Research on Mechanical Properties of Geopolymer Concrete under early Stage Curing System

2012 ◽  
Vol 164 ◽  
pp. 492-496
Author(s):  
Qing Wang ◽  
Kun Ran ◽  
Zhao Yang Ding ◽  
Lin Ge Qiu

Mechanical properties of geopolymer concrete under early stage curing system were studied. The results showed that at the early stage of curing time, compressive strength was improved significantly with the increasing of curing temperature and curing time. The compressive strength decreased and was close to that of standard curing condition at the age of 28d as the curing age increased. In addition, prolonging the storage time at room temperature before the step of high temperature curing could increase the long-term strength.

2011 ◽  
Vol 250-253 ◽  
pp. 3372-3376 ◽  
Author(s):  
Qing Wang ◽  
Xin Tu ◽  
Zhao Yang Ding ◽  
Zhi Tong Sui

Geopolymer has been gradually attracting world attention as a potentially revolutionary material that is one of the ideal substitutes of Portland cement, and fundamental studies on geopolymer are increased rapidly because of its potential commercial applications. However, little work has been done in the field of curing system of geopolymer. In this paper, influence of curing temperature, curing time and curing humidity on the mechanical properties of slag-based geopolymer was studied by using the compressive strength as benchmark parameter. Results have shown that the early age compressive strength of geopolymer increased and the long-term compressive strength decreased at first and then increased as the curing temperature increased, 80°C was the best curing temperature. With prolonging the curing time, it was found that the compressive strength of early age of geopolymer reached the maximum ( 116.3 MPa for 1d, 97.5 MPa for 3d) as the curing time was 12h, and that of 28d geopolymer was 91.3 MPa as the curing time was 10h. It was also found that the compressive strength of geopolymer reduced evidently as the humidity increased.


Materials ◽  
2019 ◽  
Vol 12 (7) ◽  
pp. 1173 ◽  
Author(s):  
Češnovar ◽  
Traven ◽  
Horvat ◽  
Ducman

Alkali activation is studied as a potential technology to produce a group of high performance building materials from industrial residues such as metallurgical slag. Namely, slags containing aluminate and silicate form a useful solid material when activated by an alkaline solution. The alkali-activated (AA) slag-based materials are promising alternative products for civil engineering sector and industrial purposes. In the present study the locally available electric arc furnace steel slag (Slag A) and the ladle furnace basic slag (Slag R) from different metallurgical industries in Slovenia were selected for alkali activation because of promising amorphous Al/Si rich content. Different mixtures of selected precursors were prepared in the Slag A/Slag R ratios 1/0, 3/1, 1/1, 1/3 and 0/1 and further activated with potassium silicate using an activator to slag ratio of 1:2 in order to select the optimal composition with respect to their mechanical properties. Bending strength of investigated samples ranged between 4 and 18 MPa, whereas compressive strength varied between 30 and 60 MPa. The optimal mixture (Slag A/Slag R = 1/1) was further used to study strength development under the influence of different curing temperatures at room temperature (R. T.), and in a heat-chamber at 50, 70 and 90 °C, and the effects of curing time for 1, 3, 7 and 28 days was furthermore studied. The influence of curing time at room temperature on the mechanical strength at an early age was found to be nearly linear. Further, it was shown that specimens cured at 70 °C for 3 days attained almost identical (bending/compressive) strength to those cured at room temperature for 28 days. Additionally, microstructure evaluation of input materials and samples cured under different conditions was performed by means of XRD, FTIR, SEM and mercury intrusion porosimetry (MIP).


1994 ◽  
Vol 370 ◽  
Author(s):  
Asif Ahmed ◽  
Leslie Struble

AbstractMechanical properties of any material, including hardened cement paste, are assumed to be controlled by its microstructure. An attempt has been made here to establish a link between bulk fracture parameters of hardened cement paste and its microstructure. Paste microstructure has been varied by changing the initial w/c ratio, curing time and curing temperature, and by addition of chemicals to change the calcium hydroxide morphology. It has been found that, like compressive strength, fracture parameters depend directly on porosity. Contrary to our initial hypothesis, CH morphology was found to have no effect on the fracture parameters.


2014 ◽  
Vol 699 ◽  
pp. 15-19 ◽  
Author(s):  
Rosniza Hanim Abdul Rahim ◽  
Khairun Azizi Azizli ◽  
Zakaria Man ◽  
Muhd Fadhil Nuruddin

Geopolymer is associated with the alkali activation of materials rich in Si and Al, and alkali activator such as sodium hydroxide is used for the dissolution of raw material with the addition of sodium silicate solution to increase the dissolution process. However, the trend of strength development of geopolymer using sodium hydroxide alone is not well established. This paper presents an evaluation on compressive strength of fly ash–based geopolymer by varying curing time with respect to different curing temperature using sodium hydroxide as the only activator. The samples were cured at room temperature and at an elevated temperature (60°C). Further analysis on the microstructure of geopolymer products cured at 60°C was carried out using Field Emission Scanning Microscopy (FESEM). It can be observed that the compressive strength increased as the curing time increased when cured at room temperature; whereas at elevated temperature, the strength increased up to a maximum 65.28 MPa at 14 days but gradually decreased at longer curing time. Better compressive strength can be obtained when the geopolymer was cured at an elevated temperature compared to curing at room temperature.


Author(s):  
Khoa Tan Nguyen ◽  
Tuan Anh Le ◽  
An Thao Huynh ◽  
Namshik Ahn

Geopolymer concrete is known as an alternative to Portland cement, with low carbon dioxide emissions compared with the conventional building materials. In this research, the influence of curing conditions and alkali hydroxide were investigated, using curing temperatures between 40 to 100℃, curing times from 4 to 12 hours, and various types of hydroxide and concentrations of sodium hydroxide solution. Geopolymerization needs energy and time to occur, and higher curing temperatures resulted in larger compressive strength, while longer curing times resulted in higher compressive strength. At the same curing temperature, longer curing time resulted in a higher compressive strength because the longer curing time extends the chemical reaction. For geopolymer concrete, sodium hydroxide is a better property than potassium hydroxide, because the atomic size of sodium anion is smaller than potassium. Further, the strength of concrete increased when the concentration of sodium hydroxide increased. In conclusion, geopolymer concrete is suitable for traditional building materials. Finding renewable materials to satisfy the increasing demand for building structures will be the primary challenge in future.


2016 ◽  
Vol 841 ◽  
pp. 7-15 ◽  
Author(s):  
Himawan Tri Bayu Murti Petrus ◽  
Joshepine Hulu ◽  
Gede S.P. Dalton ◽  
Elsa Malinda ◽  
Rizal Agung Prakosa

Silica scaling is one of major problems in geothermal power plant. Silica recovery is a promising method to solve this particular problem in regard to silica utilization as geopolimer concrete. In this experimental study, bentonite was used as raw alumina source. Experiments were conducted by means observing the geopolymerization through alkaline activator ratio, raw material ratio, and temperature optimization. After mixing and casting for 24 hours, samples were cured at 80°C, 100°C, and 120°C for certain period of time and kept at room temperature for 7 days before compressive strength test. The optimum curing time and temperature gained from this experiment were 120 minutes and 100°C with compressive strength of 29.16 MPa. The development of geopolymer bond and microstructure of samples were then investigated by SEM technique. Scanning electron microscopy (SEM) analysis also showed better improvement in geopolymer layer of concrete sample with increasing curing temperature.


2020 ◽  
Vol 8 (5) ◽  
pp. 1167-1174

The effect of different factors on the compressive strength of fly ash based rubberized geopolymer concrete has been established using Taguchi method. The factors include alkaline solution/fly ash ratio; ratio of Na2SiO3 /NaOH, molarity concentration of NaOH, temperature of curing, time period for curing, water content, rest period and amount of superplasticizer as an additional material are considered. Total twenty-seven experiments have been conducted in accordance with Taguchi orthogonal array L27. Different mixtures of the fly ash based rubberized geopolymer concrete have been examined for compressive strength at seven days. ANOVA (Variance Analysis) method was used to evaluate the influence of each factor and to identify the test mixture with the highest compressive resistance. The results of experiments show that the alkaline-to-fly ash mixture is 0.35, Na2SiO3 /NaOH 2.5, 14 M NaOH, 90°C temperature for curing, 48-hour curing time, 20% water content, 1 day resting period, and 2 percent addition of superplasticizer acquires the greatest compression strength of 59.08 MPa. The curing temperature was also identified as the main factor influencing a rubberized fly ash-based geopolymer concrete's compression strength.


2021 ◽  
Vol 11 (7) ◽  
pp. 3032
Author(s):  
Tuan Anh Le ◽  
Sinh Hoang Le ◽  
Thuy Ninh Nguyen ◽  
Khoa Tan Nguyen

The use of fluid catalytic cracking (FCC) by-products as aluminosilicate precursors in geopolymer binders has attracted significant interest from researchers in recent years owing to their high alumina and silica contents. Introduced in this study is the use of geopolymer concrete comprising FCC residue combined with fly ash as the requisite source of aluminosilicate. Fly ash was replaced with various FCC residue contents ranging from 0–100% by mass of binder. Results from standard testing methods showed that geopolymer concrete rheological properties such as yield stress and plastic viscosity as well as mechanical properties including compressive strength, flexural strength, and elastic modulus were affected significantly by the FCC residue content. With alkali liquid to geopolymer solid ratios (AL:GS) of 0.4 and 0.5, a reduction in compressive and flexural strength was observed in the case of geopolymer concrete with increasing FCC residue content. On the contrary, geopolymer concrete with increasing FCC residue content exhibited improved strength with an AL:GS ratio of 0.65. Relationships enabling estimation of geopolymer elastic modulus based on compressive strength were investigated. Scanning electron microscope (SEM) images and X-ray diffraction (XRD) patterns revealed that the final product from the geopolymerization process consisting of FCC residue was similar to fly ash-based geopolymer concrete. These observations highlight the potential of FCC residue as an aluminosilicate source for geopolymer products.


2016 ◽  
Vol 857 ◽  
pp. 400-404
Author(s):  
Tian Yu Xie ◽  
Togay Ozbakkaloglu

This paper presents the results of an experimental study on the behavior of fly ash-, bottom ash-, and blended fly and bottom ash-based geopolymer concrete (GPC) cured at ambient temperature. Four bathes of GPC were manufactured to investigate the influence of the fly ash-to-bottom ash mass ratio on the microstructure, compressive strength and elastic modulus of GPC. All the results indicate that the mass ratio of fly ash-to-bottom ash significantly affects the microstructure and mechanical properties of GPCs


Materials ◽  
2021 ◽  
Vol 14 (4) ◽  
pp. 953
Author(s):  
Michał Łach ◽  
Reda A. Gado ◽  
Joanna Marczyk ◽  
Celina Ziejewska ◽  
Neslihan Doğan-Sağlamtimur ◽  
...  

Alkali activated cement (AAC) can be manufactured from industrial by-products to achieve goals of “zero-waste” production. We discuss in detail the AAC production process from (waste) post-production clay, which serves as the calcium-rich material. The effect of different parameters on the changes in properties of the final product, including morphology, phase formation, compressive strength, resistance to the high temperature, and long-term curing is presented. The drying and grinding of clay are required, even if both processes are energy-intensive; the reduction of particle size and the increase of specific surface area is crucial. Furthermore, calcination at 750 °C ensure approximately 20% higher compressive strength of final AAC in comparison to calcination performed at 700 °C. It resulted from the different ratio of phases: Calcite, mullite, quartz, gehlenite, and wollastonite in the final AAC. The type of activators (NaOH, NaOH:KOH mixtures, KOH) affected AAC mechanical properties, significantly. Sodium activators enabled obtaining higher values of strength. However, if KOH is required, the supplementation of initial materials with fly ash or metakaolin could improve the mechanical properties and durability of AAC, even c.a. 28%. The presented results confirm the possibility of recycling post-production clay from the Raciszyn II Jurassic limestone deposit.


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