Numerical Study On High-performance Concrete With Coarse Aggregates And Electric Curing Method In Ultra-low Temperature Environment

Adding fibers with low resistivity can bring benefit for high-performance concrete's conductivity.The electrically conductive concrete has wide application such as de-icing and snow melting,electric grounding,cathodic protection,structure health monitoring and electromagnetic interference shielding.Electric curing method accelerates the hydration reaction and prevents the early frost damage of concrete by applying an alternating voltage to generate ohmic heating.High-performance concrete(HPC)has more significant content of cement than ordinary concrete,which increases the costs and shrinkage.HPC with coarse aggregates(CA)can decrease the cement content and avoid the problems above.In this study,concrete models with random packing CA were developed by MATLAB software.Diffusion simulation and finite element method were used to study CA's influence on the formation factor,uniaxial compressive stress,temperature field distribution and thermal stress.Based on the particle packing theory,the distribution modulus was modified to achieve 30% and 40% volume content of CA in HPC.Spheres with a radius of 5mm,8mm and 10 mm were chosen as CA in this study,respectively.The content of each size of CA was adjusted to the particle distribution curve.Models with 10%-40% single size aggregate and 30%-40% gradation aggregate were developed by RSA and particle packing algorithm in MATLAB.The size of REV was determined as 100 mm by porosity.Formation Factor in three directions was obtained by the diffusion simulation.It has been found that the formation factor tends to be amplified when CA content increases.CA with smaller radius has a higher formation factor when CA content is less but grow slower,while CA with larger radius lower first but grow faster.Furthermore,the gravity factor in particle packing algorithm makes the formation factor of Z-direction less than the other directions.The uniaxial compression simulation shows that CA can contribute to the elastic modulus.CA reduces the compressive stress when the radius is more extensive and improve the stress when the radius is smaller.The simulation of temperature field distribution and thermal stress shows that the temperature is related to the shape of the model.An increased radio of volume to surface leads to higher average temperature.Models with smaller CA size tend to have higher temperature and thermal stress.