Investigation of the behavior of recycled concrete and self-compacting concrete in road pavement construction using ultrasonic test and compare it with other methods

Nowadays, recycled concrete is used for the construction of many construction projects due to its low cost and environmental protection. In addition, self-compacting concrete is very important and useful due to the lack of vibration and the least possibility of creating large holes and voids. In this article, by combining these two types of concrete, its properties have been investigated. To obtain the compressive strength of concrete, non-destructive methods can be used, which can be much simpler, faster and without damage, however, there must be agreement between the destructive and non-destructive test results to be acceptable. In this article, the behavior of recycled and self-compacting concrete used in road concrete pavements has been investigated. For this purpose, the method of grinding and ultrasonic testing has been used and a comparison has been made between the results. The average compressive strength of 28 days in cement grade of 250 kg/m3 is equal to 25.2 MPa and in cement grade of 400 kg/m3 it is equal to 38.9 MPa, which has increased by 54%. Finally, it has been concluded that the results of sanding and ultrasonic testing in determining the compressive strength of concrete can have a difference between 7 and 17%, and usually the results of ultrasonic testing show lower values.