What is the primary function of a bonding agent applied before a new concrete pour?

The primary function of a bonding agent applied before a new concrete pour is to improve adhesion between the newly placed concrete and the existing substrate. Bonding agents create a chemical or mechanical bond that enhances the interfacial strength, ensuring that the new concrete adheres properly to the old surface. This is particularly crucial in applications where two different pours of concrete need to function together structurally, such as in repair work or overlay applications.

Enhancing adhesion helps prevent issues such as delamination or separation, which can lead to structural weaknesses over time. Without a bonding agent, the interface between old and new concrete might not bond sufficiently, thereby compromising the overall integrity of the construction.

While increasing compressive strength is important for concrete as a whole, a bonding agent does not directly influence the strength of the concrete mix itself. Similarly, lowering the water-cement ratio relates to the concrete mix design rather than the bonding process. Accelerating curing might be important for certain projects, but is not a function of bonding agents, which instead focus specifically on ensuring a strong bond at the interface between different layers of concrete.