The years between the 1870s and 1940s represented a golden age of new technology in structural systems. Many “fireproof” floor systems were introduced such as terra cotta arch construction, cinder concrete slabs, and other proprietary systems. Although known as “archaic” structural systems since they are no longer used and have been replaced with modern methods and materials, these systems represent a large portion of the building stock in the northeastern United States and several of the dense urban areas therein. Of these varied archaic systems, cinder slab construction became one of the most dominant systems.
Cinder concrete slab construction, also known as cinder arches, goulash construction, or even “short span arch construction” was a type of reinforced concrete slab system consisting of a low strength concrete which used cinders as a substitute for stone aggregate and was reinforced with a draped wire mesh. Widely used in conjunction with encased structural steel, these systems are both prevalent in the northeast and misunderstood by many practicing structural engineers. Once considered an innovative system, many modern structural engineers remove or abandon such systems when encountered today, likely due to a misunderstanding of their construction and performance characteristics. Having worked with many cinder slab buildings in the New York City Metro Area and the Northeastern United States more broadly, the authors have developed a keen understanding of the system’s behavior and limitations and aim to share practical experiences and insights about working with the material.
The presentation will focus on the origin, identification, testing, design, construction, and performance of these types of floor systems. Exemplar projects and strategies for dealing with challenging conditions associated with this material will be discussed. The presentation will include case studies on how to identify, investigate, and renovate these floor systems when encountered and how to repair them when deteriorated, all through the lens of aiming to preserve the historic nature of these systems while ensuring that they continue to perform for years to come.