Village of Massapequa Park, NY Specifications for Soil Cement Base Pavement

Calcium chloride shall be in the form of loose dry lumps or flakes and fine enough to feed readily through the common forms of spreaders used in roadwork and shall meet the requirements of ASTM Designation D 98.

The calcium chloride shall be delivered in containers of a type acceptable to the Engineer. The name of the manufacturer, the approximate net weight and the percentage of calcium chloride (CaC1₂) guaranteed by the manufacturer shall be plainly marked on the container.

§ 300-29 Equipment.

All equipment shall be of an approved type, in first-class mechanical and operating condition and of adequate capacity to properly perform the required work in a satisfactory manner. The equipment shall be such as to ensure proper pulverization of soils, accurate application of cement and water, thorough mixing and incorporation of all materials, compaction, finishing and curing of the pavement as required. Standby equipment shall be available to the developers and/or their contractors so as to be in operation within one hour after any breakdown occurs on the job.

§ 300-30 Preparation of subbase.

Generally. The subbase shall be defined as that portion of the roadbed or parking field upon which the soil cement base pavement is to be placed. The subbase soils shall be defined as that thickness of soils below the base pavement as may need to be stabilized by materials admixed therein to form a suitable subbase for a pavement of several or more courses. The developers and/or contractors shall remove all boulders, mulch, soft clay and other objectionable materials to such depths as may be directed by the Engineer. These areas are to be backfilled with acceptable material to subgrade for base pavement.

Preparation of base pavement soils. Depending upon the character of soil encountered at base pavement elevations, all or parts of the base pavement soils, where directed by the Engineer, shall be improved with material added from the excavation or borrowed. The developers and/or their contractors shall save, during the excavation operation, sufficient selected materials for this purpose. Suitable loamy, silty or sandy soils shall he added to form a stable base for a minimum of six inches compacted thickness. The areas to be treated in cuts shall be excavated to a depth of three inches below soil cement pavement or more as directed by the Engineer. A layer of proper-type material between three and five inches loose measure shall be spread over the area and thoroughly mixed to a depth of six inches by scarifying or other method approved by the Engineer. The base soils shall then be shaped and compacted to the approximate finished line and grade. Smooth-wheel rollers weighing at least 10 tons shall be used for compaction. Shaping, filling and rolling shall continue until the base pavement soils are compacted to a depth of six inches and are within two inches of final grade and ready for the fine-grading operation. Where required, water shall be added to effect compaction. The base pavement soils shall be kept free from ruts and depressions and properly drained.

§ 300-31 Fine grading and soil cement construction.

Prior to starting construction of the soil cement base pavement, the developers and/or their contractors shall complete all fine grading of the area as is required to establish the completed work to the lines, grades, thickness and typical section shown on the plans. All unsuitable soils or other materials shall be removed, disposed of off the site and replaced with acceptable material obtained on the site or from off-site borrow as required and directed by the Engineer.

The subgrade of the area to be paved shall be firm, stable and capable of supporting all construction equipment employed and permit the required compaction of the soil cement mixture. All soft yielding or unstable subbase soils shall be satisfactorily corrected before construction of the pavement is initiated.

After all fine grading has been completed and subbase properly prepared, the area to be processed shall be prewetted if necessary, scarified and pulverized as required. It shall then be bladed and leveled to approximate true grade and section. Pulverizing of soil materials shall continue until 100% by dry weight passes a one-inch sieve and a minimum of 80% passes a No. 4 sieve, exclusive of retained gravel and stone after completion of moist mixing. All gravel, stone and unpulverized road metal over 1 1/2 inches in size shall be removed from the site. No stones greater than two inches in size shall be permitted in the soil cement mixture.

Before the cement is distributed and spread upon the soil, calcium chloride at the rate of 0.6% by weight of soil shall be evenly distributed over the entire area of the soil cement pavement. An approved spreader shall be used to distribute the calcium chloride.

Cement.

Portland cement of the type specified shall be uniformly distributed and evenly spread over the area at the rate of not less than 47 pounds per square yard. The developers and/or their contractors shall furnish suitable equipment of an approved type for handling, accurate weighing and spreading of the cement where bulk cement is used. When bag cement is used, the containers shall be accurately spotted and spaced in such manner as to ensure that the required quantity of cement will be obtained with uniform distribution over the area to be processed.

The percentage of moisture in the soil at the time of cement application shall not exceed the quantity that will permit a uniform and intimate mixture of soil materials and cement during mixing operations.

All displaced cement shall be replaced prior to starting mixing operations.

No cement shall be applied when the soil materials or the subgrade is frozen. Air temperature in the shade shall be at least 40º F. and rising.

(5)

Distribution of bulk cement over the area to be processed shall be accomplished by a cement spreader equipped with suitable device to accurately regulate and control the quantity of cement spread.

(6)

Where bag cement and hand pumping is employed, bags shall be emptied to form a uniform transverse windrow across the processing area and spread by means of a spike-tooth harrow, nail drag or other approved equipment. A sufficient number of passes shall be made to ensure a uniform and even distribution of cement over the area.

Equipment for mixing the soil cement shall be a traveling mixing machine of the multiple-pass rotary type. Window mixing will not be permitted under any conditions. After spreading of cement has advanced sufficiently, the developers and/or their contractors shall proceed with dry mixing and blending together of cement and the soil materials. The operation shall continue only until cement is sufficiently blended with the soil to prevent formation of cement balls when water is applied. Complete and thorough mixing of the material is not essential for this phase of the processing.

Water.

Water supply shall be adequate and the equipment for its application and distribution shall be pressure type of such capacity to ensure that the complete application of the total quantity required will be accomplished within a period of not more than three hours.

The total quantity to be applied shall be such as will bring the entire soil cement mixture to optimum moisture content or slightly above. It shall not be of such excessive quantity as will result in the mixture becoming unstable during the compaction and finishing operation.

The developers and/or their contractors shall proceed with the application and incorporation of water and mixing of the soil cement immediately after the dry mixing is completed. Water shall be applied uniformly, and excessive concentrations on or near the surface shall be avoided. Each increment of water applied shall be incorporated and mixed with the soil cement mixture before applying the next increment.

After all required water has been applied, mixing shall continue until a uniform, intimate and homogenous mixture of soil, cement and water is obtained for the full width and required depth of the area being processed. The mixture shall be of a uniform color and free of wet or dry streaks or stratas.

(5)

The percentage of moisture in the completed mixture, based on over-dry weight, shall not be below or more than 20% above optimum moisture content as determined by moisture density test ASTM Designation D-1557, Method C, on representative samples of the mixture obtained in the area being processed.

Shaping.

Compaction of the soil cement mixture shall be with pneumatic tired or sheepsfoot rollers. Shaping shall be performed with a motor-grader. Spike-tooth harrow or nail drag shall be employed for removal of compaction planes.

The moisture content of the mixture shall be maintained at not less than the optimum during the entire compaction operation. The entire area shall be compacted to a density of not less than 95% of the maximum density. Weight of roller equipment shall be the heaviest that will not overstress the soil and not less than 12 tons.

Rolling shall start at the edges and proceed to the center; compaction to specified density shall be satisfactorily completed within a period of two hours.

After rolling and compaction has advanced sufficiently, the surface shall be shaped and trued with a motor grader as necessary to obtain uniform compaction and required grade and cross-section. Compacting, rolling and shaping shall continue as required until the specified density is obtained and the surface is true to line, grade and cross section. Water shall be applied as necessary to maintain and provide the required moisture content. Compaction planes shall be removed from the surface by use of equipment stipulated above.

(5)

Final surface of pavement shall be developed by use of steel wheel or pneumatic tired rollers, or both, compacting to specified density. When directed, final rolling shall be supplemented with broom drag.

(6)

The completed surface shall be smooth, dense, free of compaction planes, cracks, ridges or loose materials and true to line, grade and section. The pavement shall be at least the specified thickness and the density not less than the minimum specified. Any portion of the pavement found to have a density less than 95% maximum density as determined by standard test procedures shall be rectified or removed and replaced by the developers and/or their contractors at no additional cost to the village.

Curing.

After the soil cement has been satisfactorily finished, the developers and/or their contractors shall cure the completed pavement for a period of not less than three days. Bituminous material shall be applied to the pavement surface at the approximate rate of 0.20 gallon per square yard. Curing material shall be applied not more than 12 hours after finishing operations are completed, but not before all excess water or moisture shall have dried from the pavement surfaces.

Multiple-spray equipment of an approved type shall be employed for application of the bituminous material. The distributors shall be so constructed as to cover not less than a ten-foot width in one pass, with nozzles so arranged that each spray will overlap the next by 1/2 its width. Bituminous material shall be RC-2 and rate of application shall be such as to give complete coverage without excessive runoff. The finished pavement shall be kept continuously moistened with water until curing materials are applied.

At the completion of each day's construction, a straight construction joint shall be formed by cutting back into the completed work to form a true vertical face for the following construction to abut.

§ 300-32 Testing.

The developers and/or their contractors shall be required to retain a reputable private laboratory experienced in testing soil cement work. The laboratory must be approved by the Engineer prior to the start of the soil cement work. The cost of testing will be paid by the developers and/or their contractors and included in the price bid under this item.

The laboratory will be required to perform the following tests and services and provide five copies of all test results. No soil cement work shall begin until preliminary tests have been submitted to the Engineer and approved.

The laboratory will drill test holes into the completed base pavement soils along the roadway or parking field at points no greater than 500 feet apart in the parking fields, at the rate of one test hole for each 1,000 square yards of pavement area and at every location where a noticeable change in soil is evident. The laboratory will make a composite sieve analysis of the soils in place before the cement is added. The laboratory will provide the Engineer with a test hole location, graphical analysis of the soils, a pH test and organic content of each sample.

The laboratory will perform moisture density tests or Modified Proctor Tests (ASTM D-1557, Method C) to determine the optimum moisture content for the soil cement mixture.

The laboratory shall determine the required cement factor for the soil cement pavement by means of the short-cut test procedures as outlined in the Soil Cement Laboratory Handbook of the Portland Cement Association.