| Summary: |
The awareness of the ecological impact of construction industry and the need to address it in our modern society is becoming a factor of increasing importance. Cement and concrete industry faces challenges related to improved durability and enhanced performance while at the same time Improving the sustainability of production.
High performance concrete (HPC) can be defined as an engineered concrete in which one or more specific characteristics have been enhanced through the selection and proportioning of its constituents. Thus, there is no one single type of high-performance concrete, but rather a family of new types of high-tech concrete whose properties can be tailored to specific industrial needs. In the 21st century, to build environmentally sustainable concrete structures it is expected an increase in the use of high-performance concrete; and its increased use will be more often linked to its durability rather than its high strength. In addition, the concept of 28-day strength may become obsolete as an acceptance requirement.
As the durability of concrete is essentially linked to its permeability, a HPC with low water/binder content leading to compact microstructure and very low permeability should obviously be more durable than ordinary concrete. Since the cementitious component of HPC can be cement alone or any combination of cement with supplementary cementitious materials (slag, fly ash, silica fume, meta kaolin, rice husk ash, and fillers such as limestone) most of the early properties of high-performance concrete can be linked to its water/cement ratio while its long-term properties are rather linked to its water/binder ratio. HPC can be seen as a more ecological material in the sense that the constituent materials are fully used and high amounts of industrial by-products are incorporated, to produce a material with a longer life cycle. However, excessive early-age shrinkage and creep deformations leading to cracking can impair the durability o  |
Summary
The awareness of the ecological impact of construction industry and the need to address it in our modern society is becoming a factor of increasing importance. Cement and concrete industry faces challenges related to improved durability and enhanced performance while at the same time Improving the sustainability of production.
High performance concrete (HPC) can be defined as an engineered concrete in which one or more specific characteristics have been enhanced through the selection and proportioning of its constituents. Thus, there is no one single type of high-performance concrete, but rather a family of new types of high-tech concrete whose properties can be tailored to specific industrial needs. In the 21st century, to build environmentally sustainable concrete structures it is expected an increase in the use of high-performance concrete; and its increased use will be more often linked to its durability rather than its high strength. In addition, the concept of 28-day strength may become obsolete as an acceptance requirement.
As the durability of concrete is essentially linked to its permeability, a HPC with low water/binder content leading to compact microstructure and very low permeability should obviously be more durable than ordinary concrete. Since the cementitious component of HPC can be cement alone or any combination of cement with supplementary cementitious materials (slag, fly ash, silica fume, meta kaolin, rice husk ash, and fillers such as limestone) most of the early properties of high-performance concrete can be linked to its water/cement ratio while its long-term properties are rather linked to its water/binder ratio. HPC can be seen as a more ecological material in the sense that the constituent materials are fully used and high amounts of industrial by-products are incorporated, to produce a material with a longer life cycle. However, excessive early-age shrinkage and creep deformations leading to cracking can impair the durability of reinforced or prestressed concrete structures; and thus defeat the purpose of using such high-performance mixtures.
In spite of the complexity of cementitious materials, such as concrete, current research is dominated by a macroscopic empirical approach. By extending the scale of investigation from macroscopic to microscopic level, this project can lead to a significant breakthrough in our understanding of the phenomena occurring at the nano-microscale which determines the macroscopic behavior of cementitious materials. Besides, it is the development of advanced high performance materials that justifies fundamental research of the interface phenomena, such as paste-aggregate and paste-steel interfaces. More fundamental research and knowledge generation is necessary to create and select high performance materials by design, rather than by trial and error.
The present research project will focus in the study and development of performance based concrete mixtures, for specific applications types, having low water/binder content and optimized aggregate/binder ratio to control its dimensional stability. Synergies between cements and various supplementary cementitious materials will be explored to improve concrete properties, in the fresh and hardened states, and to make high performance concrete more economical. Scientific mix-design methods will be used dealing with constituent materials specific properties to come up with an optimized concrete mixture, for defined performance requirements. Both laboratory and full-scale tests in the construction site will be carried out. |