Pozzotive In The News

PRESIDENT’S MESSAGE

Some may think that Structural Engineering has reached its peak. Humans have been building for thousands of years. Major construction materials like wood, masonry, concrete, and steel(iron) have been in use for centuries. Even skyscrapers have been around for almost 150 years.

What else could be new?

The answer, as presented at our Annual Conference on February 8th, is “a lot”. In the US, standardization of material properties and sections only began in the early 1900s and did not reach convergence until the middle of the century. Analysis and design methods supported by test data were only developed in the last few decades.

What struck me the most is how recently we have started to understand the loads imposed on our structures. “Accuracy in stress calculation is defeated because of the ignorance of loads causing stress”, as our keynote speaker Professor Lou Geschwindner quoted from Minimum Live Loads Allowable for use in Design of Buildings, a 1924 report of the Building Code Committee of the US Department of Commerce. We saw significant changes to wind and seismic loads and load factors in recent years, as ASCE tried to establish more uniformity in return periods and probability of collapse across the country. Seismic loads are still being adjusted – Mr. Konstantinos Syngros (Associate, Langan Engineering) noted the significant increase in NYC ground motion in the most recent USGS National Seismic Hazard Model. Guidance is also being provided in the latest ASCE for new load types, some of which have gained increased intensity and prominence in recent years due to the effects of climate change. Ms. Jessica Mandrick (Partner, GMS) presented the new and markedly expanded ASCE 7-22 supplement 2 on Flood loads.

Although our profession has a long history of structural ingenuity, to consistently produce safe and reliable designs at a large scale is a relatively recent achievement, and one that is still on-going.

We are at an exciting time in our field. We are armed with a more in-depth understanding of materials and loads, and we have tools that can help optimize for cost and sustainability. We are increasing the available strength of materials like steel, concrete, and rebar, and expanding design possibilities of wood through the use of mass timber.

However, in an age with increasing capabilities of software and Artificial Intelligence, it is our understanding of design principles and enthusiasm for problem-solving, rather than the prescriptive use of equations, that enhance our value as Structural Engineers.

EDITOR’S MESSAGE

The industry of structural engineering is constantly evolving. In the noteworthy book The Death and Life of Great American Cities by Jane Jacobs, the idea that the city is a living breathing entity, encompassed by the people, places and structures we are surrounded by, is explored while also talking about how these components lead to change. We often think of structural engineering as designing the bones of a structure, but in this context of a living city, we go beyond just the bones. In this context, we as structural engineers are the key mastermind behind the lungs, the veins, and even the heart of the city we live and progress in.

It makes sense in this way that our field is also constantly evolving as new challenges and technologies arise. This issue of cross sections explores both of these catalysts of change in our industry. Unleashing the Power of Ground Glass Pozzolans talks about the ground glass pozzolans in concrete and the performance and green impact of this emerging technology. The Evolution of NYC’s Flood Hazard Maps, an article from our very own resilience committee, speaks on the development of flood maps and how climate change consequences have demanded a change in the way we design for disasters.

UNLEASHING THE POWER OF GROUND GLASS POZZOLANS:

INTEGRATING RECYCLED GLASS INTO HIGH – PERFORMING, LOW CARBON CONCRETE FOR SUSTAINABLE CONSTRUCTION

INTRODUCTION

Concrete is the most widely used construction material globally, and the production of its key component, cement, contributes to about 7% of all global carbon emissions. This is a result of the energy-intensive manufacturing process involved. The growing demand for high-performance, low-carbon solutions stems from multiple forces at play.

Building and construction contribute a significant portion of global carbon emissions and now with stricter carbon emission targets. New York State Executive Orders #22 and #23 are clear examples of such increasing pressure. Aligning with global efforts to achieve carbon neutrality, the construction industry is undergoing a transformational shift toward adopting low-carbon materials and practices.

Materials such as Ground Glass Pozzolans (“GGP”) have emerged as important, new solutions that help lower the built environment’s carbon footprint while improving structural integrity. Ground Glass Pozzolan is a revolutionary cement replacement made from 100% recycled glass. When used in concrete, it yields a higher performing “green” concrete that signifies higher performance at no additional cost. After a four-year effort involving well over 100 academic and industry leaders, spearheaded by Amanda Kaminsky, a national industry leader in sustainability, the new “ASTM C1866 Standard Specification for Ground-Glass Pozzolan for Use in Concrete” was published in April 2020, making it much easier for A&E firms to specify the material in concrete with a clear standard for its use.

Achieving Green Building Certifications and fostering a positive image among various stakeholders enhances a project’s market competitiveness. Buildings and infrastructure built with high-performance concrete offer superior energy efficiency in several different ways. The thermal properties of concrete improve insulation, reducing the need for heating and cooling. Concrete batched with GGPs also creates a lighter colored finish which helps reduce the Heat Island Effect caused by darker impervious surfaces in our urban areas. These energy efficiencies reduce carbon emissions throughout structure and infrastructure lifecycles. Using regionally harvested, post-consumer material, such as recycled glass, further contributes to LEED and Envision Certification category budgets.

Incorporating high-performance materials with low embodied carbon also creates resilient structures that can withstand environmental challenges, natural disasters, and daily use deterioration. The use of GGPs minimize the need for frequent maintenance, repair, and reconstruction, reducing the longer-term replacement costs and thus environmental impact of construction projects.

The diminishing supply of other Supplemental Cementitious Materials (“SCMs”) used to reduce CO2 in concrete, such as fly ash and slag, is also driving the need to find alternatives. The availability of fly ash, the post-industrial byproduct of coal-burning plants, is declining as we continue to close or convert coal-burning plants to natural gas.

The fly ash that is available is also of variable quality as suppliers reclaim and process previously land-filled ash. Slag is the byproduct of basic oxygen furnaces used in steel manufacturing and, as those plants move to more modern and efficient electric arc furnaces, the supply of usable slag is also declining. So, while the demand to reduce the carbon footprint of concrete is increasing, the two primary SCMs that have historically been used to achieve these goals are in diminishing supply.