Friday, August 6, 2010
Week 8 was a big week for a multitude of tasks on site. Waste water infrastructure has been installed for the two bathrooms of the school and research facilities by Ethan and Julie as seen in a following photo spread. The gray and black water have been piped separately for the opportunity to recycle the gray back into the gravity feed system that flushes toilets. The septic style pit has been built up by various workers and completed by Mindy and Max (also shown in the water photo spread).
All columns have been poured and above is a series of close up images of ten different columns. One of which the concrete was mixed on the ground. For the majority of the columns the pedreiro Joam has been mixing and the reddish tone is a product of the procedural steps in mixing in the bitonera (concrete mixer) as opposed to on the ground: Ground Mixture: sand, cement, and aggregate are mixed dry and then water is added. Bitonera Mixture: Aggregate then water then cement then sand then water = red concrete. (the aggregate being red)
Column form installation and removal was made exponentially easier with the arrival of Mercedes who brought with her a cordless 18v li-ion Makita Drill/Driver set (model: LXT 211A). More small things arrived on site this week, with Ethan having come back from Pocone, such as 30 meters of electrical cord, 300 screws, and drill bits.
The bond beam rebar infrastructure as shown above being installed by Ethan, Julie, and John. Each section is pre built by Joam and contains about twice as many retention rings as the vertical columns. Each vertical column has four rebar stub outs that tie the bond beam to the column and the bond beam will contain rebar stub outs that tie each truss to it.
Week 8 has included the building of the four main structural trusses that will be exposed to the interior space and carry the weight of the framing and roofing loads. John and I designed the truss to a specific angle specified by our solar systems engineer and began the build. They are currently cut to fit and tacked together with screws and will eventually receive metal strapping and hardware at all planar connections. The wood type is Piuva, a Brazilian hardwood and is rough sawn at best. It is milled to size with a chain saw (plain sawn technique) and the accuracy is excellent given the tools and conditions. Attention is paid to thickness when cutting stock for the king post and intersecting cords and crowning for all sloped and horizontal members is in the upward direction. The king post is left un-cut at the top where it will receive the ridge beam so fine adjustments can be made according to the varying dimensions of material that it will receive.
Week 8 brought with it four new people (Mercedes, Giorie, Dick, and Diane. Above - the finishing touches of the tijolinha foundation and the beginnings of the infill wall installations. At every third course of the tijolo (8 hole) wall system is a piece of 4/2 or 42 mm "rebar" (ferro)set in the mortar joint and drilled into the column. It is additional lateral support with the anticipation of childhood energy and futbols acting up against the parede (wall).
The header system was initially intended to be the bond beam but was revised with the realization that there was going to be too much tela (screen) and it would demand additional un-needed mullion infrastructure to support it. The roof loads will continue to be transferred through the bond beam to the columns and the header height and structure for all openings has dropped to the 215 cm. The tijolinha header will have to support only itself and the small sections of wall above. Its' construction (as pictured above consists of a wood formwork (cut from off cuts of column form), two pieces of 3/8 or .8cm rebar that is buried in the first mortar joint (massa), two courses of tijolinhas (the smaller brick), and tijolos oito furros (8 holes) above with 4/2 rebar in the mortar joint. A plumb bob is used to check for plumb and dry line is set in each course level (nivel) and strait (reta). The initial header height is pulled from the FFE (Finish floor elevation) dry line and snapped across all coloumns.
The plumbing infrastructure is installed within the "water bar" of the initial design. Water delivery will come from above and waste water will terminate below ground: all of which exist within the same bay in plan, localizing the water systems. Separate piping is run for sinks/showers and toilets. Black water being 100mm and gray being 40mm.
Thursday, August 5, 2010
The form work construction evolved into a much more strategic and directed endeavor due to previous failures. In this image one can see the new form work. It is set around the rebar infrastructure with one face off. After the face (which is labeled with a circled letter that corresponds to the column letter) is installed, braces are applied (to get close to plumb) and heights are measured from the FFE (finish floor elevation) dry line. note: the dry line has been reestablished to account for the thickness of the form rather than the finish column. In doing so we know that all columns are level and generally plumb. When shimmed to the correct height the bottom is "pinned" with stakes and a variation of materials that land us on specific dimensions. Using a plumb bob the forms are plumbed in perpendicular directions and the braces are wired to stakes that have been set in the ground. We have also been checking diagonals in plan and elevation to make sure that all is square which has been the case being that we checked our dry lines time and again. A triple check has been measuring parallel dimensions at the base and tops of the columns. These forms have been successful and we have been getting three to four uses out of them in the overcast weather. When the wood sees much sun it warps and splits at a rapid pace. We butter them up with old cooking oil two times.
This week (unusually cold) began with high expectations and our first real disappointment on the construction site. Although our first and second concrete column pours were a success the third and fourth would prove to reveal the instability of the initial form design. Furthermore, with the departure of architect/pedreiro’s apprentice, Nisha Patel, we have lost one of our strongest assets, both on the job and in design, which is a perpetual state in which we operate.
The initial form design deviated slightly from that which we have encountered thus far and may be one of the main reasons for its eventual failure. Due to the fact that we were ripping formwork by hand and each cut was taking between 20 and 30 min, we chose to rip only one piece, which gave us two sides of the form, and the other two sides ran long. Typical in the area is to have all pieces ripped to size with no excess, and nails attaching one piece to the next and wire (similar to bailing wire) wrapped around the form at about a 40cm interval. Well the third column became “pregnant” which is not uncommon, but the forth one blew out which we are told us also not uncommon by Joam. With one form still standing and un-poured John and I aborted the pours for the day and spent some time in the evening re-working the form design.
The new design included all pieces cut to specific lengths, screwed together for reuse, with a series of ribs spaced to resist the greatest outward force of the concrete load, and wrapped in wire. This was made easier with the arrival of an electric “Makita” or small sidewinder/circular saw Bosch GDC 14-40 with a cut depth of 40mm. The new method has worked exceptionally well and is only slowed by the fact that much of the column assembly has to be screwed together by hand. We have an electric drill but lack enough cord for it to reach the slab site, so we are assembling three sides permanently and installing and pulling the “face” of by hand. Thus far concrete and tijolo columns are going well and the system that is in place is working well.
This week the remaining group excluding myself ventured off to Porto Jofre and various other river villages to collect census data of the potential student population that will be utilizing the school. This included a trip out on the Cuiaba River and the delivery of some soccer balls that Greg (water systems) brought down from the states. The numbers exceeded expectations rounding out to approximately 20 students. Also, registration paperwork (to legitimize the school) has made its way to the secretary of education who is (at this point) offering funding for diesel for the school bus and other necessary components in the operation of a rural school in Brasil.