The variability in the degradation rate of a fabric treated with each of two rotinhibiting treatments was measured after burial in a biologically active soil for varying periods of time under controlled conditions. The purpose of the experiment was to determine what limits of reliability might be expected in average strength measurements as a consequence of random variations inherent in the soil burial procedure employed under practicable measures of control. The experiment utilized a random block design, which permitted estimation of the effect of soil variations among the several blocks. The design also made possible an analysis of the results as 5 replicate measurements of 10 observations, or, when combined, as a single measurement of 50 observations.The results showed that the variability in fabric strength measurements increased as deterioration progressed, reaching a maximum when 40-60% of the original strength was lost. The increase was greater in the treated than in untreated fabric, and for one treatment than for the other. The degradation rate of untreated fabric in the several soil blocks showed highly significant differences. But a similar block effect on the treated fabric could not be detected in 8 of the 10 exposure periods. The increased variability and reduced rate of deterioration resulting from the treatment evidently tended to mask the smaller effect of soil variation. At the stage corresponding to the greatest variability, the 95% confidence range for measurements based on 10 observations was for one treated fabric 43.8% of the original strength, and for the other, 22.4%. This degree of precision does not justify the high confidence often placed in soil burial test data based on 10 or fewer observations per sample. The variability measurements indicate several measures that can be taken to increase the precision of the test procedure by reducing the random variations.The shortcomings inherent in the general practice of reporting the results of soil burial tests as the average percentage of the original strength lost or retained are discussed. A novel method of presenting test data in the form of a histogram of the cumulative frequency distribution is proposed as a means of overcoming most of the disadvantages of the conventional methods of reporting data.

In recent years, 3D printing, also known as additive manufacturing (AM), has been gaining popularity in the field of construction. The application of 3D printing in construction has allowed for automation to reach an industry currently facing shortages in labor and natural resources, increasing costs, and increasing demand for sustainability and affordable housing in all markets. However, one of the primary challenges in upscaling current 3D printing technology in construction is the ambiguity in its testing procedures due both to the novel methods of applications and unique material properties. To date, only a few official testing standards for 3D construction printing are available (i.e., ICC-ES AC509, UL 3401). These standards, however, are still at their early stages and have yet widely adopted. This study focuses on the assessment of the material properties at both fresh (plastic) and hardened stages of a commercially available 3D-printed mortar. This manuscript also presents the development of new test methods to assess the interlayer adhesion strength of 3D-printed mortar and the buildability of the material. The interlayer adhesion strength in 3D-printed mortar was assessed by testing printed specimens for tensile strength perpendicular to the printing direction. The buildability of the mortar was defined by its ability to maintain its shape and integrity during the printing process without completely collapsing or showing signs of significant deformation. For this purpose, a buildability test was developed by printing and recording the maximum achievable printing height of a specific structure under specific printing parameters, such as the shape and dimension of the structure and filament, printing speed, extrusion rate, water level, and printing environment. These printing parameters were specifically defined and controlled to maintain the consistency and repeatability of the test. The buildability test results indicate that a faster vertical building rate leads to a lower maximum height for the given material and vice versa.

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