scholarly journals Durability of geopolymer concrete exposed to acidic environment – a review

2021 ◽  
Vol 10 (1) ◽  
Author(s):  
Lathi Karthi ◽  
Peter Cibi
Keyword(s):  
Sodium Hydroxide ◽  
Silica Fume ◽  
Sodium Silicate ◽  
Structural Integrity ◽  
Water Soluble ◽  
Superior Performance ◽  
Alkaline Solutions ◽  
Geopolymer Concrete ◽  
Chemical Action ◽  
Acidic Solutions

Acids attack concrete by dissolving both hydrated and unhydrated cement compounds as well as calcareous aggregates and the subsequent chemical reaction forms water soluble calcium compounds which are then leached away. The aggressiveness of the reaction depends on the pH of the acidic medium and the types of salts formed. Concrete pipes made of ordinary portland cement (OPC) carrying sewage water have always the presence acidic solutions in it. They deteriorate and service life of the pipes is affected along with the increased maintenance costs and that process cause environmental impacts.  Geopolymer binders are novel binders that relies on alumina silicate rather calcium silicate bonds for structural integrity so they have been reported as being acid resistant. Those could be produced by the chemical action between alumino-silicate material such as fly ash(FA), granulated blast furnaces slag (GGBS), metakaoline or silica fume with alkaline solutions like sodium silicate or sodium hydroxide. Geopolymers show superior performance in terms of corrosion and fire resistance due to the absence of water and calcium in their structure.Utilisation of waste materials like FA and GGBS makes geopolymer    concrete (GPC) an environment friendly construction material. This review paper looks in to the effect of various acids such as sulphuric acid, acetic acid, nitric acids on durability properties of OPC specimens, GPC specimens and GPC composite specimens when immersed in acidic solutions for certain period. The performance of geopolymer is analysed by the visual inspection and studying the parameters like weight loss, loss in compressive strength and maximum depth of penetration. Keywords- Geopolymer concrete, Sodium hydroxide, sodium silicate, metakaoline, silica fume, alumina silicate

scholarly journals Artificial Intelligence Approaches for Prediction of Compressive Strength of Geopolymer Concrete

Materials ◽  
2019 ◽  
Vol 12 (6) ◽  
pp. 983 ◽  
Author(s):  
Dong Dao ◽  
Hai-Bang Ly ◽  
Son Trinh ◽  
Tien-Thinh Le ◽  
Binh Pham
Keyword(s):  
Artificial Intelligence ◽  
Compressive Strength ◽  
Fly Ash ◽  
Sodium Hydroxide ◽  
Sodium Silicate ◽  
Steel Slag ◽  
Sodium Silicate Solution ◽  
Silicate Solution ◽  
Partial Replacement ◽  
Geopolymer Concrete

Geopolymer concrete (GPC) has been used as a partial replacement of Portland cement concrete (PCC) in various construction applications. In this paper, two artificial intelligence approaches, namely adaptive neuro fuzzy inference (ANFIS) and artificial neural network (ANN), were used to predict the compressive strength of GPC, where coarse and fine waste steel slag were used as aggregates. The prepared mixtures contained fly ash, sodium hydroxide in solid state, sodium silicate solution, coarse and fine steel slag aggregates as well as water, in which four variables (fly ash, sodium hydroxide, sodium silicate solution, and water) were used as input parameters for modeling. A total number of 210 samples were prepared with target-specified compressive strength at standard age of 28 days of 25, 35, and 45 MPa. Such values were obtained and used as targets for the two AI prediction tools. Evaluation of the model’s performance was achieved via criteria such as mean absolute error (MAE), root mean square error (RMSE), and coefficient of determination (R2). The results showed that both ANN and ANFIS models have strong potential for predicting the compressive strength of GPC but ANFIS (MAE = 1.655 MPa, RMSE = 2.265 MPa, and R2 = 0.879) is better than ANN (MAE = 1.989 MPa, RMSE = 2.423 MPa, and R2 = 0.851). Sensitivity analysis was then carried out, and it was found that reducing one input parameter could only make a small change to the prediction performance.

scholarly journals Mechanical Properties of Geopolymer Concrete Made With Partial Replacement of Coarse Aggregate by Recycled Aggregate

2019 ◽  
Vol 9 (1) ◽  
pp. 2301-2304 ◽  
Keyword(s):  
Mechanical Properties ◽  
Sodium Hydroxide ◽  
Sodium Silicate ◽  
Coarse Aggregate ◽  
Recycled Aggregate ◽  
Recycled Aggregates ◽  
Partial Replacement ◽  
Geopolymer Concrete ◽  
Recycled Coarse Aggregate ◽  
Coarse Aggregates

Construction is the one the fast growing field in the worldwide. There are many environmental issues connected with the manufacture of OPC, at the same time availability of natural coarse aggregate is getting reduced. Geopolymer binder and recycled aggregates are promising alternatives for OPC and natural coarse aggregates. It is produced by the chemical action of inorganic molecules and made up of Fly Ash, GGBS, fine aggregate, coarse aggregate and an alkaline solution of sodium hydroxide and sodium silicate. 10 M sodium hydroxide and sodium silicate alkali activators are used to synthesis the geopolymer in this study. Recycled aggregates are obtained from the construction demolished waste. The main focus of this work is to find out the mechanical properties of geopolymer concrete of grade G40 when natural coarse aggregate(NCA) is replaced by recycled coarse aggregate in various proportions such as 0%, 10%, 20%, 30%,40% and 50% and also to compare the results of geopolymer concrete made with recycled coarse aggregates(RAGPC) with geopolymer concrete of natural coarse aggregate(GPC) and controlled concrete manufactured with recycled aggregates(RAC) and controlled concrete of natural coarse aggregates(CC) of respective grade. It has been observed that the mechanical properties are enhanced in geopolymer concrete, both in natural coarse aggregate and recycled coarse aggregate up to 30% replacement when it is compared with the same grade of controlled concrete.

scholarly journals A study on the strength development of geopolymer concrete using fly ash

2017 ◽  
Vol 6 (4) ◽  
pp. 163 ◽  
Author(s):  
Ramesh Babu Chokkalingam ◽  
Ganesan N
Keyword(s):  
Fly Ash ◽  
Sodium Hydroxide ◽  
Sodium Silicate ◽  
Sodium Hydroxide Solution ◽  
Fine Sand ◽  
Strength Development ◽  
Alkali Activation ◽  
Geopolymer Concrete ◽  
Water Contaminants ◽  
Significant Difference

Cement consumption is increasing day by day due to the tremendous development in the infrastructure facilities. The production of one ton of cement emits approximately one ton of carbon dioxide to the atmosphere. In order to reduce the use of cement a new-generation concrete has been developed such as geopolymer concrete (GPC).Geopolymer Geopolymer is a new material which has the potential to replace ordinary Portland cement. It is an inorganic material synthesized by alkali activation of amorphous aluminosilicates at ambient or slightly increased temperatures having an amorphous to semi-crystalline polymeric structure. In this study, low calcium flyash from Tuticorin was used to produce geopolymer concrete. The geopolymer was synthesized with sodium silicate and sodium hydroxide solutions. The sodium hydroxide pellets was dissolved in the distilled water to make free from mixing water contaminants. The ratio of sodium silicate and sodium hydroxide ratio was kept as 2.5. The concentration of sodium hydroxide solution is 12 Molarity (12M). Other materials used are locally available coarse aggregate and fine sand in surface dry condition. A polycarboxlate HRWRA La Hypercrete S25was used. Cubes of size 100mm were cast for six mix proportions of 450kg/m3 flyash+0.35W/B, 500 kg/m3 flyash+0.35W/B, 550kg/m3 flyash+0.35W/B, 450kg/m3 flyash+.0.40 W/B, 500kg/m3 fly ash+0.40W/B and 550kg/m3 flyash+0.40W/B. The specimens after casting in moulds were kept in oven at 60°C for 6 hours and left to air dry at room temperature and tested at 7 and 28 days. The test results revealed the compressive strength of 30 Mpa was achieved. There was not much significant difference in strength development at 28 days between the mixes due to the increase of flyash content. The microstructural images at 28 days revealed that there was not much difference in the microstructure due to the variation in flyash content from 450 kg/m3 to 550 kg/m3.

Mix Design and Compressive Strength of Geopolymer Concrete Containing Blended Ash from Agro-Industrial Wastes

2011 ◽  
Vol 339 ◽  
pp. 452-457 ◽  
Author(s):  
Mohd Azreen Mohd Ariffin ◽  
Mohd Warid Hussin ◽  
Muhammad Aamer Rafique Bhutta
Keyword(s):  
Compressive Strength ◽  
Sodium Hydroxide ◽  
Sodium Silicate ◽  
Alkaline Solution ◽  
Sodium Hydroxide Solution ◽  
Mix Design ◽  
Geopolymer Concrete ◽  
Palm Oil Fuel Ash ◽  
Hydroxide Solution ◽  
Fuel Ash

Geopolymer concrete is a type of amorphous alumino-silicate cementitious material. Geopolymer can be polymerized by polycondensation reaction of geopolymeric precursor and alkali polysilicates. Compared to conventional cement concrete, the production of geopolymer concrete has a relative higher strength, excellent volume stability and better durability. This paper presents the mix design and compressive strength of geopolymer concrete manufactured from the blend of palm oil fuel ash (POFA) and pulverized fuel ash (PFA) 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 concrete with various PFA: POFA ratios of 0:100, 30:70, 50:50 and 70:30 together with sodium silicate to sodium hydroxide solution by mass at 2.5 and 1.0, are investigated. The concentrations of alkaline solution used are 14 Molar and 8 Molar. Tests were carried out on 100x100x100 mm cube geopolymer concrete specimens. Specimens were cured at room temperature and heat curing at 60°C and 90°C for 24 hours, respectively. The effects of mass ratios of PFA: POFA, the alkaline solution to PFA: POFA, ratio and concentration of alkaline solution on fresh and hardened properties of concrete are examined. The results revealed that as PFA: POFA mass ratio increased the workability and compressive strength of geopolymer concrete are increased, the ratio and concentration of alkaline solution increased, the compressive strength of geopolymer concrete increases with regards to curing condition.

scholarly journals Effect of sodium hydroxide concentration on the compressive strength of geopolymer mortar using fly ash PLTU Tanjungjati B Jepara

2022 ◽  
Vol 955 (1) ◽  
pp. 012010
Author(s):  
A Kustirini ◽  
Antonius ◽  
P Setiyawan
Keyword(s):  
Compressive Strength ◽  
Fly Ash ◽  
Sodium Hydroxide ◽  
Sodium Silicate ◽  
Coal Industry ◽  
Waste Materials ◽  
Geopolymer Concrete ◽  
Sodium Hydroxide Concentration ◽  
Alkaline Activator ◽  
Maximum Compressive Strength

Abstract Geopolymer concrete is concrete that uses environmentally friendly materials, using fly ash from waste materials from the coal industry as a substitute for cement. To produce geopolymer concrete, an alkaline activator is required, with a mixture of Sodium Hydroxide and Sodium Silicate. This research is an experimental study to determine the effect of variations in the concentration of sodium hydroxide (NaOH) 8 Mol, 10 Mol, 12 Mol, and 14 Mol on the compressive strength of geopolymer concrete. Mortar Geopolymer uses a mixture of 1: 3 for the ratio of fly ash and sand, 2.5: 0.45 for the ratio of sodium silicate and sodium hydroxide as an alkaline solution. The specimens used a cube mold having dimension 5 cm x 5 cm x 5 cm, then tested at 7 days and 28 days. The test resulted that concentration of NaOH 12 Mol obtained the maximum compressive strength of geopolymer concrete, that is 38.54 MPa. At concentrations of 12 Mol NaOH and exceeding 12M, the compressive strength of geopolymer concrete decreased.

Study of Geopolymeric Binders of Fly Ash/Metakaolin Mixtures Cured at Room Temperature

2014 ◽  
Vol 600 ◽  
pp. 338-344 ◽  
Author(s):  
Alexandre Silva de Vargas ◽  
Ruby M. de Gutierrez ◽  
João Castro-Gomes
Keyword(s):  
Compressive Strength ◽  
Fly Ash ◽  
Sodium Hydroxide ◽  
Sodium Silicate ◽  
Room Temperature ◽  
Alkaline Solutions ◽  
X Ray Diffraction ◽  
Precursor Material ◽  
Electron Microscopy Analysis ◽  
Microscopy Analysis

Geopolymerization is a chemical process in which aluminosilicate materials are precursors to obtain binders that have a low environmental impact. Fly ash has been used as a precursor for the development of these binders. However, thermal curing is needed to accelerate the polycondensation of aluminosilicate, which limits the application of this new binder in the construction industry. Thus, the objective of this study was to evaluate the feasibility to obtain such binders with good mechanical properties when cured at room temperature. The precursor material consisted of different mixtures of fly ash and metakaolin that were activated using combined sodium hydroxide and sodium silicate alkaline solutions. The effect on the compressive strength of different proportions of the alkaline solutions was studied. Compressive strengths of about 40 MPa were achieved at 91 days for the samples containing 70% fly ash and 30% metakaolin, activated using an alkaline solution of 50% sodium hydroxide and 50% sodium silicate. X-ray diffraction analysis showed the formation of natrite in geopolymeric samples, as well as the presence of crystalline compounds, such as quartz, mullite and hematite, in fly ash and metakaoline. Scanning electron microscopy analysis showed that in geopolymeric mixtures with higher compressive strength dissolution of fly ash and metakaolin particles occurred almost completely and that aluminosilicate dense gel has been formed extensively.

scholarly journals Compressive Strength of Geopolymer Concrete Composites: Modeling and Comprehensive Systematic Review

2021 ◽  
Author(s):  
Hemn Unis Ahmed ◽  
Azad A. Mohammed ◽  
Ahmed S. Mohammed
Keyword(s):  
Systematic Review ◽  
Compressive Strength ◽  
Fly Ash ◽  
Sodium Hydroxide ◽  
Sodium Silicate ◽  
Alkaline Solution ◽  
Construction Material ◽  
Assessment Tools ◽  
Curing Temperature ◽  
Geopolymer Concrete

Abstract The growing concern about global climate change and its adverse impacts on societies is putting severe pressure on the construction industry as one of the largest producers of greenhouse gases. Given the environmental issues associated with cement production, geopolymer concrete has emerged as a sustainable construction material. Geopolymer concrete is cementless concrete that uses industrial or agro by-product ashes as the main binder instead of ordinary Portland cement; this leads to being an eco-efficient and environmentally friendly construction material. Compressive strength is one of the most important mechanical property for all types of concrete composites including geopolymer concrete, and it is affected by several parameters like an alkaline solution to binder ratio (l/b), fly ash (FA) content, SiO2/Al2O3 (Si/Al) of the FA, fine aggregate (F) and coarse aggregate (C) content, sodium hydroxide (SH) and sodium silicate (SS) content, ratio of sodium silicate to sodium hydroxide (SS/SH), molarity (M), curing temperature (T), curing duration (CD) inside the oven and specimen ages (A). In this regard, a comprehensive systematic review was carried out to show the effect of these different parameters on the compressive strength of the fly ash-based geopolymer concrete (FA-GPC). In addition, multi-scale models such as Artificial Neural Network (ANN), M5P-tree (M5P), Linear Regression (LR), and Multi-logistic Regression (MLR) models were developed to predict the compressive strength of FA-GPC composites. For the first time, in the modeling process, twelve effective parameters including l/b, FA, Si/Al, F, C, SH, SS, SS/SH, M, T, CD, and A were considered the modeling input parameters. Then, the efficiency of the developed models was assessed by various statistical assessment tools like Root Mean Squared Error (RMSE), Mean Absolute Error (MAE), Scatter Index (SI), OBJ value, and the Coefficient of determination (R2). Results show that the curing temperature, sodium silicate content, and ratio of the alkaline solution to the binder content are the most significant independent parameters that influence on the compressive strength of the FA-GPC, and the ANN model has better performance for predicting the compressive strength of FA-GPC in compared to the other developed models.

Parametric study of flyash based geopolymer concrete

2018 ◽  
Vol 7 (2.31) ◽  
pp. 196
Author(s):  
Sourav Kumar Das
Keyword(s):  
Fly Ash ◽  
Ambient Temperature ◽  
Sodium Hydroxide ◽  
Sodium Silicate ◽  
Power Plants ◽  
Base Material ◽  
Alkali Solution ◽  
Curing Temperature ◽  
Geopolymer Concrete ◽  
In Situ Conditions

With the growth of civilization the demand of cement concrete is increasing rapidly which increase the production of cement and abolishing the natural source of limestone. Also contributing a lot to the global warming by generating huge amount of carbon-di-oxide. Therefore the present study concentrate on the production of concrete using the geopolymerization technology which replaces cement fully by fly ash, a waste material and alkali solution. India is presently producing approximately 190 million tons of fly ash every year from moreover 145 power plants. Present research is focused on the different parameters which are curing temperature, ratio of sodium silicate to sodium hydroxide, molarity of sodium hydroxide, curing type and the results have been studied and discussed. Previous works emphasis that only the use of fly ash as the base material confine the concrete to be heat cured which limits the applicability of geopolymer concrete to cast-in-situ conditions. So some proportion of flyash is replaced by ground granulated blast furnace slag (GGBFS) and the effect on compressive and tensile strength is observed. Ambient temperature dry curing was done without any water when some proportion of fly ash was replaced by GGBFS. The ratio of sodium silicate solution to sodium hydroxide solution by mass was kept fixed at 2.5 and the concentration of sodium hydroxide was kept 14M. The ratio of flyash to alkali solution was kept 0.35 & 0.40. Replacing 40% of Flyash by GGBFS and keeping the concentration of NaOH as 14M at ambient temperature, the compressive strength encountered was 40 MPa. 

EFFECT OF CURING TEMPERATURE ON THE PROPERTIES OF 100% CLAY-BASED GEOPOLYMER CONCRETE

2017 ◽  
Vol 4 (1) ◽  
Author(s):  
Muhammad Mukhlesur Rahman ◽  
David w. Law ◽  
Indubhushan Patnaikuni
Keyword(s):  
Structural Integrity ◽  
Curing Temperature ◽  
Superior Performance ◽  
Clay Material ◽  
Geopolymer Concrete ◽  
X Ray Diffraction ◽  
X Ray ◽  
Binder Material ◽  
Alkali Activated Binders ◽  
Alkali Activated

Substantial researches have already been carried out on alkali-activated binders for the production of geopolymer concrete but studies on clay-based geopolymer concrete is still insufficient. The aim of this paper is to identify the effect of curing temperature on the properties of 100% clay-based geopolymer concrete. Clay pre-treated at 80°C and 120°C for 24 hours were selected as the source binder material. Four Activator Modulus (AM); 1.0, 1.25, 1.5 and 1.75 for each of two Sodium Oxide (Na2O) dosages of 10% and 15% were selected as the activator material for this investigation. X-ray diffraction (XRF) was applied to characterize the clay material. Specimens were cured at 80°C and 120°C for 24 hours. Specimens were tested under compression at seven, 14, 28 and 40 days. Specimens cured at 80°C took a longer duration (>28 days) to achieve structural integrity while the specimens cured at 120°C achieved structural integrity within seven days. Compressive strength of specimens prepared with AM of 1.0 for both of the Na2O dosage of 10% and 15% exhibited superior performance to other AMs investigated.

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