Is a new batching plant supplied by a conveyor really green?

A few months ago a major producer of concrete announced that they would be building a new ready-mix plant in a gravel pit North of the capital city of the county where I live. They stated that sand and gravel will be fed directly from the gravel pit via conveyor to the ready-mix plant. This would save 2.500 truckloads and 200 tons CO2 per year. Also, the plant would produce no waste at all as all return concrete would be recycled on site and reused. The new plant will create 12 new jobs.

This is absolutely brilliant, I thought initially. It is great to see how the building materials industry is developing towards a more sustainable future. We need more companies that are bold enough to dare to change!

But then I recalled that a batch of concrete contains some 150 litre of water and 300 kg of cement, right? They are correct that receiving the aggregates from the gravel pit directly saves transport via truck, but that’s only the transport to the plant not the final user. An aggregates truck can transport 25 tons whereas a concrete truck is limited by 8 m3 or 20 tons, of which about only 16 tons are sand and aggregates. So, as the concrete is needed mainly in the city, the actually the amount of truckloads will increase!!

And then I also recalled that the city already has 3 concrete plants directly in the city and 4 around the city one of which is mothballed because there is already overcapacity. Surely building a new plant would use more CO2 than using the capacity of an existing one?

I think it is time for a hallmark that ensures the “green” in projects. It needs an independent verification whenever someone claims to be green.

What do you think?