Frost Resilience of Stabilized Earth Building Materials

Abstract

Earth-based building materials are increasingly valued in green design for their low embodied energy, humidity-buffering ability, and thermal stability. These materials perform well in warm dry climates, but greater understanding of long-term durability is needed for successful adoption in colder and/or wetter climates. The presence of stabilizers dramatically improves resistance to surface erosion from wind and rain, compared to unstabilized adobe and cob counterparts, and the influences of soil composition, fiber type, and diverse binders, on rain and wind surface erosion have been investigated in detail. Frost and freeze-thaw resistance, however, have been less well-studied, despite strong interest in stabilized earth materials in northern North America, Europe, and Asia. In particular, recent studies have relied on a widespread misunderstanding of the mechanism by which frost damage occurs in porous materials that will impede efforts to create valid models for material design and improvement. In addition, the influence of radiative thermal stresses on wall surfaces has been overlooked in favor of focus on ambient air temperatures. Here, we apply contemporary understanding of cracking by segregated ice growth to develop a macroscopic damage index that enables comparison between performance of different materials subject to different weather patterns. An examination of predicted damage patterns for two stabilized earth building materials and two conventional materials in twelve cities over two time periods reveals the dominant factors that govern frost vulnerability. We find that the frost resilience of earth building materials is comparable to that of the conventional materials we examined, and that assessments that neglect expected variations in water content by assuming full saturation are likely to yield misleading results. Over recent years, increased winter temperatures in several cities we examined predict reduced material vulnerability to frost damage, but we also find that accompanying increases in humidity levels have made some cities much more vulnerable.

Application of agro and non-agro waste materials for unfired earth blocks construction: A review

“…As the lime and rice husk ratio increased the water absorption rate decreased significantly from 9.60% to 0.80%. However, water absorption properties of all lime and rick husk blended specimens met the Indonesian Standard SNI 15-2094-2000 [18] for masonry brick.…”

“…However, some of the disadvantages of earth construction are the lack of strength, durability and vulnerability to erosion by rain [13][14][15]. Unfortunately, due to these drawbacks, the use of earth building materials in the modern construction sector has been ignored over many years [16] and is being extensively replaced by more durable and stronger construction materials such as fired brick and concrete [14,17,18]. However, unfired earth masonry provides many advantages compared to traditional fired brick and concrete masonry in terms of environmental impacts.…”

Extensive Frost Weathering Across Unglaciated North America During the Last Glacial Maximum

“…We simplify our treatment of ground temperatures by neglecting the effects of latent heat when approximating the temperature profiles. While damage is reduced under unsaturated conditions, whereas damage is enhanced by the high temperature gradients that accompany increased radiative transfer (Rempel & Rempel, 2019), we make no attempt to take such factors into account. Our focus on gauging regional variations in damage over annual cycles motivates our simplified approach in approximating surface temperatures with the output of the paleoclimate simulations described below, and assuming the conditions necessary for full saturation throughout.…”

The Effect of Soil Mineral Composition on the Compressive Strength of Cement Stabilized Rammed Earth

“…Cement CEM I 42.5 R (Table 3) was added to these mixtures, in the amount of 6% and 9% by mass of the remaining dry ingredients. These values were chosen based on the authors' own previous study, which found that 6% cement ensured an adequate compressive strength for the CSRE [3,5,30], while 9% cement was needed in regards to durability [33][34][35][36][37]. To the 14 soil-cement mixtures (Table 4) that were obtained in this way, water was added, ensuring that the optimum moisture content (OMC) of the mixture was achieved, i.e., the moisture at which compaction by ramming achieved the maximum value of dry density (the method of determining the OMC is given in Section 2.2.2).…”