224-AAM : Alkali activated materials
Technical Committee 224-AAM
Deputy Chair: Prof. John L. PROVIS
The primary aim of the Alkali Activated Materials Committee will be to develop performance-based specifications and recommendations for the development of Standards that are specifically applicable to these classes of materials. This will encompass the specific fields of alkali-activated slags and ashes, geopolymers, and other emerging technologies, and will bring together leading practitioners from academia and industry in an international forum. Probably the major obstacle hindering the widespread uptake of alkali activation technology in the construction industry is the lack of uniformly accepted Standards which would allow alkali-activated materials to be specified and tested in a similar manner to traditional cements. The prescriptive composition-based Standards that are in place for Portland-based cements in many applications and jurisdictions are effectively preventing alternative technologies such as alkali activation from being utilised as widely as their technological potential would otherwise permit. The development of performance-based Standards is critical to the acceptance of alkali-activated materials in the industrialised world. Nations such as China or the former Soviet republics, where regulatory environments are less restrictive, have seen very significant growth in the uptake of alkali activation. The wealth of experience obtained under these environments, including over 50 years’ research into alkali activated metallurgical slags in Ukraine, will be leveraged by the proposed Committee into recommendations for the development of Standards that will be acceptable in a 21st century regulatory environment.
Terms of reference
The Committee will provide documents for the use of national Standards authorities and other bodies, outlining recommendations for the appropriate specification of performance-based Standards for alkali activated construction materials. The development of these recommendations will require a concerted program of testing over a number of years, using source materials derived from a variety of industrial waste streams worldwide. A 5-year program of work is therefore proposed. Work will be conducted in both academic and industrial research laboratories, as well as extensive field testing to ensure that the Standards developed in a laboratory environment are appropriate for industrial-scale production of alkali-activated materials.
A provisional timetable for Committee work is as follows:
Year 1 – Initiate collaborative networks, select source waste material streams to be used as the basis for testing, commence preliminary analysis of raw materials and sample formulations, develop testing procedures.
Year 2 – Initiate durability testing program: exposing samples formulated according to results of preliminary work in Year 1 to aggressive environments for extended periods. Samples will be tested at regular intervals for the remainder of the project lifespan. Commence testing of different regional and variable waste streams for early and later strength development behaviour.
Year 3 – Continue durability and source material sensitivity testing. Symposium to be held either in Year 3 or early in Year 4, for participants to share and discuss results and to select targets for the remainder of the project. Prepare and release document outlining interim Standards recommendations based on work in Years 1-3.
Year 4 – Continue durability and source material sensitivity testing. Symposium to be held either in Year 3 or early in Year 4, for participants to share and discuss results and to select targets for the remainder of the project. Discussions will also be held with regard to planning for the establishment of a second RILEM committee to extend the work of the current Committee into the future (beyond Year 5).
Year 5 – Finalise results of all testing, compile all data, complete analysis and prepare final project reports. Develop and release revised Standards recommendations document, specifying performance-based requirements (addressing strength and durability aspects) for alkali activated material formulations.
The proposed Committee will consist of at least 10-15 members, drawn from academic and industrial groups with interest and experience in the study and utilisation of alkali activation technology. Strong representation from Australasia, Asia, and Eastern and Western Europe is anticipated, in addition to strong solicitation for involvement by researchers from the Americas, where these materials are not yet under such widespread examination. Membership from both academic and industrial organisations from each of these regions will be solicited via the strong collaborative academic research community that already exists in this field, as well as via the industrial linkages and partnerships that have been developed by the Chairman and the Secretary over the past decade. Researchers with expertise in Standards development for Portland-based cement systems will also be invited to participate, so the Committee will be able to utilise their skills in application to this newer class of materials. The Committee will be informally divided into sub-groups according to areas of interest and expertise – for example, focus groups looking into specific issues of durability and mechanical performance will meet separately and report to the Committee as a whole, and a similar focus group will be set up to deal with the issue developing mix formulations that are sufficiently tolerant to input component variability. The outcomes of the work of these focus groups will then be reported and discussed at the full Committee meetings.
Given that the Committee membership is expected to be globally distributed, contribution that is conducted primarily by correspondence will be encouraged to maximise the level of participation from developing nations. However, the Committee will aim to meet in full at least once every year to provide for a full discussion of outcomes and objectives. Focus groups within the Committee will meet more regularly than this – either in person or via online conferencing systems – to discuss specific areas of interest.
The industrial utilisation of alkali activated materials is not yet widespread in most part of the world, however the primary aim of this Committee will be to provide an avenue whereby this situation may be remedied, and it is anticipated that industrial involvement will increase towards the latter phase of the Committee’s existence, as the initial work of the Committee in Standards development begins to become more visible in the industrial setting.
Detailed working programme
The final goal of this project is the production of a comprehensive document laying out guidelines for the formulation of performance-based Standards for the production of cements and concretes by alkali activation of waste materials. These recommendations will be based on laboratory- and field-scale testing for early strength development, later strength evolution, and durability under aggressive conditions. There is no existing document of this type available for international use. Academic and industrial research has led to the development of a large number of alkali activated formulations which result in cements and concretes with highly acceptable physical properties and performance. These formulations will initially be used as the basis of the Committee’s investigation, however work will very rapidly be extended to incorporate the use of other waste material sources, in particular those of variable composition and/or mineralogy. The development of Standards for the formulation of cements and concretes with consistent properties independent of this variability will be of immeasurable value in the widespread utilisation of alkali activation technology.
A detailed year-by-year breakdown of Committee activities was given in Section 3 of this application. An intermediate goal of this Committee, as outlined in Section 3, will be the publication of preliminary results and an interim Standards recommendations document in the third year of the project. This will present the opportunity for end-users and other interested parties to test and provide feedback on the standards before publication of the final Committee outcomes. Standards will be designed in such a way as to correspond to the performance of Portland-based and blended cements complying with existing standards, and so will complement the existing body of work in this area. Traditional cementitious materials will be tested in parallel with alkali activated materials throughout the project to ensure complementarity and harmony between the two sets of Standards.
In addition to the data available in the international literature, a large body of work has been carried out on the activation of metallurgical slags in Kiev, Ukraine, over the past 50 years. With the proposed involvement of Prof. Pavel Krivenko, the current leader of this research group, in the committee, this extensive body of information, including long-term (30+ years) durability data, will be available to committee members. There are also ongoing collaborative projects in Australia (via the CRC for Sustainable Resource Processing) and in Germany (via the Volkswagen Foundation) that are currently focussed on developing and analysing geopolymers derived from regional waste streams. The experience that has been obtained by industrial utilisation of alkali activated materials in developing nations, in particular China, will also be utilised via the participation of researchers who have been involved in those projects for a number of years. It is anticipated that, with the involvement of participants in each of these projects in the proposed RILEM Committee, the knowledge available will be able to be leveraged into the process of Standards development.
As was noted in Section 4 of this application, the proposed committee will link with and build on work being carried out in a variety of ongoing research programs. In addition, the proposed committee would provide a very good fit with the existing RILEM activities in a variety of areas. Linkages of specific interest may include Technical Committee 209-RFC, whose work on concrete rheology may be important in the scale-up of alkali activation technology to a commercial scale and in the design of useful and practical Standards recommendations. The work of Technical Committee 205-DSC, focussing on the durability of SCC, will also correlate with the durability-related aspects of the proposed committee. We envisage that the committee would be a part of RILEM Cluster B: Materials Characterization, Properties Evaluation and Processing. The formation of a RILEM Technical Committee in the field of alkali activation will correspond closely with each of the three Main Goals of RILEM: environmental sustainability, novelty and excellence in research, and strengthening international research linkages.
The primary deliverables from the Committee will be first an interim and then a final set of recommendations for the use of national Standards bodies, whereby performance-based requirements for alkali-activated materials will be laid out in such a way as to enable reliable specification of these materials by architects and engineers, similar to the current status of traditional cements. This will be of direct benefit to academic and industrial users of alkali activation technology, as these materials are currently lacking a formal testing and specification methodology, and this is a significant hindrance in their utilisation and commercialisation.
The testing will be undertaken predominantly by the use of established test methods, harmonising the Standards generated through this work with existing Portland-based cement standards. It is anticipated that the majority of the test data will be published in the academic literature throughout the duration of the project, and that one or more major review papers, summarising these data into what will effectively be “State-of-the-Art reports,” will also be submitted for publication.
The Committee plans to organise a Symposium either in Year 3 or early in Year 4 of the projected timeline, to share and publicise outcomes and gather feedback on the interim Standards recommendations to be published.
Group of users
The Standards recommendations to be generated by this Committee will primarily be targeted at national Standards bodies around the world, practitioners and testing laboratories. The availability of such documentation will allow each national Standards body to put into place appropriate documentation to enable the use of alkali activation technology in construction applications. This will then enable architects and structural engineers to specify alkali activated materials straightforwardly and similarly to traditional cements and concretes for construction applications.
Academic utilisation of the project outcomes will also be significant, particularly in the civil engineering arena where issues such as creep and fire resistance are to be investigated using standardised formulations. To date, testing of alkali activated materials performance has generally been carried out somewhat unsystematically due to the lack of such specified Standards. Standardisation of alkali activation technologies will enable highly significant advances in this area, and will allow direct comparison of results from different laboratories and on materials derived from different waste streams, which is not currently possible to any significant extent.
Specific use of the results
This project will benefit the general public by enabling utilisation and beneficiation of large-volume waste streams that are currently discarded or landfilled, and also via the reductions in CO2 emission that are achievable by the uptake of alkali activation technology. The ability of architects and structural engineers to very easily design buildings or structures using alkali activated cements will be a significant step in the ‘Greening’ of the construction industry worldwide. The superior performance of these materials in various scenarios, in particular those requiring resistance to freeze-thaw cycling or salt scaling, will also provide highly significant economic benefits due to the lengthening of maintenance and replacement cycles for structures such as bridges and road surfaces as well as buildings. The commercialisation of alkali activation technology for applications such as these in the developed world has been greatly hindered by the absence of an established set of Standards for material specification, a situation which will be addressed directly by the work of this Committee.
The exact extent of the economic impact of the work of this Committee is difficult to quantify, as it will be highly dependent on a number of factors which currently remain the basis of much speculation – in particular, the potential imposition of a worldwide CO2 trading scheme will provide a very strong driver for the uptake of alkali activation technology due to the CO2 savings possible by the use of this technology compared to Portland cements. However, it has been estimated that USD1.6 trillion (1.6 x 1012) will be required between 2006-2011 simply to return the infrastructure systems of the USA to a ‘serviceable’ condition (J.W. Phair, Green Chem., 8 (2006), 763-780). If even a small fraction of this replacement cost could be reduced by the specification and utilisation of alkali activated materials, the economic benefit of the activities of this Committee would be highly significant.