Abstract Manager

The City of Calgary (The City) and Industry Stakeholders completed a concrete sidewalk pilot study which was conducted over a five year period between 2017 and 2022.  A concern was raised by the City regarding the deterioration of sidewalks occurring prematurely due to construction damage and a significant amount of sidewalks (up to 40%) undergoing full replacement at Final Acceptance Certificate (FAC) stage at two years after construction. The purpose of this study was to:

• Explore design alternatives to improve concrete sidewalk infrastructure;
• Identify deficiencies;
• Improve concrete quality and implement best construction practices;
• Offset high life cycle maintenance costs and mitigate construction damages; and 
• Reduce the amount of concrete replacement at final acceptance certificate (FAC) stage

The City’s current sidewalk design standard for sub-divisions utilizes 100 mm thick concrete supported by an earth subgrade compacted to a uniform density of not less than 97% SPMDD (without a granular base coarse (GBC) layer underneath the concrete). This design was designated as Control Section A in the pilot study.

An earlier study modelled various sidewalk pavement designs and formed the groundwork for selecting alternative sidewalk designs for investigation of actual field performance at three new sub-divisions within Calgary.  Four sidewalk design “test sections” were investigated:

1. Test Section B: 125 mm thick concrete with synthetic fibres and supported by 100 mm thick GBC;
2. Test Section C: 100 mm thick concrete with synthetic fibres and supported by 100 mm thick GBC;
3. Test Section D: 100 mm thick concrete without fibres and supported by 100 mm thick GBC; and
4. Test Section E: 125 mm thick concrete without fibres and supported by earth subgrade (without any GBC underneath the concrete).

The performance of the four test sections were compared to the current sub-division standard by interpreting, photographing and measuring the lengths of any observed surface distress occurring (i.e. cracks lengths) in each of the four test sections and the control section.

This presentation presents the approach of how the pilot study was carried out and based on results over the five year study period, the design section with the best field performance was identified and presented to key industry stakeholders.  The City used a collaborative approach with Industry stakeholders, who were asked to review the outcome of this study and a subsequent cost analysis. Based on field performance and cost analysis comparison, an agreement was reached on implementing an improved sidewalk design for 2023.