15 hours ago
- The author revisited a stretch of continuous concrete road on the National Road in Putnam County, Indiana, noting its lack of expansion joints.
- Continuous concrete roads in Indiana were likely built before 1925, as expansion joints were later discovered to reduce cracking.
- These old highways are in good condition partly because they were bypassed within 10-20 years, limiting wear from traffic.
- A reader explained that older concrete was ordered by ratio (e.g., 1:2:4) with higher Portland cement content, enhancing durability.