Day 28: Pouring the first wall lift

Las Animas Concrete and Pacific Coast Concrete Pumping were back again today. This time concrete grout was pumped to fill the network of horizontal and vertical cells in the APEX blocks. The grout is inspected for slump to be sure it is not too thin or too thick. Here is a vid of Mark, the inspector from PSI, performing the slump test.

We passed with a slump of 8 inches, the thinnest mix allowed per structural engineering. A thin mix is desirable because it penetrates hard to reach areas more easily than a thick mix. Mark verified proper rebar placement before pumping. He also verified that grout filled the cells by poking a ¼” diameter rod through the APEX block skin at the bottom course. The rod came out wet with concrete indicating proper fill. Finally, Mark took samples of the grout which will be tested for compressive strength over the next several weeks.

Here is a pic of the pumping crew in action: from left to right, Trevor, Mark, Georg, Todd, Joshua & Justin.

The tasks were:

• Hold the hose over a cell with minimum grout spillage while concrete is shooting out at about 3 feet per second.
• Move the vertical rebars up and down in the cells to help consolidate the grout.
• Clean any excess grout off the top of the blocks.
• Center the vertical rebar in the cell after consolidation.
• Repeat for 100 cells.

Stapling plugs after filling cells under the window openings.


Marty strikes a pose in front of some extra grout used as fill against the east wall. This grout will help facilitate water drainage at this underground wall.

A beam support bracket set in place.

Rafael has a little fun while monitoring the hose.

We finished in just a few hours with no blowouts. We have the rest of the afternoon off, wohoo!

Pastel Green comment for today:
The Portland cement ingredient in concrete has high embodied energy which typically classifies a product as non-green. However, the APEX block cells minimize the amount of concrete needed to make an acceptable structure compared to a typical Insulated Concrete Form (ICF). Additionally, the house is expected to last hundreds of years making the use of concrete more tolerable from a life cycle analysis standpoint.

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Day 20: Water, water everywhere

It was an all-plumbing Monday. Coady, Adam and Erik showed up to run all the water supply plumbing that will be cast into the concrete slab. The main drinking water supply was run into the utility room, and all of the fixtures were supplied with hot and cold water lines (sinks, washer, showers). The pic below shows the larger white supply line entering the utility room from the bottom. The blue utility sink and washer hot and cold lines can be seen on the far wall. Once all of these lines were positioned, they were capped off and the entire system was pressurized with water at 90 psi. Pressurization ensures that any damage before or during pouring of the slab can be identified and repaired.

The other plumbing task started today was routing of tubing for the underfloor hydronic heating system. For this system, PEX tubes carry warm water pumped from a storage tank into the concrete slab to heat the home. The PEX tubing is supplied on 1000 foot rolls. A device called a decoiler (see pic below) makes unspooling the PEX simpler than I had imagined.

My floor has 6 PEX tubes - called circuits - each about 175 feet long. They all start and end at the utility room. In between they run back and forth and are spaced apart appropriately to deliver uniform heat into the slab. The runs are spaced closer together near exterior walls where heat loss from the slab is greatest. The coils are spaced further apart near the center of the home where heat loss from the slab is least. The tubes are also routed to avoid being under cabinets and the refrigerator where heating is not required. The following pic shows some of the white PEX runs in the kitchen.The PEX tubing is fastened to the top of the rebar so it does not move during the concrete slab pour. Two of the 6 circuits were completed today.

Green comment for today:
Consider some form of radiant heating for your home. The advantages over a forced air heating system are:

• Greater energy efficiency because the warmth is supplied closer to where we humans want it - near our bodies. Hot air from a forced air system quickly rises to the ceiling and forces the system to turn on more often to maintain the same comfort level as a radiant heating system.
  
• The system is quiet.
  
• It is the most comfortable form of heat. We humans would rather be kept warm with radiant heat than warm air.
  
• There are no fans blowing dust around the home.

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