A few days ago, I was catching up with some friends and ran into a product manager for a concrete supply company. We shared a few stories, and I got an insight into what it is to run a concrete batching plant.
We all know what it takes to prep and pour concrete, I know some of the seasoned guys out there will have heard all this before. None the less, please bear with me while I paint a picture for everyone.
Leading up to concrete pour day
You have booked the 4th floor suspended concrete slab with 300m of concrete seven days from now. You have the block layers building the last wall on level three, with core fill tomorrow afternoon with the form workers starting in the morning.
We all know booking a concrete pour with any significant volume is an educated guess at best.
As the site team, the pressure is on leading up to the pour day and providing everything goes to plan we will have half a chance to breathe. The only things to worry about is the concrete arriving, and the concrete pump doesn’t break down.
On the day of the pour, the first truck arrives, then the second, followed by the third truck and they continue coming into the morning. Then the trucks stop, we are on the phone with our concrete supplier, “where’s our concrete, we have been waiting for 20-minutes for the next truck”?
Tensions start adding up; it’s a scorching hot day. Concreters are screaming at us; the concrete pump is getting ready to recirculate the line hoping it’s not going to block. We wait five long minutes, the phone rings, the next truck is five minutes away.
The truck arrives, and we are on, two more followed right behind parking along the street waiting their turn to unload. Game on, we are halfway, and its only 11 am, perfect, might even get home early today.
We know tomorrow is going to be full on again getting everything ready for the next concrete pour. When this pour has finished, we can take the afternoon to catch up, if that is at all possible in this game.
Organised chaos, the concrete batching plant
What about the concrete plant? They will be doing the same thing again tomorrow, and the day after that. And I thought our job could be hectic. Haha, I had a lesson on how a high-intensity job looks.
I will go over a few numbers, to help paint this picture, keep hanging in there with me.
Forgive me if I get some of the numbers incorrect, but here we go.
The plant can produce approximately 200m of concrete per hour, however, can only store enough raw materials to produce 80m of concrete at any one time.
There are 10-12 trucks allotted to the batching plant, which each truck can carry around 7m of concrete on average.
A truck’s loading time is 5 to 7 minutes, again sometimes more, sometimes less.
There are 60 minutes in an hour, that is 12 loads of concrete out the door per hour to a total of 144m give or take.
A truck can do about ten deliveries per day, that equates to around 840m with all the trucks combined.
The plant has three big concrete pours on that day; your pour at 300m, another one on the other side of the city with 200m and finally one around the corner from you of 180m. Also, each, pour has a different mix of concrete.
You are on a two truck feed, one truck every 5-minutes. The 200m pour site has a single truck feed on a 10-minute turnaround. And the last 180m pour site is on a single truck feed as well with a 10-minute turnaround. That is four trucks every 10-minutes to unload not including the three trucks to begin all the pours.
Are you lost in the numbers yet? The numbers get better.
Your 300m site and the 200m site are both a 15-minutes drive away from the batching plant with no traffic. The last 180m site is 10-minutes away from the plant.
Like most cities, the peak hour traffic is currently adding 10-minutes to the travel time for the trucks. As we are pouring in the city, we are not able to park any waiting trucks along the street until after 9:30 am.
Let’s say all the pours are booked with a 7 am start time. How do you send out your trucks? Which trucks go where? Do you have three trucks on rotation for any particular pour site?
Just like you, I have no idea. The above is a typical day for the concrete plant.
Masters of communication
The way it was described to me, the plant operators are continually talking to the truck drivers and checking on traffic. You also have to keep on top of the raw materials. Remember, that the plant can only store up to 80m of raw materials on site at any one time. Oh, don’t forget that each concrete pour has a different mix of concrete when you are ordering your raw materials, and when the trucks are backing up to the batching stand.
Yep, game on my friends. I forgot to mention the seven other jobs booked in for that morning as well. They are only small house slabs of 50m & 60m and a few driveways all starting between 7 am, and 9 am.
At this point, I gave in, forget that for a job. I know that these guys do it for a living and there is a method to their madness. The batching plant operators are masters of communication.
The pressure that we go through leading up to a concrete pour, they do that day in and day out. Up until this encounter, I took concrete delivery for granted, especially when the trucks would turn up on time. But when the concrete trucks stopped, I was never too concerned what was happening at the plant. I was always halfway through my pour.
I don’t know about you, but there are plenty of times that I forget that we are all in this together. We all have our roles to play, and without all of us developing our skills, the madness we call construction wouldn’t happen at the breakneck speeds we have achieved. It’s almost like we are the victims of our own success.