Fig. 5
Empirical distributions of inputs and outputs used in modeling. For each variable, the red line marks the median, the yellow bar indicates the mean, and the envelope shows a kernel-density estimate of the sample distribution. Notably, 28-day compressive strengths range from 85 to 136 MPa (mean 110 MPa), underscoring substantial batch-to-batch variation even under a fixed recipe. Abbreviations for variables are defined in Table 1.
