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C_1 7 SECTION 21 - CEMENTED COQUINA SHELL BASE COURSE 1. DESCRIPTION ' A. Under this item, the Contractor shall furnish all equipment. labor, materials, and transportation necessary to construct a Coquina shell base course upon the completed stabilized subgrade. The base course shall be constructed in accordance with the lines, grades, and typical section as shown on the Drawings. Unless otherwise rioted construction shall conform to the provisions of Florida D.O.T. Standard Specifications for Road and Bridge Construction, Section 2.50, 1991 Edition. 2. MATERIALS A. - Coquina shell shall conform to the requirements of Florida D.O.T. Standard Specifications, 1991 Edition, Section 915, and shall be from a source acceptable to Florida D.O.T. The material shall have a minimum LBR value of 100. Prior to placement, the material shall be crushed or broken to such a size that no less than 97 percent by weight will pass a 3 U2 inch sieve and no more than 20 percent dry weight shall wash through a No. 200 sieve. No visible clay or organic matter will be perrnitted. 3. PLACEMENT OF MATERIAL A. After the subgrade is completed and approved, the Contractor shall furnish and spread the coquina shell in a uniform distribution. Spread thickness shall be a minimum of 9 inches. Segregated areas of fine or course rock will not be permitted. Such areas shall be removed and replaced with properly graded rock, B. After the spreading is completed, the entire surface shall be scarified and shaped so as to produce the required grade and cross section after compaction, 4. COMPACTION A. The required compaction of the coquina shell base course shall be a minimum of 98 percent of the maximum dry density. B. No less than 8-10 ton steel drum or pneumatic tired roller shall be used to compact the base course. All depressions shall be filled and the process of roiling and filling shall continue until a thoroughly compacted uniform surface is produced. During final compaction Operations, if blading of any area is necessary to obtain [lie true grade ; , and cross section, the compaction operations for such areas shall be completed prior to making the field density -compaction test on the finished base. C. Should the subgrade material become mixed with the base course material at any time, the Contractor shall remove the mixture reshape and recompact the subgrade, replace the materials removed with additional W