Effect of vibratory mixing on the slump, compressive strength, and density of concrete with the different mix proportions

Abstract Mixing method plays a critical role in the properties of concrete. Vibratory mixing as a novel mixing method has its advantages in improving the properties of concrete. But the specific property of concrete is sensitive to the operation parameters of the vibratory mixing. This paper is motivated to study the effect vibration amplitude and acceleration on the concrete properties and to compare with the conventional mixing at four groups of mix proportions. The macroscopic performance was measured by slump test, compressive strength test, and density test, and the microscopic characteristics was analyzed by scanning electron microscope (SEM). The test results indicates that the slump, compressive strength, and density of the different concrete were both improved using vibratory mixing. Analysis of variance (ANOVA) results showed that vibration amplitude significantly influenced the compressive strengths. At optimum vibration parameters, the slump of M1, M2, M3, M4 was increased by 36%,15% 25%, 26%, separately; the compressive strength increased by 13%, 15%, 35%, 44%; the density was improved by 1.3%, 2%, 1.4%, 1.3%. Concrete with a low w/c ratio (0.33) requires more vibration energy. Moreover, fewer defects and denser structure were observed by vibratory mixing, which benefited to a higher bond strength. Under the same mix proportions, the slump shows a positive relationship with compressive strength by vibratory mixing. The low w/c ratio concrete has the higher change rate of compressive strength with the density.