Amerimix Introduces Water Repellent Mortar with RainBloc GP

Words: Bronzella Cleveland

Amerimix®, a manufacturer of preblended mortar, grout and stucco mixes, has unveiled its new water repellent masonry mortar: Amerimix Water Repellent Mortar (WRM) with RainBloc GP®.

With proven performance both in independent laboratory testing by The National Concrete Masonry Association (NCMA) and on the job site, Amerimix WRM with RainBloc GP inhibits water from penetrating a wall system. The mortar also is part of the total RainBloc system and, when used with concrete masonry units (CMU) that contain RainBloc, creates a wall system with superior moisture resistance, the company says.

The patented RainBloc GP technology in Amerimix WRM is the only water repellent agent that is traceable and measurable in the hardened mortar, verifying that the exact proportions for optimal water resistance are included in every bag and every batch. Amerimix WRM also performs as well as mortar without water repellent additives, offering the same superior bond strength and extended mortar board life with less re-tempering required.

And since RainBloc GP is factory blended into Amerimix WRM, masons can save time and money with no measuring, additional steps, waste or mixing mistakes at the job site — while also eliminating the need for stocking liquid admixtures. Third-party field testing by the NCMA also confirms that Amerimix WRM helps to make application easier with no impact on the feel, application or workability of the product.

Specifiers, too, can benefit from the mixture being factory blended under controlled conditions to guarantee that the precise amount of RainBloc GP repellent agent is consistently mixed in every batch for optimal performance, Amerimix reports. This helps to ensure that Amerimix WRM will work as specified — and that what you specified is what you get.

“Our Amerimix WRM formulation is an innovation that provides superior protection against moisture penetration and leakage, while also helping to make masons’ jobs easier with a pre-blended formula for no-hassle applications,” said Bob Ruby, technical product manager for Amerimix masonry products. “Also, because RainBloc GP is traceable and measurable after installation, it gives specifiers peace of mind that their project is executed as specified.”

Ideal for both interior and exterior applications, Amerimix WRM is specifically engineered to provide long water retention, exceptional workability, and superior bond strength over masonry substrates. Additionally, Amerimix products can help contribute to LEED® Materials and Resources credits for recycled and regional materials.

Building Solutions: The Critical Role of Cavity Space in Masonry Moisture Control
April 2026

Long before “rainscreen” became a popular term in building science, masonry cavity walls were functioning on that very principle. A brick veneer cavity wall is designed with the expectation that water will penetrate the exterior

A Legacy of Inspiration: Lynda Spina, CFO retires from STABILA North America
April 2026

After almost 30 years of dedicated service, Lynda Spina is retiring from her role as Chief Financial Officer of STABILA North America, closing an extraordinary chapter defined by steady leadership, financial discipline, and lasting impact.

Masonry in the Media: The Alamo, The Merchandise Mart, & More
April 2026

The scenery of films and TV shows alike is often a crucial yet underrated detail that can ultimately make or break a scene. In these American-made structures, take a look at how these movies and shows transformed iconic masonry buildings into the perfect

Announcing The Daily Digest From The MCAA
April 2026

Pay attention to your inbox starting Wednesday, April 8th. The MCAA is pleased to announce The Daily Digest, a selection of masonry news from around the world delivered right to you. “I receive daily emails from several news sou