Experimental Study On Setting Time Of Vibration-mixed Concrete

Setting time is one of the important parameters of the performance of fresh concrete,and the degree of setting determines the pourable time and load-bearing time of the concrete.Vibration stirring can destroy the agglomeration of cement particles,increase the degree of hydration reaction,and affect the setting time to a certain extent.In this paper,the influence of vibration agitation on the setting time of concrete is studied,and laboratory experiments are carried out to provide support for increasing the application range of vibration agitation.In this paper,the mechanism of the effect of vibration agitation on the hydration reaction is first explained,and the process of the hydration reaction of cement clinker and the influencing factors of the hydration reaction are analyzed.By selecting the key factors affecting the hydration reaction and the appropriate level,the orthogonal test method was adopted to carry out tests such as compressive strength,splitting strength,setting time and slump,and explored the cement temperature,vibration strength,and water-cement ratio.The influence of factors on the setting time,workability and mechanical properties of concrete.The test results show that: increasing the cement temperature from 16℃ to 60℃,the concrete initial setting time is shortened by 13.57%,the final setting time is shortened by8.39%,the 3d compressive strength is increased by 26.38%,the 7d compressive strength is increased by 13.79%,and the 28 d resistance Compressive strength decreased by 8.25%,3d splitting strength increased by 30.9%,7d splitting strength increased by 15.45%,but 28 d splitting strength decreased by 12.14%;vibration strength increased from 0g(that is,ordinary stirring)to 4g,The initial setting time is shortened by 5.25% and the final setting time is shortened by 3.25%.Compared with ordinary mixing,when the vibration strength is 4g,the concrete 3d splitting strength is increased by 12.50%,the compressive strength is increased by 5.48%,7d and 28 d are respectively increased by 6.46% and 9.56%,and 7d and 28 d are respectively increased 4.11% and 7.04%.Among the primary and secondary factors that affect the setting time,the cement temperature is the largest,followed by the water-cement ratio,and finally the vibration intensity.The primary and secondary factors that affect the compressive strength,splitting strength and slump are ranked as the water-cement ratio,followed by the cement Temperature,and finally vibration intensity.The above results show that when the temperature is high in summer,the use of vibration agitation has little effect on the setting time.When the mixing ratio is determined,it is more necessary to control the temperature of the cement into the pot.