MCV Erbium UHPC. Use of Ultra High Performance Concrete due to Its Superior Materials Properties
Concrete is one of the most widely used construction materials and is primarily characterized by its compressive strength, which determines its mechanical and durability properties. One of the recent advances in concrete materials technology is ultra high performance concrete (UHPC). The Federal Highway Administration (FHWA) has defined UHPC as concretes that exceed a compressive strength of 21.7 ksi. (Greybeal 2011) UHPC is cementitious material that utilizes particle packing at the nano scale to improve the mechanical prosperities. Highly impervious UHPC concretes limit chemical egress of corrosive chemicals and have shown improvements in delaying corrosion of reinforcing steel in structures.
One of the primary constraints that engineers use in determining the appropriate material for a project is cost. There are very few projects that have funding for emerging technologies. The cost of UHPC is about 15-18 times more expensive that traditional concrete by volume. While the additional strength allows for a reduction in material, it does not offset the increase in cost. Traditional high quality concrete mixes with minimal cement can reach about 6 ksi, which allows structural members to use up to a quarter of the material. In some application the reduction of weight and material results in cost saving, however, this is generally not the case.
Some of the additional cost can be attributed to the availability of the raw materials need for the mix. Aggregates are the primary source of strength in concrete and typically come from local rock quarries. UHPC requires the strongest aggregates available and are commonly transported from nonlocal locations. These ingredients include course and fine quartz aggregates, silica fume, cement, admixtures, and water. There are a limited number of sources for the materials needed to produce UHPC.
To achieve the performance requirements of UHPC there is a need to retrain and retool production facilities. Production of UHPC with consistent quality demands high levels of quality control. UHPC has been successfully deployed in a handful of Sates and in European markets, but there is need for more standards before this technology is more widely accepted.
Graybeal, B. (2011). Ultra-High Performance Concrete, Report No. FHWA-HRT-11-038, Federal Highway Administration, McLean, VA.
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