Problem: Protecting the property from water damage
As part of the major Watsonia RSL redevelopment, the project management team required a high-performance primary defense system for the site’s sub-structure. The design necessitated a robust, positive-side waterproofing solution for the new retaining walls to prevent groundwater ingress and long-term structural degradation. The core challenge was to implement a membrane capable of withstanding significant hydrostatic pressure, ensuring this community asset remains dry and durable for decades to come.
Symptoms identified
- Hydrostatic pressure: New retaining walls were exposed to high groundwater levels and sub-grade pressure.
- Ingress risks: Vulnerable construction joints and junctions required sealing prior to backfilling.
- Long-term degradation: Risk of chloride ion attack and reinforcement corrosion without a primary defense.
Urgency factors
- Backfill deadlines: Waterproofing and curing had to be completed within a strict window to maintain the redevelopment schedule.
- Remedial prevention: Crucial “right-first-time” application to avoid expensive repairs post-completion.
- Optimal bonding: Immediate treatment was required to ensure the positive-side membrane bonded perfectly to the new concrete.
Solution: Positive-Side Waterproofing
This approach is the industry gold standard for below ground waterproofing, as it prevents moisture from entering the concrete substrate entirely. By creating a continuous external barrier, we ensured the sub-structure was protected against hydrostatic pressure, a common requirement in high-end commercial basement waterproofing projects.
Recommended solution
To address the risk of water ingress at the Watsonia RSL, we recommended a multi-layer, positive-side retaining wall waterproofing system.
Materials and methods
We utilised a high-performance ARDEX system, specifically engineered for durability in damp, sub-grade environments:
- ARDEX WPM 300: A water-based epoxy primer used to create a structural fillet at the footing-to-wall junction.
- ARDEX WPM 157: A heavy-duty membrane applied in two coats.
- ARMA-BLUE Protection Board: An impact-resistant layer installed to prevent damage during the backfilling process.
Implementation process
- The project was completed over four days to ensure membrane integrity.
- Surface Preparation: Mechanical cleaning of the concrete to ensure a sound, contaminant-free substrate.
- Detailing & Priming: Installation of a fillet and dual-coat priming to eliminate potential leak points at the wall-to-floor junctions.
- Membrane Application: Systematic application of the WPM 157 membrane, with monitored cure times between coats to ensure a seamless seal.
- Protection & Sign-off: Installation of ARMA-BLUE board followed by a final quality inspection.
Challenges Overcome
- Strict Timelines: With backfilling scheduled immediately after our work, we managed the application and curing schedule to ensure the retaining wall waterproofing was fully cured and protected before soil was introduced.
- Environmental Factors: We carefully monitored site conditions to ensure the positive-side application achieved an optimal bond with the new concrete, essential for long-term basement waterproofing success.
Results
Full Compliance: Delivered a primary defense system that met all manufacturer specifications and project requirements for the Watsonia RSL redevelopment.
Certified Protection: Issued a 5-year warranty certificate, providing the client with long-term peace of mind regarding structural dryness.
Project Efficiency: Completed the four-day application process within the necessary timelines to allow subsequent trades to proceed without delay.
Long-term benefits
- Structural Longevity: Prevents “concrete cancer” and reinforcement corrosion by shielding the substrate from moisture.
- Preventative Protection: Eliminates the need for disruptive and costly retaining wall waterproofing repairs in the future.
- Asset Value Retention: Keeps the sub-structure dry and healthy, protecting the capital value of the Watsonia RSL redevelopment.
- Certified Security: Documented peace of mind with a 5-year warranty and a comprehensive Post-Installation Report.
- Mitigated Liability: Ensures a “right-first-time” below ground waterproofing solution for a high-traffic community space.
Service: Retaining wall waterproofing, positive-side, protection installation.
Application: ARDEX WPM 300 epoxy, ARDEX WPM 157 liquid membrane, ARMA-BLUE protection board.
Solution: Waterproofing a 24m2 retaining wall on the positive side. Utilising a high-performance ARDEX system to protect substructure against hydrostatic pressure.
Time to complete: Four days.
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