scholarly journals Resistance of fly ash geopolymer binders to organic acids

2020 ◽  
Vol 53 (5) ◽  
Author(s):  
Timothy A. Aiken ◽  
Jacek Kwasny ◽  
Wei Sha
Keyword(s):  
Fly Ash ◽  
Portland Cement ◽  
Organic Acids ◽  
Organic Acid ◽  
Construction Materials ◽  
Acid Resistance ◽  
Calcium Content ◽  
Reaction Products ◽  
Acid Attack ◽  
New Class

Abstract Fly ash geopolymers are a relatively new class of binders with the potential to reduce the CO2 emissions associated with Portland cement based construction materials. This paper reports on the organic acid resistance of fly ash geopolymers following exposure to acetic and lactic acid. Organic acids are prevalent in many circumstances including agriculture, production processes and waste management. These findings demonstrate that the surface of fly ash geopolymers had superior resistance to organic acids when compared with traditional Portland cement, evidenced by smaller mass losses. This was attributed to the formation of reaction products which were less susceptible to acid attack than those formed in Portland cement systems due to their lower calcium content. However, despite the surface of fly ash geopolymers appearing less deteriorated due to organic acid attack, they were found to have a higher porosity than their Portland cement counterparts making them more susceptible to acid ingress.

scholarly journals Evaluation of the Ecotoxicological Potential of Fly Ash and Recycled Concrete Aggregates Use in Concrete

2020 ◽  
Vol 10 (1) ◽  
pp. 351 ◽  
Author(s):  
Patrícia Rodrigues ◽  
José D. Silvestre ◽  
Inês Flores-Colen ◽  
Cristina A. Viegas ◽  
Hawreen H. Ahmed ◽  
...  
Keyword(s):  
Fly Ash ◽  
Portland Cement ◽  
Daphnia Magna ◽  
Raw Materials ◽  
Construction Materials ◽  
Recycled Concrete ◽  
Experimental Program ◽  
Concrete Aggregates ◽  
Recycled Concrete Aggregates ◽  
Natural Aggregates

This study applies a methodology to evaluate the ecotoxicological potential of raw materials and cement-based construction materials. In this study, natural aggregates and Portland cement were replaced with non-conventional recycled concrete aggregates (RA) and fly ash (FA), respectively, in the production of two concrete products alternative to conventional concrete (used as reference). The experimental program involved assessing both the chemical properties (non-metallic and metallic parameters) and ecotoxicity data (battery of tests with the luminescent bacterium Vibrio fischeri, the freshwater crustacean Daphnia magna, and the yeast Saccharomyces cerevisiae) of eluates obtained from leaching tests of RA, FA, and the three concrete mixes. Even though the results indicated that RA and FA have the ability to release some chemicals into the water and induce its alkalinisation, the respective eluate samples presented no or low levels of potential ecotoxicity. However, eluates from concrete mixes produced with a replacement ratio of Portland cement with 60% of FA and 100% of natural aggregates and produced with 60% of FA and 100% of RA were classified as clearly ecotoxic mainly towards Daphnia magna mobility. Therefore, raw materials with weak evidences of ecotoxicity could lead to the production of concrete products with high ecotoxicological potential. Overall, the results obtained highlight the importance of integrating data from the chemical and ecotoxicological characterization of materials’ eluate samples aiming to assess the possible environmental risk of the construction materials, namely of incorporating non-conventional raw materials in concrete, and contributing to achieve construction sustainability.

Characterisation of Fly Ash Hydration Reactions from Microstructure

1985 ◽  
Vol 65 ◽  
Author(s):  
R. H. Mills
Keyword(s):  
Fly Ash ◽  
Portland Cement ◽  
Distilled Water ◽  
Reaction Products ◽  
Early Strength

ABSTRACTReaction products of high lime fly ash (FA), mixed with distilled water and hydrated in contact with Portland cement (PC), and in hardened PC/FA pastes of various mix proportions, were examined by SEM and EDX. Structures contributing to early strength originated mainly through solution depositions of ettringite, and portlandite. Some evidence of ettringite instability suggested gypsum deficiency in PC/FA mixtures.

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.

scholarly journals Utilization of Brine Sludge in Nonstructural Building Components: A Sustainable Approach

2014 ◽  
Vol 2014 ◽  
pp. 1-7 ◽  
Author(s):  
Mridul Garg ◽  
Aakanksha Pundir
Keyword(s):  
Fly Ash ◽  
Construction Materials ◽  
Alternative Solution ◽  
Engineering Properties ◽  
Reaction Products ◽  
The Matrix ◽  
Building Components ◽  
Waste Particles ◽  
Brine Sludge ◽  
Nonstructural Building Components

The characterization and influence of brine sludge on the properties of cement-fly ash-sludge binders are presented. The reaction products formed during the hydration of binder provide an interlocking framework to physically encapsulate the waste particles and are responsible for the development of strength. The utilization of brine sludge in making paver blocks and bricks and the effect of sludge concentration on the engineering properties of these products are also discussed. These results clearly exhibited that brine sludge up to 35 and 25% can safely be utilized for making paver blocks and bricks, respectively. The leachability studies confirm that the metals ions and impurities in the sludge are substantially fixed in the matrix and do not readily leach from there. The utilization of brine sludge in construction materials could serve as an alternative solution to disposal and reduce pollution.

Comparison Between Ordinary Portland Cement and Geopolymer Concretes Against Sulphuric Acid Attack

2019 ◽  
pp. 126-134
Keyword(s):  
Acid Solution ◽  
Portland Cement ◽  
Sulphuric Acid ◽  
Ordinary Portland Cement ◽  
Acid Resistance ◽  
High Strength ◽  
Testing Procedure ◽  
Sulphuric Acid Solution ◽  
Acid Attack ◽  
Durability Test

This chapter covers a comparison between ordinary Portland cement (OPC) and geopolymer concretes against sulphuric acid attack. An intensive introduction to the topic is given. Lack of study about high strength of self-compacting geopolymer concrete (SCGC) against sulphuric acid attack is also one of the problems. In this research, slag and ceramics were used as replacement of OPC. The aim was to study the durability of SCGC against sulphuric acid attack which mainly incorporated ground granulated blast-furnace slag (GGBFS) and ceramics waste as a binder. Methodology of the experimental program, with emphasis on preparation of materials and mix design is described. Testing procedure of GSCC is given. Durability test for sulphuric acid resistance and cost analysis are briefly explained. In conclusion, the sulphuric acid solution had no effect on the strength of concrete and the weight after being immersed in sulphuric acid solution for 28 and 42 days.

scholarly journals Reducing the Waiting-On-Cement Time of Geopolymer Well Cement using Calcium Chloride (CaCl2) as the Accelerator: Analysis of the Compressive Strength and Acoustic Impedance for Well Logging

2021 ◽  
Vol 13 (11) ◽  
pp. 6128
Author(s):  
Nurul Nazmin Zulkarnain ◽  
Syed Ahmad Farhan ◽  
Yon Azwa Sazali ◽  
Nasir Shafiq ◽  
Siti Humairah Abd Rahman ◽  
...  
Keyword(s):  
Compressive Strength ◽  
Fly Ash ◽  
Calcium Chloride ◽  
Acoustic Impedance ◽  
Calcium Content ◽  
Cost Effective ◽  
Acid Attack ◽  
Curing Conditions ◽  
Class F Fly Ash ◽  
Well Cement

Geopolymer cement (GPC) is an aluminosilicate-based binder that is cost-effective and eco-friendly, with high compressive strength and resistance to acid attack. It can prevent degradation when exposed to carbon dioxide by virtue of the low calcium content of the aluminosilicate source. The effect of the concentration of calcium chloride (CaCl2) as the accelerator on the compressive strength and acoustic impedance of GPC for well cement, while exposed to high pressure and high temperatures, is presented. Fly ash from the Tanjung Bin power plant, which is categorized as Class F fly ash according to ASTM C618-19, was selected as the aluminosilicate source for the GPC samples. Sodium hydroxide and sodium silicate were employed to activate the geopolymerization reaction of the aluminosilicate. Five samples with a density of 15 ppg were prepared with concentrations of CaCl2 that varied from 1% to 4% by weight of cement. Findings revealed that the addition of 1% CaCl2 is the optimum concentration for the curing conditions of 100 °C and 3000 psi for 48 h, which resulted in the highest compressive strength of the product. Results also indicate that GPC samples that contain CaCl2 have a smaller range of acoustic impedance compared to that of ordinary Portland cement.

scholarly journals Characterization and acid resistance test of one-part geopolymer from fly ash and water treatment sludge

2018 ◽  
Vol 156 ◽  
pp. 05003
Author(s):  
Aileen Orbecido ◽  
Vuong Ho ◽  
Hirofumi Hinode ◽  
Winarto Kurniawan ◽  
Long Nguyen ◽  
...  
Keyword(s):  
Fly Ash ◽  
Water Treatment ◽  
Large Scale ◽  
Raw Materials ◽  
Coal Fly Ash ◽  
Acid Resistance ◽  
Resistance Test ◽  
Water Treatment Sludge ◽  
Acid Attack ◽  
Noticeable Effect

Development of geopolymers from wastes or by-products introduces a sustainable approach to replace ordinary Portland cement (OPC)-based concrete with an eco-material of lower green-house gases emissions. However, safety concerns related to the conventional two-part geopolymer has limited large-scale applications of the product. In this context, a novel one-part geopolymer from coal fly ash and water treatment sludge has been presented. The transformation of raw materials to geopolymer was observed by FTIR, SEM and XRD analyses. Acid resistance test has proved that the new binder had great durability against sulphuric acid attack. After 28 days immersion in 5% H2SO4 solution, weight of all samples was hardly changed. Compressive strength, on the other hand, has not decreased but significantly increased as curing time increased. The properties were also compared to those of control samples cured in water. It was demonstrated that strong acid immersion did not create any noticeable effect on the weight and strength of one-part geopolymer system developed from coal fly ash and water treatment sludge.

Durability of Geopolymer Concretes upon Seawater Exposure

2010 ◽  
Vol 69 ◽  
pp. 92-96 ◽  
Author(s):  
Sotya Astutiningsih ◽  
Dwi Marta Nurjaya ◽  
Henki Wibowo Ashadi ◽  
Niken Swastika
Keyword(s):  
Fly Ash ◽  
Portland Cement ◽  
Room Temperature ◽  
Ordinary Portland Cement ◽  
Calcium Content ◽  
Sodium Silicate Solution ◽  
Silicate Solution ◽  
Coarse Aggregates ◽  
Test Pieces ◽  
Calcium Silicate Hydrates

Geopolymer concrete with designed strength of 40 Mpa has been mixed from coarse aggregates, sands and geopolymer pastes. Two kinds of pastes are synthesized from different precursors, i.e. fly ash and dehydroxylated kaolin, using sodium silicate solution as the activator. Compression test pieces of 15x15x15 cm3 of both geopolymer and ordinary Portland cement (OPC) concretes (ASTM C39) have been cast and cured. Curing was done at room temperature for 1 day while Portland cement concretes were immersed in water for 28 days to provide complete hydration. After curing, the samples were immersed in ASTM seawater (ASTM D1141-90) for 7, 28, 56 and 90 days. It is found that geopolymer concretes were in general more durable upon seawater immersion than OPC concrete, This is indicated by the compressive strength retained after immersion. Dehydroxylated kaolin geopolymers show the best performance whose strength did not decrease with time of immersion. The strength of fly ash geopolymers decreased by about 20% during 56-day immersion but did not decrease further. Calcium content is suspected to cause the decrease in strength upon immersion. Kaolin geopolymers containing no calcium showed the best performance, while OPC which consist mostly of calcium silicate hydrates as the strength contributor, showed consistent decrease in strength. It is also found from the experiment that room temperature curing of fly ash geopolymer was slow but continued to progress until 28 days both under dry condition (not immersed) and immersed in water.

scholarly journals Experimental Study on Geopolymer Concrete with Replacement of Fly ASH and GGBS

2021 ◽  
Vol 9 (8) ◽  
pp. 2814-2819
Author(s):  
Pravalika Panchalingala
Keyword(s):  
Carbon Dioxide ◽  
Fly Ash ◽  
Flexural Strength ◽  
Portland Cement ◽  
Ordinary Portland Cement ◽  
Environmental Concern ◽  
Construction Material ◽  
Infrastructure Development ◽  
Acid Attack ◽  
Main Component

Abstract: In Twenty First century infrastructure development concrete has come out as the dominant construction material due to its longevity and strength. The main component used in the concrete preparation is ordinary Portland cement whose production release large amount of carbon dioxide into atmosphere that causes greenhouse effects. Various surveys suggest industries around the globe contribute about 6%of carbon dioxide that is releasing into the atmosphere. In spite of this major environmental concern, we cannot reduce the use of ordinary Portland cement for making concrete. In this study concrete is prepared by using geopolymer technology i.e. by mixing fly ash, ground granulated blast furnace slag, sodium silicates, sodium hydroxide are mixed. Specimen curing is done at regular intervals of 3 days, 7days, and 28days. Compressive, split and flexural strength obtained after 3 days, 7 days and 28 days. Acid, Sulphate test and permeability test done for 14 and 28 days of curing the specimen. More strength occurred at mix 5 of fly ash 30% and GGBS 70%. Keywords: fly ash, GGBS, compression strength, split tensile, acid attack, flexural strength.

Durability of Fly Ash Geopolymer Mortars in Corrosive Environments, Compared to that of Cement Mortars

2014 ◽  
Vol 92 ◽  
pp. 84-89 ◽  
Author(s):  
A. Asprogerakas ◽  
Aristea Koutelia ◽  
Glykeria Kakali ◽  
Sotirios Tsivilis
Keyword(s):  
Compressive Strength ◽  
Fly Ash ◽  
Building Materials ◽  
Acid Resistance ◽  
Chloride Diffusion ◽  
Strength Development ◽  
Acid Attack ◽  
Calcareous Sand ◽  
Cement Mortars ◽  
Improved Performance

In the present paper the durability of fly ash geopolymer mortars compared to that of cement mortars is investigated. Geopolymers can improve the ecological image of building materials, especially when their production is based on industrial by-products such as fly ash. Three series of fly ash based geopolymer mortars were prepared using calcareous sand to fly ash ratio (S/FA) varying from 0.5 to 2. In addition, cement mortar specimens were prepared using cement CEM I 42.5 N and CEM II 32.5 N. Durability of geopolymer and cement mortars was evaluated by means of compressive strength development, acid resistance, chloride diffusion and sulfate resistance. It was found that fly ash can be effectively used to produce geopolymer mortars with calcareous sand. Geopolymers exhibit competitive compressive strength compared to that of cement mortars. Geopolymer mortars develop their maximum compressive strength a few days after their casting. Geopolymer and cement mortars exhibit satisfactory resistance to sulphate attack. Cement mortars, generally, show better behaviour (compared to geopolymers) in chloride diffusion. Finally, geopolymers indicate improved performance against acid attack, compared to that of cement mortars.

Sign in / Sign up

Export Citation Format

Share Document