Why is it that some ready mix companies are doing this by batching at low or no slumps and then getting there flow ability from plastsisers it happened 2 me 2x so far this week Prime out perfectly and then the pressure just climbs to max pressure like you are going to plug. Then after eliminating all possible causes I call and they say they are using glenium I have had zero luck with this in the past. But then when you add water to it to bring the base slump up the pressures go down to normal. It makes me wonder why when you order a mix design that they just decide to add this when it was not asked for it baffles me.... Some ready mix companies don't get it and they don't understand that a concrete pump does not know the diff between a chemical slump and a true slump. Why they don't ad it at a base slump of 75 to 100mm I will never know...

i pumped that mix but with a 7 inch slump and had no problem.

The only problems you usually get is if the moisture meter is off caliber and they don't get enough or get way too much of it in the mix. Because it will seperate like nobody's business

 Problems like yours have pissed me off for years. You need to learn as much about thier mix designs as possible. I know its not your job, but it can help. You have allready figured out its a lot of chemical and too little water. What is the rest of the material like. Mosture content off the sand and rock can make a difference. Are they using new add mixtures they have never used before, because if so they dont know anymore than you do. I have friends that work that work for ready mix companys and I work closely with who are QC's and they can help a lot. That dos'nt mean they tell me every thing but I have caught there companys pulling shit and have usally proved my point to them and the customer. The more you know the better off you might be.

I hear you the more you know about mix designs the better and I keep a close watch on what comes to my pump because if you don't it will bite you in the ...... We all learn from mistakes whether us as operators made a mistake or from postings on here. I had a load 3 years ago the supplier thought they were putting in super P but the container was mislabeled and the load went from a 125 mm to almost rock solid in a few minutes. I barley got my pump clean and I mean barely and the pile under the hopper even after it being hit with lots of water from the wash was rock hard to the point and blade had trouble moving it a hour later. Today I had perfect loads proper stone/sand/powder which made today's job perfect.

Hi, I worked for BASF who supply Glenium admixtures to the concrete industry, and I have heard this quite a lot on low slump concrete, this is 100 slump to 120 mm, but it is refreshing to see that you understand the difference between chemical slump and natural water induced slump.

To over come this problem of massive pressures in the line the concrete producer should follow the rules of thumb,

1. Minimum cement content of 300 kg per m3, dependent on the quality of sand and coarse aggregates possible 280 kg
2. Sand to coarse ratio of 45/55
3. Slump 100 to 120 mm
4. Water around 180 to 190 litres with admixture to taste
5. If they have rubbish all crushed aggregates then a pumping aid should be used to ease the pumping pressure.

The main problems are caused by the fines either there is not enough or there is a gap grading in the sand, which allows all the fat and paste to flow straight through these tiny gaps in the concrete leaving the larger stones behind and to compensate the pump works it's nuts off.

I hope it helps you some, if you have any more techy concrete questions just fire away.