Gulf Construction Online - UHPC demonstrates exciting prospects

Concrete Technology

The Haramain High-Speed Rail (HHR) station in Saudi Arabia

UHPC demonstrates exciting prospects

Ultra-high-performance concrete (UHPC) addresses some of the key limitations of concrete in its traditional form, enabling the creation of complex structural elements and stunning facades even where speed is of essence, says PETER WALKER, Director, Architecture and Infrastructure at BFG International*.

01 September 2021

Concrete is amongst the most commonly used man-made building materials and has played a key role in construction since ancient Egyptian times, when typically materials such as limestone and crushed gypsum, chalk or oyster shells were used as the cement-forming agents.

Since the early 19th century, Portland cement has been the predominant cementing agent used in concrete production.

Although widely used, concrete has limitations in its traditional form, including relatively low tensile strength when compared to other building materials, low ductability, low strength-to-weight ratio and susceptibility to cracking.

GFRP curved formwork was used for casting the concrete elements.

Recent technological advances have sought to address these issues. A notable development is ultra-high-performance concrete (UHPC) such as Fortekret, produced by BFG Advanced Facades, a sister company of BFG International in Bahrain. This highly advanced product can be custom engineered for use in a wide range of applications as diverse as structural bridge elements, structural or decorative wall and cladding panels, and even stylish designer furniture and landscaping products.

UHPC is an advanced cementitious material increasingly used in the construction industry due to its high mechanical strength and durability.

The unique combination of high compressive strength (more than 120 MPa), self-placing properties, extreme durability, flexibility, and aesthetics makes UHPC a truly revolutionary construction material. These properties allow designers to exploit elegant architectural designs previously only accessible to high-strength steel or other complex materials systems. High packing density yields excellent flexural strength that is over four times higher than regular concrete.

The Al Majlis Pavilion

Combined with complex 3D moulds, the self-placing properties of UHPC mean that stunning architectural shapes can be achieved.

BFG International uses multi-axis robotic CNC machinery at its state-of-the-art plant in Bahrain to produce incredibly precise, highly complex moulds in GFRP (glass-fibre reinforced polymer) to dimensional tolerances of < 0.2 mm that are utilised to realise the visions of some of the world’s leading architects.

In addition to being able to produce extremely accurate, complex shapes, the use of GFRP to create moulds or formwork for concrete gives huge advantages over traditional materials. High strength-to-weight ratio means GFRP moulds and formwork are lightweight and durable. They can be used multiple times, producing consistently high-quality surfaces, and can carry significant loads with zero leakage.

High-profile examples of GFRP moulds used to produce concrete or UHPC elements include the recently completed Al Majlis pavilion at Expo 2020 Dubai, designed by US practice Adrian Smith Gordon Gill Architecture, and the iconic Foster and Partners-designed Haramain High-Speed Rail (HHR) station at King Abdullah Economic City (KAEC) in Saudi Arabia.

GFRP moulds were used to produce 6,000 geometric three-dimensional UHPC panels for the project.

To realise the architect’s vision for the Al Majlis Pavilion – which involved creating a complex, geometric façade system in eye-catching high-gloss blue colours, BFG Advanced Facades responded by manufacturing detailed GFRP moulds to produce more than 6,000 geometric three-dimensional UHPC panels which make up the striking façade. Individual elements were produced at BFG’s manufacturing facility in Bahrain and transported to site for installation.

A more industrial-level scale and speed of construction were key for the HHR station project, for which BFG produced over 8,000 sq m of curved formwork in GFRP for in-situ casting of the concrete structure for this iconic building.

With collaborative design and engineering between the contractors, project architects and engineers, BFG provided a durable, lightweight, and efficient GFRP formwork solution to streamline construction. Given the project’s size and structural-weight-bearing requirements, traditional site formworks would have significantly prolonged construction time and increased overall life-cycle cost.

Aside from traditional, large-scale construction applications, UHPC provides an exciting new materials palette for interior, furniture and landscaping designers to work with.

UHPC was used to produce the benches, landscape features, planters and recycling bins for Al Liwan mixed-use development.

In designing the recently completed Al Liwan mixed-use development in Bahrain, the developers worked closely with BFG, embracing UHPC to create beautiful landscaping features at the heart of the central plaza and boulevard, linked to all points of the development and designed for public gatherings and entertainment.

Benches, sculptural landscape features, planters – and even stylish recycling bins – in stunning, durable UHPC provide a sleek, signature look for this forward-focused development.

Introduction of new types of high-performance, highly engineered concrete, along with developments in production techniques utilising high-tech machinery and materials such as GFRP to create forms and structures hitherto unrealisable, are exciting advances in concrete technology, pushing the boundaries of what can be achieved architecturally using one of the world’s oldest construction materials.

But what’s next – and how do we maintain the momentum in this transformational process?

One exciting new initiative is being spearheaded in the region by Saudi Aramco.

In March 2021, Saudi Aramco and the American Concrete Institute (ACI) announced a new Center of Excellence for Non-metallic Building Materials (NEx) in the US to develop and promote the use of non-metallic materials in the building and construction sector (www.nonmetallic.org).

NEx envisions a future where everyone has the knowledge needed to use non-metallic building materials effectively to meet the demands of a changing world.

The centre aims to achieve more sustainable building solutions through advances in non-metallic technologies. NEx will focus on accelerating the use of non-metallic materials and products in construction, leveraging ACI’s role as a world-leading authority and resource for the development, dissemination and adoption of consensus-based standards for concrete design, construction and materials.

The centre’s mission will be to collaborate globally on using non-metallic materials in the built environment by driving research, education, awareness and technology adoption. Expanding incorporation of these materials and products in the built environment will improve sustainability, contribute to a lower carbon footprint, and enhance the durability and longevity of structures.

In the Gulf region, Saudi Aramco will drive this initiative through its Center of Excellence and in establishing R&D partnerships with the key stakeholders aimed at continual development of non-metallic materials such as concrete and polymetric materials for use in the building and construction industries.

An exciting future indeed, for a material with its origins in ancient Egypt!

* BFG International is a global leader and pioneer in composite design, engineering and manufacturing, employing over 2,000 people and with production facilities worldwide.