“Alsina Formworks worked closely with the client, and even with the site foremen to be involved in planning and provide better solutions for the completion of the project, which requires certain quality standards, not only in equipment provision, but also in the necessary engineering for Alsina’s Tech Department to fully utilize the formworking equipment.” said Rafael Caso, Alsina’s Senior Commercial Technician in this project.

In addition to the Treatment Plant, several headworks were carried out which involve several curved and straight concrete structures, among which we can count the Main and Secondary Clarifiers, the trickling filters, the tanks for unsafe drinking water, the main pumping station, the solid contact tanks, the odor control plant, the liquids chamber, the energy dissipater, the maintenance building, and the desander.

“We had structures that were, on average, 6 meters tall, so we had to carefully study the structure to work out the necessary concrete pouring outlets, as well as the circular silos that had a radius of about 17.5 and 21 meters across. None of this was an issue, however, as our equipment adapts to all shapes and sizes.” Caso said.

Engineering Challenges

An important part in this type of hydraulics construction is the matter of watertightness and the solutions are used on site to prevent water from leaking through the concrete walls as well as the preceding trickling filters while the plant is running. When coming up with these solutions, one must keep in mind the execution of the concrete pouring into the formwork, be that process industrial (as is the case with Alsina’s formworking systems), or done with traditional wooden systems, normally used in cisterns.

“Alsina proposes the use of Alsina Waterproof Cones and Plugs, which can handle pressures of up to 10 meters of water columns or m.c.a.’s. This will allow us to work safely and practically on sealing this type of holes in the concrete, which are necessary from an engineering standpoint when putting up walls” said Alsina’s Technical-Commercial Officer.

Formworking for Circular Walls

Alsina’s proposal included the use of the “Alisply Circular”, which is a modular formwork system for curved surfaces and which is the ideal formwork system for circular silos, groundwork for metallic silos, tunnel boring, and other uses.

Alisply Circular is the only one of its kind in the market and, unlike other systems; it has a plywood surface and a metallic frame, which makes it lighter allowing for a nigh-perfect finish on the concrete.

“The advantage of Alsina’s Alisply Circular system is that it’s not an assembly product of wooden beams and boards that must be custom made, braced properly and are expensive because of the necessary man hours that the assembly takes. Additionally, wood is not a long-lasting material and as such is not suited for industrial labor, as modern-day formwork systems in our country ought to be.” said Caso Tirado.

The workings of this system is fairly simple because it’s composed of modular panels of varying heights that are held together by Alsina GR-2 clamps, the same as those used in straight wall systems. They also have openings for Dywidag bars, which can be climbed to reach different heights and that are compatible with the rest of Alsina’s wall formworking systems.

“Alisply Circular is a system that is straight when being transported, making it easy to pile them up on trucks and on site. They can adapt to several radii starting from 5 meters and can be easily assembled since, with nothing more than a wrench, the turnbuckles on the metallic frame are activated and make the system take on the required radius without too much effort” explained Rafael Caso.

Other Alsina formwork systems were also used in this project, such as the Alisply Walling system for straight walls, which can be transported in sheets of up to 36 m2 with a single crane motion, which allows for great on-site performance. The C-160 Climbing Platform system was also used to make it easier to work at such heights.

For horizontal formworks for the sites many concrete structures, we used Alsina’s CL-40 and AR-80 shoring systems, which can handle loads of up to 4.000 and 8.000 tonnes, respectively.

For cases like the Maintenance Building, we used the Mecanoflex system that we talked about in our previous article.