การตรวจสอบจีโอโพลิเมอร์ที่มีส่วนผสมของกากผงเหล็กบนเงื่อนไขการบ่มร้อนจากการเหนี่ยวนำแม่เหล็กไฟฟ้า

Abstract

Geopolymer is an environmentally friendly material that has been developed and researched over the years. It is intended to be used as a substitute for concrete as a construction material. Because it can reduce carbon dioxide emissions into the atmosphere. Nevertheless, the usage of geopolymer in construction has not been widely utilized due to heat curing problems. In general, many pozzolanic materials such as fly ash, bottom ash, and etc. are universally used to synthesize geopolymer. However, there are other materials that have not received interest in civil engineering including Waste Iron Powder (WIP), which is a waste from the steel industries. Thailand's steel industries produces more than 20,000 tons of these wastes per year and the trend is increasing. This may cause long-term environmental problems in the future. WIP has good thermal properties and it can also be induced to generate heat by electromagnetic fields. The author would like to study this WIP by applying it to the production of high calcium fly ash based geopolymer by studying its properties and a new method of heat curing using electromagnetic field for heat induction compared to using oven, a conventional heat curing method. From the results, it was found that the amount of WIP affects on the physical and mechanical properties of the geopolymer. More WIP content resulted in an increase in samples' density due to the difference between the specific gravity of WIP and fly ash. The higher content of WIP also reduced the initial and final setting time of the geopolymer. The chemical reaction between WIP and alkaline solution accelerated the solidification of geopolymer. For the results of the first phase, heat curing by oven, the W20GP sample (20% WIP by weight of fly ash) mixed with 8 M sodium hydroxide, SS/SH ratio of 1.00 and L/B = 0.45 at 28 aged day were able to provide the highest compressive strength and flexural strengh of 50.5 MPa and 8.5 MPa, respectively. However, the reduction of compressive strength development was detected. Meanwhile, from the results of the second phase, it was found that the electromagnetic induction heating in the WIP mixed geopolymer sample was practical. The EIGP5 sample (5% WIP by weight of fly ash) provided the highest compressive strength of 76.8 MPa, and the EIGP20 (20% WIP) sample had the highest flexural strength of 12.8 MPa. The strength development with time occured. SEM, EDX, XRD techniques were performed to analyze the microstructure for describing the results. According to this study, electromagnetic heat induction in fly ash based geopolymer mixed with WIP was practically possible. The mechanical properties of EIGPx samples are better than oven curing samples. It can be concluded that WIP is a potential material for research in civil engineering field.