Category:310 Aggregate Surface

From Engineering_Policy_Guide
Jump to navigation Jump to search

310.1 Construction Inspection for Sec 310

310.1.1 Description

This work consists of placing and processing aggregate for a wearing course on an approved roadbed or on a newly built earth grade or on detours temporarily in use during construction. The aggregate surfacing shall be spread to meet the requirements shown in the plans or as directed by the engineer.

310.1.2 Material

All material shall be in accordance with Division 1000, Material Details, and specifically Sec 1006. The type and gradation of the surfacing material to be used will be specified in the contract.

310.1.3 Construction Requirements

310.1.3.1 General

When aggregate for detours is required, it is advisable to go over the detour road with the Area Engineer to see what road defects need correction before the aggregate is placed. The contractor shall furnish, haul and spread surfacing material on the subgrade at the designated rate. Placement may be controlled on a weight or a volume basis. The method to use will be specified in the contract. The rate of application may be varied at the discretion of the engineer, depending on the nature of the soil encountered in the subgrade. The contractor shall uniformly unload and distribute of the required quantity of material throughout each station. The subgrade shall be prepared as specified in Sec 209, and any work done in reshaping the subgrade before placing surfacing material is the contractor’s responsibility. When it is determined by the engineer to be to the Commission's advantage, hauling may be done over surfacing material previously spread, otherwise, all hauling shall be over the subgrade.

Windrows should be placed on the high side of curves. On tangent sections windrows should be placed on the same side of the roadway throughout the project. Openings are provided through the windrow at all approaches and at all low points. Additional breaks for drainage on steep grades or on long flat sections are recommended.

310.1.3.2 Surface Requirements

Material shall be spread to a uniform thickness over the subgrade and shaped as shown on the plans until the surface is free from ruts and waves. The surface shall be compacted under traffic.

Maintenance of the surface is the responsibility of the contractor until final project acceptance is made.

310.1.3.3 Stockpiles

Surfacing may be stockpiled in areas designated by the engineer.

310.1.3.4 Salvage

Salvaging is to be approved by the engineer. Designated areas are scarified to the full depth of the existing surfacing and pulverized to a maximum size of approximately 2 in. (50 mm). Uncontaminated material shall be placed in stockpiles or spread at locations approved by the engineer.

310.1.4 Vehicle Scales

Vehicle scales shall be approved by the engineer and shall be in accordance with the specifications.

310.1.4.1 Basis of Acceptance

Scale acceptance will be based on one of the allowed specification provisions.

310.1.4.2 Scale Calibration

Scales shall have been calibrated within the 12-month period immediately prior to any material being delivered or any time the engineer has cause to question the accuracy of the scale. Scales shall be accurate and sensitive to within the specified limits.

310.1.4.3 Verification

Verification of a vehicle scale may be required by comparing the weight (determining the mass of) of a hauling unit with another recently calibrated and certified scale. Reference must be made to the specifications for verifying long vehicle weights. All costs incurred in obtaining certification of calibration or verification of scales is the contractor’s responsibility.

310.1.5 Method of Measurement

310.1.5.1 Measurement by Volume

Volumes can be documented by 3 methods:

1. Stockpiles of salvaged surfacing material may be measured by the average end area method.

2. Computation of the volume in place is acceptable. A documentation record is issued to record the volume placed, i.e., (depth (ft) X width (ft) X length (ft) ) / 27 cf/cy.

3. If material is truck-delivered on a volume basis, Form C-266 may also be used. This form is issued at point of delivery. Form C-266 is so printed that the numbers and letters on each copy match. The punch marks both tickets identically to provide a true copy of date and volume information which is punched out. The truck number and type of material should be noted on the face of the ticket. The original of the ticket is torn off along the perforations and given to the driver or to such other person as the contractor may designate.

  • A diary record should be made of the measurement of each truck. The inspector who made the measurements should date and sign the record.
  • When surfacing is paid by truck-delivered volume, the inspector must ensure the material being measured is sufficient to complete the area being surfaced., i.e. the distance each load can complete is calculated by dividing the volume (ft3) of the load measured by the depth (ft) of the specified thickness and planned width (ft). Calculating the yield of each load will verify the contractor is being paid for the volume delivered and the state actually obtains the quantity being paid.

310.1.5.2 Measurement of Aggregate Surfacing by Area

Scale inspectors and weight tickets are not necessary. Thickness of the aggregate base is the control for aggregate surfacing paid by area. Final measurement of the completed aggregate surface will not be made except for authorized changes during construction, or where appreciable errors are found in the contract quantity. Where required, measurement of aggregate surface, complete in place, is made to the nearest square yard (m2). The revision or correction is computed and added to or deducted from the contract quantity.

310.1.5.3 Measurement by Weight (Mass)

Delivered quantities of surfacing by weight shall be documented using the quarry’s ticket or receipt. Assurances must be made that the quarry scale’s calibration is current and weight deductions are made for delivered material with excessive moisture.

Moisture content is to be computed to the nearest 0.5% but the moisture content may be assumed as 4% for quanties less than 250 tons per day. When the specification allows a designated moisture content, the 4% value may be reduced by the designated allowance. Material tickets or receipts are not to be issued for gross weights exceeding legal load limits that will be hauled over bridges, asphaltic concrete, or portland cement concrete pavement. Refer to Sec 105.12 Load Restrictions and instructions for enforcement of legal loads.

310.1.6 Basis of Payment

The accepted quantities of aggregate surface will be paid for at the contract unit price. If Type 1 Aggregate for Base is used for this work, payment will be based on plan quantity and contract unit price for Gravel (A), Crushed Stone (B) or Chat (C) in accordance with the contract.