【作者】 李杰；

【导师】 杜应吉； 韩苏建；

【作者基本信息】 西北农林科技大学 ， 水工结构工程， 2010， 硕士

【摘要】 本论文采用了不同试验龄期、不同水胶比及不同粉煤灰掺量(0、20%、40%、60%、80%)的方案,通过试拌、成型养护及混凝土弹性模量试验和极限拉伸试验,探讨了28d和60d龄期时不同水胶比和不同粉煤灰掺量的大掺量粉煤灰混凝土的抗压弹性模量、轴心抗压强度的变化规律及其与抗拉弹性模量、轴心抗拉强度之间的关系。经过试验和分析,可得出以下成果:(1)粉煤灰混凝土抗压弹性模量和轴心抗压强度的变化规律A.粉煤灰混凝土的弹性模量和轴心抗压强度都随粉煤灰掺量的增加而减小,亦随水胶比的增加而减小。B.粉煤灰掺量相同,不管龄期是28d或是60d,水胶比为0.45的混凝土弹性模量和轴心抗压强度要略高于水胶比为0.5的混凝土弹性模量和轴心抗压强度。C.28d龄期时,水胶比为0.5的混凝土弹性模量随粉煤灰掺量增加而减小的速率比0.45的减小速率要快;60d龄期时,水胶比为0.5的混凝土弹性模量随粉煤灰掺量增加而减小的速率比0.45的减小速率要慢。D.水胶比为0.45或是0.5时,相同粉煤灰掺量的情况下,60d龄期的粉煤灰混凝土弹性模量要略大于28d龄期的粉煤灰混凝土弹性模量,即粉煤灰混凝土的弹性模量随龄期的增长有增加的趋势,但增加的幅度比较缓和;相同情况下,60d龄期的粉煤灰混凝土轴心抗压强度明显大于28d龄期的粉煤灰混凝土轴心抗压强度,即粉煤灰混凝土的轴心抗压强度随龄期的增长有明显的增加趋势,并且增加的幅度比较大。(2)粉煤灰混凝土的轴心抗压强度与轴心抗拉强度的关系A.粉煤灰混凝土养护龄期越长,其轴心抗拉强度和抗拉弹性模量增长较大;B.28d龄期时粉煤灰混凝土的轴心抗压强度值为其轴心抗拉强度值的7倍左右;C.60d龄期时粉煤灰混凝土的轴心抗压强度值为其轴心抗拉强度值的8～10倍左右。则可知:粉煤灰混凝土的轴心抗压强度随龄期的增长速度要大于其轴心抗拉强度随龄期的增长速度;粉煤灰混凝土的轴心抗压强度值为其轴心抗拉强度值的7～10倍左右。(3)粉煤灰混凝土的抗压弹性模量与抗拉弹性模量的关系28d和60d龄期时,粉煤灰混凝土的抗压弹性模量与其抗拉弹性模量的比值波动范围均为0.9～1.1,因此两者相差不多。粉煤灰混凝土的轴心压拉比与压拉弹模的关系可以近似用三次方程的方式来表达。更多还原

【Abstract】 The paper uses the program of different test age, different water-binder ratio and different content of fly ash (0,20%, 40%, 60%, 80%).According to concrete elastic modulus test and ultimate tensile test, the change law of compressive elastic modulus and axial compressive strength of different water-binder ratio and different content of fly ash under 28d and 60d are analyzed.The relationship between axial tensile strength and tensile elastic modulus and the different initial condition is talked.We can get the following results:(1)The change law of compressive elastic modulus and axial compressive strength A. Both the elastic modulus and axial compressive strength would decrease with the increase of content of fly ash, so would the water-binder ratio. B. With the same content of fly ash, the elastic modulus of concrete with the water- binder ratio of 0.45 is a little bigger than that with the water- binder ratio of 0.5 under the test age of 28d or 60d. The axial compressive strength shows the same tendency. C. Under the test age of 28d, the decrease of elastic modulus of concrete with the water-binder ratio of 0.5 is quicker than that of 0.45 with the content of fly ash increasing; Under the test age of 60d, the decrease of elastic modulus of concrete with the water-binder ratio of 0.5 is slower than that of 0.45 with the content of fly ash increasing and the difference is quite small. D. With the water-binder ratio of 0.45 or 0.5, the elastic modulus of concrete under the test age of 60d is a little bigger than that of 28d, which indicates that the elastic modulus of concrete increases with the test age but the tendency is quite gentle under the premise of same content of fly ash; In the same condition, the axial compressive strength of concrete under the test age of 60d is a little bigger than that of 28d, which indicates that the axial compressive strength of concrete obviously increases with the test age but the extent is quite great under the premise of same content of fly ash.(2)The relationship between axial compressive strength and axial tensile strength of fly ash concreteA. The axial tensile strength and tensile elastic modulus of fly ash concrete become bigger with the maintenance age increasing; B. Under the test age of 28d, the axial compressive strength of fly ash concrete is almost seven times of its axial tensile strength; C. Under the test age of 60d, the axial compressive strength of fly ash concrete is almost 8- 10 times of its axial tensile strength.It indicated that the growth of axial compressive strength is bigger than of axial tensile strength; The axial compressive strength of fly ash concrete is almost 7- 10 times of its axial tensile strength.(3)The relationship between compressive elastic modulus and tensile elastic modulus of fly ash concreteUnder the test age of 28d and 60d, the variation of compressive elastic modulus and tensile elastic modulus of fly ash concrete ranges from 0.9 to 1.1, which shows little difference.The relationship between ratio of compressive strength and their elastic modulus of fly ash concrete can be expressed by cubic equation.更多还原