The subgrade shall be shaped to the sections, lines and grades shown on the plans, prior to applying cement.
(Ordinance 2007-106, App. B, adopted 3/20/07)
A.
Pulverization.
Soil shall be pulverized so that at the completion of moist-mixing, one hundred (100) percent by dry weight passes a one (1) inch sieve, and a minimum of eighty (80) percent passes a No. 4 sieve, excluding gravel or stone retained on the sieves.
B.
Application of Cement.
Portland cement shall be spread uniformly on the soil at the rate specified on the plans. If a bulk cement spreader is used, it shall be positioned by string lines, or other approved methods, during spreading to insure a uniform distribution of cement. Cement shall only be applied to an area that all the operations can be continuous and completed in daylight within six (6) hours of application. At the time of application, the moisture percentage in the soil shall not exceed the quantity that will permit uniform and thorough mixture of soil and cement during dry mixing operations, and it shall not exceed the specified optimum moisture content for the soil cement mixture. Only equipment used in spreading and mixing will be allowed to pass over the freshly spread cement.
C.
Mixing and Processing.
Either a multiple-pass traveling mixing plant or a single-pass traveling mixing plant can be used. The cement shall be dry mixed with the soil to prevent the formation of cement balls when water is applied. Any mixture of soil and cement that has not been compacted and finished shall not remain undisturbed for more than thirty (30) minutes. The necessary amount of water shall be applied and incorporated into the mixture immediately after the dry mixing of soil and cement is complete. The water supply and distribution equipment provided shall be sufficient to ensure continuous application of the required amounts of water to sections being processed within three (3) hours of application of the cement. Care shall be exercised to insure proper moisture distribution at all times. After the last increment of water has been added, mixing shall continue until a thorough and uniform full depth mix has been obtained.
D.
Compaction and Finishing.
Unless specifically stated otherwise on the plans, the material shall be compacted to not less than 95% of Standard Proctor Density as determined by ASTM D-698 within two (2) hours of mixing. When compaction begins, the percentage of moisture in the mixture and unpulverized soil lumps, based on oven-dry weights, shall not be greater than two (2) percentage points above or below the specified optimum moisture content and shall be less than that quantity which will cause the soil cement mixture to become unstable during compaction and finishing. If the uncompacted soil cement mixture is wetted by rain so that the average moisture content exceeds the allowable tolerance at the time of final compaction, then the entire section shall be reconstructed at the expense of the Contractor. After the soil and cement mixture is compacted, water shall be applied uniformly as needed and mixed in thoroughly. The surface shall be reshaped to the required lines, grades and cross section and lightly scarified to loosen any imprint left by the compacting or shaping equipment. Surface compaction and finishing shall proceed in such a manner as to produce, in not more than two (2) hours, a smooth, closely knit surface, free of cracks, ridges or loose material conforming to the crown, grade and line shown on the plans.
E.
Curing.
After cement treatment course has been finished, the surface shall be protected against rapid drying by one (1) of the following curing methods for a period as shown on the plans, but in no case less than three (3) days or until the surface or subsequent courses are placed:
1.
Sprinkling to maintain a thorough and continuously moist condition.
2.
Apply a two (2) inch layer of earth on the completed course and maintain in a moist condition.
3.
An asphalt membrane may be applied to the treated course. The type and quantity of asphalt shall be sufficient to completely cover and seal the total surface of the subgrade and fill all voids. The use of an asphalt membrane must be approved by the Engineer or the designated representative of the Engineer prior to placement. If approved, the asphalt membrane shall be protected from being picked up by traffic by sanding or dusting the surface. The asphalt membrane may remain in place when the proposed surface or other base courses are placed.
Base courses may be applied on the finished subgrade as soon after completion as operations will permit.
F.
Construction Joints.
At the end of each day’s construction a straight transverse construction joint shall be formed by cutting back into the total width of completed work to form a true vertical face free of loose and shattered material.
Cement treatment for large, wide areas shall be built in a series of parallel lanes of convenient length and width.
G.
Traffic.
Local traffic and construction equipment may travel on completed sections of cement treated material in place, and all traffic may travel on the completed section after the curing period, provided the cement treated course has hardened sufficiently to prevent being damaged.
(Ordinance 2007-106, App. B, adopted 3/20/07)
The Contractor shall maintain the cement stabilized material in good condition until all work has been completed and accepted. Maintenance shall include immediate repairs of any defects that may occur. This work shall be repeated as often as necessary and at the expense of the Contractor. Faulty work shall be replaced for the full depth of treatment. The Contractor shall construct the plan depth of cement stabilization in one homogeneous mass, so the addition of thin stabilized layers will not be permitted in order to provide the minimum specified depth.
(Ordinance 2007-106, App. B, adopted 3/20/07)
Allow access to completed portions of work for field density testing by the Owner using the nuclear method. Contractor shall pay for failed tests and Owner will pay for passing tests.
(Ordinance 2007-106, App. B, adopted 3/20/07)