RKF Engineering Services was engaged by our client, a Canadian mining company, during the construction phase of two 1km deep mine shafts in Canada. Our client had discovered that there were cracks developing in the temporary shaft lining.

Our brief was to inspect the lining, determine the root cause of the cracking and propose changes to the design and/or construction methodology to eliminate further cracking.

With our extensive experience in concrete technology, RKF Engineering Services was well positioned to assist on this project.

Our initial inspection found that the root causes of the cracking were: the effect of frozen ground on the lining before the concrete set; poor concrete mix design to deal with the ambient conditions; and poor curing of the lining.

RKF Engineering Services worked with the client and contractors and audited the entire concreting process – from the batch plant to the site – and provided advice and direction to improve the concrete mix design, batching, delivery and curing. As part of the work, the initial shotcrete construction was changed to formed cast in situ concrete using a high durability, high flow, high strength concrete.

We also introduced thermal maturity strength technology that allowed the actual strength of the shaft liner to be determined in time via match cured cylinders.

From the work done, the new mix designs are achieving the strengths required for design, the batching and delivery of the concrete is now occurring at a much faster pace and the quality of the overall construction has dramatically improved. The shaft is now being constructed at approximately 9 times the speed of the old construction and no further damage of the lining has been reported.

For further information on this project or in general, send us an email or phone +61 2 4225 7519.