Gulf Construction Online - Rolling out a solution

Concrete Technology

Al Wathba Wetland Nature Reserve ... CC used to provide effective erosion protection to the slope.

Rolling out a solution

Described as ‘concrete on a roll’, geosynthetic cementitious composite mats (GCCMs) provide a range of benefits over their counterparts including ease and speed of installation, safety, environment-friendliness and durability, says Concrete Canvas.

01 September 2020

A revolutionary class of innovative materials called geosynthetic cementitious composite mats (GCCMs) have been proving to be quick and durable solutions to erosion control and containment problems worldwide over the past decade.

In the Gulf region, the UK-headquartered Concrete Canvas (CC) has been making significant inroads by providing solutions for diverse projects ranging from nature reserves to industrial facilities.

Its eponymous product, created specifically for erosion control, containment and shelter applications, is a flexible, concrete-filled geosynthetic that provides a thin and durable concrete layer when hydrated.

“Typically, 10 times faster to install than conventional concrete solutions, it is essentially concrete on a roll,” Samer Hasan, Business Development Manager – Mena Region, tells Gulf Construction.

Among the most striking projects completed recently in the region is the Al Wathba Wetland Nature Reserve in Abu Dhabi, UAE.

The composition of a Concrete Canvas installation.

Concrete Canvas’ GCCM was used to line sections of embankments on a slope in the reserve in December 2018.

The developers of the project were seeking a solution that would provide effective erosion protection to the slope in order to prevent further scour. In addition, the project was required to be completed ahead of the rainy season, according to Hasan.

“Shotcrete was initially considered but it would require specialist equipment and labour as well as extending the installation time, which could affect the nature reserve,” he points out.

Hence, GCCMs were chosen as the solution.

Highlighting the speed at which the project was implemented, Hasan states that a total of 1,600 sq m of the company’s CC5 product was installed by four people in five days.

The CC5 GCCM selected for the Al Wathba Wetland Nature Reserve project consists of a three-dimensional fibre matrix containing a specially formulated dry concrete mix. A PVC backing on the rear surface provides waterproofing capability.

“CC5 is supplied in a flexible roll format (like most geosynthetics) which is deployed and hydrated, setting the cementitious material and creating a concrete layer which provides a hard-wearing surface to prevent erosion and reduce water loss. GCCMs can be hydrated by spraying or by fully immersing in fresh or saltwater. Once hydrated, the GCCM has a one- to two-hour working window before setting and will harden in 24 hours,” he says.

A total of 1,600 sq m of CC5 was installed by four people in five days at the nature reserve.

Once set, the geosynthetic fibres in the GCCM reinforce the concrete, preventing crack propagation and providing a safe plastic failure mode, to create a thin, durable, waterproof and low-carbon concrete layer.

Elaborating on the installation process at the nature reserve, he says: “Bulk rolls of CC5 were delivered to the site and mounted onto a spreader beam. The CC was positioned at the crest of the slope, with the leading edge fixed using ground pegs before the material was unrolled down the slope. Subsequent layers were overlapped by 100 mm and fixed using stainless steel screws at 50-mm offset intervals. Once complete, the CC was hydrated three times within the first hour, with 20-minute intervals due to the high rate of evaporation due to the high temperatures on site.”

Hasan adds that the benefits of GCCMs for slope protection applications, particularly when compared to traditional solutions, are many. On this particular project, the main benefits of using Concrete Canvas GCCMs over shotcrete were ease and speed of installation, safety, environment-friendliness and durability, he emphasises.

GCCMs, developed over 10 years ago, provide a geosynthetic alternative to the use of conventional concrete solutions (poured, precast and sprayed) for erosion control applications, he explains.

“They have been defined in ASTM D4439-20 ‘Standard Terminology for Geosynthetic’ as: “a factory-assembled geosynthetic composite consisting of a cementitious material contained within a layer or layers of geosynthetic materials that becomes hardened when hydrated,” Hasan says.

Among other projects in the region, CC technology was installed for slope protection at Maaden Aluminium’s facility in Saudi Arabia earlier this year. Also in the kingdom, CC was used for pond lining at a biodiversity park at Haradh Gas Plant last year.

Other major projects include channel lining at A’ali in Bahrain; channel lining in Sohar, Oman, for McDermott; and a containment project at Emirates Flight Training Academy in the UAE.

According to Hasan, Concrete Canvas’ GCCM is suitable for a number of applications including:

• Channel lining: CC can be rapidly unrolled to form a ditch or channel lining. “It is significantly faster, easier and less expensive to install than conventional concrete channel lining and requires no specialist equipment. The matting can be laid at a rate of 200 sq m per hour by a three-person team,” says Hasan.

• Slope protection: CC can be used to protect slopes from surface erosion. “Compared to shotcrete, it is typically faster to install, more cost effective, requires less specialist plant equipment, and eliminates the risks associated with rebound and debris,” he points out.

• Bund lining: CC provides a cost-effective alternative for lining secondary containment bunds. It acts as an effective weed suppressant, reducing maintenance costs as well as providing additional levels of impermeability. Its ability to be installed quickly reduces time on site, whilst the availability of man-portable rolls allows for installation in areas with reduced access.

• Weed suppression: CC is used to provide effective, durable and long-term weed suppression, reducing devegetation requirements and associated maintenance costs. CC can be used where devegetation is required to maintain operational and health and safety requirements, or where limited access and sensitive infrastructure prevents the use of traditional methods.

• Remediation: CC can be used to rapidly re-line and refurbish existing infrastructure suffering from environmental degradation and cracking. CC-lined structures can be returned to operation in 24 hours from installation. Unlike structures re-lined with traditional concrete, the internal volume of CC lined structures is maintained, ensuring that the channel design flow capacity is preserved.

• Culvert lining: CC can be used to extend the durability of new-build culverts and to upgrade existing structures, preventing the need for asset replacement. The speed, ease and flexibility of CC offers significant technical and financial advantages, whilst offering a durable means of providing erosion protection. CC is used to replace, poured or sprayed concrete and bitumen coatings, he concludes.