The early name of high performance concrete was high strength concrete. Now development of concrete technology expects high durable properties from high performance concrete too. We have learned earlier that constituents materials of this concrete are not revolutionary, rather they are normal materials usually used in construction of normal concrete. This is a controlled development of concrete technology that offer high strength and durability properties for mega structures and corrosion susceptible structures, expected to provide extended life to structures.
We will provide a classification of high performance concrete according to strength. In this post we will discuss about expectations with respect to strength perspectives. The requirements for strength may be very early or after 28 days or regular period of gaining.
Now how much strength makes a concrete to be treat as high performance. This is very difficult thing to make such demarcation about strength range. Once 6000 psi concrete was defined as high performance concrete (HPC) and later the strength requirements have grown up say 9000 psi and we expect that this requirements will grow up and up as construction industry are growing rapidly expecting small member size and always greater durability for a several hundred storied building or for a ultra-long span of bridge with slim members. Dear reader we will discuss few posts regarding high performance concrete having 12000 psi strength.
Strategic Highway Research Program (SHRP) implements different projects and developing concrete for different aspects of highway. SHRP categorize the HPC as follows:
a. Very Early strength (VES)-having minimum strength of 2,000psi at 6 hours
b. High Early strength(HES)-having minimum strength of 5,000psi at 24 hours
c. Very High strength (VHS)-having minimum strength of 10,000psi at 28 days
d. Fiber reinforced concrete-having minimum strength as that of High Early strength but have polymer reinforced criteria.
But in some publications HPC are sometimes classified according to strength like very high performance concrete; our opinion is that a concrete which is upgrading continuously should not be classified in such way.
Now question is which types of samples are taken to evaluate the strength of HPC that is either cubes or cylinders. Dear reader we will discuss about the test procedure and requirements in the next post. The strength criteria include not only compressive strength, but they also include modulus of elasticity, shrinkage and creep. Dear readers we will discuss every term in our blog, please stay with us. We have discussed about durability properties of HPC in our sister blog-“structural, concrete and foundation engineering”. Please follow this link to read this.