Atch_6_Concrete_Patch_Addendum_A.pdf

TECHNICAL SPECIFICATIONS

CONCRETE PATCH

WIND CAVE NATIONAL PARK

ELK MOUNTAIN CAMPGROUND

PMIS 242482

ADDENDUM A

I. Scope of Work

Work done under this item shall consist of the construction of a one-course Portland cement concrete patch and subgrade in accordance with these specifications and in conformity to the line established by plans and field verification of the COR/CO. Concrete material shall be fast strength gain, high durability and low shrinkage patch. The patches shall also consist of excavating and filling, for fine grading and compaction of subgrade, and all backfilling necessary to complete the work, including the disposal of surplus material and cleaning up of the work.

The concrete patch shall be used for a road crossing, walking path crossing and patch work in an existing parking lot.

A. MATERIALS

1. Concrete Patch for Parking Lot, Road Crossing and walkway

Concrete shall contain cement, coarse aggregate and with a minimum of 6,000 pounds per square inch compressive strength at 28 days and 5000 pounds per square inch at 7 days. Strength of concrete shall be verified with concrete plant mix paperwork (or similar paperwork) upon concrete truck arrival at Wind Cave National Park. The concrete patch shall be as shown on the detail sheet consisting of 6-inches of approved ¾ inch crushed gravel base (crushed limestone or approved local crushed gravel).

2. Water

Water shall be clean and free from salt, oil, or organic substances. Water from local rivers, creeks, or ditches shall not be used.

B. CONSTRUCTION METHODS – Concrete Patch

1. Subgrade Preparation

Suitable subgrade material (gravel) for concrete patch shall be formed by excavating to the required depth and shaped to the proper cross section of six (6) inches and shall be thoroughly compacted by rolling or tamping before placing any concrete patch. The subgrade material shall be approved by the COR/CO.

Where tree roots are encountered, they shall be removed to a depth of one foot for the full width of the trench.

All soft and spongy places shall be removed, and all depressions filled with suitable subgrade material which shall be thoroughly compacted in layers not exceeding six (6) inches in thickness.

2. Protection of Subgrade

In no case shall concrete be placed on frozen or muddy subgrade. Frost crystals or mud caused by freezing and thawing shall be removed and replaced with suitable material at the Contractor’s expense or allowed to dry before placing concrete patch. If ruts are formed in the prepared subgrade, the subgrade shall be scarified and thoroughly compacted. If borrow material is required because of improper handling or drainage, the cost of such will be borne by the Contractor.

3. Grading Specifications

Grading of the new concrete patches shall match the existing elevation of existing road, parking lot and walking path. Grading to be verified by the COR/CO.

4. Dimensions

The new patches will have an approximate width of a 24-inch backhoe bucket with no anticipated shoring of the trench. The minimum thickness of a patches shall be four (4) inches. The patches shall have no. 3 rebar placed one foot on center and rebar positioned in the middle of the 4-inch-thick concrete patches.

Concrete patch slabs shall have an anticipated total area of 100 square feet.

5. Alignment and Grades

Concrete patches shall be constructed in conformance to the lines on the plan view matching existing grades and verified by the COR/CO.

6.Placing Concrete

No concrete patch shall be placed until subgrade have been approved by the COR/CO. The subgrade shall be thoroughly wetted, and the concrete shall be placed thereon in one course to the required depth. The concrete shall be thoroughly spaded, vibrated, and tamped to the required grade and cross section. Successive batches of concrete shall be deposited in a continuous operation until individual sections are completed.

7. Joints, if necessary

Contraction joints shall be provided uniformly to separate the slab and shall be cut in a straight line to a depth equal to at least one-third (1/3) of the total slab thickness. The joint shall be not less than one-eighth inch (1/8”), nor more than one-fourth inch (1/4”) in width. Contraction joints to be field approved by the COR/CO.

A one-half inch (1/2”) expansion joint filled with joint filler shall be placed between the new pavement and the existing pavement and per manufacturers recommendations. Expansion joints to be field approved by the COR/CO.

8. Finishing

After the freshly-poured concrete has been brought to the established grade, it shall be floated with a wooden float to produce a surface free from irregularities. The final surface shall be obtained by troweling with a steel trowel or hand float and brushing lightly with a light weight brush in a transverse direction so as to produce a uniform gritty surface of the proper texture to match existing pavement. All edges and joints shall be rounded to one-fourth inch (1/4”). No more concrete shall be laid than can be properly finished and covered during daylight.

9. Cold Weather Pouring

Concreting operations shall not be undertaken or continued when the surrounding air temperature is below 40° F or the local weather reports indicate the possibility of temperatures of 32°F or lower within the ensuing twenty-four (24) hours, unless provisions are made to insulate or heat the concrete in a manner satisfactory to the COR/CO. In any event, the Contractor shall plan and protect his work in a manner which will assure satisfactory results. Any concrete damage by freezing shall be removed and replaced by the Contractor at his own expense.

Concrete shall have a temperature of not less than 50°F nor more than 90°F.

The concrete shall be maintained at a temperature of not less than 50°F for a period of at least seventy-two (72) hours in case of normal concrete, or twenty-four (24) hours when high early cement is used. Concrete shall not be deposited on a frozen subgrade.

10. Curing and Protection

Immediately after finishing operations have been completed, the entire surface of the concrete shall be covered and cured under burlap or other material approved by the COR/CO.

Curing operations shall be carried on at all times when the air surrounding the concrete is 50°F or greater. After finishing the concrete and the surface is hardened sufficiently or prevent marring, the entire surface shall be covered with one layer of thoroughly saturated burlap or approved material overlapping at least six inches (6”) at joints to prevent gaps.

Additional layers of burlap to result in a total of not less than twenty-four

(24) ounces of burlap per ten (10) square feet of surface shall be spread, thoroughly saturated, upon the first layer. The covering shall be maintained fully wetted for seventy-two (72) hours after the concrete has been placed. Water shall be applied by a spray fine enough to avoid damage to the fresh concrete.

11. Protection of Concrete

Immediately after the forms have been removed, traffic shall be excluded from crossing the concrete for a period of approximately fourteen days (14) days by erection and maintenance of suitable barricades. The Contractor shall be responsible for any damage resulting from traffic within the fourteen (14) day period and he shall remove and replace any concrete damage as directed by the Engineer.

12. Removal of Defective Work

The Contracting Officer shall have the authority to and shall require the removal of any concrete patch or portion thereof laid under these specifications which does not conform to the requirements as set forth herein. Upon notification in writing by the Contracting Officer, the Contractor shall take immediate action to correct the faulty work at his own expense.

13. Cleaning Site

Prior to the acceptance of the work, all surplus and rejected material and unsightly objects such as stones, stumps, limbs, roots, concrete, etc., shall be removed from the site and not be considered complete until all cleaning up has been done and the site is of a neat appearance.

C. METHOD OF MEASUREMENT AND BASIS OF PAYMENT

1. The area of concrete patch accepted shall be computed and include grading, forming, compaction, placing rebar, placing, and working concrete for the total patch work of 24 inches wide by 50-foot total length by 12 inches of subgrade/concrete patch as cubic feet.

2. The area of subgrade shall be computed cubic feet and include grading, placement and compaction of the subgrade gravel and placing the concrete patch.

3. The sum payment shall be full compensation for all materials, labor, and other costs to the Contractor.