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Expansive clays have an expanding crystal lattice in a 2:1 ratio; however, there are 2:1 non-expansive clays. [2] Mitigation of the effects of expansive clay on structures built in areas with expansive clays is a major challenge in geotechnical engineering. Some areas mitigate foundation cracking by watering around the foundation with a soaker ...
A waffle slab foundation, also called a ribbed slab foundation, is an above-ground type of foundation used to provide load-bearing capacity in expansive, rocky or hydro collapsible soils. The foundation is created by placing a series of single-use plastic forms set directly on grade to create a grid of ribs, and then monolithically pouring a ...
For instance, soils with a small amount of expansive clay minerals will not expand as much when exposed to moisture as a soil with a large amount of the same clay minerals. [5] If a soil is composed of at least 5 percent of these clay minerals by weight, it could have the ability to shrink and swell. [3]
When considering settlement, total settlement and differential settlement is normally considered. Differential settlement is when one part of a foundation settles more than another part. This can cause problems to the structure which the foundation is supporting. Expansive clay soils can also cause problems.
Slab-on-grade foundations should not be used in areas with expansive clay soil. While elevated structural slabs actually perform better on expansive clays, it is generally accepted by the engineering community that slab-on-grade foundations offer the greatest cost-to-performance ratio for tract homes. Elevated structural slabs are generally ...
Fine grained soils 50% or more passing the No.200 (0.075 mm) sieve silt and clay liquid limit < 50 inorganic: ML silt CL lean clay organic: OL organic silt, organic clay: silt and clay liquid limit ≥ 50 inorganic MH elastic silt CH fat clay organic OH organic clay, organic silt Highly organic soils PT peat
Prior to constructing concrete linings, it is common practice to ensure the sub-grade layer of soil is adequately consolidated. [4] If expansive clay is located on the site of a canal, a layer of this clay is removed and replaced with sand or gravel before the concrete lining is constructed.
The PI is the difference between the liquid and plastic limits (PI = LL-PL). Soils with a high PI tend to be clay, those with a lower PI tend to be silt, and those with a PI of 0 (non-plastic) tend to have little or no silt or clay. Soil descriptions based on PI: [8] (0) – Non-plastic (<7) – Slightly plastic (7-17) – Medium plastic