新型秸秆纤维混凝土实心砖的性能试验研究

Experimental Study on Mechanical and Physical Properties of New Straw Fiber Solid Concrete Brick

为了有效利用农业剩余物研制出具有良好综合性能的新型墙体材料,研究了秸秆纤维混凝土配合比,并对比新型秸秆纤维混凝土实心砖(new straw fiber solid concrete brick,NSFCB)与普通混凝土实心砖(general solid concrete brick,GCB)的力学性能和物理性能。进行了秸秆纤维混凝土抗压强度试验,以及实心砖大面抗压、抗折、保温隔热和干缩试验。对砖的受压应力与应变关系、早期干缩率随时间变化规律进行函数拟合分析。结果表明:氯化钙、高岭土对增强秸秆纤维混凝土强度效果明显;由于秸秆纤维的掺入,与GCB相比,NSFCB的大面抗压强度和抗折强度分别降低28.5%和6.8%,但折压比提高了30.5%,并且延性也较好;采用改进的有理分式很好地拟合了实心砖受压应力-应变试验曲线,决定系数值接近1,具有良好的相关性;NSFCB保温隔热性能突出,同GCB相比,其导热系数值下降了18.9%;7 d后NSFCB的干缩率变化较小,干缩性能良好;采用双曲线函数式拟合NSFCB干缩率-时间试验曲线,总体分布无显著差异,拟合度较高。

In order to take advantage of agricultural residues,a new type of wall material with good comprehensive properties was developed.The mix proportion of straw fiber reinforced concrete was studied.The mechanical and physical properties of new straw fiber solid concrete brick(NSFCB)and general solid concrete brick(GCB)were studied.The compressive strength of straw fiber reinforced concrete was tested.Compression tests on the largest face,flexure tests,heat insulation tests and dry shrinkage tests of solid bricks were respectively carried out.The compressive stress-strain curves and early dry shrinkage ratio-time curves of bricks were analyzed by function fitting.The results showed that the effects of calcium chloride and kaolin on strengthening the strength of straw fiber reinforced concrete were obvious.The compressive strength on the largest face and flexural strength of NSFCB were respectively reduced by 28.5%and 6.8%due to straw fiber.However,the ratio of flexural strength to compression strength of NSFCB was improved 30.5%,and it was better than GCB in the ductility.The improved rational fraction was sufficiently suitable for the compression stress-strain test curves of brick,and adjusted coefficient of determination was almost close to 1.NSFCB was outstanding in heat insulation performance,and the average thermal conductivity was decreased by 18.9%.The drying shrinkage ratio of NSFCB changed little after 7 days,and dry shrinkage performance of NSFCB was good.Early dry shrinkage ration-time test curve of NSFCB that fitted by hyperbolic function possessed a high fitting degree,and there was no significant difference in population distribution.