The Challenge
At Christchurch University in 1998, the tanking system in the basement of the eight-storey Maths & Science Building had failed. Groundwater levels were above the height of the basement, as the site adjoins a small watercourse called Ilam Stream; and pressure seepage was increasing at a significant rate.
With four “six inch” de-watering pumps operating, the basement floor was still largely covered with water, and water was seeping in through cold joints in the walls and lift shafts up to nearly 2 metres above the floor level.
The urgent objective was to arrest this water ingress and permanently prevent reoccurrence.
Solution and Results
Water was squeegeed away to apply MARKHAM’s original concrete colloidal silica treatment, via atomized spray. Additionally, the main construction joints and about 250 metres of cracking (an overall total of approximately 1200 lineal metres) were injected with a waterswellable sealant.
The success achieved was not only to stop water ingress as a liquid but also to prevent the ingress of water vapour. This second point relates to the subsequent installation of vulnerable resilient sheet flooring, carpet, and flooring tiles. These were installed using typical flooring adhesives, which quickly disintegrate when exposed to moisture and therefore must be protected from moisture vapour.
The MARKHAM team re-visited the site in 2009 to assess its current condition, and found it in successful use as classrooms and library.
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This was one of MARKHAM’s earliest waterproofing projects, and a direct result of the success of this remediation was our research team’s realization that the same principles could be applied to new construction work. This ultimately led to the development of our BASE-TECT® basement and TOP-TECT® roof deck multi-part waterproofing systems.
A more detailed case study on this project is available here.
Like to know more? Constructing a new concrete basement? Get in touch, we’re keen to chat!
