scholarly journals Pumice as Precursor in Geopolymer Paste and Mortar

2021 ◽  
Vol 10 (4) ◽  
pp. 225-236
Author(s):  
Nihat Kabay ◽  
Mumin Mert ◽  
Nausad Miyan ◽  
Tarik Omur
Keyword(s):  
Compressive Strength ◽  
Potassium Hydroxide ◽  
Gradual Increase ◽  
Amorphous Structure ◽  
Activator Concentration ◽  
Granulated Blast Furnace Slag ◽  
Mechanical And Microstructural Properties ◽  
Furnace Slag ◽  
Alkali Activated ◽  
Geopolymer Binder

Natural rocks of magmatic origin are alternative precursors in alkali-activated materials and provide opportunities in the search for more environmentally friendly binders compared to portland cement. The pumice is one of these rocks and its amorphous structure and chemical composition make it one of the candidates as a precursor in producing geopolymer binder when finely ground. Since the majority of the pumice reserves are located in Turkey increases its potential utilization in this area, even more. This paper evaluates the physical, mechanical, and microstructural properties of geopolymer pastes and mortars manufactured with pumice powder (PP) and ground granulated blast furnace slag (BFS) with the activating agents sodium hydroxide (NaOH), potassium hydroxide (KOH), and sodium silicate (SS) solution. The experimental results showed that the compressive strength of the geopolymer pastes was mainly affected by the activator concentration and the PP ratio, rather than the activator type, for single activator mixes. However, the incorporation of SS changed this trend as the KOH and SS combination resulted in higher compressive strength compared to the NaOH and SS. The gradual increase of the PP ratio in the mix design decreased the density and thermal conductivity, on the other hand, increased the water absorption values of the geopolymer mortars. However, the physical properties were insignificantly changed in geopolymer mortars incorporating 60, 70, and 80% of PP in the binder.

scholarly journals The efficiency of plasticizing surfactants in alkali-activated cement mortars and concretes

2018 ◽  
Vol 230 ◽  
pp. 03016 ◽  
Author(s):  
Raisa Runova ◽  
Volodymyr Gots ◽  
Igor Rudenko ◽  
Oleksandr Konstantynovskyi ◽  
Oles’ Lastivka
Keyword(s):  
Compressive Strength ◽  
Blast Furnace Slag ◽  
Chemical Nature ◽  
Granulated Blast Furnace Slag ◽  
Cement Mortars ◽  
Alkaline Component ◽  
Property Modification ◽  
Furnace Slag ◽  
Alkali Activated ◽  
Strength In Bending

Functionality of mortar and concrete mixes is regulated by surfactants, which act as plasticizers. The molecular structure of these admixtures can be changed during hydration of alkali-activated cements (AAC). The objective was to determine the chemical nature of plasticizers effective for property modification of mortars and concretes based on AACs with changing content of granulated blast furnace slag from 0 to 100 %. The admixtures without ester links become more effective than polyesters when content of alkaline component increase. The admixtures effective in high alkaline medium were used in dry mixes for anchoring (consistency of mortar 150 mm by Vicat cone; 1 d tensile strength in bending / compressive strength of mortar 6.6 /30.6 MPa) and in ready-mixed concretes (consistency class changed from S1 to S3, S4 with consistency safety during 60 min; 3 d compressive strength of modified concrete was not less than the reference one without admixtures).

scholarly journals Importance of Cation Species during Sulfate Resistance Tests for Alkali-Activated FA/GGBFS Blended Mortars

Materials ◽  
2019 ◽  
Vol 12 (21) ◽  
pp. 3547
Author(s):  
Youngkeun Cho ◽  
Joo Hyung Kim ◽  
Sanghwa Jung ◽  
Yoonseok Chung ◽  
Yeonung Jeong
Keyword(s):  
Compressive Strength ◽  
Magnesium Sulfate ◽  
Sulfate Solution ◽  
Magnesium Ions ◽  
Sulfate Resistance ◽  
Granulated Blast Furnace Slag ◽  
Significant Difference ◽  
Furnace Slag ◽  
Alkali Activated ◽  
Magnesium Sulfate Solution

In this study, the changes in mass, compressive strength, and length of blended mortars were analyzed to investigate their sulfate resistance according to the ground granulated blast furnace slag (GGBFS) blending ratio and type of sulfate solution applied. All alkali-activated mortars showed an excellent sulfate resistance when immersed in a sodium sulfate (Na2SO4) solution. However, when immersed in a magnesium sulfate (MgSO4) solution, different sulfate resistance results were obtained depending on the presence of GGBFS. The alkali-activated GGBFS blended mortars showed a tendency to increase in mass and length and decrease in compressive strength when immersed in a magnesium sulfate solution, whereas the alkali-activated FA mortars did not show any significant difference depending on the types of sulfate solution applied. The deterioration of alkali-activated GGBFS blended mortars in the immersion of a magnesium sulfate solution was confirmed through the decomposition of C–S–H, which is the reaction product from magnesium ions, and the formation of gypsum (CaSO4·2H2O) and brucite (Mg(OH)2).

Experimental Study on Compound Binding Material of Alkali Activated Metakaolin and Ground Granulated Blast Furnace Slag

2011 ◽  
Vol 287-290 ◽  
pp. 1275-1279
Author(s):  
Yong Jia He ◽  
Lin Nu Lu ◽  
Shu Guang Hu
Keyword(s):  
Compressive Strength ◽  
Blast Furnace ◽  
Blast Furnace Slag ◽  
Hydration Product ◽  
Alkali Activation ◽  
Granulated Blast Furnace Slag ◽  
Binding Material ◽  
Measurement Results ◽  
Furnace Slag ◽  
Alkali Activated

Compound binding material was prepared by the alkali activation of metakaolin and ground granulated blast furnace slag. Hydration product components, microstructure and mechanical properties of the hardened paste were investigated by IR, XRD, SEM, MIP, and compressive strength measurement. Results indicated that hydration products included C-S-H and geopolymer, and both of them were amorphous although there were differences in their structure and morphology. When the dosage of slag was less than 50%, the compressive strength of hardened paste increased as the dosage increased, which was mainly because C-S-H produced by the reaction of GGBFS and alkali filled void in geopolymer phase, and part of unreacted slag particles acting as microaggregate to prevent from extension of microcrack in the hardened paste, so the porosity of hardened paste decreased and compressive strength increased.

scholarly journals The Effects of Aluminium Sulphate on Slag Paste Activated with Sodium Hydroxide and Sodium Silicate

Materials ◽  
2020 ◽  
Vol 13 (10) ◽  
pp. 2286
Author(s):  
Taewan Kim ◽  
Sungnam Hong ◽  
Choonghyun Kang
Keyword(s):  
Compressive Strength ◽  
Blast Furnace ◽  
Sodium Hydroxide ◽  
Blast Furnace Slag ◽  
Aluminium Sulphate ◽  
The Third ◽  
Granulated Blast Furnace Slag ◽  
Activated Slag ◽  
Furnace Slag ◽  
Alkali Activated

This study investigates the characteristics of alkali-activated slag cement using aluminium sulphate (ALS) as an activator. The alkalis NaOH and Na2SiO3 were used as additional activators (denoted by alkali) at 5% and 10% of the weight of the ground granulated blast furnace slag (GGBFS). Three types of activators were considered. The first was when ALS was used alone. For the second, ALS and 5% alkali were used together. The third was when ALS and 10% alkali were used. ALS was used at concentrations of 2%, 4%, 6%, 8%, and 10% based on binder weight. Experimental results show that when ALS was used as a sole activator, the activity of GGBFS was low and its strength was below 1 MPa. However, compressive strength was improved when 5% or 10% alkali and ALS were used at the same time. This was effective at improving mechanical and microstructural performance when used with an additional activator capable of forming a more alkaline environment than using ALS as a sole activator.

Effect of Sodium Hydroxide (NaOH) Concentration on Compressive Strength of Alkali-Activated Slag (AAS) Mortars

2015 ◽  
Vol 754-755 ◽  
pp. 300-304 ◽  
Author(s):  
Aimi Noorliyana Hashim ◽  
Kamarudin Hussin ◽  
Noorzahan Begum ◽  
Mohd Mustafa Al Bakri Abdullah ◽  
Kamrosni Abdul Razak ◽  
...  
Keyword(s):  
Compressive Strength ◽  
Blast Furnace ◽  
Sodium Hydroxide ◽  
Blast Furnace Slag ◽  
Alkali Activated Slag ◽  
Granulated Blast Furnace Slag ◽  
Environmental Friendly ◽  
Activated Slag ◽  
Furnace Slag ◽  
Alkali Activated

Energy saving in building technology is among the most critical problems in the world. Thus it is a need to develop sustainable alternatives to conventional concrete utilizing more environmental friendly materials. One of the possibilities to work out is the massive usage of industrial wastes like ground granulated blast furnace slag (GGBS) to turn them to useful environmental friendly and technologically advantageous cementitious materials. In this study, ground granulated blast furnace slag (GGBS) is used to produce of alkali activated slag (AAS) mortar with the effect of alkaline activator concentration. Alkali activated slag (AAS) mortar is accelerated using alkaline solution of sodium silicate mixed with sodium hydroxide. The fixed ratio of sodium silicate to sodium hydroxide is 1.7 and the concentration of sodium hydroxide is varied from 6M to 12M. Concentration of 10M NaOH promotes the best properties of mortar by achieving the greatest compressive strength. Substitution of mineral admixture also influences strength performance of AAS mortars. The mortar with 20% calcium carbonate demonstrates the maximum compressive strength. The used of alkaline activation system is the best method to prepare industrial byproduct concrete. Moreover, alkali activated product itself gains superior properties which lead to the system become the most interesting method to produce sustainable concrete.

Effect of the Combined Using of Fly Ash and Granulated Blast Furnace Slag on Properties of Cementless Alkali-Activated Mortar

2011 ◽  
Vol 287-290 ◽  
pp. 916-921
Author(s):  
Kyung Taek Koh ◽  
Gum Sung Ryu ◽  
Si Hwan Kim ◽  
Jang Hwa Lee
Keyword(s):  
Compressive Strength ◽  
Blast Furnace ◽  
Fly Ash ◽  
Blast Furnace Slag ◽  
Curing Temperature ◽  
Mixture Ratio ◽  
Granulated Blast Furnace Slag ◽  
Alkaline Activator ◽  
Furnace Slag ◽  
Alkali Activated

This paper examines the effects of the mixture ratio of fly ash/slag, the type of alkaline activators and curing conditions on the workability, compressive strength and microstructure of cementless alkali-activated mortar. The investigation showed that the mixture ratio of fly ash/slag and the type of alkaline activator have significant influence on the workability and strength, whereas the curing temperature has relatively poor effect. An alkali-activated mortar using a binder composed of 50% of fly ash and 50% of granulated blast furnace slag and alkaline activator made of 9M NaOH and sodium silicate in proportion of 1:1 is seen to be able to develop a compressive strength of 65 MPa at age of 28 days even when cured at ambient temperature of 20°C.

scholarly journals A Study on the Sulfate Resistance of Alkali Activated FA Based Geopolymer and GGBFS Blended Mortar with Various Sulfate Types

2018 ◽  
Author(s):  
Youngkeun Cho ◽  
Kwangmin Park ◽  
Sanghwa Jung ◽  
Yoonseok Chung
Keyword(s):  
Compressive Strength ◽  
Magnesium Sulfate ◽  
Sulfate Solution ◽  
Sulfate Resistance ◽  
Granulated Blast Furnace Slag ◽  
Significant Difference ◽  
Mass Increase ◽  
Furnace Slag ◽  
Alkali Activated ◽  
Magnesium Sulfate Solution

In this study, the changes in mass, compressive strength and length were analyzed to investigate sulfate resistance according to ground granulated blast furnace slag (GGBFS) blending ratio and type of sulfate solution. All alkali activated mortars showed excellent sulfate resistance when immersed in sodium sulfate (Na2SO4) solution. However, when immersed in magnesium sulfate (MgSO4) solution, different sulfate resistance results were obtained depending on the presence of GGBFS. Alkali activated GGBFS blended mortars showed a tendency to increase mass, increase length and decrease compressive strength when immersed in magnesium sulfate solution, but the alkali activated FA mortars did not show any significant difference depending on the types of sulfate solution. The deterioration of alkali activated GGBFS blended mortars in the immersion of magnesium sulfate solution was confirmed by the decomposition of C-S-H which is the reaction product by magnesium ion and the formation of gypsum (CaSO4·2H2O) and brucite (Mg(OH)2).

The Influence of the Properties of the Material Used for Obtaining Geopolymers on Their Structure and Compressive Strength

2017 ◽  
Vol 68 (6) ◽  
pp. 1182-1187
Author(s):  
Ilenuta Severin ◽  
Maria Vlad
Keyword(s):  
Compressive Strength ◽  
Blast Furnace ◽  
Wheat Straw ◽  
Red Mud ◽  
Blast Furnace Slag ◽  
Complex Structure ◽  
Point Of View ◽  
Granulated Blast Furnace Slag ◽  
Furnace Slag ◽  
Straw Ash

This article presents the influence of the properties of the materials in the geopolymeric mixture, ground granulated blast furnace slag (GGBFS) + wheat straw ash (WSA) + uncalcined red mud (RMu), and ground granulated blast furnace slag + wheat straw ash + calcined red mud (RMc), over the microstructure and mechanical properties of the synthesised geopolymers. The activation solutions used were a NaOH solution with 8M concentration, and a solution realised from 50%wt NaOH and 50%wt Na2SiO3. The samples were analysed: from the microstructural point of view through SEM microscopy; the chemical composition was determined through EDX analysis; and the compressive strength tests was done for samples tested at 7 and 28 days, respectively. The SEM micrographies of the geopolymers have highlighted a complex structure and an variable compressive strength. Compressive strength varied from 24 MPa in the case of the same recipe obtained from 70% of GGBFS + 25% WSA +5% RMu, alkaline activated with NaOH 8M (7 days testing) to 85 MPa in the case of the recipe but replacing RMu with RMc with calcined red mud, alkaline activated with the 50%wt NaOH and 50%wt Na2SiO3 solution (28 days testing). This variation in the sense of the rise in compressive strength can be attributed to the difference in reactivity of the materials used in the recipes, the curing period, the geopolymers structure, and the presence of a lower or higher rate of pores, as well as the alkalinity and the nature of the activation solutions used.

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