Details:

Creators:
Arman, Ara ; Thornton, Samuel I. ;
Arman, Ara ; Thornton, Samuel I. ; Less -
Corporate Creators:
Louisiana State University (Baton Rouge, La.) ;
Corporate Contributors:
Louisiana. Dept. of Transportation and Development ; United States. Federal Highway Administration ;
Louisiana. Dept. of Transportation and Development ; United States. Federal Highway Administration ; Less -
Subject/TRT Terms:
[+]
Collapsible Soils
Loess
Organic Silts
Pimple Mounds
Silts
Soil Stability
Soil Stabilization
Soil Tests
Test Procedures
Collapsible Soils
Loess
Soil Tests

Publication/ Report Number:
Bulletin No. 111 ;
Resource Type:
Tech Report ;
Geographical Coverage:
Louisiana ;
Corporate Publisher:
Louisiana State University, Baton Rouge ;
Abstract:
In southwest Louisiana, some surface silts (up to 3 feet deep) collapse under load after moisture is added. These soils were indistinguishable from nearby normal silts through routine tests. The deposits occur as low, gently-sloping ridges. Very similar collapsible soils were found in the well-known pimple mounds of the area. In the stable silts, vermiculite is the dominant clay mineral; in the collapsible silts, montmorillonite, Kaoline and illite are also present. Moisture is held in the pores of collapsible silts by electro-chemical forces. When collapsible silts were remolded with water or ethylene glycol (both polar liquids), no water passed through under 2 meters of head. In settled mixtures of collapsible silts and a solution of Calgon, (commercial brand of Sodium Hexameta phosphate) the supernatant liquid was black. The color change is attributed to lignins. Four criteria were established for identifying collapsible silts: an in-place unit weight less than 80 lbs/cu ft; a maximum dry unit weight less than 104 lbs/cu ft; a black liquid after the soil solids have settled out in a 3% solution of Calgon; and a total strain of at least 15% in the collapse test (a modified consolidation test of an oven-dried, undisturbed sample that is then saturated under pressure to 16 tons/sq ft).
Format:
PDF ;
Funding:
State Project No. 736-01-25 ; Research Project No. 68-8S ;
State Project No. 736-01-25 ; Research Project No. 68-8S ; Less -
Collection(s):
US Transportation Collection
Main Document Checksum:
[+]
urn:sha256:f808636f256e6576b7196e9f596ba19c0de0e2dbf0c7402e25be19449964a44f
File Type:

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