This study involves the investigation of water absoption of mortar modified with combinations of polymer and pozzolan by using initial surface water absorption test (ISAT). Since surface of mortar or concrete serves as medium that will be most easily penetrated by moisture that can cause corrosion of reinforcement bars that leads to durability problem, it is imperative to make it durable.Polymer additive and pozzolanic cement replacement used in this study was Styrene Butadiene Rubber (SBR) and Fly Ash (FA) respectively. Mixes were prepared with two water to cement ratios (w/c) of 0.3 and 0.4 with different combinations of 5%, 7% & 10% SBR additive and 10%, 20% and 30% FA cement replacement. Results showed that modified mortar with combination of higher percentages of polymer additive and lower percentages of pozzolonic cement replacement have the lowest initial surface absorption rate compare to unmodified mortar. It can be concluded based on this study that high percentage of polymer addition and low percentage of pozzolanic cement replacement in mortar can enhance its resistance to water absorption
