SBR

Technical Specifications

SBR is typically supplied as a milky white liquid. When mixed with cement, it creates a co-matrix that reinforces the structure.

Solids Content: Usually between 30% and 50%.

Specific Gravity: Approximately 1.01 to 1.05.

Bond Strength: Can increase the bond strength of cementitious mixes by up to 200-300%.

Flexural Strength: Significantly improves the ability of the mortar to bend without cracking.

Freeze/Thaw Resistance: High; it creates a closed-cell structure that prevents water from entering and expanding.

Key Descriptions & Uses

1. Adhesion & Bonding (The "Slurry" Coat)

One of the most common uses for SBR is as a bonding agent. When mixed with neat cement to create a "slurry," it acts as a powerful glue between old concrete and new screeds or renders. Unlike PVA (another common adhesive), SBR is waterproof and will not re-emulsify when wet.

2. Water Resistance

SBR reduces the permeability of cement. This makes it ideal for:

Tanking and waterproofing underground structures.

Swimming pool renders.

External wall renders exposed to heavy rain.

3. Flexibility and Durability

Standard cement is brittle. Adding SBR introduces a rubberized component into the mix, allowing the mortar to withstand thermal expansion and minor structural movements. This is why it is often added to tile adhesives for "large format" tiles or floors with underfloor heating.

4. Chemical Resistance

While not as "bulletproof" as epoxy, SBR-enhanced mortars offer improved resistance to mild acids, alkalis, salts, and mineral oils compared to standard concrete.

Application Ratios

The "mix" depends on the intended use:

SBR vs. PVA: The Critical Difference

SBR: Waterproof. Use for showers, bathrooms, external walls, and swimming pools.

PVA: Water-soluble. Use only for internal, dry applications (like priming a bedroom wall for plastering). Never use PVA for tiling in wet areas, as the moisture will cause the bond to fail.