Geek alert. The following email contains technical stuff regarding construction. No foolin’.
There are so many rules and regulations when it comes to construction that it can be mind boggling. But it is all in the name of safety. Did you know that every time a concrete truck shows up on site we have a “Special Testing & Inspections” firm do work to ensure the concrete being installed meets the current building code requirements? This is an independent agency the owner (Evergreen) pays to verify that certain structural materials meet the design strengths specified. They check on numerous things done on site such as the steel welding, steel reinforcing placement, and they inspect many different aspects of the concrete being placed. One of those tests is called a “slump test”. The “slump test” is done on-site shortly after the concrete truck arrives. If you want to learn more about slump the following is a good resource: http://www.concreteexchange.com/how-to-center/concrete-mixes-and-additives/concrete-slump-test/ 
Another thing the agency does is take samples of the concrete from the truck and simulate it’s placement on site with the use cylinders that will be tested at a later date. The attached photos show C.J. Coffey (Mr. Coffee is what I call him) of Pacific Testing & Inspections doing some of his work. He puts a little concrete in each cylinder and then pokes it 25 times with a rod to replicate a vibration tool the contractor uses to get air bubbles out of the concrete (also known as “mechanical consolidation”). Then he adds a bit more concrete and does the same thing again, and then a third time until the cylinders are full. Those cylinders are capped and stored on site to cure in the same setting as the concrete poured for the building. The next day the samples are sent off to a lab and eventually crushed so the compressive strength of the concrete can be verified. If the concrete does not meet the required strength it will have to be removed from the building. Too much water in the concrete mix will make it weak and will increase its likelihood to crack. Not enough water in the mix may create voids in the concrete and again make it weak.
The required strength of the concrete may vary depending on the application. On the Lecture Hall the new infill concrete walls have to meet a designed 4,000 PSI (pounds per square inch) of compressive strength. In one example the crush test performed at seven days after the pour showed a strength of 7,370 PSI. They crushed another sample at 27 days and it measured a strength of 10,920 PSI. That is like Super Hero Strength. Can you say “WOW”? The concrete will continue to slowly build up more and more strength over time. It will eventually reached its peak strength in about 50 to 100 years, and then even more slowly lose some of that strength. I’m pretty sure I reached my peak strength some time earlier.
If you were on campus yesterday you may have noticed a number of concrete trucks coming and going from the Lecture Hall construction site. Well, yesterday was another milestone. We poured 93 cubic yards of concrete in what will become Lecture Hall 1. This concrete installation was for the footings and slab that will support the structure for the new Lecture Hall floor deck. It amounted to ten concrete truckloads! The pouring started around 8 AM and continued until just before 1 PM. Another attached photo shows that installation in process.
Today some more jackhammering will take place as they start clearing paving from around the Lecture Hall to allow for more of the addition. Most work next week will include the excavation and concrete formwork installation for the addition. Roofing weather barrier work started on the Lecture Hall this week and will continue next week as the weather cooperates with us. Formwork for foundation walls will go up for a new classroom east of Lecture Hall 1. Concrete will be poured on the newly installed Rotunda metal floor decking. Some of the excavated areas between Lab II, the Library Building, and the Lecture Halls will be backfilled and compacted, so don’t be surprised if you feel planet earth shaking a bit next week.
Have a fantastic weekend. Don’t forget Chinese New Year begins this weekend; so Happy New Year once again!
Cheers,
Tim