scholarly journals Strength and Microstructure Characteristics of Blended Fly Ash and Ground Granulated Blast Furnace Slag Geopolymer Mortars with Na and K Silicate Solution

Materials ◽  
2021 ◽  
Vol 15 (1) ◽  
pp. 211
Author(s):  
Mateusz Sitarz ◽  
João Castro-Gomes ◽  
Izabela Hager

Mineral geopolymer binders can be an attractive and more sustainable alternative to traditional Portland cement materials for special applications. In geopolymer technology the precursor is a source of silicon and aluminium oxides, the second component is an alkaline solution. In the synthesis of geopolymer binders the most commonly used alkaline solution is a mixture of sodium or potassium water glass with sodium or potassium hydroxide or silicate solution with a low molar ratio, which is more convenient and much safer in use. In this paper, we present the influence of sodium or potassium silicate solution on the physical and mechanical properties of fly ash and ground granulated blast furnace slag-based geopolymer mortars. Mercury intrusion porosimetry and microstructural observation allowed for comparing the structure of materials with a different type of alkaline solution. The evolution of compressive and flexural tensile strength with time determined for composites using 10%, 30% and 50% slag contents (referring to fly ash mass) was analysed. The tests were performed after 3, 7, 14 and 28 days. It was observed that, as the amount of slag used increases in the precursor, the strength of the material grows. Mortars with the sodium alkaline solution were characterised by a higher strength at a young age. However, the values of strength 28 days were higher for geopolymers with potassium alkaline solution reaching 75 MPa in compression. Geopolymer mortar microstructure observation indicates a high matrix heterogeneity with numerous microcracks. Matrix defects may be caused by the rapid kinetics of the material binding reaction or shrinkage associated with the drying of the material.

2020 ◽  
Author(s):  
B. Rajini ◽  
A.V. Narasimha Rao ◽  
C.Sashidhar

Now a days concrete is one of the widely used constructuction materials inconstruction industry.Portland cement is the main constituent for making concrete.Geopolymer can be consider as the key factor which does not utilize Portland cement,nor releases greenhouse gases.the geopolymer technology proposed byDavidovits(1978) shows considerable promise for application in concrete industry asan alternative binder to the Portland cement.He proposed that binders could beproposed by a polymeric reaction of alkaline liquids with the silicon and the aluminiumin source materials of geopolymer origin or by-product materials such as FlyAsh,Ground Granulated blast furnace slag ,Rice-Husk Ash etc.He termed these binderas geopolymers. Among the waste or by-product materials,Fly Ash and Slag are themost potential source of geopolymers.The objective of this project is to study the effect of class Fly Ash (FA) and GroundGranulated Blast Furnace Slag (GGBS) on the micro properties of geopolymerconcrete (GPC) at different replacement levels (FA0-GGBS100, FA25-GGBS75, FA50-GGBS50, FA75-GGBS25, FA100-GGBS0)). Sodium silicate (Na2SiO3) and sodiumhydroxide (NaOH) solution will be used as alkaline activators. The molar ratio ofhydroxide solution considered in the investigation is 10M. The result shows that themechanical decrease with increase in FA content in the mix irrespective of differentcuring periods like 7, 28, 56 and 90 days at ambient room temperature


Crystals ◽  
2021 ◽  
Vol 11 (6) ◽  
pp. 596
Author(s):  
Yasuhiro Dosho

To improve the application of low-quality aggregates in structural concrete, this study investigated the effect of multi-purpose mineral admixtures, such as fly ash and ground granulated blast-furnace slag, on the performance of concrete. Accordingly, the primary performance of low-quality recycled aggregate concrete could be improved by varying the replacement ratio of the recycled aggregate and using appropriate mineral admixtures such as fly ash and ground granulated blast-furnace slag. The results show the potential for the use of low-quality aggregate in structural concrete.


2019 ◽  
Vol 7 (1) ◽  
pp. 126-136
Author(s):  
Hakan Çağlar ◽  
Arzu Çağlar

In this study, it is aimed to make improvements on blended brick (1) which is the first building material has a history of at least 10,000 years. To the blended brick which is a traditional material was kept constant at 5% the addition of fly ash which is industrial waste. It was aim of determine of the effect on the physical and mechanical properties of the blended brick using different ratios (5%, 10%, 15% and 20%) blast furnace slag. In the first stage, the production of fly ash-based blast furnace slag doped sample of blended brick was performed. In the second stage, a variety of experiments were applied to determine the physical and mechanical properties of the blended brick sample. As a result; It has been determined that unit volume weight and compressive strength decreases with the use of industrial wastes in blended brick production. They have occured an increase in porosity and capillary water absorption values. The use of industrial wastes in the production of blended bricks will contribute both improve the properties of the bricks and   the reduction of wastes left to the environment.


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