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Screen, crushers and stackers are used to separate various gradations of the materials.
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Gulf States Materials, Inc. Specifications for Item CALSTONE FLEXIBLE BASE MATERIAL
1. DESCRIPTION
1.1 This construction shall consist of a base course composed of crushed calcium sulfate and limestone in accordance with these specifications and shall conform to the dimensions, lines and grades as shown on the plans, or as directed by the Engineer.
2. MATERIALS
2.1 Aggregate
The aggregate shall be crushed calcium sulfate and limestone. The binder shall be material obtained from the crushing operation and from the fines intermixed with the material.
The crushed material shall consist of hard, durable particles or fragments of calcium sulfate and limestone free from objectionable matter and high plasticity soils, and shall not contain an excessive amount of flat or elongated pieces. The method used in production of the crushed material shall be such that the finished product will be uniform.
All material passing the No. 4 mesh sieve produced in the crushing operation shall be incorporated in the base material, unless there is an excessive amount which, if included, would cause the material to not meet the gradation requirements. If additional fines material, in excess of that naturally present in the base coarse material, is necessary for correcting the gradation to the limitations of the specified gradation, or for the satisfactory bonding of the base material, or for changing the soil constants of the material passing the No. 40 base course material at the crushing plant or by an approved plant. There shall be no reworking of the base course material in-place to obtain the specified gradation.
2.2 Physical Requirements
The process material, when properly sampled and tested by standard laboratory procedures, shall meet the following requirements:
2.2.1 The crushed calcium sulfate material shall meet the following limitations:
|
Screened |
Sieve Size |
Percent Retained |
1 3/4" |
-0- |
7/8" |
5-35 |
3/8" |
25-50 |
No. 4 |
35-65 |
No. 40 |
55-85 |
2.2.2. The amount of the fraction of material passing the No. 200 mesh sieve shall not exceed two thirds the fraction passing the No. 40 mesh sieve.
2.2.3 The binder, or the portion of the base material passing the No. 40 mesh sieve, shall have a
liquid limit of not more than 35 and a plasticity index of not more than 10.
2.2.4 The crushed aggregate shall have a percent wear of not more than 75 ( Los Angeles Abrasion Test).
2.2.5. The processed material, when compacted to 95 percent of the modified proctor density (ASTM D 1557), shall have a CBR value of not less than 100 after a period of 30 days when tested in general accordance with ASTM D 1883.
2.2.6. The specific gravity of the processed material shall be a minimum of 1.90 as determined by ASTMC 127.
2.2.7 The moisture content of the material (F.O.B. at the Plant) shall be a 2 percent of optimum moisture content as determined by ASTM D 1557.
3. CONSTRUCTION METHODS
3.1 Preparation of Underlying Course
The underlying course shall be checked for proper compaction and grade, and shall be accepted by the Engineer prior to placement of the base course. Any soft spots, ruts or inadequately compacted areas shall be corrected and compacted to the required 95 percent of standard proctor density (ASTM D 698) before the fill course is placed. Attention should be given to proper drainage of the underlying course and to the modification of excessively plastic or organic soils with stabilizing agents.
3.2 Base Course Placement
The crushed calcium sulfate material shall be hauled to the job site in dump trucks, then deposited and spread in a uniform layer without segregation to loose depth not greater than 10 inches, that will produce the required thickness when compacted.
The Engineer shall perform laboratory tests to determine the maximum density and the optimum moisture content of the base material (ASTM D 1557). This information will be made available to the contractor. The base material shall have the proper moisture content when rolling is started, and shall be corrected, if necessary, by sprinkling or aerating.
3-3 Base Compacting and Finishing
The roller used for compacting the material to the required density may be a sheepsfoot, pneumatic roller, or a combination or both, or as directed by the Engineer. We do not recommend using any type of steel wheel rollers. Rolling operations shall start as soon as possible after the material is spread over an area large enough for efficient operation. The roller shall start at the side and work towards the center, overlapping on successive trips by one-half the width of each rear wheel. Rolling shall be done longitudinally with the sub grade. If directed by the Engineer successive rolling shall be perpendicular or diagonal to the direction of the first rolling. Rolling shall continue until the material is thoroughly compacted, voids are reduced, and indentions from the roller are no longer visible.
4. MEASUREMENT
The calcium sulfate base course construction according to these specifications and to the section shown on the plans, and accepted by the Engineer will be measured by the ton.
5. PAYMENT
The amount of accepted base material measured as specified will be paid for at the unit contract price per ton of" Flexible Base Material, ITEM CALSTONE". This price shall be full compensation for all labor, materials, equipment, and incidentals necessary to complete the work.
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