concrete

Week 77: A General Update

Students working outside on Morrisette Campus

Live from Newbern, Alabama, it’s the Thermal Mass and Buoyancy Ventilation Research Project Team! 77 weeks in Hale County and the graduate student team is still firing on all cylinders. This post, they’ve got updates on concrete panels, drainage, and the steel walkway and stair. Plus, the wonders of the Wood-Mizer, a portable sawmill, for those readers who make it to the very end!

Panel Pour Product

Section Isometric: a peak at the interior concrete panels

A couple of weeks back the TMBV team poured four, new concrete panels. These panels were designed to test tongue and groove joining system. Also, this round of test concrete panels experimented with vertical formwork.

As predicted during the struggle of formwork construction and concrete pouring, the vertically poured panels did not turn out so well. However, the team made promising headway with the new joining method. Alright, now that the panels have cured, let’s take a look at the material.

First, you’ve got to remove the panels from the formwork. You know from the team’s previous post that one of the vertically poured panels did not make it all the way through pouring. Look at that; live edge concrete!

However, the smaller vertically poured panel survived! The results were surprising, as seen abovethis panel had more air gaps than the traditionally poured panel. The students previously thought having formwork on all sides would create more even and consistent panels. But, without an open surface to trowel, the vertically poured panels were subject to more air bubbles.

The typical, horizontally poured panels turned out smooth and even as ever. And just look at that grooved edge!

Diagram showing the corresponding concrete panel surfaces and joints

Next, the concrete panels were attached to the Fabrication Pavilion pin-up wall to test how the joints. The results were inconclusive. Some tongue and groove joints turned out well, while others broke at the edges of the panel. Going forward, the team wants to attempt a shiplap joint for the panels. Also they’d like to make more, smaller test panels to assemble in a minature wall configuration.

Drainage Days

As you can imagine, in the everchanging weather of late, the Test Building site became the town swimming pool. The 18″ deep hole containing the foundations was nearly filled to the brim during the past weeks’ rain. Luckily, the team, Mason, and a mini excavator got out while the sun was shining to install the drainage. The French drain leads from the Cooling Porch, betwixt the foundations, into the forest line.

Rain between two foundations leading to woods

Walk this way

You might have been wondering how one day you might access the 30′ tall, 8′ above ground Test Buildings. Well, you’ll use the steel ships ladder and walkway of course.

Enscape rendering of Test buildings

As of late, the TMBV team students have been designing the fabrication and installation process of the stair and walkway. To detail the stair fabrication process, they partook in a classic rural studio technique; the cartoon storyboard.

cartoon showing assembly of steel stair

Next, the team planned out the order of installation of the walkway and the SIPs structural floors. First, they plan to place and secure one assembled SIPs Test Building floor. Second, place the other Test Building floor, using the walkway steel angle frame to square the two to one another. When everything is properly adjusted, lag screw the steel angle frame to the SIPs floors. Third, place 1″ metal grate on top. Next, place and bolt the stair to the walkway and ground connection. Lastly, site weld the handrails to the exterior face of the steel angle frame. Voila! It’s that easy if you only have a crane!

Wood-Mizer Wonder

And the special bonus; a portable sawmill! Adam Maggard, an Auburn University Forestry and Wildlife professor and Extension Specialist in Forest Systems Management, travels the southeast with the Wood Mizer portable sawmill conducting forestry management research and reaching out to family, forest land owners. Adam collaborates with Auburn Architecture Professor and TMBV colleague David Kennedy and Rural Studio Alum Will McGarity. The three gave the students a Wood-Mizer tutorial as well as an introduction to their research.

Rev. Walker’s Home Project team requested the visitors to help mill some gorgeous tree’s from Rev. Walker’s land. Each student took a turn milling down either the cedar or pecan tree. The students were amazed by the machine and even more amazed that freshly cut cedar is bright, pink. It was a remarkable experience, big thanks to Adam, David, and Rev. Walker from the Thermal Mass and Buoyancy Ventilation Research Project Team!

Those pour, pour foundations!

Live from on top freshly poured foundations, it’s the Thermal Mass and Buoyancy Ventilation Research Project Team! This week the students, with a little help from their friends, completed their Test Building foundations. This included installing rebar and pouring concrete. Let’s get straight to those action shots, huh?

Rebar Retreat

First, Livia’s all time favorite activity, the cutting of the rebar. The team cut sections of rebar for the bottom rebar mat, the top rebar mat, and the vertical pieces that hold the two together.

Next, it’s install time. Comprised of number 5 rebar, the bottom mat is a regular grid. The north-south and east-west pieces are joined with rebar ties. The vertical pieces were hammered into the ground at a consistent elevation. This elevation is 1” lower than the future slab surface. These vertical pieces support the top mat, comprised of number 4 rebar. The top mat only runs between future column locations.

With the rebar installation completed, the TMBV team prepared for the concrete pour. Rowe built bridges to span the foundation excavation holes. The bridges will be used to shovel and trowel the concrete in the middle of the foundations. Jeff helped test bridge durability. Livia prepped her waterproof suit, she’s quite messy and will need to be hosed down with the shovels at the end of the day. Cory practiced his elevation calling as the master of the transit.

The Big Pour

If you find yourself wondering, why do these cute, little buildings need such an intricate foundation? Well, while the volumetric form of the Test Buildings appear small, they are actually quite monumental. Reaching 25’ tall and lifted 7′ 6″ off the ground, the test buildings experience substantial overturning forces which are counteracted by the foundations.

“We get by with a little help from our friends!”

With shovel-armed 5th-years, Steve long calling shots, and Andrew Freear on the chute, the pouring began. Everyone helped move the concrete around the excavation hole until it was about level with the grade pins. Grade pins are orange-painted, vertical pieces that are set to 1/4″ under the slab surface height. When the concrete reaches the grade pins evenly, Rowe and Cory began taking elevation measurements.

In order to deem the elevation, “Good!” the students meticulously move and smooth the concrete. Next, troweling begins once several spot measurements meet the elevation mark. While Livia and Jeff began finishing the surface of the west foundation, the others moved on to the east foundation. Pour, level, rinse, repeat! It is actually a good idea to rinse your shovel in between uses it isn’t ruined by the concrete…

Like most concrete pours, the fashionable ones at least, the TMBV ordered 10% extra concrete. However, the concrete suppliers do not typically take back the extra if it isn’t used. Because all that concrete has got to go somewhere, the TMBV team built formworks that match the size of the concrete scrap they already have. Therefore, they will have plentiful pieces for the design of their Cooling Patio. In the meantime, the mini-slab acts as an executive parking spot for Andrew Freear’s sky-blue Honda FIT.

The Finished Products

Completed east and west foundations
Reserved for Andrew Freear (spikes to be installed later)

Would you look at that—two beautiful foundations ready for curing. And an extra mini slab! The TMBV team could not have completed this feat without the help from the 5th-year students and faculty. The pour went smoothly with no catastrophic events! Next up, construction-wise, the team will install drainage and the steel structure. As always, thanks for stopping by and stay tuned!

f i n

Be Groovy or Leave, Concrete!

“Either be groovy or leave, man!” – Bob Dylan

The TMBV team attempts a vertical concrete panel pour

Live from Neck Down week, it’s the Thermal Mass and Buoyancy Ventilation Research Project team! From 8:00 AM to 3:00 PM last week, the 3rd-years, 5th-years, and graduates students have bonded over manual labor and project maintenance. This is the age-old tradition of Neck Down week, the start of each semester in which all year levels put their projects aside to spruce up Rural Studio’s campus and help out at ongoing and completed projects. The TMBVRP team snuck in some more concrete panel test pours in the after hours. Let’s see how they did it!

Panel Proposals

Before we dive into construction, it’s important to highlight what is different about these concrete panels. In contrast to the team’s last test pours these panels are smaller with tongue and groove edges. We will dive deeper into the tongues and grooves later. As seen above in the unfolded wall elevations above, the team experimented with different sizes and arrangements of panels. The main difference in the schemes where whether the running bond pattern stacked vertically or horizontally. The teams chose to test pour the more rectangular panels from both the vertical and horizontal running bond options.

Panel Preparations

For both chosen designs, the team planned to test making the most commonly recurring panel and the trickiest panel. Therefore, for each option the forwork for a typical rectangular panel and the more triangular panel, created by the sloping roof, was designed. However, a certain, not-Livia team member created the “construction” drawings seen above months before actual construction. The team has made significant leaps and bounds in construction drawing etiquette since. There was also much to the tongue and groove formwork that had not been fully fleshed out. So, as seen in the marked-up construction drawing above, much was decided on the fly. It was a very design-build experience.

Next, the team used their new tongue and groove router bits. Tongue and groove is a system of joining adjacent panels by means of interlocking ridges and grooves down their sides. Seen above are the first tests of the router bits to create the tongue edges for the panel formwork. For the formwork, the tongues and grooves were routed out of PVC board. PVC board will not chemically bond with the poured concrete, therefore, creating a successful cast. Connecting the concrete panels to one another using the joining system will improve their strength. The panels will act more as one structurally, but also thermally making a more effective thermal mass.

Horizontal Panel Pour

Along with testing the tongue and grooved edges, the team attempted two different pouring strategies; horizontal and vertical. Seen below is the typical, horizontal panel pour method. The team is pretty well-versed in this recipe. After pouring the panels, the team will let them cure for about a week. Onwards to the vertical pour!

Vertical Panel Pour

The vertical concrete formwork meant to create two perfect panel faces and ease panel transportation. However, you guessed it, the vertical pour was quite difficult. First, vertical formwork requires more pieces that need to fit together more precisely. You are in a sense making a very precise sandwich that leaks Mayonaise everywhere if you don’t get it right. Second, getting the masonry anchors to stay in place and attach through both large faces required a special bolting jig. Another new piece to make. Third, to keep the formwork upright required leveling and sawhorse structure. Fourth and finally, the team built a funnel to transfer the concrete through the 1-1/8″ formwork opening. And repeat for 60 plus panels!

While the smaller, triangular vertical pour went fine enough, the large rectangular panel busted open. As you can see above the triangular panel had little leakage out of the masonry anchor attachment areas. The rectangular panel however suffered catastrophic failures in this area. For now, the team awaits the curing process to see the results. However, based on these vertical tests they aren’t sure the reward will be worth the hassle. But, hey, where else in the world do you get to test pouring concrete panels vertically than in the Rural Studio graduate program? It’s always worth the hassle.

The Wood Rack

Last, but far from least, the team can’t wait to show off their new wood racks. Because the Fabrication Pavilion is their construction headquarters, the team was in charge of cleaning it up as a Neck Down week task. They are stupidly proud of these wood racks they built to take all their lumber vertical and clear space for more activities! Please admire them!

Copper has joined to say thanks for tuning in! Stop by next week to see how the panel pours and tongue and grooving worked out for the Thermal Mass and Buoyancy Ventilation Research Project Team!

Concrete Content

Live from—wait, is that a 3′ x 4′ concrete panel? Lately, Thermal Mass and Buoyancy Ventilation Research Project Team has been delving into the interior of the test buildings. Inside, Wood and concrete thermal mass line the walls of the test buildings. The thermal masses thickness and surface area are optimally proportioned based on the thermal properties of the materials, size of the room, and ventilation required. This proportioning makes the whole passive temperature and ventilation control strategy tick. Therefore, the TMBVRP team must figure out an elegant solution for hanging the thermal mass to create a beautiful interior which also operates optimally. Let’s take a look at how they are tackling this task. Hint: it involves very big concrete panels …

Typically, designers think of concrete as the go-to material used in passive thermal mass strategies. This is why the TMBVRP team is testing it in the Testing Buildings alongside the more surprising material; Southern Yellow Pine. If you remember from previous posts when the materials are proportioned properly using the Optimal Tuning Strategy they can be equally effective at cooling and creating buoyancy ventilation cycles.

However, when it comes to hanging the two materials on the SIPs walls, Pine is obviously much more straight forward. The pine boards attach to the SIPs panel walls with a simple screw. Well, multiple simple screws. On the other hand, the team will have to get much more creative to secure the concrete panels.

To start, the team tested two strategies hanging concrete panels; masonry anchors and cone form ties. First, they cast the masonry anchors and cone form ties into two 12″ x 12″ concrete panels. Similar to the panels in the Concrete Test Box in size, but different in the attachment system as the security of the panels in the test box is far less crucial as no one will be sleeping in it. Both test panels are attached at all four corners to shear walls in the Red Barn.

Masonry anchors are fluted plastic chambers that adhere to the concrete and are screwed through tp attach concrete to wall. They allow for a connection point that looks as if the screw passes directly through the concrete. However, for the sake of durability, the team would include a washer in this scheme to keep the screw from bearing into the concrete.

Likewise, the cone form ties act the same as the masonry anchor, but are larger in diameter and thickness. Also, they are able to set into the concrete to create a nice reveal. While the team liked the effect of this reveal, team collaborator Professor Salmaan Craig revealed a possible hurdle for the experiment. Revealing edges at the attachment points could slightly disturb the direction of heat transfer. The direction of heat transfer is integral to the strategy which is why the panels are insulated on the back. And, while this is a very small area that could be affected it is multiplied enormously by the number of panels and screws. We call this problem, fastener effect loss. Fastener effect loss assumes, very conservatively, that the small area around the reveal is ineffective to the system.

Next, the team ran the numbers and if all the panels were 12″ x 12″ with four form ties each, 6% of the thermal mass would be lost to faster effect. Now, that’s not bad at all for a real building, and again that’s an extremely conservative estimate. However, for an experiment establishing the most ideal situation for a small building, 6% is not negligible enough. Going forward, if the team prefers the cone form ties, they will need to lessen the amount of panels therefore lessening the number of form ties. Fewer form ties means less fastener effect loss. Fewer form ties also means bigger panels. The team sketched out many different possible panel arrangements but decided they needed to test just how large they could cast a concrete panel. Above on the far right, you will see their biggest panel possible design. This design consists of 3′ x 4′ panels in a running bond pattern.

Next, Jeff and Rowe got to work creating the panels for biggest panel possible design. The estimated weight for these panels is 200 lbs. While this is fairly difficultl for construction, the size of panel cuts down on the number of panels needed from 128 to 39. So while it may be hard to lift, the team would have to make far fewer panels. And the fastener effect loss shrinks exponentially as the design goes from using over 500 screws and form ties to under 200. The question still remains, however, will the panels crack at this size?

To address the issue of cracking concrete panels, the team tested two different mixes for their large panels. If you remember from their blog post on concrete thermal property testing, the team obtained the thermal property data from three different standard concrete mixes. They ended up using the Quikrete Pro-Finsh for the Concrete Test Box, but thought for the large panels they should also try the Quikrete Fiber-reinforced mix. The fiber-reinforced mix is increased in structural integrity which will be beneficial for larger panels by reducing possible cracking. Jeff and Rowe built two form works to test both mixes at the 3′ x 4′ panel size.

Look at that! Both the fiber-reinforced and smooth finish concrete mixes came out great! Very smooth with zero cracks, but very heavy. Above you see the fiber-reinforced panel which turned out just as good as the professional finish and would be much stronger. This does not mean that the team will be using the enormous panels, most likely they will cut them in half. However, the team now knows their largest limit on size is possible. The team will continue to weigh their options between attachment method, panel size, and panel arrangements as they solidify their design. Keep tuning in to see where these crazy kids and their crazy concrete end up!

Formwork makes the Dreamwork

Studio

This week, the 3rd-years worked on creating detail drawings of Ophelia’s Home’s foundation. Being able to see the foundations in person while drawing them is an amazing, unique opportunity. It has quickly given the students an understanding of how crawl-space foundations work. Each student selected a unique piece of the foundation to draw. These drawings will eventually be added onto to create 7 complete section cuts. The drawings show details through the foundation piers, vents, below significant areas, and the front porch. All the drawings were organized onto one construction document sheet, which is a new and very important skill for the 3rd-years to have learned.

Horseshoe Courtyard

This week, the 3rd-years’ continued work at Horseshoe Courtyard consisted of cleaning more bricks. They also began building and setting up wooden formwork for the incoming concrete! Students worked to hammer in stakes, cut wood boards, and drill formwork into place. They are extremely excited (some may say overly excited) about the concrete pour.

Perry Lakes Park

After a few weeks of working in Hale County, half of the 3rd year students ventured out to Perry Lakes Park to help with maintenance and repair. This included working with 5th-year students and graduate students to clear large debris from pathways and replace aging timber boards on the elevated walkways and the Birding Tower. Perry Lakes Park is currently closed to the public until it is rejuvenated. However, once the Rural Studio Students are finished, the park will be open for bird enthusiasts, outdoor lovers, and adventurers alike.