Abstract
Rice husk ash is one of the most widely studied biomass ashes used in pozzolanic addition. Given its lower silica content, rice straw ash (RSA) has been explored less often, despite the fact that, according to the United Nations Food and Agriculture Organization (FAO), rice straw (RS) production is estimated at 600 million tons/year. In this work, RSA was physically and chemically characterized, and its pozzolanic properties were assessed. A controlled conditioning, burning, homogenization and grinding procedure was carried out to obtain RSA from RS. Chemical composition, insoluble residue, reactive silica, chloride content and particle size distribution were assessed for ash characterization. To determine RSA pozzolanicity, Frattini, electrical conductivity and pH measurements in an aqueous suspension of hydrated CH/RSA mixtures were obtained. Portland cement (PC) mortars with 15% and 30% RSA substitutions evaluated. The mechanical tests showed specimens with a strength activity index up to 90% and 80% with 15% and 30% RSA, respectively, after 3 days, and these values grew to 107–109% after 90 curing days.
Highlights
One of the most important challenges in the construction industry is to reduce environmental impacts, produced principally by widespread ordinary Portland cement (PC)use, given its associated large carbon footprint
We decided to modify the definitions and criterion proposed by Tashima et al for pH and the conducRSA employed in the research contains many soluble chlorides among tivityThe analysis
We decided to CH/rice straw ash (RSA) mix for time (t) is as follows (Equation (2)): modify the definitions and criterion proposed by Tashima et al for pH and the conductivity
Summary
One of the most important challenges in the construction industry is to reduce environmental impacts, produced principally by widespread ordinary Portland cement (PC). Use, given its associated large carbon footprint. For the production of 1 kg of PC, approximately 1 kg of CO2 is emitted [1]. The latest research suggests that around 8% of global anthropogenic CO2 is due to PC fabrication [2]. The use of Supplementary Materials from industrial waste can contribute to reducing the carbon footprint.
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