Abstract
Supplementary cementitious materials (SCMs) are increasingly incorporated into the concrete mix design. Silica fume, fly ash, and multi-wall carbon nanotubes are used to improve concrete mix properties. The objective of this chapter is to decipher the impact of different SCMs on the fresh and hardened concrete properties, including concrete flowing ability, initial strength, final strength, modulus of elasticity, and modulus of rupture. In addition, the impact of SCMs on mitigating the alkali-silica reactivity of concrete and increasing the hardened concrete long-term performance is investigated. Developed concrete mixes, incorporating SCMs, are used in fabricating different precast/prestressed bridge girders. The impact of improved concrete properties on precast girder performance in increased flexure, shear, and span-to-depth ratio significantly improves project sustainability and reduces the overall project life cycle cost.
Highlights
High-strength concrete is characterized by high early strength, high final strength, increased durability, and improved long-term performance
In early 2000s, the first Ultra-high-performance concrete (UHPC) bridge was built in the United States using Ductal concrete and steel fibers incorporated in the mix
Different types of supplementary cementitious materials (SCMs) are available in the global market including micro-silica, class C fly ash, class F fly ash, quartz flour, and blast furnace slag
Summary
High-strength concrete is increasingly used in the construction market in the United States and on a global scale. Concrete mixes with higher strength and improved long-term performance were developed using SCMs, steel fibers, and a very low water-to-powder ratio These mixes, commercially available in the United States construction market under the term ultra-high-performance concrete, are standardized by different agencies including the Federal Highway Administration (FHWA) in the United States, Association Francaise de Genie Civil (AFGC) in France, and the Japanese Society of Civil Engineers (JSCE). In their definition of the UHPC, the aforementioned organizations define UHPC as a cement matrix with minimum compressive strength of 150 MPa due to the high proportion of SCMs and very low water-to-powder ratio, and significant tensile strength due to the incorporation of random high-strength steel fiber. This chapter introduces different types and classifications of concrete mix designs, based on mix strength, workability, and long-term performance, different types of SCMs currently used in developing special concrete mixes, their impact on mix properties, and the main impediments to the widespread of SCMs application in precast/prestressed concrete industry
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