I recently came across an unusual case while reviewing the log of break strengths. For a 5000 psi concrete, that strength was reached in less than 3 days with very little strength gain afterwards. Literature says concrete should be at about 0.7 of its long-term strength at 7 days. I realize the time to reach this can be made much shorter for high-early strength concrete. However, there should some strength gain afterwards. Does anyone have experience that can explain this situation?