That's One Big Sink

The latest Studio Build project is wrapping up and that included installing a few small, and one very big, concrete items. It seems everything but the kitchen countertops are concrete. The fireplace surround is GFRC polished through 3000 grit and coated with beeswax. The bathroom countertops were lightly ground and sealed. The big piece was an eight and a half foot long integral sink in the master bath. It is also GFRC. This is a perfect example of where GFRC is far superior to conventional mixes. If we did this conventionally it would have weighed about 500 lbs. Since we did GFRC it only weighed 240 lbs. My biceps are still sore from carrying this in, but a 50% weight and material savings makes it manageable. It's charcoal grey and was coated with the Richard James sealer kit.

Recently I performed another sealer roundup using some scrap pieces lying around. It gives me an excuse to break out the beers on a Saturday morning. My standard test materials are vinegar, hot sauce, toothpaste, red wine, mustard, and an icy cold beer for a sweat stain. I was very impressed with the performance of the Richard James silane, epoxy, urethane combination. I normally densify the surface using a lithium silicate, which makes this a four step process. That is a lot more effort and cost than the traditional acrylic, but the results are worth it. None of these liquids had any effect on the surface. 

 

The very dark section was beeswax applied to a highly polished surface. It looks very cool and is a great color enhancer, however beeswax doesn't provide much protection against acid attack and requires constant recoating.

Arms Race

I have enough work coming up in the next few months that I could justify adding one more piece of equipment. I picked up a planetary grinder setup for dry grinding. The conventional grinder works but takes a long time and requires enough pressure that the thoughts of doing more than one kitchen make my arms hurt. The planetary grinder gets the job done about 5 times faster and has enough weight that all I have to do is hold on. This should pay off in time very quickly.

For a test I quickly ran up through 3000 grit on spare piece in the garage. Although you wouldn't go up to 3000 for a kitchen or bathroom, I just wanted to see how it works. This is a 30 inch by 20 inch piece and it took less than 20 minutes to work from 50 to 3000. The general surface texture is much better/more consistent than the single head unit. 

It will be a busy fall.

On-going and Up-coming Projects:

1. Concrete planters

2. Fireplace surround, bathroom vanities, bathroom sink, and bar top for a new remodel

3. Island countertop

4. Kitchen remodel

Buffon Residence: Final Installation Photos

The Buffon residence is cleaned up for appraisal so I took the opportunity to grab some finished pictures. The entire project consisted of twelve sections which included one giant 4 ft by 12 ft island.

 

The color is dark grey with a urethane sealer.

 

 

 

Half bath off the kitchen.

Full bath. 

Extra panels used for the color check were cut down for the fireplace surround. 

Coming Soon

Some very cool things are cooking over at creating concrete countertops. I have developed a series of low cost countertop mixes that will be marketed regionally. Along with these will come a series of training sessions. The mixes include a 1) pressed mottled finish, 2) standard countertop, 3) self-consolidating mixture, 4) glass fiber reinforced concrete face coat, 5) glass fiber reinforce concrete backer coat, 6) self consolidating fiber reinforced mixture, and 7) fiber reinforced pressed mixture for unique shapes and furniture.

In preparation for the training courses I will provide a complete how to for mold construction, concrete placement, through finishing. I am evaluating some new sealers and application techniques that should prove helpful to the budget-minded person. The whole point of this exercise is to let the average or slightly handier than average person create some great products. I'm making some new planters which should be a nice project to show the new techniques.
http://www.murraydecorative.com/mdc_seminars.php



Not Too Shabby

The other weekend it was in the mid-50's in Kansas City and sunny. Not a bad day to slurry some countertops on the back patio. 

The Buffon countertop project is well finished, but the house project is not. As soon as the countertops got installed they were covered with construction debris. Once that is cleared up I will post a big summary of the project.

Buffon Project Progress

The Buffon project is just about finished. Once everything is in place I will get the completed pictures.

Here is the setup for the island pour. The island is 44 inches by 12 feet. It was cast off site and carried into place.

 A cell phone shot after finishing the pour. The hollow spot in the back is the section over the cabinet, the rest is solid and overhangs.



It took 8 people but the island top is in place. The island is wrapped on both ends by solid concrete pieces. 

Internal Curing Concrete with Super Absorbent Polymers

In the previous post I mentioned adding a super absorbent polymer (SAP) to the mixture to improve curing and eliminate having to put plastic on the fresh concrete. I have been using SAPs for a number of years in traditional concrete and have been very happy with the results in countertops.
A little background:
Concrete gets hard through a chemical reaction called hydration. Various cement components dissolve and recombine to make concrete hard. The ultimate strength and durability is related to the cement chemistry and amount of water in the system. Lower the water-to-cement (w/c) ratio the stronger the mixture. Unfortunately the hydration products occupy a smaller volume in their hardened state than in the fresh state, so concrete shrinks. At w/c less than 0.42 this shrinkage can be significant enough to crack the concrete from within. Also at low w/c the permeability of the hydrating paste is so low that water can't get in. If you break a low w/c mixture that has been stored in water, the middle will be dry and hydration has stopped. Hey, wouldn't it be nice if we could include some extra water in the mix that the cement can use during the hydration process? Yes and in comes SAPs.
SAPs basically soak up a bunch of water, expand, and give the water back one time. They aren't like sponges and only have a single use. Since we put more water in the mix than is needed for complete cement hydration, adding a SAP to soak up the extra water will help in the long run. The other thing needed for a good SAP is a small particle size for good distribution. Baby diapers are SAPs but the polymer grains are very large and would leave big bubbles if used in concrete. The particle size of the SAP I use is designed to work well within concrete.
The version of SAP I use is called Hydromax. You can buy a 4 lb canister for about $80 which is sized for 8 cubic yards of concrete. That one container is enough for 40 or so normal sized kitchens. The dosage rate is 2 oz per 100 lbs of cementitious material in your mixture. Just throw the SAP in with the mix and proceed as normal. It will not produce any noticeable changes in the mixture. Overall these mixtures gain strength faster, have better overall strength, and less shrinkage.
One thing to note, SAPs are very fun to play with. If your kids or drunk neighbors get ahold of them you may run out from all the experiments.