Gulf Construction Online - RMD Kwikform takes on Omani challenge

Scaffolding & Formwork

RMD’s formwork solutions have been successfully used on a fertiliser plant in Oman.

RMD Kwikform takes on Omani challenge

01 December 2005

Formwork solutions and expertise from the Sharjah-based formwork specialist RMD Kwikform Middle East have helped overcome some of the challenges involved in the construction of a $968 million fertiliser plant in Oman.

Due for completion shortly, the plant for Omifco (Oman-India Fertiliser Company) will produce around 1.6 million tonnes of bulk-granulated urea and approximately 250,000 tonnes of surplus liquid ammonia a year.
Elaborating on the challenges brought about by the project, Denis Jayes of RMD Kwikform Middle East says: “Two of the challenges faced by the contractors called for specialist falsework and formwork expertise. The first was the need to provide a heavy-duty support solution for the precast concrete rafters and apex sections for the huge urea storage building. This needed to be quick to implement, easily moved and readily reusable on this and future projects. The second challenge called for devising formwork solutions that would be equally swift and effective to implement for the construction of walls and columns.
“With the relative remoteness of the site and the need to ensure prompt availability and implementation of the falsework and formwork solutions, there was an understandable attraction to seek solutions that utilised standard, readily available, ex-stock components. So RMD Kwikform engineers in the company’s Middle East head office in Sharjah in the UAE devised solutions that, predominantly, relied on three of its most proven and versatile systems; Super Slim Soldiers, Alform aluminium beams and Rapid Bar Tie connectors.”

Mobile-tower beam support
“Ingenuity and simplicity are the hallmarks of the solution that was devised to support the 23-m long precast concrete rafters and the 6.3-m-legged triangular precast concrete apex sections that were used to construct a series of twin concrete portal frames for the urea storage building.
“RMD Kwikform engineers designed a falsework support structure that measured 56.82 m across and stood, at its apex, some 24 m high, which was moved – in sections - from frame position to frame position on heavy-duty skates that ran on simple flat bar rails. This high-load capacity structure was constructed almost entirely of Super Slim Soldiers uprights, ledgers and braces - the only purpose-made components being the two structural-steel rafter support assemblies at the outer eaves positions, the structural-steel rafter support assembly at the gully position where the two portal frames meet, and the structural-steel apex panel support assembly.
“The urea storage building’s falsework support structure supported the weight of a pair of twin 40-degree portals, which are spaced seven metres apart. It had five main mobile elements: the two outer or “end” support mobile towers, the gulley or “mid” support mobile tower, and two apex or “centre” support mobile towers, all of which were connected together using Super Slim Soldiers as ledgers and braces. When the eight rafters and four apex section making up each pair of twin portals had been craned into position and the in-situ jointing had cured, the individual tower sections were moved along the flat bar rails to the next pair of twin portal positions.
“The outer mobile towers and the gulley mobile tower that, on plan, measured approximately 9 m by 9 m were positioned alongside the concrete kicker walls that stand approximately 7.87 m high. The apex mobile towers measured around 15.0 m by 11 m on plan and were approximately 18.6 m to the underside of the structural-steel apex support frames.
“To facilitate their relocation, quick-release pivot connections were built into the Super Slim Soldier framework ledgers that connected the individual mobile towers. These connections were positioned midway between the outer towers and the apex towers, and midway between the apex towers and the gully tower, to enable each tower to be independently relocated.”

Wall and column formwork
He continues: “Such is the versatility of the Super Slim Soldier system that it was also extensively used to provide the double-sided formwork for the walls of the receiving basin weir boxes and columns on the fertiliser plant project. The system was used in conjunction with RMD Kwikform’s Alform aluminium beams as the secondary bearers and the Rapid Bar Tie system to tie together the two formwork faces.
“Typically, the walls are 15.75 m high and taper on one face from 1.4 m at their base to 700 mm at the top. The vertical formwork face was assembled to its full height and was supported by raking Super Slim Soldiers that attached to the vertical sections and ground-level base plates using adjustable prop jacks. The concrete was placed in three pours of 8 m, 2.85 m and 4.9 m, with the Super Slim Soldier formwork on the sloping face of the wall being crane-lifted into position for each successive pour.
“The 8.2-m high columns are one metre square and the formwork comprises horizontal Super Slim Soldiers at approximately 1.3-m centres, with Alform vertical secondary bearers. Again, the formwork was held in place using Rapid Bar Ties.
Work on the new world-scale fertiliser plant being built for Omifco – 50 per cent owned by Oman Oil Company – started on site in 2002. Construction work is being undertaken by a joint venture involving CCIC (Consolidated Contractors Group), Snamprogetti of Italy and Technip-Coflexip of France, and the plant comprises two ammonia production trains, each with a capacity of 1,750 tonnes a day, and two urea production trains each with a daily capacity of 2,530 tonnes.

Dam project
Meanwhile, RMD Kwikform Middle East’s formwork engineering is also playing a major role in the construction of tunnels and the vertical shaft for the new $44 million Chabrouh Dam currently being built near the ski resort of Faraya in the Kesrwan district, north of Beirut.
The French specialist civil engineering company, Duzem-GTM, part of the Vinci group, and Lebanon’s Moawad-Edde construction company are building the dam, utilising fast-track construction techniques.
“The formwork solutions had to be sufficiently sophisticated to meet the project's technical demands while meeting the tight time, cost and manpower constraints,” says the spokesman.
To achieve these goals, RMD Kwikform developed solutions that included four purpose-designed and built mobile tunnel forms. These were moved on high-load-capacity skates that ran on rails. These forms ranged in size from 2.3 m wide by 3.0 m high, up to 4.0 m wide by 4.5 m high. The solutions package also included special self-supporting formwork for the dam’s 7.5-m diameter vertical shaft.
The tunnels at the Chabrouh Dam are horseshoe shaped with a flat base, however, the shape and geometry of each tunnel differs so much that RMD Kwikform engineers produced shuttering solutions that were tailored to each tunnel.
“Typically, each mobile tunnel form comprised steel shutter sections that were manufactured to match the precise shape of the tunnel. These were hinge-jointed one to another, allowing the two lower sections of shuttering to be released once the concrete tunnel liner had cured,” the spokesman explains. “A steel frame that was mounted onto RMD Kwikform’s proprietary Megashor hydraulic jacks supported the upper section of shuttering. These jacks enabled the top section of shuttering to be lowered from the concrete face, so allowing the form to be moved forward to the next concrete pour position, as the entire load of the 4-m long shuttering and support framework was transferred to the skates.
“The formwork for the 7.5-m vertical shaft utilised an entirely different technique. This time the formwork was crane-lifted from the bottom of the shaft; it was self-supporting throughout the concrete pouring operations, using what are known as click-clack brackets – sometimes spelt klik-klack – that were mounted on an internal formwork platform.
“The formwork was supported off click-clack pockets or shoes that were anchored to the cured concrete lining below the level where the concrete was currently being poured or was curing. As the formwork was raised – in the Chabrouh Dam’s shaft’s case, in 3-m intervals – the click-clack brackets disengaged from the pockets, and re-engaged in the brackets at the new higher level. Once the form had progressed sufficiently up the shaft – to the third pour – an access platform was suspended below the main formwork deck to enable the now-redundant click-clack pockets to be removed,” he adds.
While participating in some of the challenging projects taking shape in the region, the Sharjah RMD Kwikform continues to boost its range of product and has recently enhanced its lightweight Alshor aluminium shoring system with the introduction of a new system – Alshor Plus.
“In addition to an increase in the safe working load leg capacity from 80 to 100 kN per leg, the re-engineered Alshor Plus promises greater versatility, enhanced safety and improved on-site productivity and speed of construction,” says a company spokesman.
“The new fully-integrated Alshor Plus system can easily be combined with primary and secondary beams to provide effective and cost-competitive support to soffit formwork, and can be used for a range of applications that include: static slab support and mobile tables, towers and high-reach birdcage assemblies, props and back propping and flying tables," he adds.
"Available worldwide alongside the original Alshor – the new high-load capacity system boasts a number of new and improved components, accessories and features. In-house tests comparing Alshor Plus with the other leading systems currently on the market also show that Alshor Plus is clearly the fastest to erect and the easiest to in-situ modify, reducing site delays and cutting construction costs,” he claims.
The spokesman continues: "Variable ledger frame positions and a greater propping range ensure improved high- and low-level support, while an extended selection of short and long jacks further boost the system's flexibility. A simple, single action connects and secures all four blades simultaneously, making Alshor Plus the fastest frame to erect.
“In addition, the fact that it requires the minimum number of loose parts also makes a significant contribution to the system's cost effectiveness. Alshor Plus incorporates a number of safety features such as aluminium/ply access platforms, integral ladder access, and ledger frame pockets at 500 mm centres that allow the use of additional handrails.
“The many design features introduced with Alshor Plus include the use of aluminium spigots to provide fast and secure outer leg to outer leg connection, and blade-and-pocket connection between the legs and frame, which allows the frame to be installed or removed while assembled. Other innovations include extended grooves in the long screw jacks that self-clean the jack, making adjustment quick and easy, and the availability of Alshor Plus trolleys for the easy relocation of soffit tables. However, for all its added appeal, Alshor Plus retains the original system’s inherent simplicity.
The company has also released a detailed brochure of the system that details all of the major components of the system, in addition to illustrating a number of the projects on which the system has been used.
RMD Kwikform is part of an international network of RMD Kwikform companies located throughout Europe, the Middle East, Asia Pacific, Australasia and South America. It provides customer-focused formwork and falsework solutions either on a hire or sale basis.