Abstract: Concrete working in a port / wharf environment requires special attention and materials because seawater is an aggressive environment for concrete. One example of the technology used is the use of accelerators to maintain the quality of concrete. Efforts to obtain high-strength concrete are to improve the quality of the constituent materials, such as aggregate hardness and fineness of cement grains. The quality of concrete can also be done by adding additives to reduce water consumption and accelerate hardening. In this study, the addition of materials to the concrete mixture, accelerator and stone ash is used. In this test using the experimental method, there are 2 variants of the concrete test consisting of test objects with accelerator added materials. In the compressive strength test, 36 samples of cylindrical specimens of 150mm x 300mm were used to be tested.