Sabkha soils are known to have low load-bearing capacity but an innovative solution by Alyaf, that uses nonwoven polyester geotextiles, can significantly reinforce them.

01 May 2014

IN LINE with its culture of innovation, Alyaf Industrial Company of Saudi Arabia continues to expand its portfolio as a geosynthetic solutions provider, building on its in-depth experience in providing engineered solutions that have stood the test of time. One such engineered solution has played a vital role in enhancing the load-bearing capacity of the weak soils prevalent in the region, says the Dammam-based manufacturer of high-quality geosynthetics.

Alyaf’s technical support manager Khalid Meccai explains: “The terrain across the Middle East and especially Saudi Arabia is exposed to extremely hot and arid climates, where there is high evaporation and low precipitation. Such weather conditions prevailing over a period of time lead to the formation of weak, unconsolidated sediments rich in saline content, known as ‘sabkha’ soils.

“Sabkha soils have a low load-bearing capacity, acute water sensitivity and are susceptible to collapse upon wetting or flooding. Hence, these soils present several geotechnical problems in the construction of roads and railway lines, such as ravelling, cracking and the formation of potholes.”

He adds that conventionally either soil replacement or lime and cement was used to stabilise sabkha soils, but this combination has proved unsuccessful in reinforcing sediments with high clay content. However, geotextiles produced by Alyaf have provided a solution for such soils.

“A study conducted by the King Fahad University of Petroleum and Minerals (KFUPM), Saudi Arabia, to compare the influence of chemical additives and geotextiles (Alyaf nonwoven polyester geotextile) on the load-bearing capacity of clayey sabkha soil showed that while the former produced little or no improvement in soil strength, the Alyaf geotextile layer placed directly on the sabkha soil enhanced its load-bearing capacity by over three times,” Meccai points out.

Since its inception in 1992, Alyaf has fostered a culture of innovation and is committed to providing the most techno-commercially viable solutions to its customers. “Our highly qualified and experienced engineers work closely with contractors, consultants and clients to provide customised, site-specific design solutions,” he says.

Recently, Alyaf worked closely with SCEC, the design consultant, and Drake & Scull, the main contractor, for soil improvement at a project at the King Abdullah University of Science and Technology (Kaust), the client being Saudi Aramco. Dynamic cone penetration tests carried out at the site indicated an extremely weak soil to depths of 1.5 to 3 m.

“Traditional pavement construction techniques would have necessitated the excavation of the weak soil and refilling it with good engineering fill,” Meccai explains. “This would have been extremely expensive and impractical as the site was not even accessible to the construction machines. The technical support team at Alyaf interacted closely with the design consultant to arrive at a techno-commercially viable solution acceptable to client. The soil stabilisation system involved clearing and grubbing the top 0.15 m, and a combination of three elements: Alyaf A501 XL polyester geotextile, Alyaf Bi Ax geogrid and an open graded aggregate layer. The system provided the multiple benefits of:

• Isolation (or separation) of the structural fills from the soft sabkha soil;

• A capillary break layer to mitigate the rise of the saline groundwater into the structural layer; and

• Reinforcement that enabled a construction platform from where the rest of the construction was carried out without any problems.

“Based on our extensive experience, Alyaf provided technical back-up and has supplied so far over one million sq m of Alyaf geotextiles and geogrids to the full satisfaction of the contractor, consultant and client,”
Meccai adds.

In a similar project carried out earlier, Alyaf was also selected to work on the soil improvement for the prestigious Wasit Gas project for Saudi Aramco, where it worked closely with the design consultant (Khatib & Alami) and contractor to successfully stabilise more than two million sq m of a patch of weak sabkha, says Meccai.

Other major road and soil stabilisation projects include the King Abdul Aziz Road in Thuwal with consultants Khatib & Alami, the North-South Railway in Saudi Arabia with a Louis Berger-led consortium, the Sheikh Khalifa bin Salman Highway in Bahrain with Parsons Global, and the King Abdullah Economic City with Saud Consult.

“Alyaf’s products have had phenomenal success in the geosynthetics market for two decades in terms of both performance and quality. Our success in the growing Middle Eastern market has encouraged us to introduce a new range of geosynthetics products including geosynthetics clay liners (GCLs), woven
geotextiles and geocomposites,” he adds.

The company recently entered into a joint venture with Geofabrics, a leading UK manufacturer of geocomposites, to create a new range of products for civil and environmental engineering applications such as gas venting systems, landfills, vertical and horizontal drainage; green roofs, salt barriers and capillary break layers. Alyaf’s state-of-the-art production facility in Dammam will start manufacturing the geocomposite products under the AlyafGEO composites brand next month (June).

“The deal with Geofabrics puts us in an exciting position to expand successfully into new markets across the Middle East, Africa and Europe and beyond. Our ethos is to exceed the expectations of our customers with top quality products and professional technical support every step of the way. This, we believe, will propel us to become the premier choice for geocomposites in the infrastructure and construction industries,” he asserts.

The company is adding a fibre production plant for its captive consumption, and is working to add its fourth geotextile manufacturing line by 2015, which is expected to increase its nonwovens capacity to more than 20,000 tonnes per year (tpy).

Alyaf offers a unique range of market-leading geotextiles made using polyester or polypropylene engineered to offer good elongation, superior puncture resistance, excellent tensile strength, high porosity, high permeability with fine opening size and resistance to chemicals, rot, and ultraviolet (UV) rays. The portfolio of products includes:

• Alyaf A1 and A1 XL series: This includes popular ranges of needle-punched, nonwoven polyester geotextiles;

• Alyaf XP: This range comprises needle-punched, nonwoven polypropylene geotextiles;

• Alyaf XS: This range consists of needle-punched, thermally-bonded nonwoven polypropylene geotextiles;

• Alyaf TS: This is a polyester thermally set range, engineered for use in cold-applied liquid waterproofing systems;

• Alyaf PU: This range includes paving fabrics to help retard reflective cracking of asphalt pavement. Made from 100 per cent polyester fibre, this range is said to offer excellent resistance to solvents present in asphalt emulsions;

• Alfweb Cellular Confinement System: This comprises an innovative, three-dimensional cellular confinement system engineered to provide erosion protection on slopes;

• Alyaf Bi Ax Geogrids: A range of biaxial geogrids, with square apertures, and an optimised geometry of nodes and ribs that maximises interlock with soil for soil stabilisation;

• Alfgeo salt barriers and capillary break layers;

• Alfdrain range of geodrains;

• Protexia geocomposite drainage and gas venting systems; and

• Alfgeo Green roof systems.

The company has a dedicated quality control/quality assurance team at its production facilities and its products are manufactured, tested and supplied in line with stringent quality management systems certified under ISO 9001 by an external agency, adds Meccai.

“Our quality support is matched equally by our dedicated technical and professional design service with teams in Dammam, Riyadh and Jeddah working and engaging extensively with consultants, contractors and clients to provide optimal solutions,” he says.

With a host of industrial, construction and infrastructure megaprojects lined up ahead, Alyaf is ideally positioned to offer unparalleled products and services to respond to the challenging demands of the global geosynthetics market, he adds.

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