A concrete matter

Backed with a new supply of materials, we split into two gangs today.

Gang No.1 with Paul and Dave P began the work of extending the existing length of platform wall towards the southern extremity. This means building towers to position the build in the correct place and the correct height. It's quite slow work. You start from nothing, keep measuring, adjusting, removing the block again to add extra mortar, checking the height again. Here Paul checks the distance from the track. A large supply of new blocks features in the background.

That said, you still have to load them in a barrow and take them the last few yards. Here Dave brings more blocks while Paul checks the level of the topmost block of the tower he has just built by the second catch pit.
This catch pit will not be built around like the first one, but will be encased in the platform (it is a bit further back than the other one) and will be accessible from the top.
In the background is Jim H, who was part of the second gang. He has a barrow full of concrete freshly made, and is going downhill, so that's no effort, is it?.

A few seconds later, Jim is well away down the four foot, while Paul and Dave P check the position of the first tower against the track gauges in the background.

'Ere we go...

The second gang consisted of Dave D on the mixer, Jim at the controls of the barrow, and Lyndon with yours truly heaving the barrow on top of the wall and stuffing the concrete down the holes.

This is the satisfying bit, as the fairly liquid mixture is poured down the holes, four blocks deep. In every other block there is a rebar, and every few feet a weep hole form the back with a pipe in it. All this is now solidly fixed in concrete.

Poor old Dave D at the top of the slope was shovelling ballast in the mixer like there was no tomorrow, and wondering where it was all going, and if there wasn't some sort of hole at the bottom of the wall where it was secretly all running out again.

So we decided to keep a record of what went in, and from time to time Dave came down to see what was happening with the fruits of his labour.

At the end of the day he had mixed up both remaining dumpy bags of ballast, about two tons worth. This made 20 wheelbarrows of mix - Lyndon is chalking up the last one here - and this resulted in the length of 15 blocks that was filled. We have another 33 on the current stretch of platform to go, say another two days' worth,  as we ran out of ballast before the end of the day. We are now low on cement again, and the ballast has all gone - note to Central Purchasing!

Paul and Dave's first tower - lovely, isn't it?

At lunch time, we had a visitor! The class 73 trundled by slowly with a Mk1 in tow. Just like the old Coffeepot, but a modern version - a loco and a single carriage.
The wall fitted perfectly, it even has a curve to it.

After lunch, we can see Dave P in a pensive mood pointing up one of the new towers.

During the day, he and Paul set up 4 of these towers, and they now define the size and shape of the rest of the platform. Each tower consists of 10 blocks, so that is 40 blocks laid in a day, a very good result for a single team.

A tricky bit revealed itself in the late afternoon, when the step in the foundations was tackled. This step was the result of a small shortfall in the concrete delivered at the time, and it wasn't worth ordering another load, only for most of it to be wasted. It was therefore decided to create a step leading to a lower part of the foundations. Unfortunately, it was just a bit higher than a single block, what now?

The darned thing was that the break was also not in the right place for whole blocks to be used. Dave D can be seen here trying out various options. Hmmmm...

With a trial row of blocks in place with a minimum bed of mortar, what was the level like?

Still too high !

Next week will no doubt produce the answer to this puzzle.

While the block laying team were scratching their heads, Jim and Lyndon spent the last hour of the day positioning a fresh supply of blocks for the next day, when the towers will start to be linked. This is the area around the second catch pit - you can just see a corner of it behind the tower on the right.

Our last shot of the day, always taken from the same spot, shows the wall up to around the half way mark, with the four new towers in the far distance. Concrete was poured into the voids from the return around the catch pit up to the point where Lyndon is standing, about a third of the way down to the current end.

A fifth row still needs to be built all the way along the back, leaving a row at the front for the corbelling. We will build this row once the concrete is in all the holes.

This Friday for 4 weeks will see operating days, so our team at Hayles will only be able to work on Mondays. Paul is now off on holiday for two Mondays, but Jim G is back, after sailing down the river Severn on a narrow boat. See you again next Monday then.

Last but not least another little fossil puzzle for our readers. Dave P found this one in the area of the field on the other side of the fence to the site, so not in the clay but among the debris of Cotswold stone.

At first sight it looked like an old button, but on further inspection you can see a lot of fine grooves like umbrella spines radiating from the top. Would this be a sort of sea urchin, an Echinoid?