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!

April Come She Will

Putzmeister Calendar April 2016

Putzmeister Calendar April 2016

Every year, we are given promotional calendars by our two pump suppliers – Putzmeister & Schwing. Being concrete pumping nerds, we pore through them to look at the pumps and pumping contracts that are featured. Some years Putzmeister has the best calendar and some years it is Schwing’s offering that interests us the most. This year we definitely prefer Putzmeister’s calendar because … April’s page shows Camfaud’s base pour at the Brighton i360. We will have to see if we can get a job featured in the 2017 Schwing calendar!

New Schwing M24 on Mercedes Arocs 2633

Schwing M24 on MB Arocs 2633

Schwing M24 on MB Arocs 2633

We have recently taken delivery of two new Schwing mobile boom pumps. These have now been through our workshops and fitted with all of the additional equipment / signage required to make them Crossrail compliant and to compatible with our FORS Silver accreditation.

The first pump has a 24 metre boom, in Schwing terminology an S24X. The pump unit is a P2020 giving a maximum of 90m3/hour and up to 70 bar line pressure in the standard configuration. We consider this pump to be the workhorse of the fleet. The M24 boom is the most popular size with a broad range of our customers; it is very versatile and is suitable for working inside a building as well as out in the open. As with all of our pumps, it is mounted on a Mercedes Benz truck in this case a 330bhp, 3 axle Arocs chassis. The Arocs range is designed to be robust enough to withstand the rigours of the construction industry.

In addition to this pump, we have also taken a new 20 metre boom pump. Our M20 is the latest iteration of the Schwing S20 boom, designed with a very narrow outrigger spread to work in the tightest of spots. In the fullness of time, we believe that this model will supersede our M16 boom pumps and become the new City Pump.

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

Camfaud pump in Boxing Day’s Observer newspaper

Observer article on Brighton's i360

Observer article on Brighton’s i360

In an article about the iconic i360 tower currently being built on Brighton’s seafront, Boxing Day’s Observer illustrated the story with a stunning photo of the podium slab being constructed around the tower, with one of Camfaud’s 47 metre boom pumps in action. The photo, which can be seen in greater detail here, shows the start of the pour early one morning in October 2015.

The tower is due to open to visitors in June and, if the aerial photograph used in the Observer story is anything to go by, the views from the i360 visitors’ pod will be stunning.