With the Staten Island Parking Garage in New York City, unforeseen weather conditions caused the concrete to set too fast for the installer to properly place, finish, and cure it. The result was a ramp with a wavy, uneven surface that was unacceptable to the project owner.

The solution was to resurface the ramp with Rapid Set® Mortar Mix Plus (MMP) and additives designed to slow setting times and increase the material’s workability. MMP is a high-performance, polymer-modified concrete repair material with strong adhesion and excellent workability. It is air-entrained for freeze-thaw resistance and includes a corrosion inhibitor to protect embedded reinforcement. The multipurpose material is ideal for projects requiring fast strength gain, high durability, and low shrinkage.

Before applying the MMP, the crew first had to shave and shotblast the parking garage ramp and then saturate it with water until the application surface of the substrate was slightly damp with no free water remaining. This method, known as saturated surface-dry (SSD), is used to prevent rapid drying (affecting workability) and remove surplus water from the repair material, which could result in excessive shrinkage cracking when the material is applied to an existing concrete surface.

Using a Hippo mixer, the crew mixed four-bag batches of MMP and one packet of Rapid Set® FLOW Control® along with two to four packets of Rapid Set® SET Control® per batch. The additives were used to maintain fluidity and slow down setting time, which gave workers more time to place and finish the overlay. FLOW Control® also increases compressive strength by reducing the amount of mix water needed.

The overlay was placed from 1/2- to 1-inch thick and was broom finished for slip resistance and then water cured. The project was completed in two days. In all, 500 bags of MMP were used, along with 125 packets of FLOW Control and 250 packets of SET Control. The project owner was very pleased with the finished results.