In the construction process of highway engineering, concrete is an extremely important building material, which has a relatively large impact on the quality of highway engineering construction. In the concrete construction process, in order to ensure the performance of the concrete and improve the applicability of the concrete, an admixture is generally added to the concrete. As an indispensable part of concrete, concrete admixture can significantly improve the quality of concrete by adding admixture to concrete, improve the performance of concrete, reduce the amount of cement in concrete, and save construction costs. In the actual application process, different types of admixtures have different functions. In practical applications, they should be carefully selected and applied reasonably to ensure the construction quality of concrete. Therefore, it is necessary to correctly understand the concrete admixture so as to fully exert the effect of the admixture.