In this paper, the applicability of the modified Andreasen and Andersen (A&A) particle packing model for designing pumpable flowing concretes, according to ACI 211.9R-18, is analyzed. An experimental investigation is undertaken to evaluate consistency, compressive strength, and shrinkage of flowing concretes designed with this model. The results show that the modified A&A model optimizes the particle size distribution of concrete ingredients and produces pumpable concretes according to ACI 211.9R-18. The distribution modulus of the model controls the combined grading, the ratio of coarse-to-fine aggregate, and the percentage of fine aggregate passing 300 and 150 μm. At a distribution modulus of 0.35, the model serves as the ACI’s recommended boundary limit for ideal-for-pumping combined grading. A high distribution modulus results in a high coarse-to-fine aggregate ratio and lowers the drying shrinkage of concrete. This insight enables a straightforward mixture design methodology that results in concrete that meets ACI 211.9R-18 recommendations.