In this episode of the Concrete Logic Podcast, Seth and Dr. Belkowitz answer questions from students at Virginia Tech about concrete mix design. They discuss the role of aggregate size in a mix design, its impact on the cost and control of the concrete, and the importance of a well-graded gradation. They also touch on the use of recycled concrete aggregate and its potential effects on the hydration process. The conversation highlights the economic and technical considerations involved in selecting the right aggregate for a concrete mix. Additionally, Dr. Jon and Seth discuss the impact of fines in aggregate on shrinkage, the seasonality of concrete work, and the decision-making process for choosing cement types in construction projects. They also share their favorite concrete mix designs. Takeaways Aggregate size in a concrete mix design affects the cost and control of the concrete. A well-graded gradation of rock and sand helps reduce the porosity index and the amount of paste needed in the mix. Recycled concrete aggregate can have contaminants that affect the hydration process and may require rock washing. Aggregate size can also impact shrinkage of concrete. Considerations for selecting the right aggregate include economic factors, availability, and technical specifications. The fines in aggregate, such as the fine particles that pass through a sieve, can have an impact on shrinkage and other properties of concrete. Concrete work is not necessarily seasonal, as there are techniques and materials available to pour concrete in various weather conditions. The choice of cement type in construction projects is typically made by the engineer, architect, or project manager based on project requirements and local industry practices. Favorite concrete mix designs and job site stories can vary among professionals in the industry, showcasing the diverse and exciting nature of working with concrete. Chapters 00:00 Introduction and T-Shirt Discussion 10:00 The Role of Aggregate Size in Concrete Mix Design 16:11 The Impact of Recycled Concrete Aggregate on Mix Design 43:14 Favorite Concrete Mix Designs and Job Site Stories *** Did you learn something from this episode? If so, please consider donating to the show to help us continue to provide high-quality content for the concrete industry. Donate here: https://www.concretelogicpodcast.com/support/⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠ ***  Episode References Guest: Dr. Jon Belkowitz | Intelligent Concrete | Jon@intelligent-concrete.com Guest Website:⁠ https://www.intelligent-concrete.com/ Guest: Virginia Tech Myers-Lawson School of Construction Guest Website: https://mlsoc.vt.edu/ Producers: Jodi Tandett Associate Producer: Gregory Rice Donate & Become a Producer: ⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠https://www.concretelogicpodcast.com/support/⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠   Music: Mike Dunton | ⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠https://www.mikeduntonmusic.com⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠ | ⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠mikeduntonmusic@gmail.com⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠ | Instagram ⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠@Mike_Dunton⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠   Host: Seth Tandett, ⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠seth@concretelogicpodcast.com⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠ Host LinkedIn: ⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠https://www.linkedin.com