161–170 of 218 posts
> I tried to track down the original source of this idea ... Beiser cites an article from the UN, which itself cites a 2006 paper about using two types of desert sand from China in concrete. But that paper doesn’t mention the roundness of the particles at all. This seems to be a fairly common pattern where a citable source (Beiser's book and the UN article) makes a mistake, that then propagates everywhere as common k…
> And we have engineered machines that can transform big rocks into small ones.
OK, so you solve a problem of decreasing resources by using additional energy, so more CO2 emissions...
One thing that surprised me when I started running a tugboat business: A country can be both an exporter and importer of sand. Sand of one type goes from the U.S. to The Bahamas to be used in concrete. Sand of another type goes from The Bahamas to the U.S. to be used in aquariums. Specialty sands go to make regulation volleyball courts.
Just marveling as an old school computer programming geek that I happen to be in a forum that also includes someone in the tugboat business.
I didn’t exactly understand the take away from this video. In the first test he does, the river sand concrete is three times stronger than the desert sand concrete, but in the second test, the desert sand concrete is 10% stronger than the river sand concrete. What exactly is going on?
If you normalise for the the same ratio of cement / water / gravel / sand then sharp-sand (crushed rocks) is stronger.
If you normalise for workability (i.e. the concrete flows and can be worked easily) you need to add additional water to sharp-sand, which means that the smooth-sand (e.g. river-rocks) end up stronger.
Earlier quoted context omitted.
Just marveling as an old school computer programming geek that I happen to be in a forum that also includes someone in the tugboat business.
We have the programmer to woodworker pipeline, programmer to runner pipeline... is there a programmer to tugboat operator pipeline I'm missing out on?
- Programmer to farmer
- Programmer to musician
- Programmer to writer
and of course
- Programmer to landlord.
Earlier quoted context omitted.
We have the programmer to woodworker pipeline, programmer to runner pipeline... is there a programmer to tugboat operator pipeline I'm missing out on?
From what I remember from this particular code-base, there are also: - Programmer to farmer - Programmer to musician - Programmer to writer and of course - Programmer to landlord.
Earlier quoted context omitted.
We have the programmer to woodworker pipeline, programmer to runner pipeline... is there a programmer to tugboat operator pipeline I'm missing out on?
From what I remember from this particular code-base, there are also: - Programmer to farmer - Programmer to musician - Programmer to writer and of course - Programmer to landlord.
Earlier quoted context omitted.
What about eg air, wood? Used by mass or volume or?
It seems likely to me that both concrete and plastic are used in greater mass and greater volume than wood.
Per tonne, twice as much concrete is used per year than all other building materials (including wood, plastic, metal) combined.
I noticed that the two bars were breaking differently under the hydraulic press. One was crumbling and the other (manufactured) was exploding . There was no mention of this effect in the video. It couldn't be the due to force because in the 2nd half the manufactured bar broke at a lower force. Could this factor has consequences on how manufactured sand concrete behaves with natural phenomenon (hurricanes, earthquakes…
Stronger concrete requires more stress to cause it to fail, and as such it takes more force to break it. There is logically more energy because of the higher force, so more energy gets released.