scholarly journals Experimental Developments on Corrosion Resistivity of Low Calcium Fly Ash-Based Geopolymer Concrete

2019 ◽  
Vol 8 (2) ◽  
pp. 5320-5327
Keyword(s):  
Fly Ash ◽  
Portland Cement ◽  
Open Circuit ◽  
Common Source ◽  
Good Prospect ◽  
Geopolymer Concrete ◽  
Test Results ◽  
Carbon Dioxide Gas ◽  
Reinforced Beams ◽  
Main Component

Portland cement production is an main component in making of “concrete, which contributes significant amount of greenhouse gas, because in the process of production of Portland cement also releases about one ton of carbon dioxide gas into the atmosphere. Therefore, the introduction of a novel binder called ‘geopolymer’ by Davidovits promises a good prospect for application in the concrete industry as an alternative binder to Portland cement”. In terms of reducing global warming, the technology based on geo-polymer could reduce the C02 emission to the atmosphere caused by aggregates and cement industries by 80%.Fly ash-based geopolymer concrete “manufactured using fly ash as its source material and does not use Portland cement at all. Not only fly ash, alkaline solution is being utilized to make geopolymer paste which binds the aggregates to form geopolymer concrete. The geopolymer concrete possess excellent mechanical characteristics and better durability characteristics like permeability, resistance against sulphate and acids.” In reinforcement the corrosion is the single most common source of damage and it is usually clear that lack of concrete, inadequate cover to the reinforcement or the available impurities (and sometimes all three) is the prime cause. In the present work, Open Circuit Potential(OCP) method was able to determine the corrosion activity in the reinforced beams. The effect of corrosion on the tensile behavior of reinforcement under different rates of corrosion was compared. The test results reveals that the Geopolymer concrete performs superior to OPC concrete.

scholarly journals Practical Prediction Models of Tensile Strength and Reinforcement-Concrete Bond Strength of Low-Calcium Fly Ash Geopolymer Concrete

Polymers ◽  
2021 ◽  
Vol 13 (6) ◽  
pp. 875
Author(s):  
Chenchen Luan ◽  
Qingyuan Wang ◽  
Fuhua Yang ◽  
Kuanyu Zhang ◽  
Nodir Utashev ◽  
...  
Keyword(s):  
Tensile Strength ◽  
Fly Ash ◽  
Bond Strength ◽  
Prediction Models ◽  
Splitting Tensile Strength ◽  
Geopolymer Concrete ◽  
Structural Factors ◽  
Test Results ◽  
Portland Cement Concrete ◽  
Low Calcium

There have been a few attempts to develop prediction models of splitting tensile strength and reinforcement-concrete bond strength of FAGC (low-calcium fly ash geopolymer concrete), however, no model can be used as a design equation. Therefore, this paper aimed to provide practical prediction models. Using 115 test results for splitting tensile strength and 147 test results for bond strength from experiments and previous literature, considering the effect of size and shape on strength and structural factors on bond strength, this paper developed and verified updated prediction models and the 90% prediction intervals by regression analysis. The models can be used as design equations and applied for estimating the cracking behaviors and calculating the design anchorage length of reinforced FAGC beams. The strength models of PCC (Portland cement concrete) overestimate the splitting tensile strength and reinforcement-concrete bond strength of FAGC, so PCC’s models are not recommended as the design equations.

scholarly journals Study of Proportional Variation of Geopolymer Concrete which Self Compacting Concrete

2019 ◽  
Vol 2 (2) ◽  
pp. 65
Author(s):  
Purwanto P. ◽  
Himawan Indarto
Keyword(s):  
Compressive Strength ◽  
Fly Ash ◽  
Power Plant ◽  
Portland Cement ◽  
Fine Aggregate ◽  
Geopolymer Concrete ◽  
Conventional Concrete ◽  
Basic Characteristics ◽  
Carbon Dioxide Co2 ◽  
Proportional Variation

Portland cement production process which is the conventional concrete constituent materials always has an impact on producing carbon dioxide (CO2) which will damage the environment. To maintain the continuity of development, while maintaining the environment, Portland cement substitution can be made with more environmentally friendly materials, namely fly ash. The substitution of fly ash material in concrete is known as geopolymer concrete. Fly ash is one of the industrial waste materials that can be used as geopolymer material. Fly ash is mineral residue in fine grains produced from coal combustion which is mashed at power plant power plant [15]. Many cement factories have used fly ash as mixture in cement, namely Portland Pozzolan Cement. Because fly ash contains SiO2, Al2O3, P2O3, and Fe2O3 which are quite high, so fly ash is considered capable of replacing cement completely.This study aims to obtain geopolymer concrete which has the best workability so that it is easy to work on (Workable Geopolymer Concrete / Self Compacting Geopolymer Concrete) and obtain the basic characteristics of geopolymer concrete material in the form of good workability and compressive strength. In this study, geopolymer concrete is composed of coarse aggregate, fine aggregate, fly ash type F, and activators in the form of NaOH and Na2SiO3 Be52. In making geopolymer concrete, additional ingredients such as superplastizer are added to increase the workability of geopolymer concrete. From this research, the results of concrete compressive strength above fc' 25 MPa and horizontal slump values reached 60 to 80 centimeters.

scholarly journals Durability Study on High Calcium Fly Ash Based Geopolymer Concrete

2015 ◽  
Vol 2015 ◽  
pp. 1-7 ◽  
Author(s):  
Ganesan Lavanya ◽  
Josephraj Jegan
Keyword(s):  
Fly Ash ◽  
Portland Cement ◽  
Sodium Hydroxide ◽  
Ordinary Portland Cement ◽  
Geopolymer Concrete ◽  
Portland Cement Concrete ◽  
Cement Concrete ◽  
High Calcium ◽  
High Calcium Fly Ash ◽  
Ordinary Portland Cement Concrete

This study presents an investigation into the durability of geopolymer concrete prepared using high calcium fly ash along with alkaline activators when exposed to 2% solution of sulfuric acid and 5% magnesium sulphate for up to 45 days. The durability was also assessed by measuring water absorption and sorptivity. Ordinary Portland cement concrete was also prepared as control concrete. The grades chosen for the investigation were M20, M40, and M60. The alkaline solution used for present study is the combination of sodium silicate and sodium hydroxide solution with the ratio of 2.50. The molarity of sodium hydroxide was fixed as 12. The test specimens were150×150×150 mm cubes,100×200 mm cylinders, and100×50 mm discs cured at ambient temperature. Surface deterioration, density, and strength over a period of 14, 28, and 45 days were observed. The results of geopolymer and ordinary Portland cement concrete were compared and discussed. After 45 days of exposure to the magnesium sulfate solution, the reduction in strength was up to 12% for geopolymer concrete and up to 25% for ordinary Portland cement concrete. After the same period of exposure to the sulphuric acid solution, the compressive strength decrease was up to 20% for geopolymer concrete and up to 28% for ordinary Portland cement concrete.

scholarly journals STRENGTH AND DURABILITY PERFORMANCE OF FLY ASH BASED GEOPOLYMER CONCRETE USING NANO SILICA

2020 ◽  
Vol 4 (2) ◽  
pp. 1-12
Author(s):  
SAMEER VYAS ◽  
Sameer Mohammad ◽  
Shilpa Pal ◽  
Neetu Singh
Keyword(s):  
Fly Ash ◽  
Portland Cement ◽  
Geopolymer Concrete ◽  
Infrastructure Development ◽  
X Ray Diffraction ◽  
Nano Silica ◽  
Adverse Conditions ◽  
Concrete Production ◽  
Class F Fly Ash ◽  
Strength And Durability

With the increasing infrastructure development across the globe, the demand of cement  production increases day by day. However, the production of cement is associated with the emission of large amount of CO2 causing global warming. Scientist and engineers are in search of a green eco friendly alternative  for concrete production. Geopolymers are rapidly emerging as an alternative to Portland cement as the binder of structural concrete. In this respect, the fly ash based geopolymers  shows considerable prospect for application in concrete industry as an alternative binder to the Portland cement. Development of geopolymer concrete using class F fly ash brings many advantages like; enhancing workability, durability, better strength as well as lowering the price. There is not only a reduction in the greenhouse footprint but, also considerable increase in strength and resistivity to adverse conditions. In order to enhance the performance of Geopolymer concrete, the use of  Nano-silica is  found to be suitable and practiced by researchers.  Use of Nano materials as fillers in the concrete matrix has proven effective in increasing mechanical and durability properties. This research is based on performance evaluation of geopolymer concrete using different percentage of Nano-silica.. It was observed that Geopolymer concrete  with Nano-silica ( GPC-N)  shows good compressive strength as well as  durability under aggressive conditions. The materials performance were also investigated using X-Ray Diffraction technique. (XRD). Results show that the presence of nano silica  enhanced the performance of Geopolymer concrete with respect to strength and durability purposes.  

scholarly journals Effect of Elevated Temperature on Alkali Activated Slag and Fly Ash based Geopolymer Concrete

2020 ◽  
Vol 9 (4) ◽  
pp. 1241-1250
Keyword(s):  
Compressive Strength ◽  
Elevated Temperature ◽  
Fly Ash ◽  
Flexural Strength ◽  
Portland Cement ◽  
Ordinary Portland Cement ◽  
Geopolymer Concrete ◽  
Base Materials ◽  
Activated Slag ◽  
Alkali Activated

Activated Slag (AAS) and Fly Ash (FA) based geopolymer concrete a new blended alkali-activated concrete that has been progressively studied over the past years because of its environmental benefits superior engineering properties. Geopolymer has many favorable characteristics in comparison to Ordinary Portland Cement. Many base materials could be utilized to make geopolymer with the convenient concentration of activator solution. In this study, the experimental program composed of two phases; phase on divided into four groups; Group one deliberated the effect of sodium hydroxide molarity and different curing condition on compressive strength. Group two studied the effect of alkali activated solution (NaOH and Na2SiO3) content on compressive strength and workability. The effect of sand replacement with slag on compressive strength and workability was explained in group three. Group four studied the effect of slag replacement with several base materials Fly Ash (FA), Ordinary Portland Cement (OPC), pulverized Red Brick (PRB), and Meta Kaolin (MK). Phase two contains three mixtures from phase one which had the highest compressive strength. For each mixture, the fresh concrete test was air content. In addition the hardened concrete tests were the compressive strength at 3, 7, 28, 90, 180, and 365 days, the flexural strength at 28, 90, and 365 days, and the young's modulus at 28, 90, and 365 days. Moreover; the three mixtures were exposed to elevated temperature at 100oC, 300oC, and 600oC to study the effect of elevated temperature on compressive and flexural strength.

Drying Shrinkage of Fly Ash-Based Self-Compacting Geopolymer Concrete

2014 ◽  
Vol 567 ◽  
pp. 362-368 ◽  
Author(s):  
M.F. Nuruddin ◽  
F.A. Memon ◽  
N. Shafiq ◽  
S. Demie
Keyword(s):  
Fly Ash ◽  
Relative Humidity ◽  
Drying Shrinkage ◽  
Time Dependent ◽  
Geopolymer Concrete ◽  
Test Results ◽  
Shrinkage Behaviour ◽  
One Year ◽  
Curing Regime

–The drying shrinkage behaviour of fly-ash-based self-compacting geopolymer concrete (SCGC) was studied for a period of one year. Two SCGC and One OPC-based conventional mixture were used in the present investigation. Drying shrinkage test commenced on the 7th day after casting the test specimens. Once the appropriate curing regime was completed, the specimens from each mix were placed in the laboratory room where the temperature was maintained at 23°C, however, the relative humidity of the room varied between 56 and 64 percent. Strain readings taken at specific intervals were analyzed to determine the time-dependent deformations of each mixture. Test results indicated that the heat-cured fly ash-based SCGC experienced very low drying shrinkage than that of water-cured OPC based concrete. After one year of exposure, in comparison to 466 με, the value experienced by OPC concrete, the drying shrinkage strains of SCGC mix specimens ranged between 141 and 159 με. These values were about 65-70% lower than that of OPC concrete. It is anticipated that the findings of this investigation would help in predicting the behaviour of SCGC. Keywords-Fly ash, Geopolymer concrete, Self-compacting Geopolymer concrete, Drying shrinkage

scholarly journals Durability of Fly Ash Based Geopolymer Concrete against Chloride and Sulphuric Acid Attack

2020 ◽  
Vol 5 (6) ◽  
pp. 1507-1510
Author(s):  
Kartika Ilma Pratiw ◽  
Saloma .
Keyword(s):  
Compressive Strength ◽  
Fly Ash ◽  
Portland Cement ◽  
Sulphuric Acid ◽  
Test Object ◽  
Sulfate Solution ◽  
Geopolymer Concrete ◽  
Acid Attack

The aim of this study was to replace Portland cement with fly ash-based geopolymer as precursors, to serve as a binder after reacting with NaOH and Na2SiO3 activators. The test object existed in the form of a cube of size 50 x 50 x 50 mm. The mortar was treated for 28 days and then immersed in a sulfate solution at similar interval using the wet-dry cycle and non-cycle methods. The compressive strength of the geopolymer mortar was estimated as 45.90 MPa before immersion. Therefore, 35.79 MPa, 41.09 MPa, as well as 37.85 MPa were reported after submersion in the respective solutions of 5% H2SO4, Na2SO4, and NaCl, using wet-dry cycle. Based on the non-cycle approach, the resulting strength was 37.36 MPa, 43.05 MPa and 39.52 MPa correspondingly.

Fracture Parameters of Fly Ash and GGBS Based Geopolymer Concrete

2015 ◽  
Vol 764-765 ◽  
pp. 1090-1094
Author(s):  
Tippabhotla D. Gunneswara Rao ◽  
P. Alfrite ◽  
G. Mallikarjuna Rao ◽  
Mudimby Andal
Keyword(s):  
Fly Ash ◽  
Construction Material ◽  
Bending Test ◽  
Geopolymer Concrete ◽  
Test Results ◽  
Conventional Concrete ◽  
Three Point Bending ◽  
Beam Depth ◽  
New Construction ◽  
Source Materials

Geopolymer concrete (GPC) is a new construction material in which cement is totally replaced by calcined source materials fly ash and GGBS. Geopolymer utilization reduces or eliminates the use of cement whose production produces a lot of carbon dioxide. Usually fly ash as a source material for the geopolymer. The behavior of GPC has to be studied in detail to check its suitability in construction industry. In the present study, the fracture behavior of geopolymer concrete is investigated and compared. Three-point bending test on notched prisms with a/d (notch depth/beam depth) ratios 0.1, 0.15, 0.2 are considered. The values of Critical load, fracture toughness, fracture energy and ductility are presented. The test results of total of 27prisms, 6cubes, 18 cylinders with M30 grade geopolymer concrete and conventional concrete (OPC) of same grade are presented in this paper. The test results indicated that the characteristic length of GPC is about 25% more than that of conventional concrete.

scholarly journals Behavior of Geopolymer Concrete Confined by Circular Hoops

2018 ◽  
Vol 159 ◽  
pp. 01018
Author(s):  
Muslikh ◽  
N. K. Anggraini ◽  
D. Hardjito ◽  
Antonius
Keyword(s):  
Portland Cement ◽  
Concrete Cover ◽  
Geopolymer Concrete ◽  
Test Results ◽  
Portland Cement Concrete ◽  
Reinforcing Bars ◽  
Cement Concrete ◽  
Conventional Concrete ◽  
K Value ◽  
Steel Bar

This paper discusses the behavior of geopolymer concrete subjected to passive confinement under compression loads. The confinement is induced by the use of lateral hoops, assembled from un-deformed reinforcing bars. To compare the effect of confinement, identical specimens were produced using conventional concrete with the similar concrete compressive strength. The cylinder specimens were 100 mm in diameter and 200 mm in height, and the hoops were placed on the outer most fibers of the cylinders, perpendicular to the line of loading, with no concrete cover. The parameters analyzed in this study were the steel bar to concrete volumetric ratio, the hoop spacings and the steel yield stresses. The experimental results show that unconfined geopolymer concrete were very brittle compared to the unconfined Portland cement concrete. The strength enhancement (K value) of the confined geopolymer concrete was higher than K value of Portland cement concrete. Confined geopolymer concrete also has better deformability compared to the confined Portland cement concrete. The average confinement effectiveness of geopolymer concrete also has a higher value than that commonly used in the Indonesian Concrete Standard (SNI), that is 4.1. The results were further assessed to the most recent experimental test results conducted in this area.

Strength Enhancement of Geopolymer-Based Concretes by Mixed Alkaline Activators

2010 ◽  
Vol 658 ◽  
pp. 292-295 ◽  
Author(s):  
Z. X. Yang ◽  
Kyu Hong Hwang ◽  
M.C. Kim ◽  
J.Y. Yang ◽  
S.K. Lim
Keyword(s):  
Fly Ash ◽  
Portland Cement ◽  
Co2 Emission ◽  
Water Glass ◽  
Bending Strength ◽  
Construction Material ◽  
Recycled Concrete ◽  
Geopolymer Concrete ◽  
New Material ◽  
Main Components

As a relatively new material, geopolymer concrete offers benefits as a construction material for sustainable development. It utilizes waste materials such as recycled concrete sludge, fly ash,etc. To reduce CO2 emission, geopolymer concrete is expected to replace the traditional Portland cement based concrete. It’s reported that geopolymer based concrete releases only 1/6 CO2 compared to those of based Ordinary Portland Cement (OPC). In this study, to obtain a new type of construction material with lower CO2 emission and energy consumption, fly ash, waste concrete sludge and metakaolin were used as the main components. Solution of NaOH/KOH and water glass were applied as alkaline activator. The amount of water glass and the ratio of alkaline/water glass were varied to reach an optimal value. Also, silica fume was added as a bonding matrix to enhance the strength, and the specimens were cured in air and oven, then their mechanical properties such as compressive strength and bending strength were measured and their microstructures were investigated.

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