Fly ash-based geopolymer concrete

The Report presents a comprehensive summary of the extensive studies conducted on fly ash-based geopolymer concrete. Test data are used to identify the effects of salient factors that influence the properties of the geopolymer concrete in the fresh and hardened states. These results are utilized to propose a simple method for the design of geopolymer concrete mixtures. Test data of various short-term and long-term properties of the geopolymer concrete are then presented. The last part of the Report describes the results of the tests conducted on large-scale reinforced geopolymer concretemembers and illustrates the application of the geopolymer concrete in the construction industry. The economic merits of the geopolymer concrete are also mentioned

Geopolymer concrete for environmental protection

Extensive studies conducted on fly ash-based geopolymer concrete are presented. Salient factors that influence the properties of the geopolymer concrete in the fresh and hardened states are identified. Test data of various short-term and long-term properties of the geopolymer concrete are then presented. The paper describes the results of the tests conducted on large-scale reinforced geopolymer concrete members and illustrates the application of the geopolymer concrete in the construction industry. Some recent applications of geopolymer concrete in the precast construction and the economic merits of the geopolymer concrete are also included

Development and Properties of Low-Calcium Fly Ash-Based Geopolymer Concrete

This Research Report describes the first part of the work carried out by the geopolymer research group at Curtin University of Technology. It describes the development and properties of heat-cured low-calcium fly ash-based geopolymer concrete. This Report will be followed by two other Reports describing the long-term properties of geopolymer concrete, and the behaviour of reinforced geopolymer concrete beams and columns

Low-Calcium fly ash-based geopolymer concrete: Reinforced beams and columns

From 2001, we have conducted some important research on the development, manufacture, behaviour, and applications of Low-Calcium Fly Ash-Based Geopolymer Concrete. This concrete uses no Portland cement; instead,we use the low-calcium fly ash from a local coalburning power station as a source material to make the binder necessary to manufacture concrete.Concrete usage around the globe is second only to water. An important ingredient in the conventional concrete is the Portland cement. The production of one ton of cement emits approximately one ton of carbon dioxide to the atmosphere. Moreover, cement production is not only highly energy-intensive, next to steel and aluminium, but also consumes significant amount of natural resources. In order to meet infrastructure developments, the usage of concrete is on the increase. Do we build additional cement plants to meet this increase in demand for concrete, or find alternative binders to make concrete?On the other hand, already huge volumes of fly ash are generated around the world; most of the fly ash is not effectively used, and a large part of it is disposed in landfills.As the need for power increases, the volume of fly ash would increase.Both the above issues are addressed in our work. We have covered significant area in our work, and developed the know-how to manufacture low-calcium fly ash-based geopolymer concrete. Our research has already been published in more than 30 technical papers in various international venues.This Research Report describes the behaviour and strength of reinforced low-calcium fly ash-based geopolymer concrete structural beams and columns. Earlier, Research Reports GC1 and GC2 covered the development, the mixture proportions, the short-term properties,and the long-term properties of low-calcium fly ash-based geopolymer concrete.Heat-cured low-calcium fly ash-based geopolymer concrete has excellent compressive strength, suffers very little drying shrinkage and low creep, excellent resistance to sulfate attack, and good acid resistance. It can be used in many infrastructure applications. One ton of low-calcium fly ash can be utilised to produce about 2.5 cubic metres of high quality geopolymer concrete, and the bulk price of chemicals needed to manufacture this concrete is cheaper than the bulk price of one ton of Portland cement. Given the fact that fly ash is considered as a waste material, the low-calcium fly ash-based geopolymer concrete is,therefore, cheaper than the Portland cement concrete. The special properties of geopolymer concrete can further enhance the economic benefits. Moreover, reduction of one ton of carbon dioxide yields one carbon credit and, the monetary value of that one credit is approximately 20 Euros. This carbon credit significantly adds to the economy offered by the geopolymer concrete. In all, there is so much to be gained by using geopolymer concrete.We are happy to participate and assist the industries to take the geopolymer concrete technology to the communities in infrastructure applications. We passionately believe that our work is a small step towards a broad vision to serve the communities for a better future

Bond Behaviour of Reinforced Fly Ash-Based Geopolymer Concrete Beams

In view of sustainable development in the construction industry, investigation has been carried out on fly ash-based geopolymer concrete, which is an environmentally friendly material that uses geopolymer paste as binder instead of Portland cement. Previous studies on the engineering properties and structural behaviour of geopolymer concrete have shown promising potential of this material. This paper describes the bond behaviour between geopolymer concrete and reinforcing bars in tensile splices in beams. Twelve full-scale beam specimens with lap-spliced reinforcing bars were cast and tested in the laboratory to study the bond performance of geopolymer concrete. The effects of concrete compressive strength, bar diameter and splice length of the bars on bond strength of lap splices in geopolymer concrete were evaluated. Test results, including general behaviour of beams, failure modes and cracking patterns were gathered and analysed. Current analytical models and codes provision to predict bond strength for Ordinary Portland Cement (OPC) concrete were used to analyse the bond strength of test specimens. Good correlation between test and analytical results were found. This study also demonstrates the excellent potential of geopolymer concrete for use as a construction material

Early age properties of low-calcium fly ash geopolymer concrete suitable for ambient curing

Geopolymer is a promising alternative binder to Portland cement. It is produced mostly from by-product materials such as fly ash and blast furnace slag; hence recognised as a low-emission alternative binder for concrete. Recent studies have shown that the properties of geopolymers are similar or superior to those of the OPC binder that is traditionally used for concrete. Most of the previous studies employed heat curing for setting and hardening of fly ash geopolymer mixtures. Heat curing process requires special arrangements which is energy-consuming and may not be feasible to apply in cast-in-situ concreting. Therefore, development of geopolymer mixtures suitable for curing at normal temperature will widen its application. This paper presents a study on low calcium fly ash based geopolymer concrete cured in ambient temperature (23oC) without additional heat. Small amount of additives were added with fly ash to accelerate the early-age reaction. Setting times of geopolymer pastes, and workability and compressive strength of geopolymer mortar were studied. The effects of the additives and binder content in the mixtures were determined from experimental results. The results show that inclusion of additives with fly ash significantly enhanced the early age properties. Setting time reduced to reasonable values and compressive strength increased to enable early de-moulding of specimens. Compressive strength increased with the increase of binder content. However, workability results showed an optimum binder content for the fly ash geopolymer blended with the additives. The results suggest that suitable geopolymer mixtures can be designed for ambient curing with low calcium fly ash and the additives as partial replacement

Geopolymer Concrete: A Review of Development and Opportunities

Geopolymer results from the reaction of a source material that is rich in silica and alumina with alkaline liquid. It is essentially cement free concrete. This material is being studied extensively and shows promise as a greener substitute for ordinary Portland cement concrete in some applications. Research is shifting from the chemistry domain to engineering applications and commercial production of geopolymer concrete. It has been found that geopolymer concrete has good engineering properties with a reduced global warming potential resulting from the total replacement of ordinary Portland cement. The research undertaken at Curtin University of Technology has included studies on geopolymer concrete mix design, structural behavior and durability. This paper presents the results from studies on mix design development to enhance workability and strength of geopolymer concrete. The influence of factors such as, curing temperature and regime, aggregate shape, strengths, moisture content, preparation and grading, on workability and strength are presented. The paper also included brief details of some recent applications of geopolymer concrete