We sat down with Ken Kurszewski, president of Cru Concrete, Inc., to discuss his recent experience with low cylinder breaks. Kurszewski shared valuable insights from his career, including lessons learned and strategies for managing challenges in concrete construction.

Q1: IN YOUR EXPERIENCE, HOW OFTEN DO LOW CYLINDER BREAKS OCCUR, AND WHAT CHALLENGES HAVE YOU SEEN THEM CREATE FOR CONTRACTORS?

Kurszewski: In my career, I’ve only encountered this issue once, and it happened very recently. We poured a foundation in January, covered it with blankets and returned five days later to strip the forms. Unfortunately, Wisconsin experienced an extremely cold stretch—10 out of 14 nights were below zero. The builder questioned the concrete’s strength because they needed to place precast on it. Core drilling and strength tests showed results below accepted standards, but it had only been 18 days since the pour, and the cold temperatures had slowed the curing process.

I immediately turned to the CFA website and watched Kim Basham’s webinar on bad breaks multiple times to learn everything I could about ASTM and ACI standards. We waited until the 28-day mark and retested, ensuring the process followed ASTM standards. The results showed the concrete was within acceptable strength ranges, but without that knowledge, we might have prematurely replaced an $80,000 foundation. This experience highlighted the importance of understanding testing standards and the impact of curing conditions.

Q2: HAVE YOU ENCOUNTERED SITUATIONS WHERE LOW CYLINDER BREAKS WERE WRONGLY BLAMED ON BAD CONCRETE?

Kurszewski: Yes, in this case, the builder initially blamed the concrete, saying it was bad. However, we knew the extremely cold temperatures had slowed the curing process. The first round of testing wasn’t done according to ASTM standards, which added to the confusion.

I ensured the second round of testing was done correctly. The results showed the concrete, specified for 3,000 PSI, tested at 2,750 PSI. According to ASTM standards, this was within the acceptable range of 80-85% of the specified strength. Understanding these standards and the curing process helped us avoid unnecessary replacement and significant costs.

Q3: WHAT LESSONS HAVE YOU LEARNED ABOUT TRAINING TEAMS TO HANDLE CONCRETE STRENGTH ISSUES EFFECTIVELY?

Kurszewski: One key lesson I’ve learned is the importance of having a knowledgeable point person who understands the specifics of concrete testing and curing standards. It’s also critical to recognize that not everyone involved—like the builder’s engineer in this case—may be an expert on these standards. Training teams to rely on accurate resources and ensuring they understand the nuances of field versus lab testing can make all the difference in resolving issues effectively.

Q4: FROM YOUR PERSPECTIVE, WHAT’S THE BEST WAY TO MANAGE LIABILITY CONCERNS OR DELAYS CAUSED BY LOW CYLINDER BREAKS?

Kurszewski: Constant communication is key. In this case, I felt it was important to handle the situation personally, given the scale of the issue. I directly contacted the owner of the general contracting firm to ensure clear and consistent communication.

Having a thorough understanding of the testing standards and the curing process also helped manage liability concerns. By ensuring the tests were conducted properly and the results were interpreted correctly, we avoided unnecessary costs and delays. Additionally, leveraging resources like the CFA hotline or webinars can provide valuable guidance when navigating these challenges.

Q5: WHAT ADVANCEMENTS IN CONCRETE TESTING HAVE YOU SEEN DURING YOUR CAREER, AND WHICH ONES DO YOU THINK HAVE HAD THE BIGGEST IMPACT?

Kurszewski: Honestly, we’ve been fortunate not to encounter many issues with concrete strength over the years. Since I’ve owned the company in 2009, this was the first time we had to core drill a foundation to assess strength. That said, this experience underscored the importance of understanding the differences between field and lab testing, as well as the specific conditions required for accurate results.