Do I always need bonding agent?

Yes for thin overlays and patches. For deep pours over 2 inches on roughened surfaces it may not be required but still helps.

Can I mix it into the concrete?

Some products allow mixing into batch water. Check label - some are topical only.

What if the agent dries before I pour?

The bond will be weak. Apply another coat and work faster.

Concrete Bonding Agent

Concrete & Masonry

Adhesive

$10-$25 per gallon

Concrete Bonding Agent: Adhesive for New-to-Old Concrete (2026)

Prepared by Lumberama's Building Materials Team

|Last updated May 15, 2026|Sources & methodology

Concrete bonding agent is a latex or epoxy adhesive applied between old and new concrete to ensure a permanent bond. Without it, fresh concrete poured over existing surfaces often delaminates. It is essential for thin overlays, patching, and any repair where new material meets cured concrete.

Key Features

Ensures new-to-old concrete adhesion; Latex and epoxy formulas; Brush
roll
or spray application; Interior and exterior use; Prevents delamination

Specifications

Coverage: 200-300 sq ft per gallon. Apply concrete while agent is tacky (30-90 min). Shelf life: 1-2 years.

Applications

Concrete overlays; Patch repairs; Resurfacing; Mortar bonding; Stucco applications

Installation Overview

Clean and dampen existing surface. Apply bonding agent evenly. Place new concrete while agent is still tacky - timing is critical. Do not let agent dry completely before placing new material.

Pros & Cons

Pros

✓ Prevents delamination; Easy to apply; Works on most surfaces; Versatile; Affordable insurance for repairs

Cons

✗ Must apply at right timing; Surface must be clean and damp; Cannot bridge structural cracks; Some not UV stable; Short open time

Top Brands

Quikrete

Sakrete

Sika

Code Requirements

Must meet ASTM C1059 Type I (interior) or Type II (interior/exterior). Recommended by ACI 546 for concrete repair.

Buying Tips

Buy exterior-rated Type II even for interior work - it works both ways. Have all materials ready before opening. Plan pour to apply agent and concrete in quick succession.