INNOVATIVE shoring solutions from RMD Kwikform are being used to help keep Oman’s new $64-million Sultan Qaboos Mosque in Nizwa, on track while accommodating a change in programme sequencing.

In doing so, the combined strength of its Alshor Plus and Rapidshor equipment has been used, creating record-breaking shoring towers for the global formwork, falsework and shoring solutions provider.

The landmark mosque, which will be one of the largest in the sultanate, is being built by Carillion Alawi and is due to be completed next year.

The shoring towers have been erected in some parts of the structure up to 43 m tall, to support the casting of the dome, concrete slabs and beams, making up the main areas in the new mosque, which is funded by the Oman government.

The vast scale of the project required RMD Kwikform to deliver more than 1,200 tonnes of equipment to the Carillion Alawi site, which is 150 km southwest of Muscat.

Faced with a change in programme sequencing, which required both beams and slabs to be cast at the same time, engineers from RMD Kwikform designed an innovative solution to erect a run of Rapidshor shoring support inside the previously erected Alshor Plus birdcage, specified for the initial works. By combining the strengths of Alshor Plus and Rapidshor, Carillion Alawi was able to cope with the increased loading of the slab and beams construction sequencing, optimising the construction cycle for the project.

Commenting on the challenges, Carillion Alawi project manager Mohamed Tariq said: “With the top of the dome needing shoring support at a total height of 43 m and numerous concrete slabs at different levels making up the mosque, the key challenge for us was how to manage the safe erection of the shoring.

“Critically, we also had to be conscious of the distribution of loads throughout the project, to keep within the allowable working load of the RMD Kwikform equipment.

“Having worked with RMD Kwikform on numerous other projects in Oman, we were familiar with the high leg load capabilities of the product. So, for the initial sequencing for the project, we opted for this solution, with RMD Kwikform site staff supporting us with the system design and erection training.

“When we decided to change the sequencing as part of a fast-track programme, we looked to RMD Kwikform to help us design a revised solution that did not involve us dismantling the already majority erected Alshor Plus towers. Working with us, they analysed the additional pressures and came up with a solution to construct Rapidshor towers inside the Alshor Plus towers, bracing the two together to create a combined shoring tower structure.”

With both Alshor Plus and Rapidshor being modular systems, the Carillion Alawi site teams were able to quickly erect the tower structures safely, bringing forward the concreting element of the programme to meet the needs of the overall advanced programme time.

As part of the revised design of the structure and construction sequencing that included additional monolithic slabs – which had to be poured at the same time – RMD Kwikform engineers were faced with the need to install additional equipment without significantly restricting access.

Elaborating on the revised design and the project, RMD Kwikform regional sales manager Bellphine Campbell said: “With the changes made part way through the project, having calculated all of the loadings, we knew we could not release the loads in the Alshor Plus to strike these additional slabs. We, therefore, introduced a 900-mm-wide run of Rapidshor shoring that sat within the Alshor Plus birdcage support to distribute the loads and keep both systems within their loading capacities.

“In doing so, we also recognised the need to increase the size of the working platform, so we designed additional bays using Alshor Plus. To reach the 42-m top height of the dome structure, we literally put shoring on top of shoring, on top of shoring.

“Put simply, the first Alshor Plus birdcage tower arrangement was 12.5 m and 15.8-m tall. To save time and money on dismantling the Alshor Plus at this lower level, the next set of shoring combined Alshor Plus with Rapidshor, reaching from 18 m to 30 m to cast the beams and slabs at this height. This combination was required as the consulting engineers advised that additional concreting up to 46 m high would need to be cast without further striking of loads.

“With different segments of the structure requiring different shoring set-ups, like the two-level slabs next to the prayer hall, the shoring puzzle required a great deal of engineering and site support. But it was the dome that was the ultimate challenge. Rapidshor shoring, reaching a height of 17 m to the top of the dome was arranged at varying heights and adjusted using the systems jacks to support the curved structure of the dome.

“The Rapidshor shoring was founded on top of an Alshor Plus birdcage, a staggering 25 m high, erected from the main 5.5-m slab. In total, this created a record-breaking tower for RMD Kwikform, some 42 m tall.”

To enable the project to stay on track, even with the changes to the construction programme, RMD Kwikform managed to source additional equipment and deliver the new design solution without impacting on the programme time.

To support the project, an on-site team of RMD Kwikform customer service representatives was formed to provide further product training to the site operatives on the assembly of the Rapidshor within the existing Alshor Plus tables, making sure the process was carried out safely.