box reaches 9 h.Stable,its thermal insulation performance was significantly better than the other two traditional materials.The 3R2 C heat flow network model of the composite wall was established,and the accuracy and feasibility of the model were verified by the test box method.The results show that the experimental results agree well with the 3R2 C heat flow network model,and the maximum error was only 3.7%.The reliability of the model was verified.The 3R2 C model can accurately reflect the temperature change of the incubator.Taking the hot summer and warm winter area(Guangzhou)as an example,under the periodic outdoor temperature wave interference,based on the verified 3R2 C model,It was calculated that the delay time of the foam concrete insulation box was twice that of the conventional polystyrene(EPS)or ordinary concrete box.The attenuation factor was comparable to that of a polystyrene box,which was about 3.5 times that of a concrete box.In summary,fiber aerogel foam concrete has better thermal insulation performance than traditional materials such as polystyrene(EPS)and ordinary concrete,and has great application prospects in the field of building wall insulation. |
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