Concrete as the main material in almost all building structures that has the potential to be damaged. The damages that can occur in the form of cracks and it can be repaired by providing strengthening on concrete. The repair method commonly used in concrete is the grouting method. In this study, the effect of a mixture of resins and fly ash as a grouting material on the compressive strength of concrete that has been improved with the age of 7 days, 14 days and 28 days was analyzed. Three variation mixs of resin and fly ash were used in this study. The use of fly ash is 50 grams, 70 grams and 85 grams respectively, while the use of resins in each variation mixture is 200 ml. Changes in the value of the average compressive strength before and after repairs on each mix variation on the use of 50 gram fly ash from 33,45 Mpa to 26,02 MPa, this means that the compressive strength of the concrete after repair is 77,79% compared to the initial strength. Then the use of 70 grams of fly ash is from 31,42 MPa to 28,34 MPa, this means that the compressive strength of the concrete after repair is 90,18% compared to the initial strength. Furthermore, the use of 85 grams of fly ash is from 35,76 MPa to 31,35 MPa, this means that the compressive strength of the concrete after repair is 87,66% compared to the initial strength. With the results, the most optimal mixture variations for concrete repairs are variations of the mixture with the fly ash content of 70 grams.