Technical Committee 214-CCD
Deputy Chair: Prof. Mette GEIKER
Activity ending in: 2013
The objective of this technical committee is to develop a forum for considering the influence of cracking in the life-cycle performance of concrete facilities. Specifically, this committee will focus on developing a state-of-the-art report to aide designers, consulting engineers, and researcher for incorporating cracking in durability calculations. Specifically this report will consider the influence of residual stress development in concrete, the relationship between material parameters and the geometry of the crack that develops, and the relationship between the geometry of the crack and its relationship with durability performance prediction. Substantial research has been conducted on transport, early-age cracking, and fracture in concrete; however this work has not been thoroughly integrated to develop a framework that the engineering profession can use in a cohesive design and performance calculation procedure. This technical committee will also aide in identifying areas in which future research is needed.
Terms of reference
As the desire increases to move from ‘prescriptive specifications’ to ‘performance based specifications’ there is a growing need to better quantify all of the aspects that are related to the long-term performance of a concrete facility. It is known that the durability of a concrete structure is related to its ability to impede, or greatly reduce, the rate of mass transport. As a result a great deal of research has been performed to assess how the transport process can be reduced through mixture proportioning and the use of binder compositions that densify the microstructure. These findings have lead to the development of high strength and high performance concretes. The majority of previous research has been focused on assessing transport in undamaged (pristine) concrete to obtain diffusion or permeability coefficients. Comparatively little work has been performed to quantitatively describe how these properties change in the presence of damage or sustained loading, which frequently occurs in field applications. Cracking is a significant effect that needs to be considered in service life modeling as it can accelerate deterioration resulting in increased maintenance and repair costs and reduced service-life.
As new life cycle modeling procedures are developed there is a need for a more comprehensive procedures for considering the influence of cracking on the long-term performance. A need exists to collect, review, distill, and summarize the body of literature that relates cracking to overall performance. The goals of this committee are within the main goals of RILEM which are:
1) to promote sustainable construction, improved performance and cost benefit for society,
2) to stimulate new directions of research, promoting excellence in construction.
Detailed working programme
The work will start with a literature survey and lead to a state-of-the-art report. Currently, several needs exist including:
* Better understanding of the ionic ingress mechanics and binding in cracked concrete systems.
* Similarly, research is needed to better understand the role of crack sealers may have in reducing permeability/adsorption should a crack develop.
* The development of improved monitoring and reporting of field performance to characterize cracking for use in model calibration. While several lab studies have investigated crack widths on corrosion, more realistic loading/fatigue conditions are needed to fully assess the influence of crack width and cover thickness.
* The need exists to better quantify the effects of crack mitigating materials on the long-term performance of concrete structures. For example, fiber reinforcement have the ability while admixtures like shrinkage reducing agents have the ability to reduce the potential for cracks to develop. Procedures are needed to understand how to compute the effects of these materials on long-term durability.
The time necessary is estimated at 5 years.
It is fully anticipated that this committee will build on the work of several previous and existing committees.
* ACD (Prof. Masayasu OHTSU): Acoustic Emission and Related NDE Techniques for Crack Detection and Damage Evaluation in Concrete
* 187-SOC (Prof. Jaime PLANAS): Experimental determination of the stress-crack opening curve for concrete in tension
* 189-NEC (Dr. Roberto J. TORRENT): Non-destructive evaluation of the 'covercrete'
* LTP (Prof. Dr. Asko SARJA): Life time performance of materials and structures
* 178-TMC (Dr. Carmen ANDRADE): Testing and modelling chloride penetration in concrete
Data will be gathered from a variety of resources that will make use of indexes such as the web of science, TRIS, COMPENDEX, NTIS, SHRP concrete and structures program, PCI, ACI, and AASHTO. In addition, information will be gathered from the committee members.
The results of the literature survey will be compiled in a state-of-the-art report. The report will also contain the experience of field and laboratory measurements carried out by members of the TC. The report will be continuously updated during the lifetime of the TC.
A workshop is planned for the first meeting of this committee. It is the intention that this workshop will result in the development of minutes that can lead the initiation of the literature survey and detailed scope of work of this committee. It is anticipated that a workshop will be held at the conclusion of the technical committee to share the information from the state of the art report.
Group of users
The information developed by this committee will be primarily of use to academics, industrial materials manufacturers, practitioners, and designers.
Specific use of the results
The economic impact is in the more accurate design and life cycle performance simulation of concrete pavements and structures. This is crucial as many organizations are moving toward performance related specifications.