| Based on high-performance inorganic geopolymer composites, the addition of straw materials with low thermal conductivity can synthesize a new kind of energy-saving building compositions, which is hopeful to be a durable and thermal-insulated functional material. This study is not only beneficial to expand the application of energy-saving materials, but also contributed to make the sustainable development of environment friendly come true.Research is aimed to confirm the best formation of straw-geopolymer and through the preliminary tests to understand its heat insulation performance and stability in environment, further to estimate the long-term environmental and economic benefits and potential values in building applications. By SEM and TG-DTA analysis, the micro-combination ways of straw-geopolymer and micro-theory of heat insulation performance are fully speculated. The major finding are listed below: (1) Technical study shows that:when straw content increases from1.0%to6.0%, both of the compressive strength and the thermal conductivity of straw-geopolymer decrease gradually in experiments. When straw content is2.0-3.0%, the compressive strength of samples can reach above70MPa while the thermal conductivity is about0.06-0.08W/(m k.); When straw content increases to4.0-6.0%, the strength is still about50MPa, while its thermal conductivity is much close to0.05W/(m k.), as similar as that of slag cotton material. Combined with scanning electron microscopy (SEM) analysis, the perfect mechanical and environmental performances of geopolymer are mainly caused by its micro-structure which is constituted by innumerable amorphous layers, and the great heat insulation performance is resulted by interspaces between straw and geopolymer.(2) In heat resistance experiment, results show that the compressive strength of straw-geopolymer reduced with the calcining time and burning temperature increased. The compressive strength of straw-geopolymer exposed at600℃for1h is still25.08MPa remained, which is contributed to the crystal polymerized in geopolymer showed by TG-DTA analysis. Compared with cement concrete’s structure is completely collapsed at500℃, the heat resistance of straw-geopolymer is much better.(3) In freeze-thawing experiments, the compressive strength of straw-geopolymer declined gradually with the times of freeze-thawing increased. When the freeze-thawing cycle comes to25times, the compressive strength loss reached26.3%and the strength is still stay up to40MPa, which is close to the strength of the fifth freeze-thaw cycle and shows a good freezing-thawing resisting performance.(4) In sulfating experiments, since the hydrolysis of hydroxyl OH" in straw-geopolymer is easily happened in sulfate solution, the compressive strength of straw-geopolymer declined with the times of sulfate-soaking increased. After15times soaking cycle, the density of straw-geopolymer reduced but the compressive strength fell down to40MPa with the strength loss rate is25.3%, which is close to the results of6times cycle and shows a certain resistance performance of corrosion.(5) The ordinary three-seven wall painted with straw-geopolymer thermal insulation material of64.2mm thickness is designed as energy-saving model in this paper. According to the reference "the residential building energy saving design standards"(DBJ01-602-2004), every year the unit area energy-saving of straw-geopolymer composite wall turn out to44.05MJ/(kg-a), which is equal to1.5kg coal saved in unit area wall each year, and the energy-saving benefit is huge. |
