Effect Of Aggregate Varieties On Mechanical Characteristics Of Hydraulic Concrete And Numerical Simulation Of Concrete

Aggregate is an important component of concrete.The influence of different aggregate properties on the performance of hydraulic concrete is particularly significant and important.In this paper,the effects of several aggregates on the mechanical properties and deformation characteristics of concrete was comprehensive studied.In addition,the performance of the concrete structures is determined by the conformation and properties of structures at lower scales.In the past,most of the studies on concrete were made of concrete as a homogeneous material,analyzed by the finite element method,and the direction of crack propagation in the concrete was set in advance.This cannot analyze the failure mechanism of concrete from the meso level,nor can it analyze the effect of mesoscopic parameters on the macroscopic properties of concrete.Therefore,the particle flow software PFC was used to numerically simulate the concrete and the influence of the mesoscopic parameters on the macroscopic properties of the concrete was analyzed.The main findings are as follows.(1)There are differences in the mechanical properties and deformation characteristics of concrete using different types of aggregates.The order of compressive strength of later concrete specimens of different types of aggregates are: Granite aggregate concrete,Basalt aggregate concrete,Limestone aggregate concrete,Marble aggregate concrete,Sandstone aggregate concrete.This is because the strength of the aggregate influences the strength of the concrete.The higher the compression index and the uniaxial compressive strength of the aggregate,the corresponding strength of the concrete is relatively high.Under the condition of water-binder ratio,the order of elastic modulus of concrete specimens with different types of aggregates is: limestone aggregate concrete> basalt aggregate concrete> marble aggregate concrete,granite concrete> sandstone aggregate Concrete.From the early crack resistance and long-term shrinkage results,the crack-resistance and anti-shrinkage performance of limestone aggregate concrete and marble concrete are better than those of other types of concrete.(2)The pore structure characteristics of the interface transition zone of differentaggregates-cement slurryFor the 180 d hydration,the distribution of the most probable pore size in each sample was mainly concentrated at(5~50)nm.The porosity of the interface between different aggregates and slurry was high to low: basalt aggregate concrete > marble bone Concrete> Granite aggregate concrete> Sandstone aggregate concrete>Limestone aggregate concrete.(3)Concrete mesoscopic parameters affect the macroscopic properties of the concrete.The particle friction coefficient and parallel bond strength are positively correlated with the peak strength.The greater the particle friction coefficient and parallel bond strength,the greater the peak strength of the concrete.And with the increase of parallel bond strength,the uniaxial compressive strength of the specimen increases significantly.Parallel bond normal stiffness and tangential stiffness ratio and peak strength are negatively correlated.Parallel bond normal stiffness and tangential stiffness ratio are greater,the concrete peak strength is smaller.