Peri Trio wall formwork proves itself on Umlaas Trunk sewer extension

One of the Umlass Trunk Sewer Extension pipe bridges with the Trio formwork in place for the last pour.

Contract Manager Syd van Schoor
  • Contractors: Murray & Roberts Construction & Makhuba Civils
  • Contracts Manager: Syd van Schoor
  • Consulting Engineers: Stewart Scott
  • Client: Ethekwini Metro Waste Water Services

The construction of two pipe bridges on the Umlaas Trunk Sewer Extension contract outside Durban was causing headaches for contractors Murray & Roberts Construction and Makhuba Civils until Peri Wiehahn stepped in to provide a cost-effective formwork solution.

The contract called for the construction of two pipe bridges across the Umlaas River and stipulated that these should do double duty by acting as foot bridges across the river for the benefit of the communities living in the surrounding areas.

Murray & Roberts Contract Manager Syd van Schoor explained that the design of the two bridges called for them to be cast in concrete with sewage pipes running through their middles preventing tie-rods from being used to help support the shutters on the sides of the bridges.

After being called-in to suggest a solution to the problem Peri Wiehahn Durban Branch Manager Gerhard Moll recommended that the Peri Trio Wall Formwork System be used with the bridge sides being formed by two shutter panels supported at the join with compensating steel walers and tie-rods being used only above and below the bridge structure.

The contractors took the decision to implement the suggestion and ordered two sets of Trio Formwork components to enable the construction teams to work on both bridges simultaneously. The formwork was delivered to the site shortly afterwards and an immediate on-the-job training programme was instituted for the construction team by Peri Wiehahn’s Durban Branch staff.

Mr van Schoor said that his first impression of the Trio System was how much faster it was to erect than conventional formwork systems due to the fact that it requires far fewer elements such as couplers and tie-rods. The system’s simplicity was also instrumental, he said, in minimising training time and allowing its use by unskilled and semi-skilled labour.

An eye-opener for Mr van Schoor was how effective the self-aligning feature built into the system was with the alignment of the shutters taking a fraction of the time that would have been required if conventional formwork had been used on the job.

The bridge contractors had another very pleasant surprise in store when it was found that the system allowed them to erect and strip the formwork so rapidly once it was gang-formed that they were able to return one set of components to Peri Wiehahn for credit and shuttle the other set between the bridges using a mobile crane.

The mobile crane was disabled just before it was required to move the formwork from one bridge to another for the pouring of the final span but it took only one extra day to move in spite of the fact that the forwork had to be completely dismantled, moved to the other bridge and re-erected.

Another very impressive feature of the Trio System, according to Mr van Schoor, was the very high quality of the off-shutter finish provided by the system with that on the sides of the bridges being markedly better than the bridge soffits and other areas where conventional formwork was used.

Mr Moll explained that the Trio shutter panels are lined with a phenolic resin-coated plywood which provides an extremely high quality finish to concrete and that this is enhanced by the fact that the BFD coupler fastens the panels together so securely that the joints are grout-tight thus ensuring that the finish obtained is of the highest possible quality.

The contractors on the Umlaas Trunk Sewer Extension project have joined the growing list of Peri Wiehahn clients in South Africa who have found that, by using Peri products, they can save up to 50% of the time they would have needed if they had used conventional formwork systems. According to Mr Moll the ease of use of the Peri products makes for much faster cycle times which has a positive impact on the speed at which contracts are completed and thus lead to major reductions in costs.



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