At ECS, we constantly evolve and move toward the future and new capabilities in our industry. We sat with Concrete Division Specialist, Bill Denison, CCPf, FACI from our Chesapeake, VA, office, where we learned more about him, his background in concrete and what the realm of work entails.
Q: What is your current role with ECS? Please tell us about your professional journey with the company.
A: I am the concrete division specialist advising on whatever is needed as far as concrete goes, whether it be concrete semantics, materials design, troubleshooting, thermal analysis, or forensics. Also, being an American Concrete Institution (ACI) Fellow is a significant accomplishment in my 40-plus-year career. That designation means I’m in the top 200 in the country in my field. I have been working in ECS’ construction materials testing (CMT) service line for quite some time.
Q: As a concrete division specialist, what does a typical day look like for you?
A: My daily work ranges from reducing carbon footprint to creating resilient, sustainable concrete so the life expectancy exceeds approximately 300+ years. Multiple producers are steadily having to change their commercial and Department of Transportation (DOT) state designs, seemingly due to material shortages which causes me to redesign to meet project deadlines. I also do thermal mass, heavyweight, flexural, and lightweight designs to meet the durability and increased service life for various offices and clients. Lastly, the main types of specialized testing we perform daily to determine ultimate performance in concrete are low shrinkage, rapid chloride permeability, and drying shrinkage. The concrete we design today is typically crack-free, with moderate cementitious factors, lowering autogenous and drying shrinkage.
Q: How do you stay current with concrete standards and industry changes? Are there any national organizations or standards that affect concrete code requirements?
A: As an ACI Fellow, I stay current with concrete standards and industry changes. Most of the building codes, whether local or national, typically follow ACI standards. Being that I also sit on four main American Society for Testing and Materials (ASTM) committees (A-1 Steel, C-12 Grout & Masonry, C09 Concrete & Aggregates, and C-1 Cement) with the ability to vote, I see the standards before they reach the public. In addition, I also am an adjunct professor in materials engineering at Tidewater Community College and serve on the civil engineering technology board of advisors between the college and Old Dominion University; I have been an adjunct educator in civil engineering technologies since 1991.
Q: When people think about concrete, most assume it comes in one form. Can you explain some of the different uses for concrete design?
A: The typical types of concrete designs we see are:
- Thermal resistivity designs to increase electrical distribution ampacity and cable life expectancy
- Thermal mass designs for massive structures with geometric dimensions exceeding three or more feet in depth, such as for linear accelerators for hospitals or dam replacements due to Alkali-Silica Reaction (ASR), with low differentials and maximum temperature rise in both modeling and thermal plans
- Heavyweight designs in the 300-400 cu ft range are used in dry dock gates and nuclear density applications. Using controlled aggregates from nuclear shielding aggregate facilities
- Lightweight designs for structural bridges, runways, and high-rise applications in the range of 110-120 cu ft. Using structural expanded shales and clays which have been heated and air-cooled
- Normal weight designs in all classes from Air Entrainment (AE) to Non-Air Entrainment (Non-AE) in the range of 140-155 cu ft
Q: What types of tests or services does ECS provide and how would they benefit our clients?
A: Typically, we perform a wide range of testing from permeability for increased longevity, resilience, and serviceability to drying shrinkage and electrical resistivity for any type of project. These services would benefit almost any client because most of the work could contribute to helping their company save money on new products or create space for new projects because of the longevity work that ECS tries to ensure.
Q: What factors do you typically see that can change or determine a concrete project’s lifecycle?
A: The factors I see that affect a concrete project’s lifecycle include Alkali-silica reactivity (ASR) mitigation, sulfate attack and expansion mitigation, the choice or availability of cementitious materials that affect the water-to-cement ratio, density, and setting times.
ASR mitigation is significant because it produces an alkaline gel that attacks the salicaceous aggregates, causing expansion if the concrete can absorb moisture through its pores osmotically. The alkalis go into solution and attack and the aggregates cause expansion leading to failure in five to ten years. The water-cement ratio is critical to the porosity and durability of the concrete mixture, important because it controls the mechanical properties and durability of hardened concrete. I tend to look towards lower water-to-cement ratios in the 0.32-0.35 range than what ACI typically requires to almost always eliminate the quality errors. If I cannot, I will try to recommend better materials.
Last comes the setting times. Setting time is critical in the crystal growth of cementitious materials. These crystals, known as Calcium Silicate Hydrate (CSH), are important because the mixtures need the proper initial curing temperatures and enough time to hydrate to fully react and form an ultimate stonelike mass.
Q: As an American Concrete Institute Fellow (FACI), have you ever contributed to any standards or tests? If so, what are they and how do they affect projects?
A: I have contributed to the conception and design of “pervious concrete.” One might call me a pioneer of this type of permeable pavement concrete and its standards. The number one question that I received when we first started was, “Can you make a concrete that is sustainable, lets the water infiltrate back into the ground and refilter itself where we can reuse it and make sure it does not cause the aquifer to dry out or cause sinkholes?” It was a significant job for me. I ran thousands of tests and went through multiple publishers to proofread my findings. By the time I was finished, it was Internationally published in the Pervious Book STP 1551, recognized by ASTM and ACI. It is also recognized by National Ready Mix Concrete Association (NRMCA). National Ready Mix was founded in 1930 and is one of the leading industry advocates for concrete nationally.
Q: Can you provide an example of a challenging project you worked on and what you did to overcome the challenges?
A: There was a dam project I worked on that was somewhat challenging but a fun project to work on. My task was to create a plan to utilize a producer’s concrete and make my mix from theirs that I believed would last about 300 years. I let my client pick which producer they liked the most and they brought me the producer’s choice of raw material. Before reinventing the wheel, I had to develop the mix from front to back and what materials would work best for longevity and minimal consolidation. Over a couple of weeks, I developed the right mix for the project and the dam was built with a sustainable self-consolidating concrete that was pumped multiple times, anywhere from 900-1000 LF, to the bottom of the dam.
Q: Our workplace has a strong safety culture. What safety measures or training is important for the concrete division?
A: It could be many things depending on the type of project or work we are doing. When I do dam work, I know of a utility company that requires everyone involved to go through their safety program. You can’t work for them if you don’t follow their procedures correctly. For a utility company, there are multiple segments; each builds on the other and is valid for a certain number of years. We also take classes with the Occupational Safety and Health Administration, known as OSHA. For other basic needs, we follow the ECS protocol for lab and field procedures utilizing safety shoes, hard hats, safety glasses, regular PPE and full harnesses.