What can we help you with?
Technical flooring, delivered directly
- ESD flooring, urethane cement, terrazzo, and polished concrete
- In-house W-2 installation crews and experienced field leadership
- National service coverage with project-specific staffing plans
- Testing, documentation, and defined project closeout
- Dedicated support for corporate procurement and multi-site contracting
Phone: +1 (844) 687-1961
Concrete Mix Specifications
Specify the performance the concrete must achieve, then check that the selected polishing system and its warranty fit those requirements. A project design standard, a manufacturer’s mix recommendation and a warranty limit serve different purposes—even when they discuss the same materials.
GSA’s P100: Facilities Standards for the Public Buildings Service, May 2024, the RetroPlate mix guide and Ashford Formula warranty illustrate the distinction. Check these requirements and recommendations together during preinstallation coordination, before finalizing the concrete and polishing scopes.
Distinguish performance requirements from mix prescriptions
For projects governed by GSA P100 (May 2024), §3.3.5 requires performance-based concrete specifications. It identifies properties such as:
- Compressive strength and the time allowed to achieve it.
- Shrinkage.
- Exposure class under ACI 318 durability requirements.
- Modulus of elasticity, where applicable.
The same section prohibits prescribing constituent-material content, including cement content, water-cement ratio, supplementary cementitious material (SCM) content and aggregate gradation. It also requires specifications to allow ASTM C150, C595 and C1157 cements that meet ACI 318.
The cited section does not resolve how appearance-driven aggregate selection is treated. Our guide to cement, SCMs and admixtures in appearance specifications covers the related material decisions.
Read manufacturer figures according to their purpose
| Source | Published figure | What it means |
|---|---|---|
| RetroPlate mix guide | At least 4,000 psi (28 MPa) at 28 days | Recommended concrete strength for the RetroPlate system. |
| RetroPlate mix guide | Suggested water-to-cement ratio of 0.45 | A recommendation, not a stated mandatory maximum. The guide calls for as little water as possible while keeping the mix workable. |
| RetroPlate mix guide | Listed cement-replacing products should total no more than 10% of the portland cement volume | System-specific mix guidance. The guide discourages plasticizers, slag, fly ash and other cement-replacing products; if used, it gives this limit and says they should not be calcium chloride based. |
| Ashford Formula limitations | More than 15% total combined pozzolanic materials relative to total cementitious material | The stated warranty is limited to hardening and dustproofing above this threshold. This is a warranty condition, not a mix-design prohibition. |
The percentages are not interchangeable. RetroPlate uses portland cement volume as the denominator. Ashford Formula refers to total cementitious material and describes a change in warranty coverage.
The strength and readiness guide addresses when concrete is ready for polishing. The warranty-scope guide explains how product coverage differs from broader performance or service-life claims.
Resolve conflicts before adding manufacturer recommendations
On a GSA project governed by §3.3.5, copying RetroPlate’s water-cement ratio or constituent-content recommendation into the concrete specification would conflict with the restriction on prescribing mix constituents. Turning Ashford Formula’s warranty threshold into a mandatory mix-content limit would create the same problem.
Compressive strength at a stated age is different: both strength and time to achieve it are named performance properties under the GSA provision. RetroPlate’s 4,000 psi at 28 days remains that manufacturer’s recommendation, rather than a universal minimum for polished concrete.
Project Gallery
Frequently Asked Questions
No. The RetroPlate recommendations concern its polishing system, while the Ashford Formula percentage is a warranty limit. Neither becomes a general industry requirement simply because it concerns concrete intended for polishing.
No. RetroPlate’s figure uses the portland cement volume. Ashford Formula’s threshold concerns total combined pozzolanic materials relative to total cementitious material; above 15%, the stated warranty covers hardening and dustproofing only.
No. The guide describes 0.45 as a suggested ratio and recommends using as little water as possible while keeping the concrete workable. It does not state that value as a mandatory maximum.
Polished Concrete Knowledge Center
Resource links
Performance & Safety
Design & Aesthetics
Installation Guidance
Economics & Sustainability
Maintenance & Aftercare
Comparative & Decision-Making
Blog
Craftsman Publishes 2026–2027 ESD Flooring Technical Guide
ESD Epoxy Flooring Case Study: 34,000 SF Dallas, TX
