813.01 DESCRIPTION. Furnish and construct concrete approach slabs of the
type and dimensions at locations specified.
813.02 MATERIALS. Materials shall comply with the following sections and
subsections: Plastic Soil Blanket 203.10 Portland Cement Concrete Section 901 Bedding Material 1003.10 Joint Materials Section 1005 Thermoplastic Pipe Section 1006 Deformed Reinforcing Steel 1009.01 Timber Piling Section 1014 Hardware Cloth 1018.05 Geotextile Fabric 1019.01 Bedding material shall be either stone in accordance with 1003.03.1 or recycled portland cement concrete in accordance with 1003.03.2. Polyethylene sheeting shall comply with AASHTO M171. Geotextile fabric shall comply with Section 1019, Classes B, C, or D. The fabric shall be resistant to chemical, biological, and insect attack.
813.03 Construction Requirements.
813.03.1 Embankment: Construct the headers to full embankment height
as defined by the grading section elevations shown on the plans as early in construction as possible to aid settlement. If shown on the plans, construct wick drains and/or surcharge to the designated fill heights and allow to remain in place for the indicated duration. Perform structural excavation for end bent construction prior to driving piles. Place geotextile fabric as a separation layer between the embankment and the bedding material beneath the approach slab in accordance with 203.11. Do not allow any equipment on the fabric unless there is at least 6 inches of cover. When specified, place the approach slab on a layer of allowable bedding material in accordance with plan details. Place bedding material and compact as directed. Cover with approved polyethylene sheeting of at least 6-mil nominal thickness.
813.03.2 Drainage Systems: Construct underdrain systems in accordance
with the plans and Section 703.
813.03.3 Reinforcing Steel: Fabricate and place deformed reinforcing
steel to comply with Section 806.
813.03.4 Support Piles: When shown in the plans, support the approach
slab on piles in accordance with Section 804.
813.03.5 Concrete: Use Class A1 concrete for all approach slabs and
bolster blocks under approach slabs in accordance with Section 805. Use Class M concrete for headw alls for under drain system in accordance with plan details. Cure approach slabs in the same manner as bridge decks in conformance with
805.06 Do not use membrane cure on approach slabs requiring asphalt overlay.
Surface tolerances shall conform to 805.03.4.
813.03.5 1 High Early Strength Concrete: When specified or when
construction conditions merit opening up concrete approach slabs to traffic early before concrete is fully cured, the following requirements will apply for high early strength (HES) concrete. Submit to the Project Engineer for review the HES concrete mix design. Verify by trial batch that the proposed HES concrete mix achieves a minimum compressive strength of 3000 psi within 4 hours and achieves a 28 -day minimum compre ssive strength of 4500 psi as per Table 901 -3. Mold and cure compressive strength specimens in accordance with DOTD TR 226 and test in accordance with DOTD TR 230. Submit results of trial batch testing to Project Engineer for acceptance before use on bridge approach slab. Use a modified Class A1 concrete mix design for the HES concrete and conform to the following requirements:
1.Follow manufacturer/supplier’s recommendations on mixing and placing high early strength concrete.
2.Do not use chloride-type accelerating admixtures.
3.Place the concrete continuously to prevent cold joints.
4.Promptly finish the concrete as specified in 813.03.6.
5.Immediately after finishing, apply curing compound at double the normal specified quantities.
6.Permit no traffic on the HES concrete approach slab until it obtains a minimum compressive strength of 3,000 psi. Use curing boxes for the molded cylinders to emulate the strength gain of the in- place concrete. Submit to the Materials Engineer Administrator for review the maturity method for strength determination. At the contractor’s option, Type B or Type D concrete may be substituted in place of Class A1 concrete provided the mix achieves a 28 -day minimum compressive strength of 4500 psi and meets the other requirements of this section.
813.03.6 Roadway Finish: Give the roadway a metal tine texture finish.
Surface finishes shall conform to 805.08. Finish approach slabs requiring asphalt overlay in accordance with 805.08.5 without tine finish.
813.04 MEASUREMENT. Quantities of concrete approach slab will be
measured by the square foot of horizontal surface area measured to the outer perimeter. Required concrete, concrete closure placements, reinforcing steel, joint materials, bedding materials, surcharge material, geotextile fabric, polyethylene sheeting, underdrain pipe and system, rodent screen, and head walls will not be measured for payment. Asphalt overlay, when required, will be paid for under a separate item.
813.05 PAYMENT. Payment for concrete approach slabs will be made at the
contract unit price which includes all materials, labor, equipment and tools necessary to complete the work and shall be subject to the following provisions. Acceptance and payment for concrete approach slabs will be made on a lot basis. A lot will be considered as a complete approach slab or an identifiable p lacement that is completed in one day. Two random batches will be sampled for each lot, and three cylinders molded for each batch. The six cylinders per lot will be tested for compressive strength in 28 to 31 days. In the event of sudden cessation of operations, a minimum of three cylinders will constitute a lot. Acceptance and payment for each lot will be made in accordance with tables 901-4 and 901-6. Payment will be made under: Item No. Pay Item Pay Unit 813-01 Concrete Approach Slabs (Cast in Place) Square Foot 813-02 HES Concrete Approach Slabs (Cast-in-Place) Square Foot 813-03 Concrete Approach Slabs ( Precast) Square Foot 813-04 Concrete Approach Slabs (Pile Supported) Square Foot
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Source: Standard Specifications for Roads and Bridges, 2016 Edition. Pages 784–786 of 1,145. View official source ↗