Abstract
Alkali activated concretes have emerged as a prospective alternative to conventional concrete wherein diverse waste materials have been converted as valuable spin-offs. This paper presents a wide experimental study on the sustainability of employing waste sawdust as a fine/coarse aggregate replacement incorporating fly ash (FA) and granulated blast furnace slag (GBFS) to make high-performance cement-free lightweight concretes. Waste sawdust was replaced with aggregate at 0, 25, 50, 75, and 100 vol% incorporating alkali binder, including 70% FA and 30% GBFS. The blend was activated using a low sodium hydroxide concentration (2 M). The acoustic, thermal, and predicted engineering properties of concretes were evaluated, and the life cycle of various mixtures were calculated to investigate the sustainability of concrete. Besides this, by using the available experimental test database, an optimized Artificial Neural Network (ANN) was developed to estimate the mechanical properties of the designed alkali-activated mortar mixes depending on each sawdust volume percentage. Based on the findings, it was found that the sound absorption and reduction in thermal conductivity were enhanced with increasing sawdust contents. The compressive strengths of the specimens were found to be influenced by the sawdust content and the strength dropped from 65 to 48 MPa with the corresponding increase in the sawdust levels from 0% up to 100%. The results also showed that the emissions of carbon dioxide, energy utilization, and outlay tended to drop with an increase in the amount of sawdust and show more the lightweight concrete to be more sustainable for construction applications.
Highlights
Sawdust is a well-known agriculture and by-product waste material resulting from the wood industry
The results of the slump reading showed that an increasing content of sawdust replacing natural aggregates reduced the workability of the prepared concretes
The influence was more prominent at higher sawdust contents (100%)
Summary
Sawdust is a well-known agriculture and by-product waste material resulting from the wood industry. The authors found that concrete including sawdust possessed unique characteristics and presented better outcomes for the thermal and mechanical characteristics of the cement-based composite, making it economical compared to various other materials in the construction sector Several products such as geopolymer and alkali-activated materials have been introduced as alternatives to conventional concrete and have emerged as constructional materials with lower CO2 footprints [11,12,13,14,15,16,17]. According to Ismail et al [41], an early-age compressive strengths (CSs) of the FA/GBFS composite activated by the NH/NS may increase considerably with a minute quantity of hydrated lime This FA geopolymer blended with slag exhibited an excellent mechanical and durability performance [42]. Previous studies have attempted to fabricate eco-friendly high-performance LWCs, cement-free concretes, and alkali-activated geopolymers, where the primary focus was to achieve improved strength and durability characteristics
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