Unicem is a low density, high strength, shrinkage compensated, waterproof mortar for the structural repair, rendering and profiling of vertical, horizontal and overhead surfaces.

Unicem is a single component cementitious repair mortar which incorporates the most advanced cement chemistry, microsilica, fibre and styrene acrylic copolymer technology. This results in a rapid hardening, low density, high strength mortar with enhanced polymer properties. The thixotropic nature of the product enables easy high build trowel application for the structural repair of voids and the rendering and re-profiling of both vertical, horizontal and overhead surfaces. The product is supplied as a single component system ready for on-site mixing and use, requiring only the addition of clean water.

Advantages

• Incorporates the latest proven cement chemistry, microsilica, fibre and styrene acrylic copolymer technology.
• Pre-packaged material requiring mixing with clean water on-site to give an easily trowellable mortar with maximum application thickness of 80mm in vertical, horizontal and overhead situations.
• High bond strength exceeds tensile strength of concrete, thus ensuring monolithic performance of the repair.
• Dense matrix offers low permeability to water, even at 10 bar pressure, and very high diffusion resistance to acid gases and chloride ions.
• Resistant to sulphates to class DS-5/5m of BRE Special Digest 1.
• Improved tensile and abrasion resistance. Excellent low sag properties.
• Economic mortar generally requiring no substrate or inter-layer priming. Part bags can be mixed.
• Easily overcoated with specialist membranes to provide further protection and aesthetic quality.

Application

Preparation

Mechanically remove all damaged concrete or failed repairs back to a sound core. Except in new construction, expose the full circumference of the steel reinforcement 25mm behind the bars and 50mm beyond visible corrosion. On cutting back, feather edges must be avoided. Step the perimeter of the repair to a depth of 10mm preferably using a power chisel or by saw or disc cutting.

The areas to be repaired must be free from all unsound material including laitance dust, oil, grease, corrosion by products and organic growth. Smooth surfaces should be roughened and reinforcement cleaned to bright steel using wet grit blasting techniques or equivalent approved methods. Power tools such as a needle gun, angle grinder or wire brush may be used on concrete which is not chloride contaminated.

• The compressive strength of the parent concrete should be minimum 20 MPa.

The prepared substrate should be thoroughly soaked with clean water until uniformly saturated without any standing water.

Treatment of Steel Reinforcement

Treat exposed steel reinforcement with 2 x 1mm coats of STEEL REINFORCEMENT PROTECTOR 841 applied by brush.

Priming of Concrete

Unicem does not generally require a primer. Highly porous substrates may be primed with a POLYMER ADMIXTURE 850 slurry coat. The slurry coat should also be used when treating larger areas of waterproof concrete. Mixing Unicem should be mechanically mixed using a forced action pan mixer or in a clean drum using a slow speed drill and paddle.

A normal concrete mixer is NOT suitable. For normal applications, use between 3.3-3.7 litres of clean water per 25kg bag. For part bags, this equates to 5-6 volumes of powder to 1 volume of water. Typically, for high build applications use 3.5 litres of clean water per bag and mix for 2-3 minutes. Mix to entrain as little air as possible. Use without delay.

• Note - These instructions must be adhered to as Flexcrete will not be responsible for failure due to incorrect mixing.

Placing

Unicem can be applied by float or trowel in single layers up to 80mm. Shuttering may be required to allow for compaction if working to reveals. Care must be taken to ensure that an initial thickness of mortar, typically 5-10mm, is well placed and adhered before building up to larger depths. For multi-layer applications, it is important to ensure that previous layers are well keyed and stable but not fully set (typically 2-6 hours) prior to the application of subsequent layers. No inter-layer priming is required. Final profiling is achieved with a steel float.