Webinar Archives

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Concrete provides structures with strength, rigidity, and resilience from deformation. These characteristics, however, result in concrete structures lacking the flexibility to move in response to environmental or volume changes. Cracking is usually the first sign of distress in concrete. Cracking of concrete flatwork is natural, expected, and accepted. However, cracks may affect appearance, performance, and maintenance costs. This presentation will discuss the various types of concrete cracks and how to best minimize their occurrence.

Learning Objectives:
1.    Understand the different types of cracking in concrete.
2.    Understand what causes concrete to crack.
3.    Understand how to evaluate the difference between structural cracks and cosmetic cracks
4.    At the conclusion of the presentation, participants will know how to minimize concrete cracks.

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Concrete is used in nearly every structure we build today, including buildings, bridges, homes, and infrastructure. With greater emphasis placed on sustainability, design professionals are faced with the challenge of meeting traditional design criteria with evolving criteria that support green building and efforts to reduce impact on climate change. When looking at the environmental impact of a building, it is important to assess every stage of the environmental life cycle, from material extraction and product manufacturing to building operations and maintenance through to end-of-life. Concrete offers many environmental attributes that help reduce the overall environmental life cycle impacts of a building. This learning session explores how life cycle assessment can be used to measure and lower the environmental impacts of concrete buildings.

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The tilt-up industry remains characterized as a budding or growing delivery method for new construction.  This dominant method of design and construction has a rich history of more than a century of influence and nearly fifty years of dramatic growth and unmatched solutions.  This presentation will detail the progress made and highlight the features of the industry that evidence why it is an ideal platform for specialists in design and construction, returning craftsmanship to the mindset of today’s contractor. The presenter will be James R. Baty II, F.ACI, F.TCA (Tilt Up Concrete Association).

No credits will be awarded for viewing recordings of the webinar. 

The webinar is being sponsored by the Iowa Ready Mixed Concrete Association, the Minnesota Concrete Council, the North Dakota Concrete Council, the South Dakota Ready Mix Association, and the Wisconsin Ready Mixed Concrete Association. 

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Engineering ethics is a set of ethical standards for engineers to follow which can apply to most circumstances that arise on the job. These ethical standards are the engineers’ obligations towards the public, employers and the profession. The purpose of engineering ethics is to identify specific ethical issues that may arise in order to avoid a potential problem.

The presenter will be David Schultz, Professor of Political Science (Hamline University).

No credits will be awarded for viewing recordings of the webinar. 

The webinar is being sponsored by the Iowa Ready Mixed Concrete Association, the Minnesota Concrete Council, the North Dakota Concrete Council, the Oklahoma  Ready Mixed Concrete Association, the South Dakota Ready Mix Association, and the Wisconsin Ready Mixed Concrete Association. 

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This presentation will discuss materials being developed for the concrete industry that will lower the embodied carbon of a yard of concrete.  Some materials are ready to use and do not require additional support or alteration of how we produce, place, and finish concrete.  Others will require new approaches, new specification, and new understanding of chemistry. 

No credits will be awarded for viewing recordings of the webinar. 

The webinar is being sponsored by the Iowa Ready Mixed Concrete Association, the Minnesota Concrete Council, the North Dakota Concrete Council, the Oklahoma Ready Mixed Concrete Association, the South Dakota Ready Mix Association, and the Wisconsin Ready Mixed Concrete Association. 

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Forms, shores, and re-shores are a temporary structure that carries the weight and construction load of the permanent structure until it is strong enough to stand up for itself.  While serving this temporary duty, forms, shores, and re-shores impact construction safety, cost, productivity, and schedule, and influence appearance, deformations, tolerances, and cracking of the hardened reinforced or prestressed concrete. 

This presentation introduces Codes, standard specifications, OSHA, and ANSI documents that address responsibilities for forms and shores.  By an example of a multi-story building, we look at how shore and re-shore systems work, including how shoring & re-shoring plans must be synchronized with rate-of-strength-gain of the concrete, as influenced by mix-design and ambient temperature.  This complex topic demonstrates how schedule, concrete mix, weather, construction technology, lab and in-place testing all come together.

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WJE carried out independent studies related to the 2018 collapse of the FIU Pedestrian Bridge in Miami. Most significantly, WJE developed and tested full-sized specimens to evaluate the significance of the National Transportation Safety Board’s (NTSB’s) finding that the construction joint between the northernmost diagonal and deck was left in an as-placed condition, rather than intentionally roughened as required by the project specifications. The webinar also describes WJE’s independent review of shear friction strength in accordance with the AASHTO Code.

The presentation describes the details of the experimental program that demonstrated that, had the construction joint been roughened as required by the project specifications, the collapse would not have occurred. Contrary to NTSB’s findings, the contractor’s failure to roughen the surface was the primary cause of the collapse.

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Making a decision that requires ethical consideration is usually not easy. Rarely are we faced with an ethical question that has a corresponding answer that is clearly black and white. Doing the ethical thing can require effort and determining the correct path may include many variables that cause us to pause and consider what the right decision is. In this presentation, the speaker will discuss some scenarios that illustrate the grey area that can be "ethics." The presenter will work through the scenarios an offer insight on determining the correct and ethical way to proceed through a decision-making process.

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This presentation will discuss changes in the volume of air entrained concrete in pumped concrete. The work shows that during pumping the air volume will decrease and if measured immediately after pumping will be lower than what is found in the final concrete. These findings are supported by hardened air void analysis, freeze thaw tests, and measurement of the air void volume and spacing over time in the fresh concrete with the Super Air Meter. The presentation makes recommendations for modifications to the current testing specifications based on the findings.

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With the increased focus on sustainability initiatives in construction, prescriptive requirements in specifications often restrict the concrete producer’s ability to optimize concrete for sustainability without compromising functional performance for project needs. The presentation will discuss these impacts and outline the development of a guide performance specification by ACI Committee 329.