Soil: Mixture of rock particles, minerals, decayed organic materials (humus), water and air. Soils are different due to variation in composition.
Clay: Fine grained, firm cohesive is introduced by decomposition + hydration of rocks. Clay is plastic (wet) & hard (dry), impervious (relative), swells when absorbing water, shrinks when dry, very unstable & predictable for support of buildings maybe used for foundation & needs engineers.
Clay is smaller than sand or silt. Clay is cohesive.
Silt: Fine grained, sedimentary, <.002" or less Silt plus water makes mud, soft, sticky, plastic Sand: Loose granular, .002" to 1/4", not plastic, & not cohesive "course- grained solid"= sand +gravel= base foundation relative + excellent drainage = relatively permeable quick Sand= sand + moving water, unstable, "sink hole" Gravel: Larger soil particles with most void has higher permeability than clay, sand, silt. 1/4" to 3 1/2"; greater than 3 1/2"= cobblestone, greater than cobblestone= boulder Hard pan: Mixture of Gravel, clay, sand foundation phase Decomposed rock: Disintegrator rock mass that were solid Boulders: Rock detached from bedrock Shale/ slate bedrock: Fine textured soft rock (sheets); Solid material/ earth's crust. Humus: Well decomposed, more or less stable, organic matter in soil, dead plants, animals Mulch: Conserve moisture and temperature, prevent surface compaction, reduce runoff, and erosion. Improve soil structure and control weed Muck: combination of soil, water, higher mineral content than peat. The level of decomposed is high and original plant part cannot be identified. Peat: peat (turf) is an accumulation of partially decayed vegetation matter or histosol. Peat forms in wetland bogs, moors, muskegs, pocosins, mires, and peat swamp forests. Compost: Used as organic fertilizer; mixed nitrogen and soil. Compost is to permit organic material to become crumbly and to reduce carbon- nitrogen ratio of the material Mortar: Cement + water+ sand+Lime; less stiff than concrete and handle with trowel Concrete/grout: Cement + water+ sand+ Gravel; Grout: Quite fluid poured in bricks Compare large amount of loose silt site and organic soil for cost: Organic soil (peat) is elastic, weak, little cohesion and organic will cost more. It must be removed and replace. Loose silt can be compacted. Land has loose fill, sloped, and large area: Site usefulness: Identify the potentials, level the site and make recreational. Do not deny based on soils. Bulb tee foundation: Underpinning as a temporary support. Usually in gypsum concrete construction. In bridges, they are permanent. Building built to next existing building with shallower foundation: Both footings must be at same length. Temporary support: major shoring to take place. Expansive soil: Locate the footings in soils below the zone of seasonal moisture change Extend concrete piers below the zone of seasonal moisture change Design foundation for soil bearing pressure greater than the swell pressure of the expansive soil Expansive soil is silty, clayey expands wet High upward pressure Oversize the footings will not help- More area for the upward pressure. Exceeding the load bearing capacity of soil: Settlement can occur and uneven movement and cracks occur Structure fails Mat or raft foundation is good for poor soil Not enough for poor soil with insufficient soil capacity- Even for mat Overhanging to a pile is also not sufficient Piles must transfer to deep bedrock is the only response
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