Projects / Programmes
Mechanisms for the strengthening of different types of ash by means of a geopolymerization process
| Code |
Science |
Field |
Subfield |
| 2.01.00 |
Engineering sciences and technologies |
Civil engineering |
|
| Code |
Science |
Field |
| T220 |
Technological sciences |
Civil engineering, hydraulic engineering, offshore technology, soil mechanics |
| Code |
Science |
Field |
| 2.01 |
Engineering and Technology |
Civil engineering |
waste ashes, recycling, geo-polymers, alkali activated materials, bonding mechanisms, building products, durability
Researchers (1)
| no. |
Code |
Name and surname |
Research area |
Role |
Period |
No. of publicationsNo. of publications |
| 1. |
11292 |
PhD Vilma Ducman |
Civil engineering |
Head |
2014 - 2016 |
503 |
Organisations (1)
Abstract
Geopolymers are inorganic systems, consisting of (i) a reactive solid component which contains SiO2 and Al2O3 in sufficient amounts, and in reactive form (e.g. different types of ash, active clays), and (ii) an alkaline activation solution which mainly contains (apart from water) alkali hydroxides and silicates. Mixing the solid and the activator components results first in dissolution of the elements in the alkaline activators, and further in hardening due to the formation of an aluminosilicate which ranges from amorphous to partial crystalline. Geopolymers are very perspective alterantive to ordinary Portland cement (OPC) and are a widely researched field, but a complex one since there are still a lot of open questions, so that no clear methodology has yet been established for their investigation.
The aim of the proposed project is the verification of the properties of at least five types of ashes that are locally available with regard to their potential use for the geopolymerization process. In order to achieve the established goal it will be first necessary to check how many types of ash are available, and to characterize them in order to be able to assess their usefulness for geopolymers, in accordance with the latest state of knowledge in this field.
Analysis foreseen are: their chemical composition, crystal phases and amorphous phase with determination of Al and Si solubility, and among physical parameters also particle size distribution and specific surface.
Based on the results of the analyses of the ashes, samples will be prepared with the addition of different activators in different proportions: various activators in different quantities, NaOH and sodium silicate (water glass) will be added to the selected ashes.
The samples thus prepared will be tested in the fresh and hardened state, following the standard test methods for mortars. The samples will be evaluated at the same time on the microstructural level (X-ray analysis, SEM, FTIR, Hg.porosimetry, BET , and μCT), which will make it possible to determine which of the parameters of the precursor impact the final properties of the geopolymers.
Selected optimized samples will then be exposed to various accelerating tests (freezing / thawing, exposure to salts, and heating to elevated temperatures) in order to determine their resistance and durability. Analysis of the results (i.e. analysis of the incoming raw materials compared to the characteristics of the samples before and after aging along with microstructural analysis) will provide an insight into the mechanisms of the geopolymerization process, and thus allow us to design geopolymers with the desired properties.
The newly acquired materials will be evaluated for use in the construction industry (with an emphasis on their mechanical properties and durability). By means of the project new knowledge will be obtained about the design of geopolymers with various properties for other purposes than the construction sector. Most importantly, a methodology will be established for the assessment of other types of waste (e.g. locally available slags and various types of sludge) for geopolymerization. Also, at present no group in Slovenia is concerned with research into the processes involved in their production, and especially not for building applications. Thus, through this project a new research field will be opened up at the national level, with the possibility of transferring knowledge to the industry and students.
Significance for science
Over the last few years research into geopolymers has intensified. In fact, this specialized field is of high topical importance, proven by the publishing of numerous papers and citations, projects and industry transfers. Within the project the largest contribution to the science was achieved by analysing five locally available ashes and assess their potential for the process of geopolymerisation. A lot of research has been performed on fly ash so far, but not much information is available for biomass ash, and it was confirmed that they are less suitable for the process of geopolymerisation, mainly due to the absence of Si and Al ions and the presence of organic particles. Similarly, in our study it was also confirmed that only two out of the five locally available would be suitable for alkaline activation. For the ash, which is not suitable for geopolymerisation, further activities are performed, and the ash can be separated into different fractions, from which one may be of use (or used elsewhere). Within the project, foams have been successful prepared with the addition of Al powder and H2O2. By optimisation of foaming agents and curing regime, foams with a density of 0.3 g/cm3 and sufficient compressive strength were obtained. In the foaming process, the process of stabilization of foams, which is very important to achieve a stable uniform porous structure, was also studied. The paper titled "The Influence of the Stabilizing agent of SDS on porosity development and the alkali-activated fly-ash based foams" in currently under review. Research has been published in four papers in journals with SCI index and presented at several conferences and workshops. Of these, the article "Characterization of geopolymer fly-ash based foams obtained with the addition of Al powder or H2O2 as foaming agents" has already been quoted a few times. Some further papers are still under review or in preparation. Scientific, as well as professional, contributions also arise from activities related to the Rilemov Technical Committee TC DTA. Within this committee, durability tests were established or modified: FprCEN/TS 12390-10, 12: Resistance to carbonation (accelerated, natural), ASTM C666 – 92: Resistance to rapid freezing and thawing, NT Build 443: Chloride penetration, RILEM recommended test method AAR 3 (RILEM TC 219-ACS) Potential alkali reactivity, in ASTM C1012/C1012M-09 Sulphate resistance of mortars. ZAG is the only partner within this committee (out of 50) where all five durability tests were performed. Based on the results of these methods and additional analyses of the long-term behaviour of these materials under different conditions can be evaluated.
Significance for the country
Given that this is a recycling of waste material, and therefore a major contribution to the conservation of natural resources, as well as reducing the CO2 footprint of the project activities it is consistent with the guidelines of both national research policies as a priority topic of the EU. Knowing the influential parameters and mechanisms of consolidating waste or ash and other materials will form the basis for the assessment of waste (those containing Al and Si) regarding the suitability for the process of geopolymerisation. In this way, new and different products can be developed; among the potential products there are all kinds of construction products (as a replacement of concrete, micro reinforced geopolymers, foamed geopolymers, hybrid geopolymers) as well as in the refractory industry, because it can withstand high temperatures. It is also important that in Slovenia there is no other group that is actively involved in research on geopolymers, especially for the construction sector, therefore, we have opened a new research area. Thus it can be expected that these activities will generate new technologies and products useful in the construction industry as well as in other industries. Following the procedure of geopolymerisation we can recycle a variety of waste into products with higher added value. And it is important that the construction sector can absorb large quantities of materials, problems with the disposal of waste ash can be significantly reduced as well, and in this way natural resources are preserved. The introduction of new technologies could also enable new jobs. Activities arising from the project have already resulted in obtaining three international projects: - H2020 InnoWEE: Innovative pre-fabricated components including different waste construction materials reducing building energy and minimising environmental impacts (2016-2020), - EIT KIC RawMaters project MIN-PET: Mineral products from Petrit-T sidestream technology (2016-2018), - EIT KIC RawMaters project RECOVER: Innovation in Motion: Red mud and Copper slag Valorisation in Engineered Products (2017-2019). At the same time, we are involved in several international associations (RILEM, COST, KIC RawMaters ResidueFlex NOI and NOI Extreme) with the exchange of knowledge in the field of alkaline activation. In this way the latest knowledge and international experience in the field is transferred to the Slovenian economy. It can be expected that knowledge will also be applied in the programme of individual faculties both through mentorships, or through common projects (from this topic and in cooperation with ZAG, one doctoral dissertation has been undertaken at the University of Maribor).
Most important scientific results
Annual report
2014,
2015,
final report
Most important socioeconomically and culturally relevant results
Annual report
2014,
2015,
final report
