Slab Overlay, Kemsley Paper Mill

Seamless Floors was asked by George Hutchison Associates Ltd (GHA) to repair a large existing floor slab prior to the construction of a steel fibre jointless overlay floor. The flooring construction works were carried out at the Kemsley Paper Mill in Sittingborne Kent owned by St Regis Paper CO Ltd. A concrete floor overlay formed the third phase of an extension to an existing storage warehouse of which GHA were acting as Project Manager and Engineer. GHA have for a number of years been involved with design development in the concrete flooring industry and contacted Seamless Floors to help in the design process and to ultimately construct the floor slab. As the longest established laser screed operator in the United Kingdom, Seamless Floors has a wealth of experience in the construction of all types of in situ concrete floors. The company also operates a successful repair and maintenance division. Therefore when the project at Kemsley was brought to Seamless Floors attention it seemed the ideal opportunity to utilise a "combined repair and construct solution." The concrete floor posed significant problems regarding design, construction and operational constraints. The site represented an existing fully operational building and any construction works had to be carried out with minimum disruption to the client thus limiting production downtime. The project manager had the delicate balancing act of ensuring all works were choreographed to run as smoothly as possible. As a result Seamless Floors were required to present specific and detailed method statements and construction schedules well in advance of the proposed works. The existing warehouse floor was used to store round paper reels and plasterboard placed directly onto the concrete surface, over years of trafficking the floor had lost the majority of its surface laitance resulting in damage to the products. Given the clients requirements to maintain production and minimise off site storage costs it was paramount that construction of a new floor provided adequate areas for ongoing storage whilst maintaining access routes. Breaking out and constructing a new floor was rejected at an early stage, as the impact on the clients operations would be too great. Additional concerns were also brought into play mainly due to existing construction joints within the floor. A survey of these joints made it clear from and early stage that mirroring the joints would be impractical and result in additional future requirements with repairs to the numerous joint arris's. Given the age of the floor and with further monitoring of the joints it was clear that movement within the floor had ceased. An option for filling the joints with an epoxy resin was chosen which would effectively provide a monolithic section throughout the existing floor reducing the risk of reflective cracks propagating into the new overlay floor. A jointless steel fibre reinforced concrete overlay was then constructed over the existing floor with a separating slip membrane. The floor was designed in accordance with current techniques as detailed in " The Concrete Society Technical Report 34 3rd edition" utilising recent historical beam test results. The JSCE - SF4 beam test provided up to date Re3 values which were used to determine the fibre reinforced concrete's equivalent strength. The slab itself was designed to accommodate pattern loading from the reel paper and significant high impact point loads associated with the client's machinery. 1* Laser Screed technology was employed to achieve the stipulated tolerance.2* A dry shake topping fibre suppressant was applied using an automated spreader thus ensuring an even distribution at a rate of 4kg/m2. Seamless Floors added super plasticiser and the steel fibres at site using its own machinery and operatives. This ensured that the correct dosage rate of fibres was added to every load and the concrete mix was at the optimum workability standard for operatives at the construction interface. The floor was a joint -free design with steel arris protected day joints separating the daily pours in excess of 1500m2. Surface water spillage from the client's trailers would normally stand local to the trailer and if not removed would pose a slip hazard to the clamp trucks. A dished area falling to local drainage channels was constructed beneath the designated parking area and this removed all standing water. In addition a roughened surface ensured a resulting dry safe platform for the operatives to work off. Fully laden articulated wagons were required to park within the warehouse for loading and unloading of paper and as such Health and Safety Requirements had to be fully addressed. All Seamless Floors operatives are directly employed and CSCS carded and this was a critical factor in ensuring a smoothly run and safe site. The flexible and focused approach to this project ensured that the client benefited from an effective elimination of his past operational difficulties and an end product that what ideally suited to his fixture requirements. Future maintenance costs were greatly reduced and all this was achieved on schedule with the minimum of disruption to the client. 1. UDL. 60kn/m2 and a 4 tonne clamp truck wheel load. 2. FM2 ( Property 4 )

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