Experimental Studies On Durability Of Rammed Earth Building Material

Adobe building is the major form which prevails in the rural areas in China. This kind of structure includes rammed earth duilding, structure with compacted bricks, and structure shielded with soil. The rammed earth building is the most prevailing type in the long history with characters not only of convenient achievement of materials at economical cost, but also of sound monolithic structure, excellent thermal property, and bearing capacity. Yet, rammed earth building has deadly defects in terms of materials property, such as the soil materials is unable to resist against water, becoming softened to low strength when meeting water. This limits the application of rammed earth building. This paper attempts to strengthen the property of soil materials in terms of water-resistance, anti-freezing, by adding certain modified materials so as to durability of raw soil structure.At first, the paper makes analysis on soil particle, liquid limit and plastic limit, and chemical composition of soil toward soils in two typical areas (Shaanxi and Yunnan )in western China, studies the compositions, structures, classifications and basic substances of different soils. Secondly, it mainly applies studies of water-resistance, anti-freezing by adding certain mixtures into different soil, making experiments of water-soakage, water sprinkling, and frost-thaw resistance with different compactness. The experiments indicate that adding less quantity of mixtures can obviously alternate the soil quality, strengthen the water resistance and anti-freezing capability, reducing the cost of soil structures and saving natural resources. Meanwhile, The experiments reveled that adding single materials such as cement, iron ore, lime, fly-ash, or gypsium results in different modified effects for different soils. For example, cement and iron ore are more suitable toYunhuang and Yunhong soil, while various modified materials, especially cement and iron ore are suitable to Shaanxi-II soil. As to the self-designed modified materials of PI, P2 and P3 of compound additives, Shaanxi-II is suitable well to all, with P3 being the best. Yunhuang and Yunhong soil suit PI the best. For soils added with organized materials, water-resisting capability takes the increasing tendency along with the quantity increase of additives of the organized materials. Different compactness laid different certain impact upon water-resistance and anti-freezing capabilities, with high compactness being beneficial to the capability increasing of water-resistance and anti-freezing. Adding aggregate into modified soil can further increase water-resistance and anti-freezing capability of the soils. The paper also makes further study of modification principle of water-resistance and anti-freezing capability of the soils.