Effective concrete mixes for Saskatchewan sidewalks using locally available pop-out prone aggregates

Background

In cold climates, damage in concrete infrastructure caused by freezing and thawing cycles is a persistent challenge, especially in regions like Saskatchewan. One of the most frequent issues—aggregate pop-outs—stems from both physical (freeze-thaw) and chemical (alkali-silica reaction) mechanisms.

Our study addresses the prevalent surface deterioration observed in Saskatoon’s sidewalks. Despite current CSA limits on deleterious materials and local specifications, pop-outs continue to occur, particularly where soft or reactive aggregates are used. This is largely due to a widespread shortage of high-quality aggregates in the region and the complex nature of mitigation strategies.

Engineering Service

• Petrographic Analysis and Field Sampling:
  We assessed concrete samples affected by pop-outs and performed detailed petrographic investigations to distinguish between physical and chemical causes of degradation. Core samples provided insight into aggregate performance under environmental stress.

• Root Cause Identification:
  Freeze-thaw damage and alkali-silica reactions were confirmed as the primary contributors to deterioration. Air void characteristics, moisture susceptibility, and aggregate type were key parameters examined.

• Durability-Oriented Mix Recommendations:
  Using this understanding, we proposed mix adjustments including SCM incorporation, optimized air entrainment, and finishing best practices suited to locally available aggregates. These designs balance durability performance with economic feasibility.

Outcome

This project provided municipal stakeholders with actionable, cost-effective mix design recommendations tailored to regional material constraints. By targeting the underlying mechanisms of damage and aligning mitigation strategies with practical realities, this work supports more resilient, aesthetically reliable, and longer-lasting sidewalks across Saskatchewan.