Combination Of Sodium Silicate Research Articles

Performance Evaluation of M20 Grade Geopolymer Concrete using Fly Ash and GGBS with Super Plasticizer

Abstract: This study aimed to evaluate the strength properties of geopolymer concrete using fly ash and ground granulated blast furnace slag (GGBS) with the addition of a super plasticizer at a grade M20. The study used 70% fly ash and 30% GGBS to replace the cement content of the concrete mix, and sodium hydroxide and sodium silicate were used as Alkaline activators. The concentration of (NaOH) solution was maintained at 8 molarity and the dosage of activator ratio is 2.5 is a combination of sodium silicate and sodium hydroxide ratio. The compressive strength of the geopolymer concrete was tested at different ages (7, 14, and 28 days) to evaluate the strength properties. The results showed that the addition of fly ash and GGBS significantly improved the strength properties of the geopolymer concrete. Moreover, the optimized dosage of the super plasticizer was found to be 1% of the total weight of the mix. The study concludes that the use of fly ash and GGBS in geopolymer concrete can significantly improve its strength properties, and the addition of a super plasticizer can enhance its workability. This finding suggests that geopolymer concrete could be a viable alternative to conventional concrete in construction applications .The test result shows encouraging results of ordinary Portland cement concrete and geo polymer concrete so one can easily replace ordinary concrete with geopolymer concrete for precast applications.

Physico-Mechanical and thermal behavior of prolong heat Cured geopolymer blocks

Geopolymer has played an important role in the development of environment friendly building material using waste from various industries, agriculture and municipal waste. Most of the waste obtained from various industries are pozzolanic in nature or can be made reactive upon processing. Thus, are easy to incorporate in the mix design to achieve desired physical and mechanical properties. However, in practical scenario the total cost of the building materials is controlled by incorporating non-reactive materials as fillers. Considering this, an experimental investigation is carried out to develop with an objective to develop thermally efficient geopolymer block containing a fixed amount of crusher dust as filler and fly ash as the primary precursor and either rice husk ash or bottom ash as partial replacement of fly ash (i.e., 20, 30 and 40 % of fly ash). A combination of sodium silicate and sodium hydroxide mixed in the ratio of 2.5 was used as the alkaline solution and are cured at a constant temperature of 60 °C. The obtained results show that the developed geopolymer has lower thermal conductivity as compared to the traditional bricks and has lower water absorption and porosity values. The compressive and flexural strength are found to be greater than the strength requirement of first-class bricks.

Evaluation of environmental sustainability of one-part geopolymer binder concrete

Production of ordinary Portland cement (OPC) is a carbon-intensive process that generates significant amounts of carbon dioxide (CO2) gas from the combustion of fossil fuels and thermal decomposition of limestone. Overall, cement industries are responsible for around 7 % of global CO2 emissions which poses a considerable threat to global climate change because of its greenhouse effects. The recent advent of geopolymer shows great potential to reduce carbon footprints by utilizing the industrial by-products, such as fly ash and ground granulated blast furnace slag (GGBS) and convert into a binding material. Generally, geopolymer binders are made using aluminosilicate compounds (fly ash and or GGBS) and an alkali activator (combination of sodium silicate and sodium hydroxide solution) called “two-part geopolymer”. Despite having superior engineering properties to conventional OPC concrete, geopolymer concrete has not been widely adopted in concrete industry so far. The safety hazards in mixing and handling geopolymer concrete posed by sodium hydroxide is one of the barriers to the adaptation of geopolymer concrete. Replacing liquid sodium hydroxide with less hazardous alkali materials, such as sodium carbonate powder not only makes the geopolymer binder less hazardous and easier for mixing and handling process but also makes it more environmentally sustainable because of its lower embodied energy compared to sodium hydroxide. This study investigates the environmental sustainability of structural grades one-part geopolymer concrete and compares the results with OPC concrete of same strength grades. This investigation also includes a comparison between various types of geopolymer concrete of 40 MPa and 50 MPa grades produced in previous studies. This study found that one-part geopolymer binder concrete emits around 65 % less CO2 than OPC concrete of same strength grades, which is also 23 % less than geopolymer concrete of same strength grades produced in previous studies.

Effect of Composite Impregnation on Properties of Recycled Coarse Aggregate and Recycled Aggregate Concrete

To improve the properties of recycled aggregate concrete, single and composite impregnation treatments were carried out on recycled coarse aggregates with sodium silicate solution, silane slurry, and polyvinyl alcohol solution. The effects of the three chemical modifiers and different impregnation methods on the apparent density, water absorption, and crushing index of recycled coarse aggregates, as well as the basic properties of recycled aggregate concrete, were investigated. Additionally, the microstructure of the surface of recycled coarse aggregate and the interior of recycled aggregate concrete were analyzed by scanning electron microscopy. The experimental results show that the water absorption of recycled coarse aggregate soaked in polyvinyl alcohol solution decreases most significantly, reaching 64.56%. Only the combination of sodium silicate and silane impregnation produces a positive compounding effect, with a significant increase in the apparent density and a significant reduction in the crushing index of the recycled coarse aggregate. Compared with untreated concrete, the slump, compressive strength, splitting tensile strength, and flexural strength of recycled aggregate concrete prepared by sodium silicate and silane composite impregnation are increased by 9.8%, 26.53%, 21.70%, and 14.72%, respectively. The microstructure analysis shows that the composite impregnation treatment of sodium silicate and silane is most conducive to filling the cracks and holes on the surface of recycled coarse aggregate, which makes the interfacial transition zone of recycled aggregate concrete more compact and the structure more stable.

Effect of immersing geopolymer slag-fly ash mortar in sulfuric acid on strength development and stability of mass

This article presents the findings of a study aimed at assessing the effect of immersing mortar with alkali-activated ground granulated blast furnace slag and fly ash binders in highly acid solution, on compressive strength development and stability of mass. Effects of slag & fly ash contents on strength development and mass change were evaluated by testing mortars with three groups of binders including 100%slag, 75%slag + 25% fly ash, and 50% slag + 50% fly ash. The precursors were activated using a combination of sodium silicate (SS) and sodium hydroxide (SH) solutions. It was found that immersing samples in 10% sulfuric acid solution, one day after casting, didn’t not cause decrease in strength or mass from 7 days to 90 days, and the pattern was consistent for NaOH concentrations from 10 M to 16 M. This was attributed to presence of water in the sulfuric acid solution which provided a closed curing environment. Similar samples cured by direct exposure to air developed lower compressive strength at the age of 28-days than samples immersed in sulfuric acid solution. At lower solution molarity (NaOH concentration = 10 M), mortars with 75% slag and 25% fly ash binder developed the highest compressive strength of 87 MPa after 28 days of immersion in sulfuric acid solution, compared to 49.85 MPa for samples cured in air, further confirming the positive effect of water as curing medium. The study also found a strong correlation between splitting tensile strength and compressive strength of air-cured mortar when the binder is 100% slag. The relationship weakens as fly ash content is increased from 0% to 50%.

Analytical modeling and experimental validation of balanced reinforced geopolymer concrete beams

Structural analysis is used to assess the behavior of engineering structures under the application of various loads. Commonly used structural analysis methods include analytical, experimental and numerical methods. The finite element method has become very popular among engineers and researchers as it is considered to be one of the best methods for solving complex engineering problems efficiently. There are various finite element software packages such as ATENA, ABAQUS, Hypermesh, Nastran and ANSYS to solve the engineering problems. Hence, in the present study ANSYS (Analysis System), finite element software is used for solving the reinforced concrete beams. The results thus obtained are verified with the experiment carried out. The experimental work highlights the study on flexural behavior of conventional and geopolymer reinforced beams with different grades of concrete namely M-30, M-40 and M-50. The test specimens was 100 x 200 x 2000 mm reinforced beams cured at room temperature. The alkaline solution used for present study was the combination of sodium silicate and sodium hydroxide solution with the ratio 2.50. The molarity used for the preparation of geoploymer solution was 12. The beams considered for the study were designed as balanced reinforced sections with percentage of reinforcement varying in the range of 1.45, 2.10 and 2.40. It was observed that the experimental values of reinforced concrete beams were in par with the results obtained with ANSYS modeling.

Combined effect of high temperatures and crystalline slag on the mechanical behavior of geopolymers mortars

As part of protecting the environment from carbon dioxide emissions, all research aims to reduce the use of cement in concrete with cheaper and energy efficient materials. Geopolymer mortar is an environmentally friendly mortar made from industrial solid waste and by-products such as crystalline slag (CS). This research aims to produce a geopolymer mortar from local materials available in Algeria which are not sufficiently valued at present. The aim of this study is to provide geopolymer mortar at high temperatures, operating with a constant hardening temperature of around 60° C. The alkaline activator used in this study was a combination of sodium silicate (Na2SiO3) and 10 M NaOH solution. In addition, crystalline geopolymer mortars (MCS) as the binder material at a curing temperature of 60 °C, ratios of two mixtures of binder were prepared by substituting the sand with 40% CS and 100% CS. For this purpose, the mortar sample with the highest compressive strength was subjected to temperatures of 200, 400, 600 and 800 °C for exposure times of 10 °C per minute and changes in temperature and changes in the physical and mechanical properties was analyzed. As a result of the experiments, the highest mechanicals values were obtained from the mortar samples with a 40% CS content. Following the high temperature tests, 400 °C and 600 °C were determined as critical temperatures for changes in mechanical properties and changes in physical properties, respectively. However, the geopolymer mortars lost around 60% of strength at 800 °C which is the final temperature.

Determination of shear strength by Iosipescu (V-notch) method of metakaolin-based geopolymeric resins activated by different silicate and hydroxide combinations

Geopolymers (inorganic polymers) were developed and patented by Joseph Davidovits in the 1970’s and have gained significant attention in the civil construction industry. Since then, the properties of geopolymers have been studied by many researchers, such as their use as a repair material on reinforced concrete structures. Thus, this study aimed to evaluate the mechanical properties of metakaolin-based repair geopolymeric resins. The geopolymeric resins were prepared with alkaline activators composed by sodium and potassium silicates combined to sodium and potassium hydroxides to determine the properties of fresh mixtures (workability, setting times), the adhesion coefficient at the interface substrate/resin and the gain in compressive and indirect tensile strengths up to 28 days of age. The Iosipescu or V-Notch shear tests were used to determine the shear strength and shear modulus, according to ASTM D 5379 (1998) specifications, as these are the most important mechanical properties when studying structural repairs. The results indicated that all geopolymeric resins achieved high mechanical strength in the early ages, which is fundamental for structural repair applications. The gain in compressive strength ranged from 60% on the first day to 85 to 93% after 3 days when compared to the results obtained at 28 days of age. All resins reached compressive strengths greater than 80 MPa and indirect tensile strengths between 5 and 6 MPa at 28 days of age. The shear strength (τ) values were around varied from 4.31 to 7.55 MPa. The resins with combination of sodium silicate with potassium hydroxide and potassium silicate with sodium hydroxide showed higher shear moduli, being respectively 6,13 and 8,20 GPa. The results obtained show that the resins developed in this work have enormous potential for use in repairing reinforced concrete structures.

Increasing the efficiency of water shut-off in oil wells using sodium silicate

Purpose. Substantiation of technology for creation of a water-blocking zone below an oil reservoir and calculation of the proper composition of a gel-forming compound based on sodium silicate, in order to reduce water cut in production wells. Methodology. The goal of the work was achieved by conducting theoretical and experimental studies on technological processes of water blocking in an oil reservoir, and by identifying patterns of gel formation of sodium silicate and hydration of a micro-cement solution in reservoir conditions on full-scale models. The gel compound included sodium silicate (Na2SiO3, also referred to as liquid glass) and an aluminum salt cross-linker (AS-1). The plugging material mixture of Portland micro-cement and sodium silicate contained calcium oxide, to allow expansion, and a GL-1 reaction inhibitor. The criteria for assessing the creation of a reliable water-blocking zone in an oil reservoir are: the mobility of the aqueous solution of the gel-forming compound during its movement from the wellhead to the bottom of the well, the low permeability of the zone following its creation, and the sufficient strength of the non-shrink micro-cement in the annulus of the well. Findings. A new technology is suggested used to create a water isolation zone is a gel-forming compound based on sodium silicate, which provides a significant reduction of water cut in oil production. It is found that perforation of production string below the oil reservoir at the level of the water-saturated zone followed by injection into a well through perforated channels, the mixture of fresh water and the gel-forming compound prevents water inflow to the bottom of the well. Experiments established that with a gelation time of 2 hours at a temperature of 80 C, the viscosity of the gel is in the range of 1.22.9 Pas, and the density is 10801109 kg/m3. These values for the viscosity of the gel allow transportation from the top of the well to the bottom with the least resistance to motion. Following gelation time, the viscosity increases significantly, and after 3 days the gel viscosity reaches a range of 3.46.7 Pas. The values indicated for the viscosity of the gel are much greater than those of oil. Therefore, the proposed gel-forming compound provides a reliable water shut-off zone at the bottom of an oil reservoir, and prevents the influx of water at the bottom of a well. Originality. The proposed sodium silicate compound allows for the creation of a reliable water shut-off zone and an enhanced grouting material, based on the combination of sodium silicate and micro-cement, which together provide a significant reduction in water cut in wells during oil production. Practical value. A method for studying technological processes of oil reservoir water-blocking has been devised and the rational composition of gel-forming compound and micro-cement grout slurry with an expanding additive and a reaction retarder in reservoir conditions on full-scale models has been established. The application of the research results in oil fields allows reduction of water cut in production wells to 010%, against existing values of 7090%, and an increase in flow rate in producing wells by 2030%.

Compressive Strength Development of Slag-Based Geopolymer Paste Reinforced with Fibers Cured at Ambient Condition

Geopolymer mixtures (such as concrete, mortar, and paste) were used as sustainable alternatives to Portland cement, and enhancement the mechanical properties by addition fibers, due to their great potential in reducing environmental pollution and reducing consumption of raw materials. In this paper, verified the effect of different fibers added to slag based geopolymer paste, on compressive strength development. Ten mixes were preparing and curing at ambient condition. The variables included; type of fibers added (i.e. micro steel fiber, carbon fiber, or polypropylene fiber), and volumetric ratio of fibers included, (1%, 2%, or 3%) of micro steel fiber, and (0.2%, 0.4%, or 0.6%) of carbon fiber and polypropylene fiber. The alkaline solution was combination of sodium silicate (Na2SiO3), and sodium hydroxide (NaOH) with concentrically 10 molar. The results were found that the addition of fibers led to improving significant of the compressive strength. Generally, the development of compression was estimate by about (30% and 23%) at ages (7 and 28) days, respectively. Finally, the slag based geopolymer paste is more suitable to use in construction sites as alternative sustainable of Portland cement.

The influence of activator type and quantity on the transport properties of class F fly ash geopolymer

It is known that transport properties of porous materials were important in terms of its durability aspect. In this paper, the effect of activator type, Na amount on the transport properties of geopolymer mortar made with class F fly ash were explored. Two different class F fly ash were employed in producing geopolymer that activated alkaline solutions. As alkali activator, sodium hydroxide solution, and combination of sodium silicate with sodium hydroxide were used. Activator contained 6%, 9%, 12% and 15% of fly ash weight as Na amount. Heat curing regimes were imposed to specimens at 100 °C temperature for 24 h duration. Tests were carried out on the geopolymer samples including water absorption, volume of permeable voids, sorptivity, depth of penetration of water under pressure, chloride ion penetration and accelerated corrosion. It is found that the transport properties of geopolymer samples are improved by increasing the Na amounts of mortar mixtures from 6% to 15%. In general, better results were obtained with 15% Na ratio. The mortars produced with only sodium hydroxide have shown better transport properties than mortars made with combination of sodium hydroxide-sodium silicate mixture.

Microstructural Properties of Alkali-Activated Metakaolin and Bottom Ash Geopolymer

This paper presents a study on the use of alkali-activated metakaolin (MK) and Bottom Ash (BA) blend in geopolymer concrete. A preliminary attempt was made on alkali-activated metakaolin and bottom ash-based geopolymer (MK–BA-GPM) mortar with river sand as fine aggregate to find a suitable mix to produce geopolymer concrete (GPC). The liquid alkaline activator is a combination of sodium silicate and sodium hydroxide solution. The molarity of NaOH was 8 M. Molar ratio of Na2O and SiO2 was 2, and ambient curing mode was selected. Also, M30 grade control concrete was made using OPC and cured in water. Further, GPC and control concrete specimens were tested for compressive strength, split tensile, flexural strength and modulus of elasticity. Also, XRD, SEM and EDAX studies were carried out to analyse element/mineral compounds present and the microstructure and morphological characteristics of GPC to substantiate the strength development. MK–BA GPC demonstrated 49% higher compressive strength than that of control concrete at 28 days. More so, the early as well as later strength gain of GPC was remarkably higher than that of OPC. Strength was due to densification of microstructure over a period of time and due to the formation of additional crystalline phases in geopolymer concrete.

Mix composition and characterisation of one-part geopolymers with different activators

To improve the commercial viability of geopolymers, there is a need to develop one-part geopolymer mixes. In this research, 100% fly ash or a mixture of fly ash and slag was employed as the precursor. Meanwhile, the highly corrosive alkali solutions used as activators in conventional geopolymers were replaced by different solid activators (in powder form), such as sodium silicate, calcium hydroxide, sodium oxide, lithium hydroxide, potassium carbonate or their combinations. The mixes were subjected to both ambient and heat curing to check the influence of curing conditions. Effects of type/combination of the solid activators on the workability, early and final strength, hardened density and microstructure of these one-part geopolymer mixes were examined. The incorporation of slag in the binder increased the early and final strength of mixes but reduced the workability. Furthermore, the type/combination of solid alkaline activators affects the microstructure of the geopolymer gels and subsequently impacts the mechanical properties. Among the investigated ambient cured geopolymers, a relatively high compressive strength of 38 MPa at 28 days was obtained when the geopolymer precursor was composed of 50 wt% fly ash and 50 wt% slag activated by a combination of sodium silicate, calcium hydroxide and lithium hydroxide.

Optimization of metakaolin-based geopolymer reinforced with sisal fibers using response surface methology

The geopolymer appears as an ecologically viable alternative when compared to Portland cement, due to the lower CO2 emission rates. The objective of this work was to produce and characterize geopolymer pastes reinforced with long sisal fibers through toughness and modulus of elasticity responses. For this purpose, metakaolin was used as an aluminosilicate source material and a combination of sodium silicate and sodium hydroxide as the activator solution. The variables studied were the percentage of fibers in the composite, the ratio between the amount of activator and base material and the cure time. The statistical model of central composite planning was used in order to optimize the results obtained and scanning electron microscopy analysis was used to analyze the microstructure of the final composite. Modulus of elasticity values of 3.19 GPa were obtained with the use of 5.15%, by volume, of sisal fiber, an activator/metakaolin ratio of 0.41 with 24 days cure. The optimization of the toughness results occurred with the use of 5.19% of fiber by volume, a curing time of 7 days and a ratio between activator and binder of 0.55, reaching a result of 2.09 kJ/m2.

Mechanical properties and durability of unconfined and confined geopolymer concrete with fiber reinforced polymers exposed to sulfuric acid

Abstract This study reports the mechanical properties and durability of unconfined/confined sustainable geopolymer concrete (GPC) exposed to sulfuric acid attack under static and cyclic loadings. A low calcium (Class F) fly ash incorporating nano-silica was activated by a combination of sodium silicate and sodium hydroxide solutions to make the GPC. Unconfined/confined ordinary Portland cement concrete (OPCC) counterparts were also made for comparison purposes. The confined GPC/OPCC specimens were wrapped by one/three layers of basalt/carbon fiber-reinforced polymers (BFRP/CFRP). Effects of type and number of wrapping layers, along with wrapping and testing ages on the mechanical properties and durability of confined GPC/OPCC were investigated. In addition, microstructure of the unconfined/confined GPC specimens was compared with that of the unconfined OPCC counterparts. The results showed confinement of the GPC with BFRP/CFRP fabrics enhanced the strength, ductility and durability of the GPC exposed to sulfuric acid. The GPC confined with CFRP fabric was more ductile and durable than that confined with BFRP fabric. In addition, the GPC confined with three layers of BFRP/CFRP fabric was more ductile and durable than that confined with only one layer. Further, the unconfined/confined GPC was more durable than the corresponding unconfined/confined OPCC.

Behaviour of fly ash geopolymer binders under exposure to alkaline media

Alkaline agents are primary binder components of geopolymer systems. In the converse, however, the hardened geopolymer binders can be adversely affected under exposure to strong alkalis. This paper presents an investigation conducted to evaluate the effects of highly alkaline exposure environment on fly ash geopolymer binders. In the study, a combination of sodium silicate and 12 M NaOH solution was used as the alkali activator to prepare a low calcium (Class F) fly ash-based geopolymer binder. Fly ash geopolymer pastes or mortars were cast into 50 mm cubes and 25 × 25 × 285 mm prisms, then immersed in different media consisting of water or 1–3 M NaOH solutions maintained at varied temperatures of 23, 38, and 80 °C. The tests done include compressive strength, expansion, and weight changes. Analytical studies were done using X-ray diffraction, X-ray fluorescence, Fourier transform infrared spectroscopy, scanning electron microscopy. Leaching analysis of storage solutions was also conducted. Results showed that alkali attack occurred when the concentrations of storage solutions exceeded 1 M NaOH. The severity of attack increased with increase in NaOH concentration and in storage temperature. It was found that the alkali attack causes damage to the polymeric structure of the binder, leading to release of Al and Si. A gel-like substance is formed, causing expansion and microcracking. New crystalline zeolite phases comprising phillipsite, zeolite-P and chabazite, also formed under exposure of the fly ash geopolymer binder to elevated alkali concentrations.

Engineering properties of natural pozzolan/slag based alkali-activated concrete

Abstract The current study aims to assess engineering properties of alkali-activated concretes made with hybrid aluminosilicate precursors having different proportions of natural pozzolan as a low calcium precursor and blast furnace slag as a high calcium precursor which activated with different concentrations and combinations of sodium hydroxide and sodium silicate. The studied parameters included aluminosilicate precursor combination (natural pozzolan/slag proportions of 70/30, 50/50 and 30/70), sodium hydroxide concentration (1, 1.75 and 2.5 M), and activator combination (sodium silicate/sodium hydroxide proportions of 20/80, 25/75 and 30/70). The resulting concrete mixtures were tested for slump, setting time, unit weight, compressive strength, tensile strength, elastic modulus, drying shrinkage, absorption, and chloride penetration. The performance of developed alkali-activated concretes was also compared with that of a reference portland cement concrete. The findings of this study revealed that alkali-activated concretes can be designed to perform similar or superior to portland cement concrete. In view of overall performance, an equal proportion of natural pozzolan and slag (50/50) and a 30/70 combination of sodium silicate and sodium hydroxide proved to be the optimum precursor and activator combinations, respectively. The optimum sodium hydroxide concentration was dependent on the precursor and activator combinations as well as the expected fresh, strength, dimensional stability and transport properties.

Effect of Curing Conditions on Compressive Strength of FA-POFA-based Geopolymer Mortar

This paper presents the effect of curing conditions on geopolymer mortar prepared from the blend of palm oil fuel ash (POFA) and fly ash (FA) as full replacement of cement with a combination of sodium silicate and sodium hydroxide solution used as alkaline liquid. The density and strength of the geopolymer mortars with FA:POFA mass ratios of 70:30 together with sodium silicate solution-to-sodium hydroxide solution by mass is 2.5, are investigated. The concentration of alkaline solution used is 14 Molar. Tests were carried out on 70 × 70 × 70 mm cube geopolymer mortar specimens. The effects of curing conditions including the duration of heat curing, temperature of heat curing and delay time before heat curing on compressive strength of mortar are examined. The results revealed that as the temperature increased the compressive strength of geopolymer mortar are increases, the delay time before heat curing increased, the compressive strength of geopolymer mortar reduced and suitable duration for heat curing is within one to two days.

The Application of PVA Fiber to Improve the Mechanical Properties of Geopolymer Concrete

This paper presents an experimental investigation on the improvement of geopolymer concrete properties through the use of polyvinyl alcohol (PVA) fibers mixed in the fresh concrete. For the purpose of obtaining the optimum mechanical properties, the volume fraction of PVA fibers was varied at 0%; 0.3%; 0.5%; ad 0.8%. All mixtures were cast by mixing fly ash, alkali activator, and aggregates. The activator used in this study was a combination of sodium silicate (Na 2 SiO 3 ) and sodium hydroxide (NaOH). The mechanical properties of geopolymer concrete were obtained from the results of compressive strength, splitting strength, uniaxial tensile strength, elastic modulus, and flexural strength. It is found that the variation of 0.8% PVA fibers resulted in the highest strength for overall test. The utilization of 0.8% PVA fibers also contributed to increasing the direct tensile up to 50%. However, it is noticed that the elastic modulus was more prone to decrease as the fiber content in the mixture increased.

Experimental Investigations on Geo Polymer Concrete based on Class C Fly Ash

Background/Objectives: To address the environmental constraints due to cement production, strength properties of high-calcium fly ash based Geo Polymer Concrete (GPC) has been explored in this paper. Methods/Statistical Analysis: High-calcium (class C) fly ash from Neyveli Thermal Power Plant has been used for the production of GPC. Combination of sodium silicate and sodium hydroxide solution was used as alkaline solution. Alkaline solution to fly ash ratio was varied as 0.35 and 0.45. Concentration of sodium hydroxide solution was maintained as 8M and 12M. Three types of curing such as ambient curing, oven curing and External exposure curing were adopted. Findings: The compressive strength of Geo Polymer Concrete was tested at 7, 14, 28 and 60 days. Flexural strength was determined at 28 days. From the test results it was found that 1) Alkaline solution to fly ash ratio of 0.35 and 12M concentration of NaOH solution produced high strength in Geo Polymer Concrete, 2) Compressive strength of external exposure concrete was more than that of oven and ambient cured concrete. Application/Improvements: Class C fly ash can be used for the production of Geo Polymer Concrete with acceptable strength.