Effects of different wood aggregates on the compressive strength of fly ash and metakaolin-based geopolymer lightweight composites

Abstract

Class F fly ash with 30% substitution of metakaolin was used as an alumino-silicate source to produce lightweight geopolymer composites. The investigations focused on different types of wood aggregates that influence the compressive strength of lightweight geopolymer composites. Wood particles (WP), wood flour (C100), and wood fiber (WF) were added to fly ash and metakaolin-based geopolymers at 10% solid content as reinforcement materials. NaOH in combination with Na2SiO3 was used as the alkaline activator with a liquid-to-solid ratio of 1.33:2.00. The samples were cured at 20 °C for 7, 14, and 28 days, and at 80 °C for 6 and 24 h (two different curing temperatures and five different curing times). It was observed that the types of wood aggregates affected the properties and compressive strength of lightweight geopolymer composites. The highest compressive strength of about 38.4 MPa was achieved for the sample containing wood flour that was cured for 28 days.

Keywords

• geopolymer
• lightweight composite
• fly ash
• metakaolin
• wood aggregate