106 General Materials Inspection, Sampling And Testing
Control of Material 106 provides that all materials are to be inspected, tested, and in compliance with the specifications prior to incorporation in the work. Minimum requirements for sampling materials are given in C&MS Section 700, Material Details. Samples of materials taken to meet these requirements are called job control samples. Job control samples also include samples taken as judged necessary to determine continued compliance of materials previously approved. These samples always represent a definite quantity of material.
Advance notice by the Contractor of the intended source of supply for specified materials is required to permit sampling and testing of the materials. Evidence of the approval of the materials by the Laboratory is required.
The purpose of material sampling and testing and construction inspection is to determine that only approved materials are used and that the materials are processed and placed in accordance with all contract provisions. Systematic record keeping is necessary to furnish documented evidence that this has been accomplished. The minimum requirements for the necessary records are stated under the individual items of work covered in this section of the manual.
The administration of the unit price contract also requires the determination of pay quantities. The contract states the method of measurement for each item of work and it is very important that each pay quantity determination be adequately documented.
The term flexible pavement, used throughout this manual, includes pavement or surfacing material construction composed of asphalt material and aggregate mixtures or various combinations of layers of these mixtures on layers of aggregate base or subbase. Although designs may vary in the combination of these materials, the flexible pavement functions in a definite manner under traffic loads. It is the intent of the design that deflection of the pavement in reaction to wheel loads will not stress the materials to the point of fracture within a reasonable life expectancy of the pavement.
Except for chip seals and other surface treatments, the strength of all flexible pavement layers, including subgrade, is dependent upon the density of the material and the gradation of the particle sizes. In addition, the strength of the subgrade and granular base material is dependent on moisture content, and the strength of asphalt mixtures is partially dependent on the quantity and viscosity of the asphalt material. While the strength of granular base materials is less affected by moisture content than soil subgrade material, adequate drainage of this material is necessary to prevent saturation of soil subgrade material and loss of subgrade strength.
All flexible pavement courses, except microsurfacing, etc, are placed loose by means of spreading and leveling equipment and then compacted with compaction equipment. The typical sections or other plan details specify the width and thickness of the individual courses. For granular subbase and base courses, the thickness shown in the plans is the actual compacted thickness to which the course is to be constructed. Normally, the thickness specified for all other courses is to be used to calculate a weight of material to be placed per unit of area.
Aggregate may be hauled to the paving site from approved stockpiles located at the source, on the project, or at some intermediate storage point. In any case, it is necessary to maintain sufficient surveillance to assure that loading is from approved stock and that identity of the stockpile is not altered by addition of material or other cause. It also is necessary to inspect the aggregate for uniformity as it is being loaded or placed. When such observations are made, they should be recorded for the project record.
Two fundamental requirements are included in 703.01 for aggregate stockpiles: separate identity and freedom from contamination. In addition to these considerations, knowledge of the method used in constructing the stockpile is necessary to have an understanding of the characteristics of the material as it is drawn from the pile for use.
The characteristic of an aggregate most affected by the method of stockpiling is its gradation. The larger size aggregate particles have a tendency to separate from the smaller size particles in parts of the stockpile; this is called segregation. A reduction in aggregate particle size also can occur due to breakage or wear; this is called degradation.
Segregation is more likely to occur in an aggregate having a relatively large particle size range from coarse to fine. The amount of segregation of aggregate particle sizes usually depends on the degree of freedom the aggregate has to flow from one place to another during stockpiling or handling. Usually, segregation is minimized when the stockpiles are formed by placing the aggregate in successive small mounds or layers. Small pockets of segregated aggregate are not objectionable in the stockpile, when re-mixing occurs in the loading and spreading operations, resulting in a uniform appearance. When these pockets are sufficiently large that non-uniform areas can be observed in the material placed on the grade, however, the results are unsatisfactory and corrective measures assuring uniform material in place are required.
Degradation of an aggregate may occur during stockpiling due to the action of hauling and spreading equipment operating on the stockpile. Aggregate particles may be broken into smaller sizes by heavy compressive forces exerted by such equipment: also, excess fine particles may be produced by interparticle abrasion caused by repeated application of these forces. Normally, however, degradation is severe only in the case of very brittle or very soft aggregate particles.
The Laboratory maintains a certification program throughout the year with all participating liquid asphalt material producers. Reference should be made to Supplement 1032, regarding forms used for identification of loads from approved stock. Loads arriving without proper identification are not to be used until specification compliance can be determined.
Since liquid asphalt materials may become contaminated and errors in shipment may occur, it is necessary to observe the delivered materials. Where there is a question concerning the quality of the material, the Contractor should be notified and a check sample should be taken.
The quality control of an asphalt concrete mix is performed by the Contractor in accordance with 401.02, 441, and/or 442.
When asphalt concrete is designed and controlled in accordance with 401.02, 441, and 442, the Contractor is required to provide a laboratory and quality control technician meeting the requirements of Supplement 1041. The duties of the Contractor’s quality control technician include all necessary sampling and testing of the materials for the items controlled in accordance with 401.02, 441, 442. The Department monitors the quality control testing when performed by the Contractor. This monitoring program, also known as a quality assurance program, is in accordance with Laboratory policy and may include observing the Contractor’s test procedures, testing sister samples of the Contractor’s samples, or testing randomly obtained sample.