RKF Engineering Services was engaged by our client during the construction phase of two 1 km deep mine shafts in Canada. Our client had discovered that there were cracks developing in the temporary shaft lining above the boring machine during the initial works. Our brief was to inspect the lining, determine the root cause of the cracking and propose changes to the construction to eliminate further cracking. 

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 due to 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 liner construction was changed to formwork and cast in situ concrete using a high durability, high flow, high strength concrete.

The new mix designs achieved the strengths required for design, the batching and delivery of the concrete increased to a much faster pace and the quality of the overall construction improved. The shaft is now complete with both the temporary liner and final liner being completed with no defects related to concrete mix design, delivery and placement. 

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