Crossrail – Technical paper on Moorgate shaft base slab

As previously reported, Crossrail now has a Learning Legacy website dedicated to “the collation and dissemination of good practice, lessons learned and innovation from the Crossrail construction programme”. The material, consisting of case studies, technical papers, documents, templates and datasets, is being “shared for use by other major projects and is relevant to clients, corporates, and suppliers from main contractors to small and medium enterprises.”

Recently a technical paper was published on the Learning Legacy website about the design, detailing and construction of the Moorgate shaft base slab – a 1750 m3 pour carried out using Camfaud pumps.

Moorgate shaft base pour

Moorgate shaft base pour

The technical paper makes for fascinating reading, especially in regard to the pour preparations. As the paper concludes: “Careful planning of the concrete pour from reinforcement detailing through to road closures to give access to a constrained site in the heart of the City of London, the contingency measures for disrupted concrete supply and the control of concrete temperature led to the successful execution of what was at that time Crossrail’s largest concrete pour.”

Concrete magazine article – pumping heavyweight concrete

Crossrail C610 - Heavyweight concrete pumping

Crossrail C610 – Heavyweight concrete pumping

The February 2017 edition of the Concrete Society’s magazine Concrete, has an article about placing heavyweight concrete to form part of the Crossrail track slab in central London. The joint venture contractor installing the track on this project is ATC jv (Alstom, TSO and Costain), the concrete is supplied by London Concrete and the concrete pumping is being carried out by Camfaud.

Heavyweight concrete was considered the best option for this section of track bed in order to minimise the noise and vibration generated by the Elizabeth line when it is in service, especially in noise sensitive areas with recording studios above.

The heavyweight concrete used contains MagnaDense, a natural aggregate which is approximately twice as dense as normal aggregate. MagnaDense from LKAB Minerals is formed of black ferrimagnetic natural iron oxide (magnetite) and is mined in Kiruna and Malmberget in northern Sweden.

As the article notes, Camfaud Concrete Pumps chose a Putzmeister BSA2110HP static pump as the main pump, with another high-pressure pump being used as a backup and also to clean the lines using a water wash-out system. The concrete has been pumped through 1100m of pipeline, during which time there was approximately 40 tonnes of material contained in the line.

The same edition of Concrete magazine has an article about the new Medway valley crossing, built by BAM Nuttall to give access to the new 1000 home, Peters Village. Camfaud carried out the concrete pumping on this project too and further information about Camfaud’s work on this innovative bridge construction can be found here.

Peel Ports Great Yarmouth – Outer Harbour Works

Breheny Civil Engineering - Peel Ports, Great Yarmouth

Breheny Civil Engineering – Peel Ports, Great Yarmouth

We have recently been working for Breheny Civil Engineering on their Outer Harbour works for Peel Ports Great Yarmouth. Breheny’s contract is for the construction of primary infrastructure and ground works for the offshore Galloper Wind Farm and East Anglia ONE Wind Farm projects. The contract includes the delivery of a yard storage and marshalling area, as well as the installation of heavy-lift quay facilities.

Breheny Civil Engineering

Breheny Civil Engineering

Last year, ScottishPower Renewables selected Peel Ports Great Yarmouth as its port of choice for the construction and installation activities for its £2.5 billion East Anglia ONE offshore wind farm.

The turbines for the project will be supplied and installed by Siemens, which also announced Great Yarmouth as the assembly and installation base for Galloper Wind Farm which is currently being constructed by innogy SE on behalf of the project partners.

(Camfaud have had another involvement with the Galloper Wind Farm project – pumping concrete for North Midland Construction on their contract to construct a new onshore substation to link the export cables from the wind farm to the National Grid.)

Peel Ports Great Yarmouth

Peel Ports Great Yarmouth

Siemens will supply 56 six-megawatt turbines for Galloper Wind Farm and 102 seven-megawatt turbines for the East Anglia ONE Wind Farm, which will have the combined capacity to generate enough energy for up to 836,000 homes a year.

To showcase the work that they have been carrying out for Peel Ports Great Yarmouth, Breheny commissioned a video which, shows a Camfaud boom pump working to construct an external slab for the yard storage and marshalling area. And, by happy coincidence, the video also shows our sister company Premier Concrete Pumping feeding a CFA piling rig of their customer Bachy Soletanche.

The Breheny video is embedded below:

Achieve something remarkable

Bishopsgate - Early one Saturday morning

Bishopsgate – Early one Saturday morning

In May 2016 Camfaud Concrete Pumps Ltd supplied pumps and staff for London Underground’s (LU’s) Liverpool Street Diamond Crossover Renewal. This contract was carried out by Track Partnership, a strategic alliance between LU and Balfour Beatty Rail, responsible for delivering track and drainage renewals across the Tube network.

The Liverpool Street Diamond Crossover is situated approximately 50 metres east of the station, allowing Central line trains to enter and exit the two sidings. At over 60 years old, the track condition was in line for a full renewal. To facilitate the work, over 300 cubic metres of concrete were pumped from street level over 15 metres, down a vent shaft on Bishopsgate Road. Over 400 tonnes of rubble were removed and new track was installed to complete the project, which involved extensive collaboration between a number of stakeholders including Transport for London (TfL), Track Partnership, Broadgate Estates, the City of London Corporation, Hanson Concrete and Camfaud Concrete Pumping.

BSA1409 - Pump 1

Pump 1 BSA1409 – the start of a long day

BSA1409 - Pump 2

Pump 2 BSA1409 – the roads are getting busy

Three pumps were used for the contract, two working and one on standby. The working pumps were both Putzmeister BSA1409D static models while the standby pump was a Schwing S20 high pressure mobile one. The mobile pump was chosen as the standby because it’s quicker to deploy in the event of one of the statics failing. Fortunately, the backup solution was not required. Both of the static pumps were used for the duration of the pour, the pumps fed separate pipelines to supply concrete to two concreting gangs working in parallel in each of the running tunnels and the cavern.

The pumps were situated in Bishopsgate in the northbound bus lane with traffic lanes subject to a road closure. Track Partnership were extremely careful to protect the environment in this sensitive area with polypropylene sheeting, geotextile fabric, rubber mats, plywood sheets, bubble wrap and drip-trays all being used.

Down the shaft and into the tunnel

High pressure pipeline – down the shaft and into the tunnel

Working in the cavern

Working in the cavern

The pipeline route was rather convoluted and required a large number of bends, more than ideal, but was chosen as the best solution in the circumstances. The pipeline exited the pumps and ran along the Bishopsgate pavement turning down into a 15m deep shaft. A 90 degree bend diverted the pipeline along a cross-passage before another 90 degree bend took the pipeline down 6m into the tunnels. A final 90 degree bend, a footed bend to add support, diverted the line along the tunnels to the work area.

The concrete for the project was supplied by Hanson Concrete. The mix used was designed for an earlier contract, the major engineering works on the Victoria line at Walthamstow, carried out in August 2015. It was successfully pumped through 500m of pipeline on that contract and so it was an easy decision to choose the same mix for the Liverpool Street works. The mix contained a CEM 1 / GGBS blend, superplasticiser and retarder admixtures and a small addition of microsilica slurry to ensure that the mix held together in the line and did not bleed as it was placed and finished. Hanson also supplied 4 cubic metres of ready-mixed grout ahead of the concrete to grout the pump and pipelines.

Concrete flowing into the trackbed

Concrete flowing into the trackbed

The concrete pumping operation was completed in two stages. Firstly, two parallel chambers in the cavern beneath the track had to be filled: each chamber had a volume of approximately 105 cubic metres. These were filled through five ports opened along the length of the chambers. Secondly, the track bed had to be poured, embedding the sleepers into the concrete slab.

Filling the chambers was a relatively simple process. The concrete was introduced through the ports and vibrated to ensure that it was fully compacted and the chambers were completely full. The concrete to fill the chambers was pumped at approximately 50 cubic metres per hour. Consideration was given to designing a separate mix for the chambers but, given the proven quality, flow and ‘pumpability’ of the slab mix, it was decided to use this mix for both sections of the job.

Pouring the slab concrete was a more onerous task due to the obstructions presented by the sleepers and the track, and the complex finishing required. The pumping rate was reduced to around 15 cubic metres per hour and this part of the job was a much more stop / start affair.

Job done!

Job done!

Pump washed out - ready for collection

Pump washed out – ready for collection

At the end of the pour, the pipes were cleaned out by Camfaud’s staff using compressed air. This is an efficient method of cleaning medium length pipelines but must be carried out by competent, experienced operatives. Using the latest blow- out adapters fitted with pressure gauges and oversized safety vents, the pressure in the line was very closely controlled at 2 bar with the line full, 1.5 bar once the line was half empty and 0.5 bar at the end of the blow-out procedure. Despite having this fine control, all of the concreting gang were required to stand in a safe area behind the pipeline or in the other running tunnel while the concrete was being cleaned from the pipeline.

In total, just over 300 cubic metres of concrete was poured during the concreting works. The pour took 12 hours to complete and this included grouting the pipelines, pumping the concrete into the chambers and track slab, and cleaning out the pipeline and pumps. With good planning and first class teamwork between Track Partnership and Camfaud Concrete Pumps, the concrete pumping operation was completed ahead of schedule allowing Track Partnership more time to complete their works prior to handing the Central line back to Transport for London.

Achieve something remarkable - we did!

Achieve something remarkable – we did!

New Medway Valley Crossing to Trenport’s Peters Village

Aerial view of Medway Valley Crossing

Aerial view of the new Medway Valley Crossing linking to Trenport’s Peters Village

During this winter, Camfaud has been helping contractor BAM Nuttall to construct a new bridge over the Medway valley in Kent. The bridge is being built to provide access to Trenport Investments Ltd’s new residential development of Peters Village, with the road from the bridge joining the A228 at a new roundabout between Snodland and Halling.

In December, Camfaud poured the main span of the bridge. Two M36 boom pumps were supplied and were set up either side of the river on the temporary jetties that had been built to accommodate the plant needed to construct the bridge.

Both of the pumps were equipped with a one side support (OSS) system that allowed them to set up on the narrow jetties. This system made it possible for the pumps to short rig on the off side whilst extending the outriggers fully on the working side. The OSS system prevents the boom from slewing into the unsupported area and so the pumps were completely stable at all times.

The two pumps worked in tandem all day with the concrete initially being placed at the centre of the bridge span. As the pour progressed, the two booms worked outwards thus ensuring that the loading, imposed on the bridge by the concrete, was balanced across the structure.

For this technically challenging and project critical pour, Camfaud supplied two of their most experienced pump operators who, between them, have over 50 years experience pumping concrete for Camfaud.

Medway Valley Crossing from Peters Village side

Medway Valley Crossing from Peters Village side

Pouring the centre span of the new Medway Valley Crossing

Two pumps, working together, to balance the loading on the centre span of the bridge

Two M36 pumps working at the new Medway Valley Crossing

Two M36 pumps working in tandem at the new Medway Valley Crossing