Abstract: A modified mortar or concrete composition in which a polymeric binding material is combined with sand, cement, and fine fillers. Use of the higher than previously considered functional ratio of latex binding material to cement permits the resulting mortar or concrete composition to increase the percentage of fine fillers, and reduces the amount of voids as a result of less water loss. The latex material partially fills the voids becoming a part of the structure of the system. This leads to a higher degree of flexibility and coherence of the system.