208 — SUBGRADE PREPARATION 2026 STANDARD SPECIFICATIONS FOR CONSTRUCTION AND MATERIALS CATEGORY 200 GRADING SECTION 208 — SUBGRADE PREPARATION
208.01 Description
Prepare, protect, and maintain the subgrade prior to the construction of succeeding courses.
208.02 Materials
Refer to Section 916.
208.03 Construction
After roadway excavation and embankments are completed in conformance with Section 204, fine grade and compact the subgrade to at least 97 percent of the maximum dry density according to T 180.
208.03.01 Removal and Replacement of Unsuitable Material. Remove and dispose of all soft
and unstable material and any other portions of the subgrade that will not properly compact. Replace with suitable material and compact.
208.03.02 Subgrade Control. Bring the subgrade surface to line and grade and shape it to the
specified cross section. Set grade for subgrade control both longitudinally and transversely with fixed controls not exceeding 25 ft spacing. Limit the finish subgrade deviation to 1/2 in. from the established grade. Compact and smooth the subgrade over its full width by the use of an approved smooth faced, steel-wheeled roller approved by the Engineer. Use mechanical tampers and vibratory compactors if rolling is not feasible.
208.03.03 Bleeder Ditches. Maintain adequate open bleeder ditches along the subgrade at all
times to keep it thoroughly drained. Maintain erosion and sediment control practices as specified in Section 308.
208.03.04 Subgrade Maintenance. Prevent damage by heavy loads or equipment. Repair or
replace any defects or damage.
208.03.05 Subgrade Approval. Do not place subsequent cover material upon a frozen subgrade
or any subgrade until it has been checked and approved. 208 — SUBGRADE PREPARATION 2026 STANDARD SPECIFICATIONS FOR CONSTRUCTION AND MATERIALS
208.04 Measurement and Payment
Subgrade preparation, including bleeder ditches and any mechanical tamping will not be measured but the cost will be incidental to the pertinent items specified in the Contract Documents.
Subgrade Preparation in other states
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