Stunning Floors Begin With The Right CSP

A Closer Look at Portland-Limestone Cement
and the Questions It Raises

In the race toward reducing carbon emissions and building a more sustainable future, the construction industry has placed significant emphasis on material innovation. One of the most talked-about shifts in recent years is the rise of 1L concrete, also known as Type 1L Portland-limestone cement (PLC). While its environmental intentions are clear, the execution and field performance of this material have sparked deep concerns among contractors, finishers, and construction professionals across the country.

What Is 1L Concrete?

1L concrete is a blended cement product made by intergrinding Portland cement clinker with up to 15% finely ground limestone. It falls under ASTM C595 and was promoted as a more sustainable option than traditional Type I or Type II cement, with a claimed reduction in embodied carbon of about 10%.
This transition is part of a broader movement toward lowering the construction industry’s carbon footprint. However, for many professionals working in the field every day, the reality of 1L’s performance has not aligned with its promise.

Why the Push—And Why the Pushback?

Advocates of 1L cement cite decades of successful use in Europe and a growing need for climate-conscious practices. Major producers in the U.S. began shifting almost entirely to Type 1L in 2022 and 2023, often with little consultation or consideration for the practical realities faced by contractors and specialty finishers.
This sudden change, often framed as a “drop-in replacement,” has led to a number of serious challenges:
Surface Defects & Finish Failures
Many contractors have reported inconsistent finish quality, scaling, dusting, and difficulty achieving color uniformity in decorative and exposed applications. In some cases, these issues have led to litigation over failed installations.

Lack of Field Testing & Support

Although some densifiers and admixtures are being promoted as compatible with 1L, most have not undergone sufficient independent testing to ensure reliable long-term performance. Contractors are left to troubleshoot on their own, often at their own expense.

Distrust from the Field

For many in the construction world, especially those working on architectural concrete, decorative finishes, or high-performance surfaces, the lack of transparency and technical support has created a deep sense of frustration and mistrust.

What Industry Experts Are Saying

While many material producers remain committed to 1L cement, an increasing number of contractors, specifiers, and consultants are raising red flags. Some are now avoiding 1L altogether in high-exposure projects or are specifying additional treatments, sealers, or surface hardeners to compensate for performance issues.
Yet even these remedies come with asterisks: most haven’t been thoroughly tested alongside 1L, and results vary based on climate, substrate, and finishing practices. While some contractors are beginning to find combinations that work, there is no universally endorsed solution at this time.

Proceeding with Caution

There’s no question that sustainability is an urgent priority—but true sustainability must also account for durability, performance, and constructability. When cement fails in the field, the environmental impact of replacement materials and labor far outweighs any initial carbon savings.
As the industry continues to explore lower-carbon alternatives, many experts are calling for a more thoughtful, transparent, and inclusive approach—one that includes rigorous testing, real-world data, and support for the contractors on the front lines of implementation.

The Bottom Line

1L concrete may represent a step toward sustainability, but for now, it’s a step that should be taken with full awareness of its limitations. The current landscape demands caution, continued evaluation, and an honest dialogue between producers and practitioners.
Until field data improves and manufacturers take stronger accountability for performance, the use of 1L cement should be considered on a case-by-case basis, especially in projects where finish quality, color uniformity, or long-term durability are critical.

The artistry of a stunning concrete floor captivates our attention, but its strength and endurance hinge on a meticulous process that often goes unnoticed. This vital process, known as surface preparation, is paramount in the floor’s creation. As defined by the International Concrete Repair Institute, surface preparation encompasses various techniques aimed at removing deteriorated or contaminated concrete while roughening and cleaning the substrate to improve the adhesion of repair materials or protective coatings.

Some common surface preparation techniques include shot-blasting, scarifying, grinding, and acid etching, which are essential for modifying the texture and roughness of the concrete surface to achieve the desired concrete surface profile. By understanding the various levels of CSP, you can effectively assess how well your floor is prepared for a coating or overlay. Achieving the correct concrete surface profile is crucial, as it significantly influences the strength of the mechanical bond between your coating and the concrete surface.

Selecting the appropriate concrete surface profile for your project may not always be specified by the manufacturer, which is where the ICRI’s 10 CSP classifications come into play, outlining their specific applications. Lower-numbered profiles provide a smoother finish, with CSP 1 being nearly flat, while higher numbers indicate a rougher surface with increased “tooth.

Choosing the right CSP by Application

CSP 1-3 is recommended for the optimal application of acrylic sealers, water-based stains, reactive acid stains, and dyes while CSP 4-6 enhances the concrete surface to establish the strongest mechanical bond for thin cement-based overlays and resinous coatings such as epoxies. For thicker applications like stampable overlays, self-leveling compounds, urethane cement, and more substantial resinous flooring, a Concrete surface profile of 5-10 may be necessary.

ApplicationMilsDesired CSP
Sealers0-31-3
Thin Films4-101-3
High-Build10-403-5
Self-Leveling50-1254-6
Polymer Overlay125-2505-10

CSP by Surface Prep Type

Choosing the right Concrete Surface Profile level is crucial for each application, whether it’s a polished floor, a coating system, or an industrial surface. Understanding CSP and its significance ensures that concrete surfaces meet the specific requirements for bonding, safety, and visual appeal, contributing to long-lasting and functional concrete structures.

Here is a guide to the different surface profile levels achieved through various surface prep techniques.

ApplicationCSP
Detergent Scrubbing1
Low-Pressure Water1
Acid Etching1-2
Grinding1-3
Sand Blasting2-5
Steel Shot Blasting3-8
Scarifying4-9
Ultra-High Pressure Water Jetting6-10

An Essential CSP Tool

CSP Chip Set by ICRI

The International Concrete Repair Institute offers chip sets that enhance your understanding of the surface texture associated with each of the ten Concrete Surface Profile levels. Integrating this chipset into your toolkit will not only facilitate effective training for your team but also enable your customers to recognize the superior quality of your floor preparation compared to competitors. You can purchase the set of 10 CSP chips without being an ICRI member, but ICRI members enjoy a generous 50% discount. To acquire this essential surface preparation tool, visit the ICRI website.

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