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Section 30 – Concrete Structures

30-15.05 Concrete Repair

Evaluate the unsuitable concrete area to determine whether the concrete repair should be

made with concrete, mortar (dry pack), shotcrete, or topped with an overlay.

30-15.05.B Replacement with Concrete

When there are extensive honeycombs or large voids in new construction, or extensive

deterioration of existing concrete, the affected area shall be removed to sound concrete and the

area cleaned of deleterious material. Forming may be required. Concrete for the repair shall be

similar to the original in cement-water ratio and aggregate size.

30-15.05.C Mortar (Dry Pack)

This method is suitable for snap-tie holes, spalls, and cavities (rock pockets) with a relatively

high ratio of depth to width. Unsuitable concrete must be chipped by hand or mechanical

means to sound and clean concrete. Flush the patch area with water and allow to dry. Coat

surface with epoxy compound or acrylic bonding compound and allow to dry until tacky to the

touch. Mix mortar composed of portland cement, sand, and water. White cement shall be

added when matching the color of the surrounding concrete is required. Proportion of cement

to sand, by volume, shall be no more than 1:2. Add only enough water to permit placing and

packing. The mortar shall be rammed into place in thin layers and leveled to the plane of the

surrounding concrete. Cure with liquid-membrane cure, wet burlap, or water. Fast-setting,

cementitious, pre-mixed packing materials may be used when approved by the Agency and

shall be applied per manufacturer’s instructions.

30-15.05.D Shotcrete

Shotcrete is suitable for repairs to overhead or vertical surfaces and shall be placed

according to procedures in ACI Manual of Concrete Practice, 506R.

Topping may be placed with or without surface hardener on a pre-existing base slab. Prior

to placing, the entire area to be topped shall be cleaned and free of all loose and unsound

materials by abrasive blasting or machine scarifying, and clean aggregate exposed. The

cleaned base shall be kept wet for a period of 24 hours prior to the application of topping.

Excess water shall be removed and a neat cement bonding grout shall be applied. It shall be of

equal parts cement and sand and enough water to make a creamy mixture. The cement

bonding grout shall not be allowed to dry or set before topping placement. Bonding agents

other than cement grout may be used with prior Agency approval. The topping shall then be

placed to grade, compacted, and floated. The Contractor shall check for trueness of surface

with a 12-foot straightedge. Surface hardener, when used, shall be applied according to

manufacturer’s instructions. Trowel or broom finish as specified in Contract.

30-16 MEASUREMENT AND PAYMENT

Except as otherwise provided, pay quantities of concrete in structures will be measured by

the cubic yard in accordance with the dimensions shown or specified in the Contract, or as

ordered in writing by the Agency. No deduction will be made for volume of reinforcing steel.

The price paid per cubic yard for concrete in structures includes full compensation for

furnishing all labor, materials, tools, equipment, and incidentals and for doing all the work

involved in constructing concrete structures, complete in place, including furnishing and building

all necessary forms and falsework, furnishing and placing all concrete, reinforcing steel,

expansion joint material and waterstops, curing the concrete, providing weep holes in walls, and

finishing all concrete surfaces, as shown or specified in the Contract, specified in these

Specifications, and directed by the Agency.