9.1. SR 01-07-2013 - Laserfiche WebLink

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DEFINITIONS RELATING TO PAVEMENT CONSTRUCTION TOP OF SUBGRADE Grade which contacts the bottom of the aggregate base layer. SAND SUBBASE Uniform thickness sand layer placed as the top of subgrade which is intended to improve the frost and drainage characteristics of the pavement system by better draining excess water in the base/subbase, by reducing and "bridging"frost heaving and by reducing spring thaw weakening effects. CRITICAL SUBGRADE ZONE The subgrade portion beneath and within three vertical feet of the top of subgrade. A sand subbase, if placed, would be considered the upper portion of the critical subgrade zone. -GRANULAR BORROW Soils meeting Mn/DOT Specification 3149.2131. This refers to granular soils which, of the portion passing the I" sieve,contain less than 20%by weight passing the#200 sieve. SELECT_GRANULAR BORROW Soils meeting Mn/DOT Specification 3149.2132. This refers to granular soils which, of the portion passing the 1" sieve, contain less than 12%by weight passing the#200 sieve. MODIFIED SELECT GRANULAR BORROW Clean, medium grained sands which, of the portion passing the I" sieve, contain less than 5% by weight passing the#200 sieve and less than 40%by weight passing the#40 sieve. GEOTEXTILE STABILIZATION FABRIC Geotextile meeting Type V requirements defined in Mn/DOT Specification 3733. When using fabric, installation should also meet the requirements outlined in Mn/DOT Specification 3733. COMPACTION SUBCUT Construction of a uniform thickness subcut below a designated grade to provide uniformity and compaction within the subcut zone. Replacement fill can be the materials subcut, although the reused soils should be blended to a uniform soil condition and recompacted per the Specified Density Method (Mn/DOT Specification 2105.3171). TEST ROLL A means of evaluating the near-surface stability of subgrade soils (usually non-granular). Suitability is determined by the depth of rutting or deflection caused by passage of heavy rubber-tired construction equipment, such as a loaded dump truck, over the test area. Yielding of less than I" is normally considered acceptable, although engineering judgment may be applied depending on equipment used, soil conditions present,and/or pavement performance expectations. UNSTABLE SOILS Subgrade soils which do not pass a test roll. Unstable soils typically have water content exceeding the "standard optimum water content"defined in ASTM:D698 (Standard Proctor test). ORGANIC SOILS Soils which have sufficient organic content such that engineering properties/stability are affected. These soils are usually black to dark brown in color. 0 1 REPO 19(08/07) AMERICAN ENGINEERING TESTING,INC.