International Concrete Abstracts Portal

A new type of green ultra-high-performance glass concrete (UHPGC) was developed at the Université de Sherbrooke using waste glass having varying particle-size distributions (PSD). UHPGC provides several technological, economical, and environmental advantages. It reduces the production cost of ultra-high performance concrete (UHPC) and carbon footprint of traditional UHPC structures. This paper presents the rheological and mechanical properties of selected UHPGCs. The rheology of the UHPGCs was improved by using non-absorptive glass particles. UHPGC greatly improves the concrete microstructure, resulting in higher mechanical and durability properties, which are comparable to those of the conventional UHPC. These strength and rigidity gains were due to the fact that the glass particles acted as inclusions with very high strength and elastic modulus. A special mix design of UHPGC was developed for innovative pedestrian bridges at the Sherbrooke University campus. Concrete performances of this UHPGC are also presented in this paper.

The aim of this paper is to examine the feasibility of using recycled tires steel fibres (RTSF) in recycled aggregate concrete (RAC) for structural applications. The utilization of recycled materials in concrete can potentially conserve the environment by eliminating unnecessary consumption of limited landfill areas and reduce energy consumption. The use of recycled aggregate (RA) from construction and demolition waste and the use of RTSF derived from post consumed tires are good examples. However, the variability in the characteristics of RA and RAC are the main engineering concerns which hinder the use of RAC in structural application. This paper examines the effect of the addition of RTSF and RA on the behaviour of concrete. The results show that RTSF significantly improve the mechanical properties of RAC. The flexural performance of RAC with 2% (by mass) RTSF is better than normal concrete without fibres and equivalent to normal concrete with 2% fibres.

In recent years, because of developments in materials technology, by the understanding of fundamental relationships as well as due to experimentally and numerically driven modelling and design, the use of steel-fibre-reinforced concrete (SFRC) is steadily increasing. One major issue which needs to be taken particularly into account for most SFRC applications is the evidence of their structural safety under fire exposure. This paper gives an overview of nationally and internationally available normative and pre-normative requirements and codetype regulations to model and design both the material and structural behaviour of fireexposed SFRC. The paper will also illustrate that the fire behaviour of SFRC needs to be mandatorily considered both from a technical and legal perspective. Since an implied fire design approach is still pending, experimental verifications are still recommended on a material level but primarily on a structural level in order to provide technically and economically reasonable solutions which do not restrict innovative stages due to conservative assumptions.

Innovative structures can be designed with flowable concrete. A homogenous fibre distribution has to be assured by adequate mix design, whereas the fibre orientation depends on the flow and casting conditions, fibre length and rheological properties. Important work has been carried out during the past years on test methods and methods for non-destructive testing highlighting the necessity for on-site assessment of material behaviour of fibre concrete. The translation of results of small scale specimens tested in bending or in uniaxial tension is not necessarily straightforward and easy to execute considering a larger number of affecting parameters in the case of flowable concrete. This paper reviews the progress in understanding of how test results of small scale specimens relate to the structural behaviour of flowable fibre reinforced concrete. Studies reported in literature and carried out by members of fib Task Group 4.3 are considered.

Fibre-reinforced self-compacting concrete (FR-SCC) combines the benefits of highly flowable concrete in the fresh state with enhanced performance in the hardened state in terms of crack control and fracture toughness provided by the dispersed fibre reinforcement. A “holistic” approach can be conceived to the design of structure made with highly flowable/selfconsolidating FRC, which encompasses the influence of fresh-state performance and casting process on fibre dispersion and orientation, and the related outcomes in terms of hardened state properties. In this framework, this paper, after a review of the current state of the art on the aforementioned topics based on the research performed by the author in the last decade, the research needs will be discussed which have to be urgently tackled in order to address the use of this kind of advanced cement based materials for high-end structural applications.