Ultra-High Performance Concrete (UHPC), is also known as reactive powder concrete (RPC). The material is typically formulated by combining portland cement, supplementary cementitious materials, reactive powders, limestone and or quartz flour, fine sand, high-range water reducers, and water. The material can be formulated to provide compressive strengths in excess of 29,000 pounds per square inch (psi) (200 MPa). The use of fine materials for the matrix also provides a dense, smooth surface valued for its aesthetics and ability to closely transfer form details to the hardened surface. When combined with metal, synthetic or organic fibers it can achieve flexural strengths up to 7,000 psi (48 MPa) or greater.
Fiber types often used in UHPC include high carbon steel, PVA, Glass, Carbon or a combination of these types or others. The ductile behavior of this material is a first for concrete, with the capacity to deform and support flexural and tensile loads, even after initial cracking. The high compressive and tensile properties of UHPC also facilitate a high bond strength allowing shorter length of rebar embedment in applications such as closure pours between precast elements.
If we in the US could only build concrete roads from presumably longer lasting UHPC, or better yet Roman concrete.
Unlike (as I understand it) Europe’s life cycle bidding our remote rural area builds asphalt roads from the lowest bidder that (from a civil engineer friend) are designed to last for 7 years before needing maintenance. We then let them deteriorate to, or normally past, needing replacement. They can get federal highway money to replace, but not maintain them, so maintenance is limited to some cold patch in the spring
Our highways are not built like European ones, with the concept of at least 20 years existence - and that under speed; instead we build the cheapest ones we can get away with and then tolerate their poor condition. Were we to have the autobahn-type roadways, we could well tolerate the same “no speed limit” approach to driving. Instead we waste our cash on EBT cards.
Were we to restart the kind of Public Works we had in the depression and eliminate EBT carda, the economy just might wake up - again.
