Section_301_untreated_aggregate_courses_new.doc

Section 301

Section 301

Section 301. — UNTREATED AGGREGATE COURSES

Description

301.01 This work consists of constructing one or more courses of aggregate on a prepared surface including water for compaction.

Subbase and base aggregate grading is designated as shown in Table 703-3.

Material

301.02 Conform to the following Subsections:

Aggregate 703.05

Water 725.01

Construction Requirements

301.03 General. Prepare the surface on which the aggregate course is placed according to Section 204 or 303 as applicable.

Set target values within the gradation ranges shown in Table 703-3 for the required grading.

301.04 Mixing and Spreading. Determine the optimum moisture content according to AASHTO T 180, method D. Mix the aggregate and adjust the moisture content to obtain a uniform mixture with a moisture content within 2 percent of the optimum moisture content. Spread and shape the mixture on the prepared surface in a uniform layer.

Do not place the mixture in a layer exceeding 6 inches in compacted thickness. When more than one layer is necessary, compact each layer according to Subsection 301.05 before placing the next layer. Route hauling equipment uniformly over the full width of the surface to minimize rutting or uneven compaction.

301.05 Compacting. Determine the maximum density of the mixture according to AASHTO T 180, method D.

Moisten or dry the aggregate to a uniform moisture content suitable for compaction. Operate vibratory steel wheel rollers with a minimum weight of 5 tons. The roller shall be equipped with amplitude and frequency controls and specifically designed to compact the material on which it is used. Operate rollers that meet the requirements over the full width of each layer until visual displacement ceases, making no fewer than three complete passes.

301.06 Surface Tolerance. If grade finishing stakes are required, finish the surface to within ±0.05 feet from staked line and grade elevation.

If grade finishing stakes are not required, shape the surface to the required template and check the surface with a 10-foot straightedge. Defective areas are surface deviations in excess of 1/2 inch in 10 feet between any two contacts of the straightedge with the surface.

Correct all defective areas by loosening the material, adding or removing material, reshaping, and compacting.

301.07 Maintenance. Maintain the aggregate course to the correct line, grade, and cross‑section by blading, watering, rolling, or any combination thereof until placement of the next course. Correct all defects according to Subsection 301.06.

301.08 Acceptance. See Table 301-1 for sampling and testing requirements and the acceptance quality characteristic category.

Aggregate gradation and surface course plasticity index will be evaluated under Subsection 106.05. Other aggregate quality properties will be evaluated under Subsections 106.02 and 106.04.

(a) Aggregate gradation. The upper and lower specification limits are equal to the calculated mean of all test results plus or minus the allowable deviations shown in Tables 703-2 and 703-3, except as follows:

(1) If the calculated mean value for any tested sieve exceeds the maximum gradation value shown in Table 703-2 or 703-3, the upper specification is equal to the maximum gradation value plus the allowable deviation, and the lower specification is equal to the maximum gradation value minus the allowable deviation.

(2) If the calculated mean value for any tested sieve is less than the minimum gradation value shown in Table 703-2 or 703-3, the upper specification is equal to the minimum gradation value plus the allowable deviation and the lower specification is equal to the minimum gradation value minus the allowable deviation.

(b) Plasticity index. The upper and lower specification limits for surface courses are shown in Table 703-3.

Construction of untreated aggregate courses will be evaluated under Subsections 106.02 and 106.04.

Preparation of the surface on which the aggregate course is placed will be evaluated under Section 204 or 303 as applicable.

Measurement

301.09 Measure the Section 301 items listed in the bid schedule according to Subsection 109.02 and the following as applicable.

Measure aggregate by the cubic yard as per Design Quantity.

Measure square yard width horizontally to include the top of aggregate width including designed widenings. Measure the square yard length horizontally along the centerline of the roadway.

Payment

301.10 The accepted quantities will be paid at the contract price per unit of measurement adjusted according to Subsection 106.05 for the Section 301(01) pay items listed in the bid schedule.

Table 301-1

Sampling and Testing Requirements

in work

Split

Sample

material

Sampling

Frequency 1 per type & source of material

& T 11

for conformance

(106.04& 105) Statistical

(106.05)

703.05(a) Subbase courses grading A & B

Table 301-1 (continued)

Sampling and Testing Requirements

Split

or roadbed after processing From windrow or roadbed after processing

Sampling

of material 1 per 500 tons

& T 11

method D (1) AASHTO T 310 or other approved procedures

Category

density

(max. density) Compaction

(106.05) Measured and tested for conformance (106.04)

grading C, D, & E Subbase & base course grading A, B, C, D & E

Reporting

Time

in work Before placing next layer Before using in work

(1) Minimum of 5 points per proctor.

Split

or roadbed after processing

material

on roadbed after processing

Sampling

of material

& T 11

method D (1) AASHTO T 310 or other approved procedures

ASTM D5821

Category

density

(max. density)

(106.05) Measured and tested for conformance (106.04)