BEAUTY AND THE BEAST
The versatility of concrete is often overlooked as a construction material. This is most probably linked to its grey 1960s block image. Great strides have been made in residential construction and concrete is invariably used by cutting edge architects to showcase their innovative approach to the use of traditional materials. Even commercial property development is getting in on the act with new buildings making use of large amounts of concrete that is not only structural but integral to design.
However civil engineering has traditionally not been overtly concerned with aesthetics and the tendency is to think civil engineering and immediately think back to that 1960s block image. But times are changing. Advances in concrete production and development are giving rise to new opportunities in civil engineering and new kinds of concrete structures - those that not only provide excellent performance but those that are pleasing to the eye and fit seamlessly within the natural landscape.
The benefits of using precast concrete in construction are well accepted - low whole life costs, fast and efficient builds, low maintenance, strength and durability and good environmental credentials. However, concrete is not only incredibly strong and hard-wearing. Different surface treatments can give rise to a range of different textures and finishes, while different conditioning admixtures can produce an array of different colours.
However, the use of coloured and finished concrete in contracts of this type present the industry with a new set of challenges that require a wholly customer focused approached to business.
Tarmac has been awarded the contract to supply the concrete for the new Blackpool sea defences - a major piece of civil engineering that is not only structural but beautiful too.
Background
For over 100 years, the old sea wall has provided Blackpool with protection from coastal erosion and flood alleviation. But constant bombardment from the sea has taken its toll and much of the defensive structure now needs to be replaced. The new sea wall and defence scheme has been designed to continue to protect the town while at the same time improving public access to the sea and providing a clean and modern look for Blackpool's seafront
The contract
Tarmac’s contract is to supply two schemes - the Blackpool Council Central Area Coast Protection Scheme and Wyre Borough Council Cleveleys Coastal Defense Scheme. Tarmac is supplying main contractor, Birse Civils Engineering Limited, with all its insitu concrete requirements and SLP Engineering with concrete for the precast elements of both schemes.
The three year contract will see the old structures replaced with 65,000 m3 of in situ concrete and 44,000m3 of pre-cast concrete in grey, white and sand colours to blend in with the sea, beach and promenade.
A bespoke solution
To ensure that the solution meets performance and aesthetic demands, each of the concretes was developed by Tarmac specifically to meet client specifications and limiting factors for durability. These include water cement ratio, minimum cement content, colour and inclusion of structural fibres. Tarmac Toproc AA has also been supplied as the Cleveleys Coastal Defense Scheme requires a concrete capable of withstanding the constant abrasion and scouring characteristic to the North Fylde coast.
Tarmac has undertaken a long period of pre-contract trials and experimentation to optimise the concrete mixes - all of which are filed and processed through Tarmac's electronic distribution system which is linked directly to Batching Plants, ensuring that only approved mixes are sent to site.
Challenges
The nature of the contract - the sheer volumes of concrete needed combined with the aesthetic requirements - has created a variety of challenges that concrete producers should come to expect from civil engineering projects as they become increasingly focused on form as well as function.
Not only are these North Fylde Coast sea defence contracts architecturally and aesthetically demanding but the variety of concretes required to fulfill client specifications has created unusual operational and manual handling challenges. Specifically, the specifications require large amounts of colour conditioners and fibres to be added to certain concretes and separate storage for white cement.
Demand for the Blackpool and Cleveleys sea defences contracts, as well as for the local market is being met through Tarmac's existing ready mixed concrete plants on the Fylde coast. At our Thornton Cleveleys plant, two cement silos have been refurbished and a new freestanding silo has been installed to accommodate the white cement. In addition, new admixture tanks have been installed to accommodate the different admixtures, new aggregate storage bays have been created to store six different types of material together with installation of hot water facilities, for winter concreting, and a new micro silica storage and dispenser system.
Also, our new plant at Poulton-le-Fylde was finished as an enclosed, frost free wet batch facility. The two plants combined currently have an output of 90m3 per hour.
As with most sea defence schemes, tidal working provides only a narrow window for deliveries when construction takes place within the tidal zone. There is therefore an overriding need to ensure that all supplies are handled efficiently, Tarmac routes daily requirements through a dedicated distribution office via a single point of contact. The office has direct responsibility for both the Thornton Cleveleys and Poulton-le-Fylde plants and manages transport to meet the needs of the contract. The nature of these contracts lead Tarmac to appoint a dedicated coordinator to liaise directly with different project teams to ensure all issues are promptly dealt with.
Looking forward
The Wyre Borough Council and Blackpool Council Schemes are due for completion in January 2008 and August 2009 respectively. By that time, there will no doubt be underway yet more civil engineering contracts that value design as highly as function. Concrete may be a traditional construction material but its versatility is constantly being developed. Hopefully its days of being perceived as a grey material from the 1960s are numbered.
