Holdfast Training Services Trial Blog

The dispute on the surface finish for upper basement columns has apparently been settled, though I am not too sure it has really started yet. The tender design specified grade 3 columns throughout the building as from ground floor up they will be sheathed and those levels below ground were only going painted for the car parks and storage areas so there was no requirement for anything better. The intention to paint the car-park columns was decided to be a maintenance issue (questionable) and that the columns should now be bare concrete. About 2 months ago the clients representative (CR) said that the finish on the basement columns was not suitable, and though it easily met the class 3 finish it was not quite what they wanted. The CR have promised to submit a variation order to change the spec from Class 3 to Class 2 but this is still pending.  The initial issue was with the spiral “Ezy-Tube” forms giving a spiral effect on the outside – though not anything to do with the surface finish (concrete wise) it was really the catalyst. So the last few months has seem several test columns poured to reach the fables grade 3 column with a grade 2 look, it didn’t happen and was beginning to stall progress.

EzyTube form for circular columns

The decision by the construction director was made to purchase grade 2 forms (GSC) and provide 5 test columns (1.2m sample height poured and vibrated in different manners for the CR to choose from – the fact none of them had rebar in made the test fairly nugatory mind). This produced a definitive sample which was then required to be tested on a full column to produce a standard column from which to work to.  The column was poured using the standard 65MPa, 20mm Agg, 150 Slump column mix but with a slump of 190mm which in my view is out of spec according to Aus Standards (>150 = (+or–) 40mm). This soup was always going to give a good finish and the addition of 10 minutes of vibro-poker action cranked up to 11 just finished it off nice.

The resulting test column is magnificent, it is so smooth I could lick it (it is clearly Class 1), but the additional vibration has clearly had an effect on the structural capacity as there is no way that 10 minutes of uber-pokering could not have the effect of separating the large agg to the bottom and the small agg to the top. This is apparently falling on deaf ears as JHG attempt to suck up to the client promising something which in my opinion we will never produce again, well not on my watch – I have been quite rigid on concrete spec and will no doubt get my arse chewed shortly for turning away too much concrete! (60.7m3 from 1336.7 so far (4.5%)). I am gaining commercial experience of how to pass the buck though.

I called an on-site meeting with the Quality Manager to discuss this issue and asked him to transmit to the CR the annex from the Aussie Standard that showed images of the surface finish grades as I do not believe that they even know what they are.

We were ready to pour 18 columns on Zone 4 on Tuesday but were held up by a 500m3 pour in the North. Unlucky really as the CR mentioned to me whilst on the deck that they had received no correspondence from JHG with reference to the column finish and that if we were to pour it would be entirely at our risk and we could be made to rip them out and start again if they were not happy. Strange really as JHG contractually carry all the risk anyway but stern words all the same.  They also stated that they required confirmatory test columns to be poured too. This was conveyed to the upper echelons of the NCH and it was decided to pour 3 more test columns.

The pour was started on time for a change, but the first test I did on the mix gave a slump of 230mm so I immediately retested as per AS and got 220mm so turned it away and got the next one on. It was tested at 230mm and then 220mm so I turned it away too. I spoke with the concrete ninja at the supplier and he said it must just be a bad batch as both drivers  claim not to have added additional water. The pour was aborted and rescheduled for the afternoon. This pour went relatively smoothly with a 140mm slump (added 10l to the mix to bring it to 160mm, and a 160mm slump for the next truck) and 3 columns plus a ramp wall were finally poured.

All the detail about quality mentioned above said, the columns were stripped this morning and I would assess them as high class 2 so pretty happy considering. Now I just have to deal with the admin of turning away vehicles and the fact the pump operators decided that blowing out their slurry mix onto the access slab was a good idea.

In other news the rumour mill is in overdrive as the management have decided to re-organise the teams to inspire better teamwork. This has been widely conveyed yet with no detail, so everybody is in limbo. The only definite is my comrade in the South who is moving North, so I fully expect the workload to increase as he goes. The unions have started a new campaign, portraying JHG as a circus, including a ringmaster and animals – actually quite funny.

The Circus animals

Nicky and I also went to cheer on the British and Irish Lions on Wed, fairly average game and pretty poor stadium for an atmosphere, but town was alive and good fun – still on the hunt for tickets to the 3^rd test, so keep your ears/eyes open please.