Zero-Cement Concrete for Piling Applications to Significantly Cut Carbon Emissions in Construction

Over the last 60 years the piling industry has expanded owing to a rise in medium to large scale developments. As areas become more developed construction techniques used to form deep foundations must move away from disruptive, vibration producing and noisy methods to protect local structures and minimise ground surface settlements. Consequently, rotary bored piles are frequently preferred over driven piles resulting in an increase in concrete bored piles. The production of cement is widely cited as generating 8% of global man-made carbon dioxide emissions. A UK government initiative, Construction 2025, was written to address a number of construction issues, one of which includes reducing embodied carbon by 50% by the year 2025. Cemfree, a zero-OPC cement binder substitute, has been developed by DB Group (Holdings) Limited which reduces the embodied carbon by up to 88% compared with conventional OPC-based concrete. The material typically comprises 95% GGBS (ground granulated blast furnace slag) and 5% patented alkali activator. Developments have been necessary to produce various concrete mixes suitable for a range of piling applications that behave comparably with, or outperform, conventional OPC concrete in fresh, hardened and long-term states. This paper describes Cemfree concrete and reports on a case study where Cemfree was used in the construction of a pile. Long term durability testing has also been conducted on OPC and Cemfree concrete, demonstrating improved performance of the new concrete.