Study On Quasi Static And Dynamic Mechanical Properties Of Desert Sand Concrete

Concrete is one of the most extensive material applied in structural engineering in the world, throughout the area of buildings, road constructions and hydraulic engineering etc.. As the essential resources for concrete, medium sand can not satisfy the rapid increasing need of engineering. It is an abundant resources of desert in China, if the desert sand can be used for concrete instead of medium sand, it could reduce the project cost and is beneficial for environment protection. For the target of rational development and utilization, research in using of desert sand is very necessary. The achievements and research situations at home and abroad was cited in paper, experiment was carried out for the research of quasi static and dynamic mechanical properties of desert sand concrete. The following is my research contents:(1)An orthogonal experiment was carries out to analyze the influence of water-binder ratio, fly ash dosage, sand ratio and desert sand replacement ratio on 7d,28d,56d compressive strength and 28d splitting tensile strength of desert sand concrete. The result shows that the optimal mixture ratio of the desert sand concrete for water-binder ratio 0.34,10% dosage of fly ash, sand ratio, desert sand replacement rate of 30% and 30%.(2)Based on the experimental results, for 0%,10% and 15% amount of fly ash cement replacement respectively; at the same dosage of fly ash, the common sand respectively by 0%,20%,30%,40%,60%, 80% and 100% replaced by desert sand. The compressive strength and splitting tensile strength of 28 days was carried out with different dosage of fly ash and the desert sand replacement, and the influence law was found as follows: â‘  Keep the fly ash constant, with the increase of desert sand replacement ratio, the compressive strength and splitting tensile strength of desert sand concrete at the age of 28d increases firstly, then declines. When desert sand replacement ratio amounts to 20%, the 28d compressive strength and splitting tensile strength of desert sand concrete reaches maximum. â‘¡ Keep the desert sand replacement ratio constant, with the increasing of fly ash dosage, the 28d compressive strength and splitting tensile strength of desert sand concrete also increases firstly, then decline. When fly ash dosage amounts to 10%, the 28d compressive strength and splitting tensile strength of desert sand concrete reaches maximum.(3)The mechanical behaviors and dynamic properties of desert sand concrete with different desert sand replacement ratio were carried out by compression testing machines for analysis of servo-hydraulic machine and Split Hopkinson Pressure Bar (SHPB) with the diameter of 74mm, respectively. Results show that: â‘ With the increase of strain rate, the desert sand concrete peak stress, peak strain, the specific energy increases gradually, so the rate of desert sand concrete is related materials;â‘¡Under the same strain rate, as the desert sand replacement rate increases, the peak stress of the desert sand concrete decreases gradually; â‘¢Desert sand concrete specimens keep intact without damage and obvious crack on surface under aim pact velocity of 10 m/s. As the strain rate increased, the damage of desert sand concrete showed:perfect specimen to the cones connected opposite, fragments larger to small cones and chippings.