Preparation and pouring of the concrete ceiling
Since our last report on the pouring of 38 columns earlier in July, we are thrilled to share yet another update on the progress of the Nile Institute Rwanda construction works. After wrapping the 38 columns in blankets & moistening them regularly, the formwork could eventually be removed without risking rapid drying and reduced concrete quality.
The next phase has been kicked off: pouring of the ceiling columns and plates. Firstly, the wooden formwork for the ceiling columns is propped, followed by the support of the ceiling plates. 28 days after the columns are cast, the entire structure is then solidified in concrete. While the wooden supports are custom-made, their exact height is still adjusted on-site. The clear height under the beams is 250 cm in the cafeteria and the laboratory, and 300 cm in the exhibition hall. The work started with the entrance and the cafeteria; then, the research center, and finally, the higher exhibition space.
After the formwork of the columns and plates, the 90 cm protruding canopy with an inclined rise is supported all around the building except at the back. From the end of August, the reinforcements were woven and placed. Initially, the columns were reinforced; the plate reinforcement consists of 2 layers everywhere. Meanwhile, two temporary stairs were built on the outer sides of the building to facilitate the smooth transport of concrete.
While the wooden formwork was covered with plastic sheeting to obtain a smooth concrete structure, unexpectedly – within a new set of environmental regulations – a law had been issued prohibiting such sheeting. The formwork that was not yet covered was supplemented with cement bags as an alternative. The electrician provided the necessary electrical wiring for light fixtures and alarm systems, and the plumber installed the necessary drains.
From September 25th, concrete was poured over a period of 2 weeks. Concrete samples labeled with their pouring dates were sent to a laboratory in Kigali for inspection. After concreting, a necessary curing period follows; the concrete also requires a drying period of 28 days before the supports are removed.
The next phase is the interior and exterior masonry work. The flat cutting of the rock stones for the outer walls can begin. A meticulous task! After the masonry work, the entire concrete structure will be smoothly finished with a layer of cement.