Fully waterproof natural cement mortar for aggressive marine environments above and below the waterline (incl. tidal/scour zones).
What it is
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Dry, ready-mixed Prompt Natural Cement with selected natural sands — no Portland cement, no synthetic polymers, no lime (so no carbonation phase).
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The first fully waterproof mortar in the Roundtower Marine range, designed for rapid strength development and an accelerated fast set.
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Formulated to be more flexible than typical OPC mortars at similar strength, with high adhesion to reduce debonding risk and natural sulphate resistance.
Performance at a glance
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Working/open time: ~48 minutes at 17 °C (ambient and substrate suction dependent).
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Fast initial set + high early strength to resist washout and scouring.
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Waterproof in service; choose where zero permeability is required.
Selection guide:
• Need water-resistant but not fully waterproof? Choose P30.
• Need fast-set with NHL binder? Choose LP6 / LP8.
• Need cement-free, slow set above water? Choose L4.
Suitable applications
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Pointing and bedding of quay and harbour walls, bridge abutments, revetments, lock chambers, culverts, coping stones in saltwater or freshwater.
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Tidal and submerged zones demanding full waterproofing, robust durability and reliable early set.
Coverage & yield
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25 kg → Approx14.5 L fresh mortar.
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Approx. 1.5 m² of joint at 10 mm depth (actual yield varies with joint width/depth and substrate texture).
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On-site trials recommended to confirm consumption.
Application essentials
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Preparation: Rake out to sound arrises; remove salts/bio-growth; pre-dampen.
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Mixing: Add clean water gradually to a cohesive, plastic consistency; do not over-water. Discard material that has begun to set.
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Placing/finishing: Compact fully to the back of the joint; finish when the mortar begins to firm.
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Curing & protection: Protect from frost, rain, direct sun, drying winds and washout through initial set; maintain gentle curing.
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Temperature window: +5 °C to +30 °C (consider wind-chill/radiant heat). Avoid use if freezing is forecast during early cure.
Colour & batching
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Natural, pigment-free tan; final tone varies with curing and exposure. Custom colours not available.
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For colour-critical projects, request curing guidance and order sufficient material from a single batch.
