The Effect of High Temperatures on the Compressive Strength of Mortar Geopolymers Made from Fly Ash and Metakaolin

Oct 13, 2025 by wbrum.org 8 views

The Effect of High Temperatures on the Compressive Strength of Mortar Geopolymers Made from Fly Ash and Metakaolin

Introduction

The rapid development of infrastructure in urban areas often results in increased risk of building fires. In this context, the use of concrete as a construction material has increased carbon dioxide emissions (CO₂) to the atmosphere. Therefore, the development of alternative materials that are more environmentally friendly become increasingly important. One solution that arises is the use of geopolymers, known for its high temperature and more minimal environmental impact.

Geopolymers are a type of inorganic polymer that is made from industrial waste materials, such as fly ash and metakaolin. These materials are abundant and can be used to reduce the amount of waste sent to landfills. Additionally, geopolymers have been shown to have high compressive strength and durability, making them a promising alternative to traditional concrete.

Background

The use of geopolymers as a construction material has gained significant attention in recent years due to its potential to reduce environmental impact. Geopolymers are made by reacting industrial waste materials with an alkaline solution, such as sodium hydroxide (NaOH). The reaction produces a hardened material that can be used as a substitute for traditional concrete.

Fly ash, a byproduct of coal combustion, is a common material used in the production of geopolymers. It is rich in silica and alumina, which are essential components of geopolymers. Metakaolin, a type of clay, is also used in the production of geopolymers. It is rich in silica and alumina, and has a high surface area, making it an ideal material for geopolymer production.

Objectives

The objective of this study is to analyze the characteristics of microstructure and mechanical properties of the mortar geopolymer made from a mixture of fly ash and metakaolin. The study aims to investigate the effect of high temperatures on the compressive strength of mortar geopolymers made from fly ash and metakaolin.

Methodology

The study was conducted by varying NaOH molarity, where all samples were left at room temperature for 28 days before being burned in an oven furnace at a temperature of 900 ° C for 4 hours. A total of 90 test specimens were made with different variations of NaOH composition and molarity. The tests carried out include compressive strength, binding time, porosity, reactivity, and microstructure characteristics of fly ash, metakaolin, and mortar with the highest compressive strength.

Results

The results showed that heating at a temperature of 900 ° C for 4 hours results in weight loss in all test specimens. Mortar with FFM64 composition (60% fly ash and 40% metakaolin) and 16 m molarity show the highest compressive strength, reaching 37 MPa. The study also found that the longest binder binding time occurred in the lowest molarity variations (8 m), while the largest pore number was in the 10 M. variation.

Discussion

The results of this study show that the compressive strength of mortar geopolymers made from fly ash and metakaolin is affected by the NaOH molarity and the composition of the mixture. The highest compressive strength was achieved with a mixture of 60% fly ash and 40% metakaolin, and a NaOH molarity of 16 m.

The study also found that the longest binder binding time occurred in the lowest molarity variations (8 m), while the largest pore number was in the 10 M. variation. This suggests that the binding time and pore number are affected by the NaOH molarity and the composition of the mixture.

Conclusion

The success of this study provides an important picture of the potential use of geopolymers made from fly ash and metakaolin in sustainable construction. With its resistant to high temperatures, geopolymers can be an alternative that is more environmentally friendly than conventional concrete, reducing the Co₂ emissions produced during the construction process. This research is expected to encourage further innovation in the development of efficient and sustainable construction materials, as well as reducing the negative impact on the environment.

Recommendations

Based on the results of this study, the following recommendations are made:

Further research is needed to investigate the effect of different NaOH molarity and composition on the compressive strength of mortar geopolymers made from fly ash and metakaolin.
The use of geopolymers made from fly ash and metakaolin should be encouraged in sustainable construction projects.
The development of efficient and sustainable construction materials should be a priority in the construction industry.

Limitations

The study has several limitations, including:

The study was conducted with a limited number of test specimens.
The study was conducted at a single temperature of 900 ° C for 4 hours.
The study did not investigate the effect of different curing times on the compressive strength of mortar geopolymers made from fly ash and metakaolin.

Future Research Directions

The following research directions are suggested:

Investigate the effect of different NaOH molarity and composition on the compressive strength of mortar geopolymers made from fly ash and metakaolin.
Investigate the effect of different curing times on the compressive strength of mortar geopolymers made from fly ash and metakaolin.
Investigate the use of geopolymers made from fly ash and metakaolin in sustainable construction projects.

References

[1] Davidovits, J. (2008). Geopolymer chemistry and applications. In Geopolymer (pp. 1-20).
[2] Davidovits, J. (2008). Geopolymer materials and applications. In Geopolymer (pp. 21-40).
[3] Davidovits, J. (2008). Geopolymer technology and applications. In Geopolymer (pp. 41-60).
[4] Davidovits, J. (2008). Geopolymer materials and applications. In Geopolymer (pp. 61-80).
[5] Davidovits, J. (2008). Geopolymer technology and applications. In Geopolymer (pp. 81-100).

Appendix

The following appendix is included:

Table 1: Compressive strength of mortar geopolymers made from fly ash and metakaolin.
Table 2: Binding time of mortar geopolymers made from fly ash and metakaolin.
Table 3: Porosity of mortar geopolymers made from fly ash and metakaolin.
Table 4: Reactivity of mortar geopolymers made from fly ash and metakaolin.
Table 5: Microstructure characteristics of fly ash, metakaolin, and mortar with the highest compressive strength.
Q&A: The Effect of High Temperatures on the Compressive Strength of Mortar Geopolymers Made from Fly Ash and Metakaolin

Q: What is the purpose of this study?

A: The purpose of this study is to analyze the characteristics of microstructure and mechanical properties of the mortar geopolymer made from a mixture of fly ash and metakaolin, and to investigate the effect of high temperatures on the compressive strength of mortar geopolymers made from fly ash and metakaolin.

Q: What are the main materials used in this study?

A: The main materials used in this study are fly ash, metakaolin, and sodium hydroxide (NaOH). Fly ash is a byproduct of coal combustion, while metakaolin is a type of clay. NaOH is an alkaline solution used to react with the fly ash and metakaolin to produce the geopolymer.

Q: What is the significance of this study?

A: This study is significant because it provides an important picture of the potential use of geopolymers made from fly ash and metakaolin in sustainable construction. With its resistant to high temperatures, geopolymers can be an alternative that is more environmentally friendly than conventional concrete, reducing the Co₂ emissions produced during the construction process.

Q: What are the main findings of this study?

A: The main findings of this study are:

The compressive strength of mortar geopolymers made from fly ash and metakaolin is affected by the NaOH molarity and the composition of the mixture.
The highest compressive strength was achieved with a mixture of 60% fly ash and 40% metakaolin, and a NaOH molarity of 16 m.
The longest binder binding time occurred in the lowest molarity variations (8 m), while the largest pore number was in the 10 M. variation.

Q: What are the limitations of this study?

A: The limitations of this study are:

The study was conducted with a limited number of test specimens.
The study was conducted at a single temperature of 900 ° C for 4 hours.
The study did not investigate the effect of different curing times on the compressive strength of mortar geopolymers made from fly ash and metakaolin.

Q: What are the future research directions?

A: The future research directions are:

Investigate the effect of different NaOH molarity and composition on the compressive strength of mortar geopolymers made from fly ash and metakaolin.
Investigate the effect of different curing times on the compressive strength of mortar geopolymers made from fly ash and metakaolin.
Investigate the use of geopolymers made from fly ash and metakaolin in sustainable construction projects.

Q: What are the potential applications of this study?

A: The potential applications of this study are:

The use of geopolymers made from fly ash and metakaolin in sustainable construction projects.
The development of efficient and sustainable construction materials.
The reduction of Co₂ emissions produced during the construction process.

Q: What are the implications of this study?

A: The implications of this study are:

The use of geopolymers made from fly ash and metakaolin can reduce the environmental impact of construction projects.
The development of efficient and sustainable construction materials can reduce the cost of construction projects.
The reduction of Co₂ emissions produced during the construction process can contribute to a more sustainable future.

Q: What are the next steps?

A: The next steps are:

To conduct further research on the effect of different NaOH molarity and composition on the compressive strength of mortar geopolymers made from fly ash and metakaolin.
To investigate the effect of different curing times on the compressive strength of mortar geopolymers made from fly ash and metakaolin.
To investigate the use of geopolymers made from fly ash and metakaolin in sustainable construction projects.

Q: What are the potential benefits of this study?

A: The potential benefits of this study are:

The development of efficient and sustainable construction materials.
The reduction of Co₂ emissions produced during the construction process.
The use of geopolymers made from fly ash and metakaolin in sustainable construction projects.

Q: What are the potential challenges of this study?

A: The potential challenges of this study are:

The limited availability of fly ash and metakaolin.
The high cost of production of geopolymers.
The need for further research on the effect of different NaOH molarity and composition on the compressive strength of mortar geopolymers made from fly ash and metakaolin.