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Section 30 – Concrete Structures

Contract, expansion joint material shall be as specified in Section 50-4, “Premolded Expansion

Joint Filler”, of these Specifications, except that partial depth expansion joint filler material with a

minimum penetration of two inches (2”) will be permitted in minor concrete structures, slope

paving, sidewalk, curb, and gutter applications as specified in Section 90-10, "Minor Concrete”,

of the State Specifications.

30-11 CONSTRUCTION JOINTS

Construction joints are required when sequencing concrete placement of large areas.

Construction joints shall be made only where shown or specified in the Contract or

authorized or directed by the Agency. When it is necessary to make a joint because of an

emergency, as determined by the Agency, reinforcing steel shall be placed through the joint as

directed by the Agency. Furnishing and placing such reinforcing steel shall be at the

Contractor's expense and no additional compensation will be paid.

After the concrete in a poured segment has hardened, the entire surface of the joint shall be

thoroughly cleaned of surface laitance, and aggregate shall be exposed by abrasive blast

cleaning. Wire brushing, air, or water blasting may be used while the concrete is fresh,

provided results equal to abrasive blast cleaning are obtained.

Construction joints shall be keyed. Keyways shall be formed by beveled strips or boards

placed at right angles to the direction of shear or as directed by the Agency. Except where

otherwise shown or specified in the Contract, keyways shall be at least one and one-half inches

(1-1/2”) deep over at least twenty-five percent (25%) of the area of the section.

When new concrete is to be joined to existing concrete, holes shall be drilled in the existing

concrete and bar reinforcing steel dowels shall be grouted in, as specified in Section 51-1.13,

“Bonding”, of the State Specifications.

Waterstops, when shown or specified in the Contract, shall conform to the requirements of

Section 51-1.14, “Waterstops”, of the State Specifications.

Curing of concrete is essential for development of specified strength and durability. When

not curing by forms-in-place, then exposed surfaces shall be cured by one or more of the

following methods: burlap or rugs kept continuously wet, waterproof membranes such as paper

or plastic, or spraying liquid-membrane curing compound applied as soon as free water on the

surface has disappeared but before surface drying begins. Unless otherwise shown or

specified in the Contract, curing compounds shall conform to the requirements in Section 50-6,

“Curing Compounds for Concrete”, of these Specifications.

Curing practices for concrete placed in extreme weather conditions must prevent too-rapid

hydration or cold-weather freeze-thaw damage as specified in ACI Manual of Concrete Practice

(most recent) or Section 90-7 of the State Specifications.

30-14 PROTECTING CONCRETE

In addition to the requirements of Section 5, "Control of Work and Materials”, of these

Specifications, the Contractor shall protect concrete as provided in this Section 30.

All concrete that has been frozen or damaged by other causes, as determined by the

Agency, shall be removed and replaced by the Contractor at the Contractor’s expense.

All concrete in structures shall be maintained at a temperature of not less than forty-five

degrees (45°) F for seventy-two (72) hours after placement, and at not less than forty degrees