SECTION 601 - STRUCTURAL CONCRETE
601.01 Description. This work consists of furnishing and placing hydraulic cement
concrete for specified structures in accordance with these specifications and in reasonably close conformity with the lines, grades, and dimensions shown on the plans or established by the Engineer. Structural concrete will be divided into two groups. One group will be designated as Structural Concrete. The other group will be designated as Structural Concrete, Minor Structures. Unless otherwise specified in the contract, Structural Concrete, Minor Structures, will include inlets, catch basins, junction boxes, pipe headwalls, and pipe collars, regardless of the concrete quantity required for each of these structures; and other small structures containing less than 3.00 cubic yards of concrete each.
601.02 Materials.
601.02.1 General. Materials for structural concrete and their use, care, and handling shall
be in accordance with Subsection 804.02. Sampling and testing will be in accordance with TMD-20-04-00-000 or TMD-20-05-00-000, as applicable.
601.02.2 Classification of Concrete. Concrete for this work shall be the class specified
on the plans or in the bid schedule of the cont ract. Classes of concrete are identified in Subsection 804.02.6.
601.02.3 Precast Units. Design standards normally contemplate that structural concrete
will be cast in place. However, the Contractor may request approval from the Engineer to furnish and install precast units in lieu of cast-in-place units. The request shall be accompanied by detailed drawings of the pr ecast units and design data certified by a registered Professional Engineer as to structural and functional adequacy. The foundation for precast units shall be carefully shaped to the precise contour and grade of the bottom of the unit before the unit is placed. Precast units which are to be joined to other units shall be designed and manufactured with proper and adequate joints. Joints shall be sealed with a joint material meeting the applicable requirements of Section 707. MDOT Drawing Sheet Nos. PCU-1 and PCU-2 address Department’s approved precast drainage units. The Contractor must make a request to the Project Engineer for approval to use precast units other than the ones show n on Drawing Sheet No . PCU-1 or PCU-2. Precast drainage unit tops are only allowed on units shown on Drawing Sheet No. PCU-1. Cast-In-Place drainage unit tops are required on units shown on Drawing Sheet No. PCU- 2. No additional payment will be allowed for precast units approved for use. Pay items and quantities will be as in cast in place in accordance with design standards.
601.03 Construction Requirements.
601.03.1 Composition of Concrete . The composition of the concrete shall be in
accordance with Section 804.
601.03.2 Batching. Measuring and batching of component materials shall be in
accordance with the applicable provisions of Section 804.
601.03.3 Mixing and Conveying Concrete . Concrete shall be mixed and conveyed in
accordance with the applicable provisions of Subsection 804.03.5.
601.03.4 Cold or Hot Weather Concreting . Requirements for placement, protection,
and curing of concrete during cold or hot weather are stipulated in Subsection 804.03.16.
601.03.5 Consistency. The slump of the concrete, determined in accordance with the
provisions of Subsection 700.03, shall confor m to the applicable requirements of Section 804.
601.03.6 Falsework and Forms.
601.03.6 1--Falsework. Falsework shall be in accordance with the appli cable provisions
of Subsection 804.03.13.
601.03.6 2--Forms. Forms shall conform to the requirements of Subsection 804.03.14.
601.03.6 3--Removal of Falsework, Forms, and Housing . The removal of falsework,
forms, and the discontinuance of heating, shall be in accordance with the provisions and requirements of Subsection 804.03.15, excep t that the concrete shall conform to the following compressive strength requirements: Wingwall and Wall Forms not Under Stress ....................................... 1000 psi Wall Forms under Stress ..................................................................... 2200 psi Backfill and Cover clear ...................................................................... 2400 psi In lieu of using concrete strength cylinders to determine when falsework, forms, and housings can be removed, an approved maturity meter may be used to determine concrete strengths by inserting probes into concrete placed in a structure. The minimum number of maturity meter probes required for each structural component shall be in accordance with Subsection 804.03.15. Procedures for using the maturity meter and developing the strength/maturity relationship shall follow the requirements of Subsection 804.03.15. Technicians using the maturity meter or calculating strength/maturity graphs shall meet the requirements of Subsection 804.03.15. When the walls and top slab of box culverts and box bridges are not to be poured monolithically, extreme care shall be used when forming and pouring the top slab on walls in which the concrete has not attained its full design strength. In order to prevent damage to fresh concrete, either of the following methods of forming and pouring may be used:
a.Subject to approval by the Engineer, the wall forms and deck forms may be so constructed and separately supported and braced that the walls may be poured and the wall forms removed as for wall forms not under stress. The Engineer may require a detailed plan of the proposed method of forming for approval. When this method of forming is used, the deck forms shall be in place and adequately and independently supported throughout before pouring the walls. Deck forms shall overlay the top edge and be flush with the face of the inside wall forms, but shall not be dependent upon any part of the inside wall forms for support. The intersection of the wall and deck forms shall be mortar tight. The wall forms may be constructed slightly less than the specified inside clear height of the structure and wedged upward from the bottom of the riser wall to permit easier removal. When this method is used, the concrete in the wall shall be poured flush with the top of the deck form.
b.At the option of the Contractor, the walls may be formed, adequately braced, and poured before the deck forms are in place. In this case the forms may be removed as for walls not under stress. Before erecting any part of the forming for the top slab, the concrete in the walls shall have attained the age or the strength specified for the removal of wall forms under stress.
c.The Contractor may elect to form and adequately support and brace the wall and deck forms as a composite unit before pouring the walls. In this case the outside forms may be removed as indicated for wall forms not under stress provided adequate provisions are made for form ing the outer (vertical) surfaces for the subsequent deck pour. The inside wall forms shall remain in place as indicated for wall forms under stress.
601.03.6 4--Damage to Previously Placed Concrete . In the event previously placed
concrete is damaged, all work on the affe cted structure shall cease immediately for an engineering assessment of the damage and the corrective work to be performed. No additional work shall be performed until this determination has been made, and the Engineer has given the Contractor approval to proceed with the corrective work and subsequent construction. All corrective work required shall be performed by the Contractor at no additional cost to the State.
601.03.7 Foundations and Footings . Foundations for structures shall be prepared in
accordance with the requirements and provisions of Section 206. All footings shall be poured "dry." Where footings can be placed in the "dry" without the use of cribs or cofferdams, the Engineer may permit back forms to be omitted, and concrete poured against the faces of the excavation.
601.03.8 Placing Reinforcing Steel. Reinforcing steel shall be placed in accordance with
the requirements of Section 602 and as shown on the plans.
601.03.9 Handling and Placing Concrete . Handling and placing concrete shall be in
accordance with the provisions of Subsection 804.03.6.
601.03.10 Expansion and Fixed Joints. All expansion and fixed joints shall conform to
the applicable provisions of Subsection 804.03.18.
601.03.11 Finishing Concrete Surfaces. Unless otherwise authorized, the surface of the
concrete shall be finished immediately after form removal. Surface finishes shall conform to the applicable provisions of Subsection 804.03.19.
Referenced in this section
Structural Concrete in other states
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Source: Standard Specifications for Road and Bridge Construction, 2017 Edition. Pages 392–394 of 1,113. View official source ↗