Handout1 - University o f Missouri-Columbia Dept o f Civil...

Info iconThis preview shows pages 1–3. Sign up to view the full content.

View Full Document Right Arrow Icon
University of Missouri-Columbia Dept of Civil & Environmental Engineering Ori2in and Nature of Soils Soil Fonnation: The ultimate origin of soil is bedrock, which is broken down into successively finer and finer particles by physical (mechanical) and chemical disruption. This process is called weathering. Mechanical Weathering: (Disintegration) Breakdown ofmasses by mechanical means. 1. Abrasive Action ofwind, water, ice 2. Gravity -~ landslides, rockfalls, cave-ins 3. Action of organisms -~ plant roots, wonns, microorganisms 4. Tectonic action - volcanoes (heat/pressure) 5. Freezing/Thawing (ice expansion cycles) 6. Rapid temperature changes (deserts significant) 7. Action of man - mining, oring, blasting, excavations, etc. "Soils formed by mechanical weathering basically retain the properties of the original rock since they have the same mineral composition. " Chemical Weathering: Breakdown of masses by chemical processes (decomposition). 1. Dissolution - dissolving action of water 2. Hydration - combining with water e.g., Anhydrite CaS04 (G s = 2.9) e.g., Gypsum CaS04 • 2H20 (G s = 2.3) 3. Hydrolysis - fonnation of hydroxides (OH-) with H+ separated from water molecule 4. Oxidation - losing electrons 5. Reduction - gaining electrons 6. Carbonatization - formation ofweak carbonic acid to produce carbonates and clay minerals e.g., calcite (CaC03) reacts with bicarbonate to produce calicum cations (Ca+ 2 ) 7. Base exchange - cation exchange on colloid surfaces, dispersion and flocculation.
Background image of page 1

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
University ofMissouri-Columbia Dept of Civil & Environmental Engineering Origin and Nature of Soils (Con't) p2 "Soils formed by chemical weathering usually have chemical and physical properties fundamentally different from their parent
Background image of page 2
Image of page 3
This is the end of the preview. Sign up to access the rest of the document.

This note was uploaded on 09/23/2011 for the course CIVIL ENGI CE 3400 taught by Professor Rosenblad during the Spring '11 term at Missouri (Mizzou).

Page1 / 7

Handout1 - University o f Missouri-Columbia Dept o f Civil...

This preview shows document pages 1 - 3. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online