Production of Hollow Load-Bearing Concrete Masonry Blocks from Fly Ash-Based Geopolymer
Abstract
This research aimed to study the effects of aggregate content, sodium hydroxide (NaOH) concentrations and curing temperature on compressive strength and water absorption of geopolymer concrete block. The geopolymer concrete block were prepared from Mae Moh fly ash with sodium silicate (Na2SiO3) and sodium hydroxide (NaOH) solutions. The molar ratio of SiO2/Al2O3 was kept constant and concentration of NaOH was varied at 12, 14, 16, and 18 molar. The ratio of 1:4 (S), 1:6 (M) and 1:8 (L) by weight of fly ash : dust limestone were used as an aggregate. The geopolymer concrete block were prepared by using the Cinva-Ram machine. The samples were air cured at room temperature (25oC) and 65oC for 24 hours and continuous curing until the age test in air. The geopolymer concrete block was tested for compressive strength at 7, 14, and 28 days. In addition, water absorption of geopolymer concrete block was tested at 28 days. The results showed that the compressive strength of geopolymer concrete block increase with the increase in NaOH concentration and curing temperature. The water absorption of geopolymer concrete block is low with the concrete of high compressive strength. An increase in amount of aggregate as high as M (the ratio of 1:6 by weight of fly ash : dust limestone) result in increased compressive strength; however, the compressive strength was found to decrease when using high amount of aggregate L (the ratio of 1:8 by weight of fly ash : dust limestone). In addition, high temperature curing has more effective on increasing of compressive strength in geopolymer concrete block with lower NaOH concentration than that with higher NaOH concentration.
Key words : fly ash, geopolymer, load-bearing concrete masonry blocks, compressive strength,
sodium hydroxide concentration
This research aimed to study the effects of aggregate content, sodium hydroxide (NaOH) concentrations and curing temperature on compressive strength and water absorption of geopolymer concrete block. The geopolymer concrete block were prepared from Mae Moh fly ash with sodium silicate (Na2SiO3) and sodium hydroxide (NaOH) solutions. The molar ratio of SiO2/Al2O3 was kept constant and concentration of NaOH was varied at 12, 14, 16, and 18 molar. The ratio of 1:4 (S), 1:6 (M) and 1:8 (L) by weight of fly ash : dust limestone were used as an aggregate. The geopolymer concrete block were prepared by using the Cinva-Ram machine. The samples were air cured at room temperature (25oC) and 65oC for 24 hours and continuous curing until the age test in air. The geopolymer concrete block was tested for compressive strength at 7, 14, and 28 days. In addition, water absorption of geopolymer concrete block was tested at 28 days. The results showed that the compressive strength of geopolymer concrete block increase with the increase in NaOH concentration and curing temperature. The water absorption of geopolymer concrete block is low with the concrete of high compressive strength. An increase in amount of aggregate as high as M (the ratio of 1:6 by weight of fly ash : dust limestone) result in increased compressive strength; however, the compressive strength was found to decrease when using high amount of aggregate L (the ratio of 1:8 by weight of fly ash : dust limestone). In addition, high temperature curing has more effective on increasing of compressive strength in geopolymer concrete block with lower NaOH concentration than that with higher NaOH concentration.
Key words : fly ash, geopolymer, load-bearing concrete masonry blocks, compressive strength,
sodium hydroxide concentration
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