From geopolymerization, a new technology has been introduced, which is geopolymer cement, also known as green cement. Geopolymer cement is also said to reduce its greenhouse gas footprint when compared to conventional cement slurries used in oil and gas well cementing operations. In this project, the writer was assigned to conduct the study on the characteristic properties of palm oil fuel ash (POFA) geopolymer and its effects as a geopolymer cement material. The main objective is to determine the relationship between compressive strength with setting time and other influencing factors such as the concentration of the alkaline solution. Detailed impact studies were conducted throughout the project.
The cement paste is then poured into a mold of a certain size and allowed to harden at different curing times. In conclusion, POFA geopolymer cement gives higher compressive strength in 12 M sodium hydroxide solution and increasing the ratio of alkaline activator to POFA mass ratio will increase the compressive strength. First and foremost, the author would like to express her utmost gratitude to Almighty God for his blessings and bestow good health and life in all the semesters to complete this final year.
Nur Fitri Ismail and Mr. Muhammad Aslam Md Yusof, FYP Coordinators for their help and guidance during the project. Last but not least, the author would like to express her deepest appreciation to her family and friends for providing endless support, encouragement, valuable advice and understanding to complete this project.
INTRODUCTION
- Background of study
- Problem Statements
- Objectives and Scope of Study
- The Relevancy of the Project
- Feasibility of the Project
Therefore, it is one of the best methods to use in agricultural waste processing. On the other hand, the use of geopolymers in oil well cementing is a new technology that needs a proper study to determine the advantages of geopolymer cement compared to conventional cement. This article discusses the study on the effect of palm oil fuel ash (POFA) on the properties of geopolymer cement for use in oil well cementing.
It is important to determine the compressive strength of geopolymer cement using POFA with optimum curing temperature and time. Geopolymer cement is estimated to reduce CO2 emissions depending on the types of materials used. Therefore, further research on the geopolymeric properties of POFA-based cement should be carried out to determine the advantages of POFA.
The aim of this paper is to study the effect of POFA in geopolymer properties as a cementitious material. The results of geopolymer cement based on POFA will be compared with the conventional cement used in cement activities in accordance with American Petroleum Institute specifications to ensure the compatibility of the cement with the oil and gas well conditions.
LITERATURE REVIEW
Geopolymer
Geopolymerization
Geopolymer Cement
Ordinary Portland Cement
Cement Properties
- Compressive Strength
- Curing Temperature and Time 9
- Alkali Concentration
Figures 3, 4 and 5 below show respectively the strength gain of concrete with age for different moist curing periods and the relative strength gain of concrete cured at different temperatures. At lower pH values, the geopolymeric mixture remained viscous and behaved like cement, while at higher pH the mixture acquired a more fluid gel composition, which is less viscous and more workable. With increasing pH, there was a predominance of smaller chain oligomers and monomeric silicate available to react with soluble aluminum.
Further, as the pH increases, soluble aluminum increases and reacts with the calcium available for reaction. Khale and Chaudhary reported that the strength measured from pH 14 samples was five times greater than that of samples formed from pH 12 traps; and they found that the pH range of 13–14 is the most suitable for the formation of geopolymers with higher mechanical strength. 10 N KOH showed a maximum strength of 60 Mpa, but the strength decreased with increasing KOH concentration from 10 N to 15 N, probably due to excess K+ ions in the framework.
Addition of K2O was found to benefit the compressive strength and also to reduce the occurrence of cracks. Higher the alkalinity of the hydration water, slower the rate of hydration during the binder hydration. Since K+ is more basic, it allows a higher rate of solubilized polymeric ionization and dissolution resulting in a dense polycondensation reaction that provides greater overall network formation and an increase in the compressive strength of the matrix.
Classification of Cement
Curing for 3 days and 10 M sodium hydroxide solution showed the compressive strength of 0.63 Mpa. For a concentration of 12 M sodium hydroxide solution, the compressive strength obtained over a curing time of 3 days is 0.70 Mpa. It can be seen from Figure 8 that the compressive strength increases from 3 days to 14 days of curing time for all concentrations of sodium hydroxide solution.
The compressive strength increases to 1.26 Mpa on increasing the molarity concentration of sodium hydroxide to 12M. The compressive strength also increases as the concentration of sodium hydroxide solution increases from 10M to 12M for both geopolymer cement compositions. The ultimate goal of this project is to determine the compressive strength of POFA geopolymer cement and compare the results to API specifications for oil well cement.
The method used to determine the compressive strength was determined by making POFA geopolymer cement cubes and testing their compressive strength. From the results in Table 6, the compressive strength increases as the molarity of the sodium hydroxide solution increases from 10 M to 12 M. The compressive strength obtained from this experiment shows a very low strength of the POFA geopolymer cement.
Nevertheless, adding fly ash to the geopolymer cement composition improves the compressive strength. Azreen et al., (2011) found that the compressive strength of POFA geopolymer cement with the addition of FA is improved at the mixed ash ratio of 70:30. The results show that the compressive strength increases with the increase of the ratio.
The compressive strength of POFA geopolymer cement increases from 0.70 Mpa to 0.83 Mpa when the alkaline activator/POFA ratio increases from 0.4 to 0.8. In this study, it shows that the compressive strength of POFA geopolymer cement gradually increases with extended curing time. The increase in compressive strength can be observed at all sodium hydroxide solution concentrations tested.
The source of raw materials is recognized as one of the factors that somewhat influence compressive strength. Galau and Ismail's research shows that the compressive strength of geopolymer cement containing POFA from different palm oil mills produces different results. The compressive strength of POFA geopolymer cement is significantly affected by the concentration of NaOH solution.
However, additions of additives and other types of fly ash can help increase the compressive strength of geopolymer cement.
