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Mastermix HSR

Ultra-Fast Setting, High-Strength Concrete Repair Compound

HSR is a high-performance repair compound designed for rapid setting and early strength gain. Acid-resistant and trowelable to a feathered finish (when used with Multi-Cote as a primer), HSR is ideal for demanding applications where speed and durability are critical.

Key features:

Very Fast Setting: Sets in just 7 minutes, ideal for urgent repair situations.
High Strength: Achieves 20 MPa compressive strength in 3 hours for rapid load-bearing capacity, and up to 50 MPa in 28 days, providing long-term durability.
Water Plug Capability: Can be mixed into a putty for use as a rapid-setting water stop.
Easy to Mix: Requires only 200 mL of clean water per 1 kg of product.
Flash Setting: Rapid heat generation indicates readiness for placement.
Pre-blended Formula: Contains correct levels of plasticizers and additives—no additional materials needed.
Complies with NZ Standards: Designed to meet NZS 4201:2001 Code of Practice for Masonry Construction.
Suitable for: resetting hinge pins and bolts, concrete repairs (pre-stressed & reinforced), pipe and kerb repairs, water plugging in active leaks, raising manhole lids quickly.

HEALTH & SAFETY

HSR is cement-based and free from aggressive chemicals. Avoid excessive skin contact, eye contact and swallowing. Freshly mixed concrete or mortar may cause skin irritations including alkaline burning and dermatitis. Avoid contact with skin by wearing suitable clothing and gloves. In the event of contact with skin or eyes, rinse thoroughly with water. If swallowed drink plenty of water and induce vomiting. If irritation persists seek medical advice.

MIXING & APPLICATION

Measure 200mls of clean water to 1kg of HSR in a clean container. Mix thoroughly, ensuring the water is mixed evenly through the product. If necessary, add small amounts of water to achieve the desired consistency. Once placed and finished DO NOT REWORK.

For use as a water plug: Mix with less water, and knead by hand to the consistency of putty and the product gets very warm, then plug the hole. The product will ‘Flash’ set.

IMPORTANT

Mix only what is needed to effect repairs, this product sets in 7 minutes.

HSR contains the correct levels of plasticizer, adding extra plasticizer may reduce the bonding strength of the mixture. HSR is designed to meet NZS 4201:2001 Code of Practice for Masonry Construction. Once product has been placed and finished off, do not rework as this may affect the final setting time.

The surfaces where HSR is to be used should be clean, sound, and free from dust, oil, grease and loose particles.

WARRANTY

Warranties may be offered, subject to project assessment and application by a MasterMix-approved applicator.

Disclaimer: Technical details and recommendations are based on our best knowledge and experience. The user must ensure suitability for the specific project before application, and is fully responsible for the product’s use and its consequences.

TECHNICAL DATA

Compressive Strength	• @ 3 hours: 20 MPa • @ 24 hours: 30 MPa • @ 28 days: 50 MPa
Flexural Strength	5 MPa
Shrinkage	>0.05%
Acid Resistance	Excellent. No degradation after 56 days at pH 3.5, 45°C
Application Temperature	Between 7°C and 25°C
Set Time	7 minutes @ 16°C
Shelf Life	3 months (stored in cool, dry conditions)