Research On Water Transmission Characteristics And Two-dimensional Water Seepage Monitoring In Concrete

As the world's most significant building materials,concrete is wildly used.In the meantime drawbacks are gradually emerging,which one of the most prominent problem is the durability of concrete.Water is not only one of the necessary conditions for the deterioration of concrete durability,in addition it shows great effect on the strength,shrinkage and creep of concrete.Therefore,it is very meaningful to study the water transport in concrete.At present,laboratory experiments show that the Smart Aggregate(SA)sensor can be used to monitor the structure of fractures,the concrete debonding of concrete-filled steel tubes,and the impact load monitoring of concrete.This provides the possibility of monitoring the seepage process of concrete.In this paper,the seepage process of concrete is studied.The simulation model is established to verify and forecast the corresponding test.The concrete seepage process is monitored.Specific contents include:In order to study the diffusion law of water in concrete,the seepage test of concrete column was designed,and the seepage distribution of concrete was obtained by slicing method.The seepage process of concrete is described by Fick 's second law,and the diffusion coefficient of water is determined by test.The influencing factors of water diffusion were discussed.The results show that the water diffusion coefficient obtained from the results of seepage distribution is consistent with the long water seepage time,which shows that the water law of concrete under long time can be described by Fick's second law.The mixing ratio,cross-sectional have little influence of the diffusion coefficient of concrete water.Based on the ABAQUS,the simulation of concrete seepage process was carried out due to the consistency of the heat conduction equation and Fick's second law.In order to deepen the model,a three-dimensional spherical aggregate model was established based on the Monte Carlo method,influence of aggregate volume rate and concrete cross section on t he seepage process of concrete was studied later.The results show that the water seepage simulation are consistent with the experimental results,furthermore,the feasibility of Fick's second law was verified.The simulation results based on the spherical random aggregate model show that randomly distributed aggregates and the cross section shape have little effect on seepage of concrete,the presence of aggregate will hinder the seepage process,the greater the volume rate will lead to more serious hinder effect.In order to explore the feasibility of SA application in concrete seepage monitoring,the monitoring signal amplitude and percussion signal of each pair of aggregate were recordded via experimental methods.Through the data processing technology,the relation between the monitoring signal and the seepage process of concrete were built.The results show that the signal amplitude is associated with the degree of water seepage.However,the signal amplitude is is recommended as early warning index for concrete seepage,as the signal is vulnerable to environmental interference.The frequency response of percussion signal is highly correlated with the seepage process and experimental results exhibit excellent stability,sensitivity and practicality.Due to its remarkable property the frequency response of the percussion signal is suggested to be the main indicator of concrete seepage monitoring.