Experimental Study On Strength Monitoring Of Recycled Concrete Based On PZT Sensor

In recent years,the number of demolition and new buildings has gradually increased,and the number of abandoned concrete has increased,which continues to encroach on land space,pollute the environment and increase economic burden,and the use of recycled concrete technology is an effective measure to solve the above problems.Strength is an important indicator of quality control of concrete structures,and the commonly used strength nondestructive testing technology has shortcomings such as inaccurate intensity measurement and cumbersome operation.Therefore,PZT piezoelectric intelligent sensor was used to carry out the research on age strength monitoring of recycled concrete.The relationship between the compressive strength of concrete and the conductivity signal of different recycled coarse aggregate content(0,30%,60%,100%)was established by using the piezoelectrical reactance method and the evaluation indicators RMSD and CC as the medium.(1)The relationship model between recycled coarse aggregate content and concrete compressive strength was established.The compressive test results of recycled concrete show that the compressive strength gradually decreases with the increase of recycled coarse aggregate.In the strength prediction model of each amount of recycled concrete established in this way,the maximum error between the predicted strength and the test strength is 0.046,which indicates the accuracy and feasibility of this model in strength prediction.(2)RMSD and CC were used as the medium to clarify the conductance change law of the target age of recycled concrete.In the three frequency ranges set by the experiment,the regularity of the conductivity curve shift in the monitoring period of 2～15 h was poor,and the conductivity curve tended to the right with the increase of age after 15 h,and the resonance frequency showed an increasing trend,which was consistent with the development law of recycled concrete strength,and the equivalent parameters RMSD and CC changes of conductance signal were correlated with the increase of recycled crude aggregate content and the development of compressive strength.(3)Based on RMSD and CC,the test conductivity data were quantified,and a prediction model for the compressive strength of recycled concrete considering the content of recycled coarse aggregate was established.The maximum error between the predicted strength and the test intensity with RMSD as the parameter was 0.0675,and the maximum error between the predicted strength and the test intensity with CC as the parameter was 0.0992,indicating that the model was reasonable and feasible,and it was clear that the strength prediction with RMSD had higher accuracy.The effectiveness of monitoring the development of compressive strength of recycled concrete based on PZT sensors is demonstrated.