Item 106 - COMPACTION EQUIPMENT AND DENSITY CONTROL STRIPS

106.1 Description

When specified, this procedure will be used to determine density requirements of selected embankments, subgrade, bases, and bituminous concrete. The procedure will consist of control strip construction to establish target densities for the specified course plus use of sand-cone method of density testing equipment to determine in-place desities obtained during the construction process.

106.2 Construction Equipments

Compaction equipment shall be capable of obtaining compaction requirements without detrimentally affecting the compacted material. The equipment shall be modern, efficient compacting units approved by the Engineer. The compacting units may be of any type, provided they are capable of compacting each lift of material as specified and meet the minimum requirements as contained herein. Minimum requirements for rollers are as follows:

1. Sheepsfoot, tamping or grid rollers shall be capable of exerting a force of 45 Newton per millimeter of length of roller drum.
2. Steel-wheel rollers other than vibratory shall be capable of exerting a force of not less than 45 Newton per millimeter of width of the compression roll or rolls.
3. Vibratory steel-wheel rollers shall have a minimum mass of 6 tonnes. The compactor shall be equipped with amplitude and frequency controls and specifically designed to compact the material on which it is used.
4. Pneumatic-tire rollers shall have smooth tread tires of equal size that will provide a uniform compacting pressure for the full width of the roller and capable of exerting a ground pressure of at least 550 kpa.
5. Heavier compacting unit may be required to achieve the specified density of the embankment.

106.2.2 Construction of Control Strips and Determination of Target Density

To determine target density, a control strip shall be constructed at the beginning of work for each course of material to be compacted. Each control strip, constructed to acceptable density and surface tolerances shall remain in place and become a section of the completed roadway. Unacceptable control strip shall be corrected or removed and replaced at the Contractor's expense. A control strip shall have an area of approximately 335 square meters and shall be of the same depth specified for the construction of the course which it represents.

The materials used for construction of the control strip shall conform to the specification requirements.. They shall be furnished from the same source and shall be of the same type to be used in the remainder of the course represented by the control strip. The underlying grade or pavement structure upon which a control strip is to be constructed shall have the prior approval of the Engineer.

The equipment used in the construction of the control strip shall be approved by the Engineer and shall be of the same type and mass to be used on the remainder of the course represented by the control strip.

Compaction of control strips shall commence immediately after  the course has been placed to the specified thickness, and shall be continuous and uniform over the entire surface. Compaction of the control strip shall be continued until no discernible increase in density can be obtained by additional compactive effort.

 Upon completion of the compaction, the mean density of the control strip will be determined by averaging the results of ten in-place density tests taken at randomly selected sites within the control strip. The mean density of the control strip shall be target density for the remainder of the course which it represents.

If the mean density of the control strip is less than 98 percent of the density of laboratory compacted specimens as determined by testing procedures appropriate for the material being placed, the Engineer may order the construction of another control strip.

A new control strip may also be ordered by the Engineer or requested by the Contractor when:

1. A change in material or job-mix formula is made.
2. Ten days of production have been accepted without construction of new control strip.
3. There is reason to believe that a control strip density is not representative of the material being placed.

 106.3 Method of Measurement

No measurement for payment will be made for this Item.

106.4 Basis of Payment

Unless otherwise provided, the cost of constructing the control strip will be considered incidental to the cost of the work item for which a control strip is required. Payment for the work item shall be deemed to include compensation for performing the work herein specified and the furnishing of all materials, labors, tools, equipment and incidentals necessary to construct the density control strip. No payment will be made for any material used in the construction of unacceptable control strip.