--- title: Why Premcrete Must Approve Your Concrete Mix Before Using Hydrocrete description: Premcrete's high-performance concrete additive requires formal sign-off. Why - and how? Discover more in our latest blog. image: https://insights.premcrete.com/hubfs/HYDROCRETE.jpg --- #### Insights # Why Premcrete Must Approve Your Concrete Mix Before Using Hydrocrete - - - - [mailto:?subject=Check%20out%20this%20article:%20why-premcrete-must-approve-your-concrete-mix-before-using-hydrocrete](mailto:?subject=Check%20out%20this%20article:%20why-premcrete-must-approve-your-concrete-mix-before-using-hydrocrete) - Michaela Rowland | August 6, 2025 When specifying [Hydrocrete](https://premcrete.com/products/premcrete-hydrocrete-admixture/), Premcrete's high-performance waterproof concrete additive, we require formal sign-off on your proposed mix design - even if it's already been developed by the structural engineer and ready-mix supplier. That's because achieving truly watertight concrete is not jut about what you add to the mix - it's about the mix itself.  #### Hydrocrete Mix Requirements - Explained  #### 1. Minimum 350kg/m³ Cementitious Content  This ensures a dense, durable matrix that supports low permeability and effective waterproofing.  - Well-graded aggregates are essential - The sand content must contain **at least 10kg/m³ of fines <75 microns** **![HYDROCRETE](https://insights.premcrete.com/hs-fs/hubfs/HYDROCRETE.jpg?width=373&height=373&name=HYDROCRETE.jpg)** #### 2. Blended Cements Permitted (e.g. GGBS, PFA) Hydrocrete is compatible with **blended cementitious materials**, including: - **GGBS (Ground Granulated Blast-furnace Slag)** – improves long-term durability - **PFA (Pulverised Fuel Ash)** – enhances workability and reduces heat of hydration Up to **70% GGBS** is permitted within the cementitious content. #### 3. Maximum Water-to-Cement Ratio: 0.43  A low w/c ratio is essential for waterproof concrete. Ratios above 0.43 increase porosity, cracking, and reduce long-term performance.  #### 4. Consistence Class S3 (BS EN 206) S3 workability ensures balance between flow and stability, ideal for watertight concrete with complex reinforcement and limited segregation risk.  #### 5. Crack Width Limitation **:** ≤ 0.3mm (BS EN 1992 Eurocode 2)  Even the best waterproof concrete won't perform if cracks are uncontrolled.  Your rebar design must limit crack widths to 0.3mm max, especially in large pours or water-retaining structures.  ![ADITL July 2.0-2 (2)](https://insights.premcrete.com/hs-fs/hubfs/ADITL%20July%202.0-2%20(2).jpg?width=366&height=549&name=ADITL%20July%202.0-2%20(2).jpg) #### Mix Submission Process To maintain full compatibility with Hydrocrete and meet BS 8102:2022 standards:  - Contractors must email the **Concrete Mix Design Certificate** from the ready-mix supplier to **[technical@premcrete.com](mailto:technical@premcrete.com)** - Premcrete will review and provide written confirmation - Any changes to the mix must also be resubmitted for sign-off #### Why We Take This Seriously  As the manufacturer of Hydrocrete, Premcrete assumes **design liability** when it's used as part of a project-specific waterproofing strategy. That means we stand behind: - The performance of your **watertight concrete** - The long-term durability of your structure - Compliance with all relevant UK and European standards **Quick Summary – Hydrocrete Mix Design Criteria** If you’re a contractor, supplier, or engineer — here’s the short version you need to follow: - **Min 350kg/m³** cementitious content with **well-graded aggregates** (Sand must include **≥10kg/m³** fines <75 microns) - **Blended cements allowed** (e.g. **GGBS**, **PFA**, OPC) - **Max water/cement ratio**: **0.43** - **Consistence class**: **S3** (BS EN 206) - **Crack width ≤ 0.3mm** (BS EN 1992) - **Submit your mix certificate** for approval to [technical@premcrete.com](mailto:technical@premcrete.com) before works begin Want it watertight? Let's get the concrete right.    [facebook-f icon ](https://www.facebook.com/profile.php?id=61556750189067) [youtube icon ](https://www.youtube.com/@premcreteltd/videos) [linkedin icon ](https://www.linkedin.com/company/premcrete-ltd/) ### Posts By Topics - [Insights (48)](https://insights.premcrete.com/tag/insights) - [Structural Waterproofing (11)](https://insights.premcrete.com/tag/structural-waterproofing) - [Gas protection systems (7)](https://insights.premcrete.com/tag/gas-protection-systems) - [Waterproofing membranes (4)](https://insights.premcrete.com/tag/waterproofing-membranes) - [waterproofing (4)](https://insights.premcrete.com/tag/waterproofing) - [Ground heave solutions (3)](https://insights.premcrete.com/tag/ground-heave-solutions) - [Civil Infrastructure Repair (1)](https://insights.premcrete.com/tag/civil-infrastructure-repair) [see all](https://insights.premcrete.com/why-premcrete-must-approve-your-concrete-mix-before-using-hydrocrete#) ### Latest articles [AI & Digital Twins: Inside The Shift Towards Smarter Basement Waterproofing Design](https://insights.premcrete.com/ai-digital-twins-inside-the-shift-towards-smarter-basement-waterproofing-design) [Understanding Waterproofing Compliance: Testing, Certification and Design Responsibility](https://insights.premcrete.com/understanding-waterproofing-compliance-testing-certification-and-design-responsibility) [How to Make Concrete Waterproof in Civil Engineering Projects](https://insights.premcrete.com/how-to-make-concrete-waterproof-in-civil-engineering-projects) [Introducing Premtrac 2.0: Built for Compliance, Built for Confidence](https://insights.premcrete.com/introducing-premtrac-2.0-built-for-compliance-built-for-confidence) [Retrofit Basement Waterproofing: Bringing Modern Protection to Older Structures](https://insights.premcrete.com/retrofit-basement-waterproofing-bringing-modern-protection-to-older-structures) ### Subscribe to our blog This is a search field with an auto-suggest feature attached. - There are no suggestions because the search field is empty. ## More Insights [![Understanding Waterproofing Compliance: Testing, Certification and Design Responsibility](https://insights.premcrete.com/hubfs/Premcrete%20Images-303.jpg) ](https://insights.premcrete.com/understanding-waterproofing-compliance-testing-certification-and-design-responsibility) ## [Understanding Waterproofing Compliance: Testing, Certification and Design Responsibility](https://insights.premcrete.com/understanding-waterproofing-compliance-testing-certification-and-design-responsibility) [Read more](https://insights.premcrete.com/understanding-waterproofing-compliance-testing-certification-and-design-responsibility) [![How to Make Concrete Waterproof in Civil Engineering Projects](https://insights.premcrete.com/hubfs/Premcrete%20Images-234.jpg) ](https://insights.premcrete.com/how-to-make-concrete-waterproof-in-civil-engineering-projects) ## [How to Make Concrete Waterproof in Civil Engineering Projects](https://insights.premcrete.com/how-to-make-concrete-waterproof-in-civil-engineering-projects) [Read more](https://insights.premcrete.com/how-to-make-concrete-waterproof-in-civil-engineering-projects) [![Introducing Premtrac 2.0: Built for Compliance, Built for Confidence](https://insights.premcrete.com/hubfs/image002.jpg) ](https://insights.premcrete.com/introducing-premtrac-2.0-built-for-compliance-built-for-confidence) ## [Introducing Premtrac 2.0: Built for Compliance, Built for Confidence](https://insights.premcrete.com/introducing-premtrac-2.0-built-for-compliance-built-for-confidence) [Read more](https://insights.premcrete.com/introducing-premtrac-2.0-built-for-compliance-built-for-confidence) [![Retrofit Basement Waterproofing: Bringing Modern Protection to Older Structures](https://insights.premcrete.com/hubfs/Taxi%20House-9.jpg) ](https://insights.premcrete.com/retrofit-basement-waterproofing-bringing-modern-protection-to-older-structures) ## [Retrofit Basement Waterproofing: Bringing Modern Protection to Older Structures](https://insights.premcrete.com/retrofit-basement-waterproofing-bringing-modern-protection-to-older-structures) [Read more](https://insights.premcrete.com/retrofit-basement-waterproofing-bringing-modern-protection-to-older-structures) [![The Future of Waterproofing Isn’t Passive. 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