Design Of Cement Mortar Uniformity Detection System Based On Ultrasonic

Since 1949,along with the rapid recovery of China’s economic development,the construction industry has continued to develop.As an important industrial material in the construction industry,the homogeneity test is a key indicator to discern the quality of cement mortar.At present,the testing of cement mortar quality exists mainly in the detection of solid cement after setting,and if unevenness occurs there will be huge losses,so the testing of mixing quality during cement mortar mixing has more practical significance.In current production,however,the homogeneity of cement mixing is often judged by worker experience and the lack of practical testing equipment.A system for testing the homogeneity of cement is therefore needed to reduce or even eliminate the problem of uneven mixing.Firstly,the principle of uniformity testing is analysed to determine the relationship between uniformity and density.A variety of density measurement methods are then compared and the ultrasonic sound attenuation method is selected.The propagation characteristics of ultrasonic waves in cement mortar are analysed,and the relationship between the amplitude of the received waveform and the uniformity of cement mortar is finally established.Secondly,in designing the cement mortar uniformity testing system,the ABAQUS finite element simulation software was used for simulation design.The ultrasonic sound attenuation method was chosen to detect the received amplitude at five different locations of the cement mortar and compare the difference in received amplitude to measure the cement mortar uniformity.The tests were carried out in homogeneous cement mortars of different densities and temperatures,as well as in cases where the mixing was not homogeneous or where impurities were added to the homogeneous cement mortar.According to the simulation results,the method can easily and accurately perform quantitative measurements of cement mortar homogeneity,and certain thresholds can be set for qualitative judgements in the actual measurement to support the hardware system design.Afterwards,based on the simulation results,the hardware design of the detection system is carried out,and the frequency of 100 KHz ultrasonic probe is finally selected.The STM32F407ZGT6 chip was used as the main chip,and the STM32 minimum module,power supply circuit,ultrasonic transmitter circuit,ultrasonic receiver circuit and conversion circuit were designed.The power supply circuit includes a 24V-5V circuit and a 5V-3.3V circuit to achieve power supply diversity.The ultrasonic transmitter circuit emits a square wave signal through the PWM interface of the STM32 chip,and then changes the waveform by driving a step-up transformer through the LU3410 MOS tube to output a 300 V sinusoidal signal to the transmitter sensor.The receiver circuit uses an AD8052 bandpass filter with a centre frequency of 100 KHz to design the ultrasonic receiver circuit.Finally,experiments are carried out and the data is processed.The experimental results prove that it is feasible to use the received waveform amplitude to detect the uniformity of cement mortar.The cement mortar uniformity detection system studied in this project can be used in everyday life.