(A) The work consists of the construction of a base course composed of limerock. It shall be constructed on the prepared subgrade, in accordance with these specifications and in conformity with the lines, grades, and cross-section shown on the plans.
(B) The spreading of the rock shall be done by methods approved by the Engineer. All shaping shall be done utilizing a motor grader.
(C) The limerock shall be transported to the point where it is to be used, over rock previously placed, if practicable, and dumped on the end of the preceding spread. No hauling over the subgrade or dumping on the subgrade shall be permitted. If at any time the subgrade material should become mixed with the base course material, the contractor shall without additional compensation, dig out and remove the mixture, reshape and compact the subgrade and replace the materials removed with clean base material, which shall be shaped and compacted as specified above. All segregated areas of fine or coarse rock shall be removed and replaced with properly graded rock.
(D) When the specified compacted thickness of the base is greater than eight inches, the base shall be constructed in two courses. If, through field tests, the contractor can demonstrate that the compaction equipment can achieve density for the full depth of a thicker lift, and if approved by the engineer, the base may be constructed in successive courses of not more than eight inches compacted thickness. The thickness of the first course shall be approximately one-half the total thickness of the finished base, or enough additional to bear the weight of the construction equipment without disturbing the subgrade. At no time shall more than three days’ work of the first course be spread ahead of the second course.
(E) For single-course base, after the spreading is completed the entire surface shall be scarified and then shaped so as to produce the required grade and cross-section after compaction.
(F) For double-course base, the first course shall be bladed if necessary to secure a uniform surface, and brought to a surface cross-section approximately parallel to that of the finished base. Prior to the spreading of any material for the upper course, the density tests for the lower course shall have determined that the required compaction has been obtained. After the spreading of the material for the second course is completed the surface of such course shall be scarified and shaped so as to produce the required grade and cross-section after compaction. When the material does not have the proper moisture content to ensure the required density, wetting or drying will be required. When water is added it shall be uniformly mixed in by discing to the full depth of the course which is being compacted. Wetting or drying operations shall involve manipulation, as a unit, of the entire width and depth of the course, which is being compacted.
(G) As soon as proper conditions of moisture are attained, the material shall be compacted to an average density not less than 98% of the maximum density obtainable under FM 1-T 180, Method “D”. For double course base, average density shall be determined separately for each course. Limerock base for shoulder pavement shall be compacted to a density not less than 95% of maximum density by FM 1-T 180, Method “D”. During final compacting operations, if blading of any areas is necessary to obtain the true grade and cross-section, the compacting operations for such areas shall be complete prior to making the density determinations on the finished base. At least three density determinations shall be made on each day’s final compaction operations on each course, and the density determinations shall be made at more frequent intervals if deemed necessary by the engineer.
(H) If cracks or checks appear in the base, either before or after priming, which in the opinion of the engineer, would impair the structural efficiency of the base course, the contractor shall remove such cracks or checks by rescarifying, reshaping, adding base materials where necessary and recompacting.
(I) The finished surface of the base course shall be checked with a template cut to the required crown and with a 15-foot straightedge laid parallel to the center line of the road. All irregularities greater than a quarter-inch shall be corrected by scarifying and removing or adding rock as required, after which the entire area shall be re-compacted as specified herein before. In testing the surface, the measurements will not be taken in small holes caused by individual pieces of rock having been pulled out by the grader.
(J) If, in the opinion of the Engineer, the surface of the base has a glazed or cemented surface sufficient to prevent proper penetration of the prime coat, and after he/she determines that the condition of the base meets all requirements, he/she will direct that the surface be hard-planed with a blade grader and broomed immediately prior to the application of the prime coat. This hard-planning shall be done in such a manner that only the glazed or cemented surface is removed, leaving a granular or porous condition that will allow free penetration of the prime material. The material planed from the base shall be removed from the base area. The hardplanning operations, when required, shall follow the surface-testing operations specified below.
(K) The prime coat shall be applied only when the base meets the specified density requirements and the moisture content does not exceed 90% of the optimum moisture of the base material. At the time of priming, the base shall be firm, unyielding and in such condition that no undue distortion will occur.
(L) The contractor will be responsible for assuring that the true crown and template are maintained, with no rutting or other distortion, and that the base meets all requirements, at the time the surface course is applied.
(M) Thickness of the base shall be measured at intervals of not more than 200 feet. Measurements shall be taken at various points on the cross-section through holes not less than three inches in diameter.
(N) Where the compacted base is deficient by more than one-half inch from the thickness called for on the plans, the contractor shall correct such areas by scarifying and adding rock.
(O) The base shall be scarified and rock added for a distance of 100 feet in each direction from the edge of the deficient area. The affected areas shall then be brought to the required state of compaction and to the required thickness and cross-section.
(Ord. 2010-05, passed 4-27-2010) Penalty, see § 10.99