ORCID Profile
0000-0003-2847-0699
Current Organisations
Kumamoto University
,
Université de Lyon
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Publisher: Springer Science and Business Media LLC
Date: 12-2019
DOI: 10.1186/S40069-019-0375-7
Abstract: This work quantified the hierarchy of the influence of three common mixture design parameters on the compressive strength and the rate of strength increase over the long term of low-calcium fly ash geopolymer concrete (FAGC) through designing 16 mixtures by the orthogonal experimental design (OED) method. The parameters used in the study were liquid to fly ash (L/FA) ratio, sodium hydroxide concentration (SHC) and sodium silicate solution to sodium hydroxide solution (SS/SH) ratio. The L/FA ratio showed little effect on compressive strength when it was varied from 0.40 to 0.52. SHC showed the greatest influence on compressive strength with little impact on the rate of strength increase after the initial heat curing. Even though the SS/SH ratio showed a small effect on the initial compressive strength, it had a considerable influence on the rate of strength increase over the long term. It was found that the compressive strength at 480 days was positively related to the Na 2 O/SiO 2 molar ratio when it was varied from 0.49 to 0.80 and the Si/Al molar ratio was increased up to 1.87. Analysis of the failure types of specimens demonstrated that compressive strength of FAGC was associated with the strength of the mortar–aggregate interface zone (MAIZ).
Publisher: MDPI AG
Date: 07-08-2019
DOI: 10.3390/MA12162501
Abstract: The influence of using cement on the residual properties of fly ash geopolymer concrete (FAGC) after exposure to high temperature of up to 800 °C was studied in terms of mass loss, residual compressive strength and microstructure. The mass loss was found to increase with the increase of exposure temperature, which is attributed to vaporization of water and dehydroxylation of sodium aluminosilicate hydrate (N-A-S-H) gels. The dehydroxylation of calcium silicate hydrate (C-S-H) gels and the disintegration of portlandite were responsible for higher mass loss ratio of FAGCs containing cement. The results showed that cement could increase compressive strength of FAGCs up to 200 °C, after which a significant reduction in residual strength was observed. It was found that FAGCs without cement yielded higher residual strength than the original strength after heating up to 600 °C. The observed increase of compressive strength up to 200 °C was attributed to the secondary geopolymerization which was evidenced in the scanning electronic microscopy (SEM) images.
Location: United Kingdom of Great Britain and Northern Ireland
No related grants have been discovered for Gaochuang Cai.