The Four Seasons Raft Slab Project

  • PROJECT:

    Four Seasons Raft Slab

  • CUSTOMER/OWNER:

    Menkes / Four Seasons Hotel & private residences

  • ENGINEER:

    Stephenson engineers

  • LOCATION:

    Downtown Toronto,Ontario

  • VALUE-ADDED PRODUCT:

    Agilia

  • DATE OF POUR:

    November 29, 09

  • VOLUME:

    4211 m3

Single largest self-consolidating pour in North America!


SPECIFICATION

The high fuidity of Agilia made it possible to increase pouring rates with the use a drop pipes. Located around the sides of the raft, a total of 5 drop pipes and 2 pumps were used to access the raft. The drop pipe method increased the average pour rates to 450 m3/hr for a better part of the pour.

On November 29th, a total of 4211 m3 of Agilia was poured in a raft slab that is the future foundation of the Four Seasons hotel and private residences in Toronto. The pour taking only 14 hours to complete, had originally been planned as two separate pours with standard concrete. This time saving realized by using Agilia is just one of the benefits which attracted Menkes, the customer, to the product.

The raft slab was located 60 feet below the grade, with a raft depth of 8 feet. The geothechinal engineers decided that a raft slab foundation was well suited for the 55 story building for the type of soil and bedrock located beneath.

To withstand the pressures applied by Agilia, a concrete perimeter wall was constructed to take place of traditional forwork. The reinforcement in the raft slab was made up of approximately 800 tonnes of rebar.

A total of 123 trucks carried Agilia to the job site from 4 plants in the Greater Toronto area. The trucks pulled in from the staging area right up to the drop tubes to unload Agilia in approximately 4 minutes time. This process was very systematic, maintaining a fast rate of pour, which amounted in cost savings for Menkes.

Strategic planning was critical for a pour this size to be the success including everything from plant organization and material handling, trac planning, onsite dispatchers, maintenance and quality control. The organization in preparing the plants and material handling demanded precise timing and schedule planning. This was the largest Agilia pour for these batchers, QC technicians, maintence workers and loader operators; all personnel who played a valuable role in ensuring the consistency of each load that went out.

Product Performance

Agilia was necessary for the design of the raft slab, providing ample fluidity for pouring in the congested rebar, with no segregation. Not requiring vibration, allowed for ease of placement and nishing, where no workers were even on the slab during the pour. For this reason, Agilia was also the safer choice. No labourers were on the slab during placement therefore, minimizing the safety risks on site.

The absence of vibration and finishing labour also translated directly to cost savings for the customer. Where a signicant amount of workers would have been required to properly place, level and finish conventional concrete.

To control the heat of hydration the agilia mix was designed with high SCM replacement, including Slag and Type F Fly Ash, and was batched with cold water to minimize the initial temperature. This helped to keep the peak heat temperature below 70*C with a dierencial as low as 7*C, well below the max limit of 20*C. When the entire 4211 m3 Agilia pour was completed.

The specication also called for 60 MPa strength at 90 days. The compressive strength of Agilia was 73 MPa in 28 days with and ultimate strength of 85 MPa.

Agilia had been previously used in the two similar raft slabs in the Minto Midtown Condominiums. Poured in June 2005 and January 2006, the south tower had volumes totaling over 2500 m3 and over 3000 m3 in the north tower. The pour method of these two raft slabs used a similar drop pipe method, proving to be very successful and giving Menkes great condence when presented with this innovation in contruction methods.

The pour went o without a hitch, surpassing the customer’s expectations entirely. Reecting the innovation of Lafarge and Innocon, this pour most impressively marked a world wide record for Agilia. The project received great attention and the Agilia pour also appeared on the Daily Planet, a Discovery Channel program that features leading-edge products, innovations and new technology.