Geopolymer Concrete Research Papers - Academia.edu (original) (raw)

Fire is one of the most severe environmental conditions that concrete structures might be subjected to, especially in closed conduct structures, such as tunnels. Concrete in general can withstand fire but its properties degrade when exposed to fire at high temperatures. The effect of heating duration, at a high temperature, on the performance of fly ash-based geopolymer concrete is presented. Cubes of low, medium and high strength grades of geopolymer concrete that had been cured for 28 days, were exposed to a fire flame at 1000 °C for 30, 60, 90, 120, 150 and 180 min. After the fire exposure, the cubes were cooled to the ambient temperature before further testing. A visual observation was performed on the cubes to detect any colour change, cracking and spalling. The losses of mass and residual compressive strength of the cubes were recorded. The results showed that as the heating duration increased from 30 to 90 min, the compressive strength of the cubes also increased. Contrarily, the compressive strength decreased as the heating duration increased beyond 90 min indicating that the extended heating duration induced the loss of free water and decomposition of aluminosilicate products in geopolymer concrete. The evaporation of water by virtue of the heating for the extended duration, at high temperature, led to a loss in the mass of concrete. The findings suggest that geopolymer concrete was able to sustain its structural integrity without any noticeable spalling and hence, it can be classified as a fire-resistant material.

- by
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- Civil Engineering, Geopolymer Concrete, Fly Ash, Fly Ash Based Geopolymer Concrete

Waste foundry sand (WFS) and fly ash D-Optimal mixture design/response surface methodology/design of experiments Statistical optimization Geopolymer concrete (GPC) Compressive strength A B S T R A C T This work examines the partial replacement of fine aggregates with waste foundry sand (WFS) and fly ash, process by-products, to synthesize geopolymer concrete (GPC). D-optimal mixture design of experiments was adopted to guide the proportion of mixture constituents (fine aggregates, WFS, and fly ash) to obtain desired responses (high compressive strengths). The experimentally measured responses/compressive strengths were successfully fitted to Scheffe polynomial model to obtain cubic models which represent compressive strengths of solidified GPC at 7 th day curing time (CS 7) and at 28 th day curing time (CS 28). The models were statistically evaluated by the standard error of design estimation and experimentally verified by comparing their predicted responses to the independently performed experiments. The models were subjected to analysis of variance (ANOVA) and residuals (diagnostics) for statistical significance and validation, respectively. The established models, hence obtained, were used to assess the impacts of relative proportions of mixture constituents at CS 7 and CS 28. It was observed that, although the highest compressive strength requires a high proportion of fine aggregates, yet, some mixture compositions could be proposed for better utilization of waste materials. Finally, the optimization was performed to maximize the usage of WFS and fly ash. A recipe was identified which yielded 18.9 N/mm² CS 7 and 22.3 N/mm² CS 28 by mere 32 wt. % contribution of fine aggregates in a (fine aggregates + WFS + fly ash) mixture. This study can be helpful in designing experiments and optimizing the utilization of similar waste materials into useful products.

- by Izhar H Shah
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- Industrial Ecology, Cleaner Production, Concrete, Geopolymer Concrete
- by Rakesh Paswan
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- Civil Engineering, Geopolymer Concrete, Absorption, Fly Ash

Geopolymer is now a more advanced alternative to cement and available substitute for OPC while graphene nanoplatelets (GnP) are new nanomaterials with extraordinary properties that can enhance and improve the strength of cementitious materials. Although graphene reinforced concrete has intriguing potential, its implementation in construction requires better knowledge of the impact of GnP on the properties of concrete related to durability. Studies on the compressive and tensile strength performance of geopolymer concrete (GPC) containing GnP are needed. The present study investigated the influence of reinforcing GPC with varying percentages of GnP on the compressive and split tensile strengths of GPC. The addition of GnP ranged from 0.0%, 0.25% and 0.5% by weight of total binder. It has been observed that the addition of GnP increased the compressive strength by 30% and the tensile strength by 22% in comparison to a reference sample with a specified composition of fly ash and sodium metasilicate. In addition, the effect of GnP on enhancing the compressive strength of the geopolymer was shown to diminish as the amount of sodium metasilicate increased.

- by Nadzhratul Husna
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- Materials Science, Graphene, Geopolymer Concrete, Compressive Strength

Geopolymer mortar is cement less which is gaining popularity globally towards the sustainable development. It can be produced from mineral admixtures such as fly ash, clay, red soil with user-friendly alkaline-reagents. Production of Ordinary Portland Cement (OPC) requires large amount of energy as well as carbon footprint. It is shown that OPC emits approximately 5% of global CO 2 emissions annually, which works out to nearly more than ½ ton of CO 2 emission for every one ton production of OPC. So it is badly needed to reduce the global CO 2 which has encouraged the researchers to search alternative sustainable building materials those are available in locality with lower embodied energy and carbon dioxide emissions. Clay and red soil are the best selection for that and both are usable as an eco-friendly building materials also available in locality. So an attempt has been made to explore the possibility of using clay and red soil based mortar in construction industry. The composition and microstructure were characterized by x-ray fluorescence (XRF), scanning electron microscopy (SEM) &particle size analyzer. Studies were carried out for both materials with respect to compressive strength, ultrasonic pulse velocity, effective porosity and coefficient of absorption. The results indicated that geopolymer mortar with clay and red soil can be used as an alternate construction material in the construction industry.

In the present paper, a numerical and experimental study about creep and shrinkage behavior of a high strength self-compacting concrete is performed. Two new creep and shrinkage prediction models based on the comprehensive analysis on the available models of both conventional concrete and self-compacting concrete are proposed for high strength self-compacting concrete structures. In order to evaluate the predictability of the proposed models, an experimental program was carried out. A concrete which develops 60 MPa within 24 h was used to obtain experimental results. Several specimens were loaded: (i) at different ages and (ii) with different stress-to-strength ratios. Deformation in non-loaded specimens was also measured to assess shrinkage. All specimens were kept under constant stress during at least 600 days in a climatic chamber with temperature and relative humidity of 208C and 50%, respectively. Results showed that the new models were able to predict deformations with good ac...

- by Lino Maia
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- Civil Engineering, Concrete, Concrete Technology, Precast Concrete

In order to meet the environmental pollution effects caused by concrete made using ordinary Portland cement, geopolymer concrete has been developed which is also known In order to meet the environmental pollution effects caused by concrete made using ordinary Portland cement, geopolymer concrete has been developed which is also known as cementless concrete. It is known that alkali-activated aluminosilicates are able to produce alumino-silicate geopolymers. This study focuses on producing geopolymer concrete using a combination of kaolinite, flyash and GGBS in various proportions and their compressive strengths at different stages have been studied. Initially in 100% fly ash based Geopolymer concrete, fly ash was replaced with kaolinite clay by 10%, 20%, 30%, 40%, 50% and 60% by weight. Later on in 100% kaolinite based Geopolymer concrete, kaolinite clay was replaced with GGBS by 10% 20% and 30% by weight. Finally a combination of kaolinite clay, fly ash and GGBS in the ratio of 80:1...

From environmental aspect, the world is concerning about the Global warming & increase in environmental pollutions, which is caused in engineering field mainly by cement production. While producing cement a huge amount of carbon dioxide is emitted to atmosphere. To overcome this phenomena, either we can partially replace cement with fly ash, GGBS, Rice husk ash etc…or we can use the Geopolymer technology. Geopolymer concrete which can also be called zero cement concrete is an innovative construction material that has alkaline solution i.e. (sodium hydroxide & sodium silicate) and the fly ash as a binding material. Fly ash is a rich source of silica and alumina which react with alkaline solution and produces alumina silicate gel that acts instead of cement in concrete.

Geopolymer concrete (GPC) is an emerging construction material that uses a by-product material such as fly ash as a complete substitute for cement. This paper evaluates the bond strength of fly ash based geopolymer concrete with reinforcing steel. Pull-out test in accordance with the ASTM A944 Standard was carried out on 24 geopolymer concrete and 24 ordinary Portland cement (OPC) concrete beam-end specimens, and the bond strengths of the two types of concrete were compared. The compressive strength of geopolymer concrete varied from 25 to 39 MPa. The other test parameters were concrete cover and bar diameter. The reinforcing steel was 20 mm and 24 mm diameter 500 MPa steel deformed bars. The concrete cover to bar diameter ratio varied from 1.71 to 3.62. Failure occurred with the splitting of concrete in the region bonded with the steel bar, in both geopolymer and OPC concrete specimens. Comparison of the test results shows that geopolymer concrete has higher bond strength than OPC concrete. This is because of the higher splitting tensile strength of geopolymer concrete than of OPC concrete of the same compressive strength. A comparison between the splitting tensile strengths of OPC and geopolymer concrete of compressive strengths ranging from 25 to 89 MPa shows that geopolymer concrete has higher splitting tensile strength than OPC concrete. This suggests that the existing analytical expressions for bond strength of OPC concrete can be conservatively used for calculation of bond strength of geopolymer concrete with reinforcing steel.

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Geopolymer foams (highly porous materials) have emerged as one of the most exciting materials over the past few years due to their remarkable properties, low cost and green synthesis protocol, enabling their use in various high added-value applications. Review papers on porous geopolymers are uncommon, and the emphasis has been given to materials processing and properties, while the applications were only briefly addressed. This review aims to fill this gap by presenting a comprehensive literature survey and critical analysis of the most recent and exciting research carried out on geopolymer foams. Up to now, these bulk-type (not powders) materials have been mainly considered as thermal and acoustic insulators. However, besides addressing their use as building material, this review also shows that their use in less investigated, but environmentally and economically relevant applications (e.g. bulk-type adsorbents, pH buffering agents and catalysts), is feasible and might ensure performance and technical advantages over their powdered counterparts. The limitations, challenges and future prospects associated with the different applications are presented. This review shows the remarkable potential of geopolymer foams in high added-value applications, far beyond their historical use as Portland cement replacement, which may encourage the widespread technological use of these materials.

- by Robert C Pullar
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- Catalysis, Lightweight Concrete, Geopolymer Concrete, Porous Materials

Ever since the beginning of the space program, lunar habitation has always been on peoples' minds. Prior researchers have explored habitat building materials– some based on earth-based construction materials, some based on in-situ lunar resources. Geopolymer cement is a cementitious binder made of aluminosilicate materials such as lunar regolith. A cementitious binder made of lunar regolith as the main geopolymer precursor, instead of as an added aggregate, is a solution that has not been deeply explored in prior works. This research explores the curing process of lunar regolith based geopolymer cement in an environment that loosely approximates the lunar environment, using the lunar average daytime temperature and a vacuum. The results did not show much promise for the samples cured under both heat and vacuum as the longest-cured data point did not meet compressive strength standards, but another pathway to lunar habitation may be found in a separate set of samples that cured under heat and ambient atmospheric pressure.

- by Gabrielle Davis
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- Lunar Science, Geopolymer Concrete

High Performance Concrete (HPC) is now a days used widely in the construction industry worldwide. To produce HPC with normal ingredients one use mineral admixtures like silica fume, fly ash and metakoline. In addition admixtures including Superplasticisers are also used. This paper investigates the effect of silica fume (SF), added in varying percentages (0, 3, 5, 7.5, 10, 12.5%), on concrete strength. Superplasticiser-(Viscocrete Tempo 12)-was added to the concrete mixtures as well. Compressive strength, shear strength and tensile strength tests were conducted, and the results were discussed. Results showed that the compressive strength changes with the varying percentage addition of silica fume. The highest compressive strength (88 MPa) was obtained when the percentage of silica fume was 7.5 % of the cement weight. Beyond 7.5 % silica fume, the compressive strength started descending. Tensile and shear strength were found to vary in an inverse relationship with the increasing percentage of silica fume. A significant reduction in tensile strength and shear strength were recorded when the silica fume percentage is increased. However, the 10% ratio between tensile and compressive strength for normal concrete, was not found to be, relevant for HPC with SF.

Geopolymer concrete is a novel development in concrete technology and still it is developing. In the present investigation, effect of different curing systems on compressive strength of fly ash based geopolymer concrete is highlighted. Three system of curing were considered for study by varying fineness and quantity of fly ash. Two types of low calcium processed flyash were taken from thermal power plant of fineness 600m2/kg and 400m2/kg. Ten geopolymer mixes were prepared and tested for compressive strength using cubes of size 100x100x100 mm. The systems of curing are hot air oven curing, solar oven curing and atmospheric curing. The results shows enhanced compressive strength by solar oven curing as compare to atmospheric temperature curing of geopolymer concrete. Similarly, there is no large variation in compressive strength of geopolymer concrete using Electric oven curing and solar oven curing for fineness of FA 400m²/kg.

Dans le présent chapitre, on présente les différents résultats expérimentaux relatifs aux essais effectués sur le BHP conformément aux modes opératoires mentionnés au chapitre précédent, une analyse et une discussion des résultats sera faite à la base des résultats obtenus. Le tableau ci-dessous représente l'ensemble de résultats des mélanges étudiés dans ce présent programme expérimental. V.2 feuille de calcul d'un BHP On présente ci-après une feuille de calcul pour un BHP composé à 100% du ciment.

- by Dr. Imed Beghoura
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- Geopolymer Concrete

Glass fibre waste (GFW) coming from wind turbine blade production was used for the first time as a reinforcement agent in inorganic polymer (geopolymer) production. The influence of glass fibre content and length on the inorganic polymer microstructure, apparent density, and compressive and tensile strength was evaluated. Results demonstrate that the use of short, randomly distributed fibres significantly enhance the geopolymers' compressive strength (by up to ~162%) and tensile strength (by up to ~77%), while overcoming the brittle nature of the geopolymers. It was also found that the glass fibre content, rather than the fibre length, is the dominant factor affecting the geopolymers' mechanical properties. These results demonstrate the possibility of using an unexplored waste stream (glass fibre waste) as a reinforcement agent in inorganic polymers, which may reduce the amount of wastes in landfill and lower inorganic polymer production costs, while simultaneously contributing towards the circular economy.

- by Robert C Pullar
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- Wind Energy, Waste recycling, Geopolymer Concrete, Wind Power

On peut fabriquer des bétons en utilisant seulement du ciment Portland. Cependant la sub stitution partielle d'une certaine quantité de ciment par un ou plusieurs ajouts minéraux lorsqu'ils sont disponibles à des prix compétitifs peut être avantageuse, non seulement du point de vue économique, mais aussi du point de vue rhéologique et parfois du point de vue résistance et durabilité. La plupart des ajouts minéraux ont en commun de contenir une forme de silice vitreuse réactive qui, en présence d'eau, peut se combiner à la température libérée par l'hydratation du C2S et du C 3 S avec la chaux pour former un silicate de calcium hydraté du même type que celui qui est formé durant l'hydratation du ciment Portland (N F P 18-508). On peut écrire donc une réaction pouzzolanique de la façon simple suivante : Pouzzolane + chaux + eau  Silicate de calcium hydraté Il faut noter qu'à la température de la pièce, cette réaction est généralement lente et peut se développer sur plusieurs semaines. Cependant plus la pouzzolane est fine et vitreuse, plus sa réaction avec la chaux est rapide [4]. L'hydratation du ciment Portland libère une grande quantité de chaux par suite de la réaction d'hydratation du C 2 S et du C 3 S (30 % de la masse anhydre du ciment). Cette chaux contribue à la chute de résistance de la pâte de ciment hydratée. Elle peut même être responsable des problèmes de durabilité puisqu'elle peut être assez facilement lessivée par de l'eau, ce lessivage augmente alors la porosité de la pâte de ciment. Le seul aspect positif de la présence de chaux dans un béton est qu'elle maintient un pH élevé qui favorise la stabilité de la couche de l'oxyde de fer que l'on retrouve sur les armatures d'acier. Quand on fabrique des bétons, si on utilise 20 à 30% de pouzzolane, théoriquement, on pourrait faire réagir toute la chaux produite par l'hydratation du ciment portland pour la transformer en C-S-H. Cependant, les conditions dans lesquelles on utilise le béton sont très différentes de cette situation idéale et la réaction pouzzolanique n'est jamais complète. Ces matériaux étant des sous-produits industriels, leurs compositions chimiques sont en général moins bien définies que celle du ciment Portland [4].

- by Dr. Imed Beghoura
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- Geopolymer Concrete

Sodium silicate (Na2SiO3) and sodium hydroxide (NaOH) solution will be used as alkaline activators. The molar ratio of hydroxide solution considered in the investigation is 10M. The result shows that the mechanical decrease with increase in FA content in the mix irrespective of different curing periods like 7, 28, 56 and 90 days at ambient room temperature.

- by IAEME Publication
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- Geopolymer Concrete, Compressive Strength, Fly Ash, Sodium Hydroxide
- by Haruna Sani and +1
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- Geopolymer Concrete

Due to the advantage of decrease in carbon footprint with the use of cement-less geopolymer concrete, researchers had focused towards the study of the behaviour of geopolymer concrete on micro-and macro-scales. Recent researches are in a continuous process to improve the mechanical properties of geopolymer concrete by replacing natural river sand with other admixtures as fine aggregate. The objective of this review is to summarize and discuss the reported findings on the replacement of river sand with various materials like fine bone China ceramic, recycled fine aggregate, Waste marble aggregate, shredded rubber, iron tallings etc., The micro-structural properties of the such developed Geoploymer Concrete are discussed with the help of XRD and SEM results. It is also to be noted that the strength parameters are greater than that of Conventional Concrete.

Previous research has not sufficiently addressed the availability of geopolymer concrete raw materials, which influences adoption for infrastructure constructions. The overview herein assesses the supply, demand, and cost of these raw materials, including fly ash, slag cement, metakaolin, sodium hydroxide, sodium silicate, and silica fume. The results suggest that geopolymer concrete is a viable partial replacement for ordinary Portland cement (OPC) in the United States and Europe. Limitations exist in the rest of world, specifically China. Fly ash-based geopolymer concrete represents an opportunity due to low cost along with significant global production and reserves. Additionally, an activating solution composed of sodium hydroxide and silica fume with 25% Portland cement as a partial replacement appears to be most desirable. However, approximately only 7% replacement of OPC with geopolymer concrete is currently feasible globally due to limitations in sodium hydroxide supply. The analysis reveals a need for continued research to reduce the use of sodium hydroxide to improve availability and reduce cost of geopolymer concrete.

- by Lateef Assi and +1
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- Geopolymer Concrete, Fly Ash Based Geopolymer Concrete

To divert fly ash from hazardous waste stream to beneficial uses, this work aims to improve the solidification of fly ash as a geopolymer material by using graphene oxide (GO). The hydration precursors, morphology, elemental composition, mineralogy, chemical structure and ordering of GO-modified fly ash geopolymer were investigated by means of Raman spectroscopy, SEM/BSE, EMPA, XRD/TGA and 29 Si/ 27 Al MAS-NMR, respectively , to unravel the role of GO. The experimental results suggest that GO regulated the Ca/Si, Si/Al and Ca/ (Si + Al) mole ratios to facilitate the formation of fly ash hydrates with improved mechanical strength, as GO showed the ability to selectively affect the distribution of different hydration precursors. GO also promoted the formation of low quartz and jennite-like hydrates. Overall, the 28-day compressive strength of fly ash geopo-lymer (w/b = 0.35) in this study was improved by 23% (from 33.6 MPa to 41.4 MPa) with GO admixed at 0.02% by mass of fly ash. The NMR study showed that GO improved the polymerization degree of fly ash geopolymer by increasing the total Q 3 and Q 4 Si-tetrahedrons, which suggests potential for improving the immobilization of heavy metals in fly ash.

- by xianming Shi and +1
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- NMR Spectroscopy, Geopolymer Concrete, Fly Ash, Graphene Oxide
- by Editor IJRET
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- Civil Engineering, Geopolymer Concrete
- by Dr. Imed Beghoura
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- Geopolymer Concrete
- by Dr. Imed Beghoura
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- Geopolymer Concrete

Due to their good performance and environmental friendliness, fly ash-based construction materials have great potential as alternatives to ordinary Portland cement. To realize sustainable development and beneficial use of fly ash in the construction industry, this paper presents a comprehensive review of relevant literature to evaluate the properties and performance of fly ash, with a particular focus on recent advances in characterization, compositional understanding, hydration mechanism, activation approaches, durability and sustainability of fly ash as a construction material. Several key aspects governing the performance of fly ash, including chemical composition, activator type and hydrates evolution in concrete, are highlighted. Finally, the important needs, pertinent to the optimal and broad utilization of fly ash as an integral part of sustainable construction materials, are identified for further research and development, where large-scale application studies, further classification of fly ash, advanced characterization tools and technology transfer to biomass fly ash are recommended.

- by xianming Shi
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- Construction Materials, Nanotechnology, Geopolymer Concrete, Fly Ash

The geopolymer concrete has stepped in the construction industry as an alternate to the cement based concrete. Many of the research about geopolymer concrete states that it has potential to replace the cement based concrete in many countries depending on the locally available resources. The present review deals with the study of constituents of geopolymer concrete. Attempt has been made to collect information about the locally available constituents of geopolymer concrete and the ongoing research and few mechanical properties with and without fibres in concrete were discussed. The geopolymer concrete chosen is based on 100% ground granulated blast furnace slag (GGBS) cured in laboratory in typical tropical ambient environmental conditions.

This article discusses the utilization of palm oil fuel ash (POFA) in normal and geopolymer concrete. Malaysia, one of the world's largest producers of palm oil, produces more than 10 Mt/year of palm waste as ash, which is called POFA. Since 1989, extensive research has been conducted on its utilization in concrete. Several published studies have noted POFA's enormous potential as a partial replacement of cement in concrete. This paper describes the effects of using POFA on different fresh and hardened properties of concrete. The latest studies on the use of ground POFA revealed that concrete made from this material possesses better fresh properties and medium to higher strength than ordinary Portland cement (OPC) concrete. One of the major findings is that concrete that incorporates 20% fine POFA by weight of cement showed better durability properties than OPC concrete. Because limiting CO 2 emissions has become a matter of increasing importance in the construction industry, concrete that uses less cement in its production and utilizes an increased amount of waste, such as POFA, offers an environmentally viable solution. Moreover, 100% cement-free geopolymer concrete can be produced using blended ash, such as POFA and fly ash.

- by Elnaz khankhaje and +2
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- Concrete, Concrete Technology, Geopolymer Concrete, Sustainable Concrete

Engineering properties of geopolymer concrete developed using palm oil fuel ash and slag as binders, manufactured sand and quarry dust as replacement materials for fine aggregate, and oil palm shell (OPS) as coarse aggregate were investigated along with carbon footprint. The use of binder content of 425 kg/m3 with OPS based lightweight concrete produced the highest compressive strength of 33 MPa. Ultrasonic pulse velocity of normal weight geopolymer concrete (NWGC) shows it as “good quality”. The development of structural grade OPS geopolymer concrete comparable to NWGC shows its potential application for structural purposes. OPS geopolymer concrete has lower carbon footprint of 50–60% compared to conventional concrete.

- by Azizul Islam and +2
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- Geopolymer Concrete
- by Dr. Imed Beghoura
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- Geopolymer Concrete

Present investigation embodies the flexural behavior of Geopolymer Concrete (GPC) beams cured under ambient temperature. Twelve reinforced concrete beams of size 700 mm x 150 mm x 150 mm were tested. The beams were tested under four point bending over an effective span of 660 mm. The behavior was studied with reference to first crack load, service load and ultimate load. The results were found to be similar to that of conventional cement concrete reinforced beams. The studies showed that the conventional RC theory could be used for reinforced GPC flexural beams for the computation of moment capacity, deflection within reasonable limits.

- by GJESR Journal and +1
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- Geopolymer Concrete, Reinforced Concrete Structures, Flexural Behaviour of Rc Beams, Beams

Cement is the world's most used construction binder material. Cement production emits large amounts of CO2 and consumes significant amount of energy. As a result, it is necessary to find a new concrete material to replace traditional Portland cement concrete, which is environmentally stressful, yet provides an effective building material. Geopolymer is an emerging alternative binder to Portland cement for making concrete. Geopolymer concrete is principally produced by utilizing industrial by-product materials such as fly ash, blast furnace slag, and other aluminosilicate materials. RCC structures undergo serious durability problems like spalling, erosion, wear, cracking, corrosion etc. years after the construction. Repair to damaged concrete are important not only to ensure the planned useful life, but also to provide good performance and security. This paper review the literature related to the studies conducted on geopolymer and repair materials. I. INTRODUCTION Cement is the world's most used construction binder material. Cement production emits large amounts of CO 2 and consumes significant amount of energy. Production of one ton of Portland cement releases one ton of CO 2 into the atmosphere. The global cement industry contributes around 6% of all CO 2 emissions. It is a common viewpoint that finding an alternative material to the Portland cement is imminent. Some researchers have stated that CO 2 emission could increase by 50% compared with the present scope. Therefore, the impact of cement production on the environment issues a significant challenge to concrete industries in the future. As a result, it is necessary to find a new concrete material to replace traditional Portland cement concrete, which is environmentally stressful, yet provides an effective building material. Promoting low-emission concretes is essential in order to face the crucial challenge to reduce the environmental impact of the construction sector and the concrete industry and to limit the impact of climate change. One way of reducing these CO 2 emissions is the use of blended cements in which a part of the Portland cement clinker is replaced with supplementary cementitious materials (SCMs). The most common SCMs used in high-volume applications are fly ash (FA) and ground granulated blast furnace slag (GGBFS). Fly-ash-based and GGBFS based blended cements are extensively used but limits are imposed on the OPC replacement. In most cases, blended cements still contain more OPC clinker than SCM. On the other hand, geopolymer is a new construction material which could be produced by the chemical action of inorganic molecules, without using any Portland cement. The geopolymer binder could be produced through chemical reaction between alumino-silicate materials such as fly ash or metakaolin that are rich in SiO 2 and Al 2 O 3 and alkaline solutions such as Sodium Hydroxide or Sodium Silicate. Fly ash is a suitable material for making geopolymeric binder because of its pertinent silica and alumina composition and low water demand. Low-calcium fly ash-based geopolymer concrete cured in high temperature has been reported to have good mechanical properties in both short and long term tests. The structural behaviour of heat-cured fly ash geopolymer concrete was found to be similar or superior to that of OPC concrete when tested for reinforced columns and beams, bonding and fracture properties. The hardening mechanism for geopolymers essentially contains the polycondensation reaction of geopolymeric precursors, regularly aluminosilicate oxides, with alkali polysilicates yielding a polymeric silicon –oxygen aluminium framework.

— This paper presents a comprehensive review on factors affecting strength and durability of geopolymer. The review is subdivided into different sections to appreciate the state of research carried out till date starting from the terminology, mechanism of geopolymerisation and various properties of geopolymer. Effect of curing temperature, curing duration, silicate to aluminum ratio, silicate and hydroxide ratio, alkaline liquid to fly ash ratio on physico-mechanical properties of geopolymer has been reviewed and highlighted in this paper. In addition, a brief review of previous research on durability of geopolymer exposed to acids and sulphates is also presented. It is observed that geopolymer can attain high compressive strength even in a day and is also superior to ordinary Portland cement in terms of durability.

- by shyamananda SINGH and +1
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- Geopolymer Concrete, Experimental Study on Geopolymer Concrete
- by Editor IJRET
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- Civil Engineering, Geopolymer Concrete, Fly Ash, Sodium Hydroxide

Concrete is one of the widely used composite materials. The demand for concrete in the construction field is increasing day by day. Cement is used as a binder material in concrete which is highly energy intensive and emits CO2 to the atmosphere which is responsible for global warming. So, to protect pollution it is necessary to find the alternatives for OPC which is eco-friendly with the environment. Geopolymer is a best solution that utilizes industrial by-products as a binding material and is similar to cement. In this study, fly ash and GGBS is used as a binder material to prepare a geopolymer concrete for replacing cement by 100% to investigate the fresh and hardened properties in addition with different percentages of basalt fibers. Six cubes for each decreasing rate of fly ash (90%, 80%, 70%, 60% & 50%) and in other hand increasing rate of GGBS (10%. 20%, 30%, 40% & 50%) with active alkaline liquids like sodium hydroxide (NaOH) of 10 molarity concentration and Sodium silicate (Na2Sio3) was cast and cured on ambient temperature and tested. From different trial mixes, the optimum percentage of fly ash and GGBS was taken as 90% and 10% respectively. With this percentage, specimens like cubes, cylinder and prism were cast with a different percentage of basalt fibers at a dosage increment of 0.1% from 0.1% to 0.50% to find the optimum fiber percentage. Other properties like a split tensile, flexural strength, stress-strain curve test were also conducted and the results were compared with control geopolymer concrete. The test result implies that fiber reinforced geopolymer concrete yields better results in all the aspects when compared to geopolymer concrete without basalt fibers and also strength increases by 60 to 110%.

Fly ash released from the thermal power plants constitutes a major portion than bottom ash. As a major portion of the coal ash, fly ash has been recognized widely as a source material for geopolymers while the utilization of bottom ash has received very less attention. In order to promote greater usage of bottom ash in construction, this paper focuses on the study of ground bottom ash in geopolymer mortar. The effect of molar ratio of SiO 2 /Na 2 O, Na 2 SiO 3 /NaOH ratio and curing mode were considered on compressive strength of bottom ash based geopolymer mortar. Molarity of sodium silicate solution was maintained as 8M. Ambient curing and steam curing at 60ºC was attempted. Test results indicate that Na 2 SiO 3 /NaOH of ratio 2 with SiO 2 /Na 2 O molar ratio 1 mortar achieved higher compressive strength under both ambient curing and steam curing.

- by Revathi V
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- Geopolymer Concrete, Self Compacting Concrete, Pervious Concrete

Paver block is used in various applications like in street road and other construction places. Portland cement generates large amounts of carbon dioxide (CO 2) which is responsible for global warming hence it is a greenhouse gas. And the concrete paver block production consume large amount of water and space for curing purpose. The other great problem today is disposal of solid waste from Coal fired thermal power plants generate fly ash and pond ash. This project combined sustainability, curing free with waste management leading to a wonderful product called geo-polymer concrete pavers. This paper represents the results of the geopolymer concrete paver block with the mix of M40 grade Test results indicate that low calcium fly ash based geopolymer concrete pavers has excellent compressive strength within short period (3 days) without water curing & suitable for practical applications

Geopolymer concrete is a recent development in the concrete research aiming for an alternate for the conventional cement concrete. As the rate of emission of CO2 from cement and concrete industries is increasing day by day, more more researchers are diverted to investigate an alternate binder to conventional Portland cement. Geopolymer in its most effective development process involve the utilisation of a source material with sodium based alkaline activator and hot curing at 60oC-100 oC. However, it is still in the laboratory level due to many constraints like, typical constituents, casting procedure, hot curing and compatibility with the reinforcing or prestressing steel. Also, most of the works reported are based on low calcium flyash and only a few studies using high calcium flyash. Therefore, being more cementitious, development of GPC using high calcium flyash with sodium based activating solution having liquid ratio of 2.5 is dealt. The influence of Molaity on the workability and strength of three grades of GPC equivalent to conventional M20, M30 and M40 grades of cement concrete are studied. It is observed that the expected strength of GPC can be achieved for specific molarity of NaOH by hot curing.

- by mohd azreen mohd ariffin and +1
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- Civil Engineering, Microstructure, Geopolymer Concrete, Compressive Strength

Introduction The vast increase in CO 2 and waste generation in recent decades has been a major obstacle to sustainable development and sustainability. In construction industry, the production of ordinary Portland cement is a major greenhouse gas emitter with almost 8% of total CO 2 production in the world. To address this, Alkali-activated materials and geopolymer have more recently been introduced as a green and sustainable alternative of ordinary Portland cement with significantly lowered environmental footprints. Their use to replace Portland cement products generally leads to vast energy and virgin materials savings resulting in a sustainable concrete production. In doing so, it reuses the solid waste generated in industrial and manufacturing sectors, which is aligned with circular economy. In turn, it reduces the need for ordinary Portland cement consumption and its subsequent CO 2 generation. Objective To provide further insight and address the challenges facing the substitution of ordinary Portland cement, this article reviews different types, mechanisms, and result of mechanical and durability properties of alkali-activated materials and geopolymer reported in literature. Finally, it discusses future projections of waste materials that have cementitious properties and can replace ordinary Portland cement and be used in alkaliactivated materials and geopolymer.

- by Mehrab Nodehi and +1
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- Geopolymer Concrete, Circular Economy, Sustainable Concrete, Fly Ash Based Geopolymer Concrete

Geopolymber bricks were prepared using fine cyclone waste from wall tile industry. Compressive strength increased with degree of polymerization. Water absorption of bricks generally increase with both curing time and temperature. A mix of dust with 10% Ca(OH) 2 , 1% NaOH resulted in compressive strength of about 9 MPa. a b s t r a c t The fine dust waste from the cyclones connected to the spray dryer in ceramic tiles manufacture was used in the preparation of geopolymer bricks. Dust was characterized after firing using XRD, XRF, PSD, and its bulk density was determined. Caustic soda was used at 1% NaOH level together with slaked lime at Ca(OH) 2 percentage ranging from 6 to 10%. These were mixed with the fine dust waste and molded to form geopolymer bricks. The properties of produced bricks were studied after 28 days. Results indicated that the 28 days compressive strength increased with the degree of geopolymerization. It was found that the results abide by the Standard ASTM C 62/2013 for a recipe consisting of 1% NaOH, 10% Ca(OH) 2 and 38% water. The results were confirmed by SEM imaging. The use of waste raw materials (except for caustic soda) resulted in a substantial reduction in the estimated production cost of the bricks.

- by Aya Aboelmagd
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- Geopolymer Concrete, Cement and Concrete Materials
- by pugar septia girdayanto
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- Geopolymer Concrete