Learn about different philosophies used in the determination of soil bearing capacity.
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Author Archives : Dr. N. Subramanian, Ph. D., F. ASCE
Dr. N. Subramanian, Ph. D., F. ASCE, FNAE, is a consulting engineer living in Gaithersburg, MD. With a doctorate from the Indian Institute of Technology, Madras (IITM), he also worked in Germany for two years as an Alexander von Humboldt Fellow in TU Berlin and Hochschule der Bundeswehr (Now Universität der Bundeswehr), Munich; He has over 46 years of professional experience in consultancy, research, and teaching. He has designed more than 800 projects. Dr. Subramanian Dr. N. Subramanian, Ph. D., F. ASCE, FNAE is a consulting engineer living in Gaithersburg, MD. He has a doctorate from IITM, India, and he also worked in Germany for 2 years as an Alexander von Humboldt Fellow. He has over 45 years of professional experience in consultancy, research, and teaching. He can be reached at (drnsmani@gmail.com).
Cylinder vs. cube conversion.
Ultra-High-Performance Concrete (UHPC) is a concrete class initially developed in the 1990s. UHPC contains no coarse aggregates. When fibers are used in UHPC, it is called Ultra-High-Performance Fiber Reinforced Concrete (UHPFRC) and offers increased strength and durability. The compressive strength of UHPC may have values exceeding 21,750 psi (Graybeal&Davis, 2008). It has been found by researchers, especially at the Kassel Universität, Germany, that UHPC can be designed to reach compressive strengths up to 36,250 psi. In addition to its high compressive strength, UHPC offers enhancements of high strength concrete (HSC) such as very high tensile strength (over 2175 psi) and flexural strength (over 7250 psi), very high ductility, very high durability to freeze-thaw cycles, chloride penetration, abrasion resistance, and carbonation. These enhanced properties will result in the overall improved performance of structures using this material, thus increasing construction safety, providing longer service life, and lower maintenance costs.
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Are We Testing for Flow Properties Correctly?
The rheological (flow) properties of concrete are essential for the construction industry, because concrete, for different elements of a structure, is placed into the formwork while it is in its plastic state. The flow properties affect not only proper concrete placement, consolidation, and finishing but also the hardened state properties such as strength and durability. Concrete that is not correctly placed and consolidated may have defects, such as voids and honeycombing, and be prone to aggregate segregation. Improper placement and consolidation may result in reduced compressive strength and increased permeability, reducing the concrete’s durability and sustainability. …