Alkali Silica Reaction in "Online Literature"

Google introduced an interesting graphics tool to present keywords search in literature. According to Official google blog "datasets backing the Ngram Viewer, produced by Matthew Gray and intern Yuan K. Shen, freely downloadable so that scholars will be able to create replicable experiments in the style of traditional scientific discovery".

And, I was instantly curious to see results for our topic. Here is a snapshot from the website or you can follow this link: Ngram Results.

It is true that reliability for this figure is dependent on available online dataset used, and limited to keyword matches, nevertheless gives a quick general idea on ASR.

Christmast came early to TU Delft

A long, long time ago. In a lab far, far away....

For a long time now, we have been waiting for our equipment to arrive. Finally it did.
Brand spanking new, they are all set up and ready to run.

Apparently we've behaved well enough throughout the year, Thank you Santa...

PAT-ASR Team

A new MSc Project proposed in TU Delft

Study outline

Concrete is a heterogeneous building material consisting of natural and man made products. The inherent heterogeneity of these material makes it hard to set a standard procedure for reactivity assessment. Common practice is to avoid reactive aggregates, where reactivity tests are either time consuming (impractical for engineers) or not reliable enough. Thus, there exists no internationally accepted ASR performance testing procedure; however studies on RILEM AAR-4 performance testing procedure is still in progress, yet not published. It is still a challenge to estimate the ASR effect on the existing structures together with potential impacts. There exist several recommendations, around the world, on ASR detection and prevention around the world. None, so far, has been internationally accepted.

In Netherlands, CUR regulations committee, CUR Technical Committee VC 62: Alkali Silica Reaction in concrete was set up in 2000. After severe criticism on CUR recommendation 38 (1994), the new committee published CUR recommendation 89 – ‘Measures to prevent damage to concrete by alkali-silica reaction (ASR)’ in 2002, which was followed by CUR recommendation 102 ‘Inspection and assessment of concrete structures in which the presence of ASR is suspected or has been established’. These recommendations are mostly provide decision trees suggest a ‘GO-NO GO’ decision.

A great number of studies, carried out worldwide, investigate the material performance considering various aspects of ASR effect. Most of these studies aim to determine the sole effect of ASR on micro-to-macro structural elements. Yet, there are missing links between chemical reaction parameters and gel product’s deleterious behaviour. Due to discontinuity of material properties in a mix, there may occur variations between laboratory test results and real structure measurements. A statistical approach to sample space data, harvesting available literature, can be used to increase the reliability of such a prediction model.

The aim of the project is to develop a material performance model for simulation of ASR effect on concrete durability. The final outcome of this project is an integrated support tool for engineers for ASR conscious design – a guideline for engineers.

Welcome to PAT-ASR

1- About Research

In the recent years, alkali silica reaction (ASR) has been regarded as one of the critical aspects for durable concrete design. Common practice is to avoid the reactive aggregate and to use low-alkali cement, which is seemingly an easy solution. It is often too risky for an engineering office to use one particular accelerated ASR test result and design for a service life of decades. Or, as often encountered, it is important to estimate the remaining service life of a structure showing ASR cracks.

In The Netherlands, the first reference an engineer would consult for an ASR-proof structural design is CUR Recommendation No. 89 - a decision tree on the assessment of ASR risk. The parameters involved are cement type, alkali content, aggregate type and results of accelerated tests. The tool eventually suggests either to continue with the design or to modify the concrete composition. By definition it is a decision tree. Therefore it lacks a precise recommendation on the modification method and its possible consequences i.e. effect of limestone filler or other mineral additives. Furthermore CUR has produced Recommendation No. 102, which deals with inspection and evaluation of concrete structures with ASR. This is a beneficial tool to examine a structure showing symptoms of ASR damage and decide if the structural safety is still guaranteed. However the propagation of the ASR mechanism and the consequences for the structure is not part of the evaluation with CUR recommendation 102.

Therefore the aim of PAT^ASR is to combine the tasks of above-mentioned recommendations in a single interactive tool where it is possible to include alternative materials, environmental profiles and structural parameters in the design process of ASR-proof concrete.

PAT^ASR project attempts to develop a unique comprehensive integrated tool for engineers for modelling possible ASR development in new concrete structures as well as evaluating the remaining durability of existing structures. The outcome provides a full-scale technical report as well as financial implications of the desired concrete design. The software will also provide an option, a database to keep track of ASR related characteristics of concrete materials, structural properties and environmental profiles which enables transfer of knowledge to the future projects.

2- Who is involved?

This Project is founded by STW, INTRON, RWS, TNO DIANA.

Leader of the project, Dr. O. Copuroglu is assistant professor in the section of Materials and Environment, Faculty of Civil Engineering and Geosciences, Delft University of Technology. His research field is the microstructure of cement-based materials, durability aspects, self healing and materials characterization. Dr. Copuroglu has published over 40 journal and conference papers mainly on durability of concrete, including ASR.

Dr. ir. E. Schlangen is an associate professor in the section of Materials and Environment / Microlab. His research interest involves fracture mechanics, early age behaviour of concrete, numerical modelling, chemomechanics and self healing. Dr. Schlangen is the developer of the world-wide and renowned Delft-Lattice model.

Dr. ir. M.A.N. Hendriks is an assistant professor in the Section of Structural Mechanics, Faculty of Civil Engineering and Geosciences, Delft University of Technology. His research field is computational modelling of structures and has over 20 years of experience in finite element modelling.

Currently two PhD researchers are appointed for this project.

Guðbjartur Jón Einarsson - Ph.D. Project I – Experimental Study.

Spent 5 years doing carpentry, before getting a Bachelor’s degree in civil engineering from the University of Reykjavik, Iceland. And after two years of working in a concrete testing and research lab in Iceland, came to Delft for a Master’s degree also in civil engineering, upon completion of which he joined the PAT^ASR team in April, 2010.

Main goals are:

- Determination of vital parameters.

- Organizing lab-based accelerated and real-time experimental parameter study.

- Organizing national/international round robin tests.

- Gathering information on the national/international ASR experience.

- Analysis of test results and integration in the PAT^ASR tool.

Caner Anac - Ph.D. project II – Micro/Meso scale modelling Study.

Got his Bachelor’s and Master of Science Degree in Civil engineering from Middle East Technical University, Turkey. After working in the industry for several years and participating in a 2 year research project in University of Reading, UK, joined the PAT^ASR team in April, 2010.

Main goals are:

- Setup model to simulate effect of tested parameters in experimental program. Feedback loops with article of the experimental program.

- Setup template of PAT^ASR.

- Run examples with PAT^ASR and compare with examples from practice.

3- Aim of this Blog?

The idea came up to keep a diary of the progress in the project. We also believe that using a blog will create an opportunity for effective brainstorming and international collaboration. We are hoping this blog will help to create a register of interesting experiences, memories throughout these 4 years, as well as publicising research results as soon as possible with the hope of getting comments and criticism from people in the field of ASR research.