【作者】 刘发明；

【导师】 马芹永；

【作者基本信息】 安徽理工大学 ， 结构工程， 2008， 硕士

【摘要】 本文在理论研究的基础上,首先,对钢纤维粉煤灰混凝土抗压强度和抗折强度进行了试验研究;其次,对钢纤维粉煤灰混凝土经过75次冻融循环后的抗压强度进行了试验研究;最后,对钢纤维粉煤灰混凝土小梁的抗折疲劳特性进行了试验研究。试验研究结果表明:粉煤灰掺量对钢纤维混凝土的强度影响规律受龄期及钢纤维掺量的影响。混凝土的抗折和抗压强度均随粉煤灰掺量的提高而趋下降,但下降的趋势随龄期的增长而趋缓和。随着钢纤维掺量的提高,粉煤灰和钢纤维之间体现了较强的复合效应,即适量掺入粉煤灰后(掺量30%以下),钢纤维粉煤灰混凝土的抗压强度降低的较少,其抗折强度增长的较多,而超过30%以后抗压、抗折强度损失的非常严重。如当粉煤灰掺量30%、钢纤维体积率1.2%的28天抗压强度比素混凝土降低了7.6%,抗折强度提高了12.1%;而当粉煤灰掺量50%、钢纤维体积率1.2%的抗压强度、抗折强度损失的高达62.3%和36.2%。素混凝土的抗冻能力较差,75次循环后抗压强度损失率高达45.695%,而掺入钢纤维和粉煤灰后,可以显著地提高混凝土的抗剥落能力,改善冻融性能。粉煤灰对试件抗冻性能的提高程度比钢纤维的提高程度要强,即掺入粉煤灰的混凝土在冻融循环后的抗压强度损失率比较低。如在75次冻融循环后钢纤维混凝土的强度损失率为17.699%,而粉煤灰混凝土的强度损失率只有0.810%。应力水平对钢纤维粉煤灰混凝土梁抗折疲劳寿命有着显著影响。低应力水平下的疲劳寿命远远高于高应力水平下的疲劳寿命,钢纤维粉煤灰混凝土梁在抗折疲劳变形过程中,抗折疲劳寿命大致可以分为疲劳裂纹的潜伏阶段、萌生及稳定扩展阶段、失稳破坏阶段三个不同阶段。经过拟合得到lgS-lgN的曲线方程:lgS=0.11735-0.0613lgN。钢纤维粉煤灰混凝土梁疲劳损伤演化过程可划分为损伤潜伏阶段,损伤稳定扩展阶段和损伤失稳扩展或破坏阶段等三个不同阶段。在较高应力水平下钢纤维粉煤灰混凝土的损伤发展速率明显高于低应力水平下的损伤发展速率。通过疲劳试验,测定其疲劳寿命,得到疲劳寿命与应力水平之间的关系,并分析抗折疲劳变形特性和损伤特性。从而为重载交通条件下路面设计提供试验依据,也发展了粉煤灰的综合利用途径,保证了我国能源的可持续发展。更多还原

【Abstract】 Based on theoretical investigation,first,experimental investigations were conducted on the compressive strength and bending strength of steel fiber reinforced fly ash concrete.Secondly,experimental investigations were conducted on the compressive strength of steel fiber reinforced fly ash concrete after 75 times freeze-thaw cycles.Finally,experimental investigations were conducted on the flexural fatigue of steel fiber reinforced fly ash concrete beams.The exprimental result indicated,volume of fly ash effect on strength of steel fiber reinforced fly ash concrete was influenced by age and volume of steel fiber.Compressive strength and bending strength of concrete decreased with the increment of fly ash incorporation.But descend trend ease up with the increment of age.Fly ash and steel fiber incarnate stronger compound effect with the increment of steel fiber volume.Compressive strength of steel fiber reinforced fly ash concrete decreased less and bending strength increased more after proper fly ash is mixed(volume under 30%).But compressive strength and bending strength lose very seriously when volume exceed 30%.When the volume of fly ash was 30%and volume ratio of steel fiber was 1.2%,28 days compressive strength of steel fiber reinforced fly ash concrete had decreased 7.6%and bending strength had improved 12.1%.But when volume of fly ash was 50%and volume ratio of steel fiber was 1.2%,compressive strength,bending strength loss rate as high as 62.3%and 36.2%. Freezing ability of concrete is worse.Compressive strength loss rate as high as 45.695%after 75 times freeze-thaw cycles.Improve antistripping and freeze-thaw properties significantly when steel fiber and fly ash are mixed.Fly ash improves frost resistance of specimen stronger then steel fiber.Compressive strength loss rate less when fly ash was mixed after freeze-thaw cycles.For example,strength loss rate of steel fiber concrete was 17.699%after 75 times freeze-thaw cycles,but loss rate of fly ash concrete was only 0.810%.Stress level has significant effect on flexural fatigue life of steel fiber reinforced fly ash concrete beam.Fatigue life under low stress is much higher than high stress.Flexural fatigue life can be divided into latency stage,stable development stage and in stability development stage in the course of flexural fatigue deformation of steel fiber reinforced fly ash concrete.Obtained curve equation of lgS-lgN which was lgS=0.11735-0.06131gN through fitting.The damage evolvement process can be divided into latency stage,stable developing stage and instability development stage.Damage developing rate of steel fiber reinforced fly ash concrete in high stress level obviously superior then low stress level.Measured fatigue life through fatigue expriment.It is obtained that the relationship between fatigue life and stress level.Analysis deformation properties and damage properties of flexural fatigue.It is can offer that the experimental gist for pavement design in heavy traffic and develop comprehensive utilization ways of fly ash.Ensure sustainable development of China’s energy.更多还原