Statistical sample size for quality control programs of cement-based “solidification/stabilization”

Abstract

Sampling requirements for the quality control (QC) of cement-based “solidification/stabilization” (S/S) construction cells do not currently specify the sample size considering the accuracy of the estimated effective hydraulic conductivity of the cells from the samples, nor considering the risk associated with drawing the wrong conclusions about the acceptability of the cells. In this paper, probabilistic simulations are performed to examine the influence of a soil–cement material’s mean, variance, and correlation length on sampling requirements for a QC program of cement-based S/S construction cells. The sampling requirements are determined by considering a hypothesis test, having nulled that the constructed material is unacceptable, and targeting acceptable probabilities of making an erroneous decision. Two types of errors can be made: (i) concluding that the material is acceptable when it actually is not, or (ii) failing to conclude that the material is acceptable when it actually is. The paper investigates how many samples are required to keep the probabilities of making these errors acceptably small. Plots are provided, which can be used to estimate the required number of samples. The paper concludes by discussing how the simulation-based results compare with current sampling requirements for the QC of an actual set of cement-based S/S construction cells.