PRE-CON BUILDERS
Project Overview
The Zu project was the redevelopment of an existing hotel at 425 Wardlaw Ave in Winnipeg, Manitoba. The project consisted of the demolition of an existing hotel and bar and the construction of a new four story apartment building with a 5th floor penthouse. The main floor is leasable commercial space and includes underground parking. Pre‐con Builders, acting as the general contractor, sourced Multicrete Systems Inc to construct 280 lineal feet of 8” concrete foundation walls with pilasters below grade at the parade level.
Project Scope
Shotcrete Construction
Multicrete Systems Inc collaborated with the structural engineering team, Tower Engineering, to design a foundation wall system utilizing shotcrete as the structural component. Due to the space constraints of the project site, the client was seeking to maximize the footprint of the building. Multicrete Systems presented Pre‐Con Builders with a unique concrete wall installation to be applied using shotcrete. With the design of the shoring panel system, using 6” x 8’ x 20’ trench boxes, Multicrete was able to maximize the footprint of the building by placing the shoring panels behind the shoring piles gaining a full 2’ of overall distance vs conventional lagging between piles.
The temporary shoring served as a backdrop to install a fully weatherproofed below grade exterior wall. The first layer of the wall system was a layer of 2” rigid insulation held in place using a lumber forming system at the top and bottom of the walls. A waterproof fabric membrane was then applied to the surface insulation complete with a flat drain tile system. The reinforcing steel was then tied and fed between the shoring piles. Shotcrete was then applied to the backdrop of the weatherproofing membrane over the insulation to create a solid concrete foundation wall. The shotcrete was applied in two layers, the 6” thick base layer being Multicrete’s own proprietary XPR Shotcrete.
XPR shotcrete, with its integral accelerator, is suitable for application in colder conditions. Achieving 20 mPa in 3 hours and a final strength of up to 45 mPa, XPR allows the contractor to remove the shoring in as little as 24 hours so it can be moved to the next application area. Within as little as 2 hours, the 2” HPC topcoat can be applied to finish the surface. Multicrete’s HPC blend is designed to adhere to vertical surfaces and is a highly workable product for a smooth polished concrete finished surface.
Shotcrete Equipment
Multicrete Systems Inc fabricates and distributes shotcrete equipment and is an authorized dealer of the Aliva line of shotcrete products fabricated by Sika Canada. Sika components are often integrated into Multicrete’s unique designs of specialized and custom shotcrete equipment.
The highly portable Aliva 252 shotcrete unit was used for the Zu project. The unit was fully integrated with Multicrete’s controls system and is capable of spraying coarse aggregates up to 20mm. The shotcrete unit is a “dry” applicator, meaning the dry, pre‐blended aggregates pass through the applicator nozzle using compressed air and exit the nozzle at 40psi. The water is introduced to the dry concrete mist at the nozzle, and consolidates the mix prior to contact with the receiving wall surface. Concrete consistency can be adjusted immediately simply by controlling the flow of water at the nozzle. With the Aliva 252, the application rate can be as much a 300ft² of concrete at 6” within an 8‐hour work day.
Final Product
Multicrete shotcrete systems can apply to a variety of installations including concrete walls, underground tunnels, slope stabilizations and more. Using shotcrete as a concreting method saves time as well as the cost of wood forming materials. The Zu project was completed on time and with the original quoted amount to engineered specifications. The result was a fully weatherproofed concrete foundation wall which used less Labour and materials than conventional form work systems.
