scholarly journals Modification of AA Binder Matrix with the Use of PP Fibres – Strength Investigations

2020 ◽  
Author(s):  
Szymon Dawczyński ◽  
Anna Stokłosa
Keyword(s):  
Fly Ash ◽  
Bending Strength ◽  
Waste Product ◽  
Strength Properties ◽  
Laboratory Research ◽  
Fibre Reinforcement ◽  
Polypropylene Fibres ◽  
Strength Tests ◽  
Alkali Activated Binders ◽  
Alkali Activated

The alkali-activated (AA) binders are assumed to be more ecological than ordinary Portland cement (OPC) binders, because of lower energy requisition and lower CO2 emissions during the production processes. The purpose of using polypropylene(PP) fibres in traditional concrete, geopolymers and mortars is to improve strength properties by inhibiting the growth of cracks that usually occur due to shrinkage, as well as improving the mechanical properties. This paper presents laboratory research into the fibre reinforcement impact on the strength properties of an AA binder made of fly ash suspension. In addition to the suspension, which is a waste product from the coal power plant, recycled ground glass and metakaolin were used as the precursors. The chemical activator of the geopolimerisation reaction was prepared using sodium hydroxide and sodium silicate. Five different sets of the prism samples 40x40x160 mm were made (with different PP fibres ratio,  from 0% to 2%  by weight) and then the flexural and compressive strength tests were performed.  The addition of polypropylene fibres increased the bending strength, which produced the beneficial effect of reducing crack propagation in cases of tensile stress occurrence. Keywords: alkali-activated binders, geopolymers, polypropylene fibres, fly ash suspension, bending strength

scholarly journals Feasibility and strength properties of the geopolymeric binder made of fly ash suspension

2019 ◽  
Vol 262 ◽  
pp. 06001
Author(s):  
Szymon Dawczyúski ◽  
Marek Soczyúski ◽  
Marcin GÓrski
Keyword(s):  
Fly Ash ◽  
Waste Product ◽  
Strength Properties ◽  
Inorganic Materials ◽  
Curing Temperature ◽  
Laboratory Research ◽  
Heat Curing ◽  
Energy Consuming ◽  
Main Components ◽  
The Impact

Geopolymeric binders, or in general geopolymers, are nowadays applied in many different branches of the industry –also in building construction. This relatively new group of inorganic materials has similar strength properties as ordinary Portland cement (OPC) and in some features, it is even better (for example in terms of fire resistance or chemical resistance). It is also environmentally friendly material because industrial or mining tailings are used as its main components and the production process is not so energy consuming as in case of OPC. Paper presents laboratory research focusing on the curing temperature impact on strength properties of geopolymeric binder made of fly ash suspension. Besides the suspension which is a waste product from coal power plant, also recycled ground glass and metakaolin were used as the additions. The chemical activator of geopolimerisation reaction was prepared with the use of sodium hydroxide and sodium silicate. Prism samples 40x40x160 mm were done and then the flexural and compressive strength tests were performed. The paper also presents the impact of covering the moulds during heat curing on condition of geopolymeric binder samples.

scholarly journals Long-Term Strength Development of Fly Ash-Based One-Part Alkali-Activated Binders

Materials ◽  
2021 ◽  
Vol 14 (15) ◽  
pp. 4160
Author(s):  
Sani Haruna ◽  
Bashar S. Mohammed ◽  
Mubarak M. A. Wahab ◽  
Mubarak Usman Kankia ◽  
Mugahed Amran ◽  
...  
Keyword(s):  
Compressive Strength ◽  
Fly Ash ◽  
Water Absorption ◽  
Sodium Metasilicate ◽  
Strength Properties ◽  
Experimental Result ◽  
Term Strength ◽  
Alkali Activated Binders ◽  
Alkali Activated

This research aims to study the effect of the dosage of anhydrous sodium metasilicate activator on the long-term properties of fly ash-based one-part alkali-activated binders (OPAAB) cured at ambient conditions. Powdered sodium metasilicate activator was utilized in the range of 8–16% by weight of the fly ash in producing the OPAAB. The properties examined are hardened density, compressive strength, flexural strength, water absorption, efflorescence formation, and microstructural analysis. The experimental result revealed that the binders exhibited excellent long-term strength properties. The compressive strength of the OPAAP is well correlated with its hardened density. The pastes were found to exhibit good soundness characteristics over the long-term. The absorption of water decreases with an increase in the activator dosage from 8–12%, and beyond that, the water absorption relatively remains the same. Field emission scanning electron microscope (FESEM) micrograph revealed uniformly formed solid matrices with the micro-crack present were observed in the samples. The larger pore size promotes the crystallization of the resulting hydrate substances (N, C)-A-S-H gel. The initial dissolution of the OPAAP occurred within the first 30 min. At longer age of curing, mixtures with a higher dosage of powdered activator tend to absorb less water. Strength properties beyond 28 days are considered as the long-term strength.

scholarly journals Effect of CaSO4 Incorporation on Pore Structure and Drying Shrinkage of Alkali-Activated Binders

Materials ◽  
2019 ◽  
Vol 12 (10) ◽  
pp. 1673 ◽  
Author(s):  
Hyeongmin Son ◽  
Sol Moi Park ◽  
Joon Ho Seo ◽  
Haeng Ki Lee
Keyword(s):  
Fly Ash ◽  
Pore Structure ◽  
Drying Shrinkage ◽  
Phase Changes ◽  
X Ray Diffraction ◽  
Activated Slag ◽  
Capillary Tension ◽  
Alkali Activated Binders ◽  
Internal Pore Structure ◽  
Alkali Activated

This present study investigates the effects of CaSO4 incorporation on the pore structure and drying shrinkage of alkali-activated slag and fly ash. The slag and fly ash were activated at a 5:5 ratio by weighing with a sodium silicate. Thereafter, 0%, 5%, 10%, and 15% of CaSO4 were incorporated to investigate the changes in phase formation and internal pore structure. X-Ray Diffraction (XRD), thermogravimetry (TG)/derivative thermogravimetry (DTG), mercury intrusion porosimetry (MIP), nuclear magnetic resonance (NMR), and drying shrinkage tests were carried out to find the correlation between the pore structure and drying shrinkage of the specimens. The results showed that CaSO4 incorporation increased the formation of thenardite, and these phase changes affected the pore structure of the activated fly ash and slag. The increase in the CaSO4 content increased the pore distribution in the mesopore. As a result, the capillary tension and drying shrinkage decreased.

scholarly journals Leaching, carbonation and chloride ingress in reinforced alkali-activated fly ash mortars

2018 ◽  
Vol 199 ◽  
pp. 02025 ◽  
Author(s):  
Gregor J. G. Gluth ◽  
Petr Hlaváček ◽  
Steffi Reinemann ◽  
Gino Ebell ◽  
Jürgen Mietz
Keyword(s):  
Fly Ash ◽  
Visual Inspection ◽  
Electrochemical Behaviour ◽  
Transport Coefficients ◽  
Chloride Penetration ◽  
Chloride Ingress ◽  
Reaction Products ◽  
Steel Bars ◽  
Alkali Activated Binders ◽  
Alkali Activated

Alkali-activated fly ash mortars were studied with regard to durability-relevant transport coefficients and the electrochemical behaviour of embedded carbon steel bars on exposure of the mortars to leaching, carbonation and chloride penetration environments. The transport coefficients differed considerably between different formulations, being lowest for a mortar with BFS addition, but still acceptable for one of the purely fly ash-based mortars. Leaching over a period of ~300 days in de-ionized water did not lead to observable corrosion of the embedded steel, as shown by the electrochemical data and visual inspection of the steel. Exposure to 100 % CO2 atmosphere caused steel depassivation within approx. two weeks; in addition, indications of a deterioration of the mortar were observed. The results are discussed in the context of the different reaction products expected in highand low-Ca alkali-activated binders, and the alterations caused by leaching and carbonation.

Synthetic Fibres for Fibre Concrete Composites

1993 ◽  
Vol 305 ◽  
Author(s):  
Dorel Feldman ◽  
Zhihong Zheng
Keyword(s):  
Volume Fraction ◽  
Fibre Volume Fraction ◽  
Dynamic Strength ◽  
Strength Properties ◽  
Fibre Volume ◽  
Fibre Reinforcement ◽  
Polypropylene Fibres ◽  
Fibre Concrete ◽  
Deformation Properties ◽  
General Aspects

AbstractThe use of fibrous reinforcement to improve the strength and deformation properties of concrete is now well established. The concept of fibre reinforcement is to use the deformation of the matrix under stress to transfer load to the fibre. Substantial improvements in static and dynamic strength properties could then be achieved if the fibres are strong and stiff, and loaded to fracture, provided there is, of course, a minimum fibre-volume fraction.Besides fibres like asbestos, glass and steel, different kind of synthetic fibres such as polyethylene, polypropylene, polyamide and others are recently used for cementitious composites.Together with general aspects of synthetic fibre concrete composites, original results concerning the study done on a hybrid composite based on steel and polypropylene fibres will be presented and discussed.

Alkali-activated binders based on incinerator bottom ash combined with limestone-calcined clay or fly ash

2022 ◽  
Vol 320 ◽  
pp. 126306
Author(s):  
Jun Liu ◽  
Zhen Liang ◽  
Hesong Jin ◽  
Gediminas Kastiukas ◽  
Luping Tang ◽  
...  
Keyword(s):  
Fly Ash ◽  
Bottom Ash ◽  
Calcined Clay ◽  
Alkali Activated Binders ◽  
Alkali Activated

Durability of Alkali-Activated Fly Ash/Slag Concrete

2017 ◽  
Vol 904 ◽  
pp. 157-161 ◽  
Author(s):  
Mao Chieh Chi ◽  
Hsian Chen ◽  
Tsai Lung Weng ◽  
Ran Huang ◽  
Yih Chang Wang
Keyword(s):  
Fly Ash ◽  
Total Charge ◽  
Test Results ◽  
Mass Ratio ◽  
Modulus Ratio ◽  
Granulated Blast Furnace Slag ◽  
Alkali Activated Binders ◽  
Furnace Slag ◽  
Alkali Activated ◽  
Better Than

This study investigated the durability of alkali-activated binders based on blends of fly ash (FA) and ground granulated blast furnace slag (GGBFS). Five fly ash-to-slag ratios of 100/0, 75/25, 50/50, 25/75, and 0/100 by mass were selected to produce alkali-activated fly ash/slag (AAFS) concrete. Sodium oxide (Na2O) concentrations of 6% and 8% of binder weight and activator modulus ratios (mass ratio of SiO2 to Na2O) of 0.8, 1.0, and 1.23 were used as alkaline activators. Test results show that the total charge passed of AAFS concrete is between 2500 and 4000 coulombs, higher than the comparable OPC concrete. However, AAFS concrete exposed to sulfate attack performed better than OPC concrete. Based on the results, 100% slag-based AAFS concrete with Na2O concentration of 8% and activator modulus ratio of 1.23 has the superior performances.

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