Catalysis

Composite number

Curing (chemistry)

Metallurgy

Materials science

Sodium hydroxide

Acetic anhydride

Ultimate tensile strength

Telecommunications

Computer science

Durability

Organic chemistry

SISAL

Degradation (telecommunications)

Cement

Lime

Alkali metal

Composite material

Chemistry

Wetting

Flexural strength

Calcium hydroxide

Construction and Building Materials

The degradation of sisal fibre in a cement-based matrix due to the highly alkaline environment reduces the strength of the composite. In this research, to avert this degradation, alkaline treatment and acetylation were respectively performed with sodium hydroxide (NaOH) and Acetic Acid or Acetic Anhydride to improve the resistance of the fibre to alkaline attack. In addition, single fibre pull-out (SFP) tests were performed to evaluate the influence of chemical treatment on fibre strength, fibre-matrix interaction and also determine the critical fibre length. Specimens were tested in indirect tension (flexure) at 28 days to determine the strength of the composite. Additional ageing tests by extended curing in water at 24 °C, lime saturated hot water at 70 °C, and alternate cycles of wetting and drying were done. Aged samples were further tested at 90 days to evaluate the durability of the fibre. It was found that a combination of alkali treatment and acetylation was the most effective treatment condition, followed by that of alkali treatment at low concentrations of sodium hydroxide. At higher concentrations of sodium hydroxide, a significant reduction in strength was observed. Chemical treatment improves the durability of sisal fibres in concrete, albeit slight degradation still occurs.

Durability of chemically modified sisal fibre in cement-based composites