3.2         Test Specimens

he tests reported in this study were performed on block molded expanded polystyrene (EPS) Types IX, I, VIII and IX for which minimum densities are specified in ASTM-C-578 as 12, 15, 18 and 29kg/m³, respectively. Four sizes of specimens were used, conventional 0.05m cubes, cylindrical samples of 0.08m diameter of different heights, prisms with square cross section and 0.1m dimension and of different heights and 0.6m cubes. Different EPS manufacturers supplied the test materials in 0.6m cubes and 0.08m diameter cylinders. Desired cylindrical lengths, 0.05m cube samples and the prisms were further trimmed using a hot wire cutter in the lab. All samples were kept at an ambient laboratory temperature of 20 to 22ºC for one week before trimming or testing. The weight and dimensions of each specimen were recorded. Although the bead type and the regrind percentage and the molding process are not considered in this study, all of the tested material are samples of the common EPS types that is likely to be used in construction projects.

As was mentioned in chapter two, there is a variation in density within the same block. Figure 3.1 shows the densities for twenty-five specimens of 0.05m cubes that were used in this study. From this figure it can be noticed that the variation between densities is least for type XI, the 12kg/m³ minimum density geofoam. The higher the density is the higher the variation between the specimens. Figures 3-2 and 3-3 give the average, the minimum and the maximum densities within the 0.05m cubes and the 0.6m cubes respectively. The larger size has less variation as can be seen from the standard deviation in figure 3-4 and the coefficient of variation in figure 3-5.

Figure 3‑1 Densities of the 0.05m Cube Specimens

Figure 3‑2 Density Variations of the 0.05m Cube Specimens

Figure 3‑3 Density Variations of the 0.6m Cube Specimens

Figure 3‑4 Density Standard Deviation for Different Specimen Sizes

Figure 3‑5 Density Coefficient of Variation for Different Specimen Sizes