Screen, crushers and stackers are used to separate various gradations of the materials.
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Gulf States Materials, Inc.
Specifications for Item GS-50
CALCIUM SULFATE (GYPSUM) BLEND MATERIAL,
1. DESCRIPTION
1.1 This material shall consist of a blend material composed of crushed calcium sulfate 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 Blend
The material shall be calcium sulfate. The binder shall be material obtained from the fines intermixed with the material.
The calcium sulfate shall consist of durable particles or fragments of calcium sulfate free from objectionable matter and shall not contain an excessive amount of flat or elongated pieces.
2.2 Physical Requirements
The processed material, when properly sampled and tested by standard laboratory procedures, shall meet the following requirements:
2.2.1 The crushed calcium sulfate blend material shall be within. the following gradation:
|
Screened |
Unscreened |
Sieve Size |
Percent Retained |
Sieve Size |
Percent Retained |
1 3/4" |
-0- |
1 3/4" |
0-10 |
No. 4 |
15-65 |
No. 4 |
15-65 |
No. 40 |
30-80 |
No. 40 |
30-90 |
2.12 The malarial fraction passing the No. 200 mesh sieve shall 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 processed material, when compacted to 95 percent of the modified proctor density
(ASTM D 1557), shall have a CBR value of not less than 35 after a period of 30 days when tested in general accordance with ASTM D 18(3.
2.2.5 The specific gravity of the processed material shall be a minimum of 1.90 as
determined by ASTM C 127.
3. CONSTRUCTION METHODS
3.1 Preparation of Underlying Course
The underlying course shall be Proof Rolled and checked for proper compaction and grade, and shall be accepted by the Engineer prior to placement of the bleed 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 blend 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 Blend Gouge Placement
The calcium sulfate material shall be delivered to the job site in dump trucks, then deposited and spread in a. uniform layer, without segregation to loose depth not greater than 12 inches. Attention must be given to proper drainage.
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 he made available to the contractor. The blend material shall have the proper moisture content when rolling is started, and shall be corrected, if necessary, by sprinkling or aerating.
3.3 Blend Compacting and Finishing
The roller used for compacting the blend material to the required density may be a sheepsfoot, pad foot, pneumatic roller, or a combination, or as directed by the Engineer. Gulf States Materials does not recommend using any typo of steel wheel rollers. Rolling operations shall start as soon as moisture is checked 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 tips 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 creeping ahead of the roller is no longer visible. Vibratory compaction should be completed within the first 4 hours of compaction.
The Engineer shall perform compaction control tests to determine the density of the inplace material. Rolling shall continue until the base material has been compacted to not less than 95 percent of the modified proctor density (ASTM D 1557). Blading and rolling shall be done alternately, as necessary, to obtain a smooth, even and uniformly compacted blend course that conforms to the required cross section, and established grade.
After the material has been firmly compacted, it shall be sprinkled with water and seal rolled Sprinkling and seal rolling shall be continued until the surface is sealed and hard, and is acceptable to the Engineer.
4. MEASUREMENT
The calcium sulfate material shall be measured by the ton, on Texas State approved, certified scales.
5. PAYMENT
The amount of accepted blend material measured as specified will be paid for at the unit contract price per ton of "Calcium Sulfate (Gypsum) Blend Material, ITEM GS-50". This price shall be full compensation for all labor, materials, equipment, and incidentals necessary to complete the work.
