Roundtower Marine P15 Mortar
Roundtower Marine P15 Mortar is a ready-mixed natural cement mortar developed for building, bedding, and pointing masonry in marine and water-bearing environments. Manufactured using Natural Cement and 5mm down sharp washed flint sand, it provides rapid strength development, high adhesion, and excellent resistance to washout, making it suitable for use both above and below the water line.
Marine P15 is the most widely specified mortar within the Cornerstone Marine range and is suitable for tidal zones, coastal structures, harbour walls, seawalls, bridges, and conservation projects. Unlike lime mortars, it does not rely on carbonation to harden, allowing it to perform in permanently damp or submerged conditions.
Technical Data
| Property | Value |
|---|---|
| Product Type | Ready-Mixed Marine Mortar |
| Binder | Natural Cement |
| Aggregate | 5mm Down Sharp Washed Flint Sand |
| Mix Ratio | 1 : 2 |
| Colour | Natural Tan |
| Application | External |
| Workability Time | Approx. 50 Minutes at 17°C |
| Yield | Approx. 14.5 Litres per 25kg Bag |
| Coverage | Approx. 1.5m² Pointing @ 10mm Depth |
| Compressive Strength | 21.8 N/mm² |
| Fire Rating | A1 |
| Standard | BS EN 998-2:2016 |
| Packaging | 25kg Bags |
Key Benefits
Water Resistant
Suitable for masonry exposed to regular wetting, tidal wash, and submerged conditions.
Rapid Set
Provides approximately 50 minutes working time before rapidly developing strength, helping reduce the risk of washout.
No Carbonation Required
Hardens hydraulically, making it suitable for permanently damp and underwater environments.
High Adhesion & Sulphate Resistance
Developed for demanding marine environments where durability and bond strength are critical.
Portland Cement Free
Contains no Portland cement, synthetic polymers, or pigments.
Typical Applications
| Application | Suitability |
| Sea Walls | ✓ |
| Harbour Structures | ✓ |
| Coastal Masonry | ✓ |
| Tidal Zone Repairs | ✓ |
| Lock Walls | ✓ |
| Bridge Masonry | ✓ |
| Marine Pointing | ✓ |
| Submerged Masonry | ✓ |
| Conservation Projects | ✓ |
Why Use Marine P15?
Marine P15 is designed for situations where conventional lime mortars may be vulnerable to washout and where masonry is exposed to frequent or continuous water contact.
Its combination of rapid setting, water resistance, sulphate resistance, and high adhesion makes it particularly suitable for marine construction and repair work, especially where work must be completed within tidal windows or where masonry may become wet shortly after application.
Installation Overview
1. Surface Preparation
Substrates should be clean, sound, and free from loose material.
2. Mixing
Mix with clean water or clear seawater free from biological contamination, silt, and sand.
3. Application
Suitable for pointing, building, and bedding in marine and water-bearing masonry applications.
4. Protection
Do not apply below 5°C or above 30°C. Protect fresh work from frost, heavy rain, direct sunlight, and drying winds.
5. Storage
Store dry, covered, and protected from moisture and frost.
