Some remarks on statistic approach to strength testing of soil-cement composites

Abstract

Results of laboratory testing of organic soil-cement samples are presented in the paper. The research program continues on the authors previously reported experiences with cement - organic soil sample testing. Over 150 compression tests have been carried out altogether. Several samples were cured for over 3 months before they were tested. Several factors, such as: the large amount of the pieces under test, long observation time, carrying out the tests in complex cycles of loading and the possibility of continuous registering the loads and deformation in the axial direction – made it possible to control numerous interdependencies, some of which have been presented in this work. Compressive strength and elastic modulus of cubic samples were examined. Samples were mixed and stored in laboratory conditions. The results clearly point to the fact that designing the DSM dry columns in the organic soil may be linked with a considerable risk and needs special precautions. During in situ mixing, the organic material surrounded by sand layers surely mixes with one another in certain areas. However, it has not been examined and it is difficult to assume such mixing already at the designing stage.

Uniaxial Testing of Soil–Cement Composites to Obtain Correlations to Be Used in Numerical Modeling

“…Such a phenomenon was observed in the former authors' experiments. The need to control composite's density was also expressed in a piece of work [36] concerning the stabilization of organic soils.…”

“…The advantage of DSM columns, however, is the guaranteed diameter (sometimes enlarged in relation to the dimensions of the mixing tool), which ensures column strength despite the potential lack of perfect mixing. That issue was already discussed in the work [36], where the variability of composite parameters was presented in light of statistical analysis.…”

“…In the tests conducted in the AG atories, a range of 0.30-0.70 Rc was used (where Rc is just the compressive stress of the sample), similar to the ranges used in earlier research projects by MENARD out in cooperation with the Wroclaw University of Technology. Exemplary pic samples in a testing machine (WrUST laboratory) are shown in Figure 6 [36].…”

“…The wet method uses the slurry, and in the case of dry mixing, the binder needs the groundwater to initiate the hardening (setting) process. The problems that are still under study, due to the diversity of combinations of tested soils, binders and mixing technologies, are issues related to the final product quality control [29][30][31][32] and further applications of measured or presumed parameters in numerical studies [33][34][35][36]. At the same time, the requirement of continuous technological progress in the aspect of mixing techniques and used binders makes unconventional technologies more and more popular.…”