Characterisation of mechanical and thermal properties in flax fabric reinforced geopolymer composites

This paper presents the mechanical and thermal properties of flax fabric reinforced fly ash based geopolymer composites. Geopolymer composites reinforced with 2.4, 3.0 and 4.1 wt% woven flax fabric in various layers were fabricated using a hand lay-up technique and tested for mechanical properties such as flexural strength, flexural modulus, compressive strength, hardness, and fracture toughness. All mechanical properties were improved by increasing the flax fibre contents, and showed superior mechanical properties over a pure geopolymer matrix. Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM) studies were carried out to evaluate the composition and fracture surfaces of geopolymer and geopolymer/flax composites. The thermal behaviour of composites was studied by thermogravimetric analysis (TGA) and the results showed significant degradation of flax fibres at 300 °C

Valorisation of agricultural biomass‑ash with CO2

This work is part of a study of different types of plant-based biomass to elucidate their capacity for valorisation via a managed carbonation step involving gaseous carbon dioxide (co2). the perspectives for broader biomass waste valorisation was reviewed, followed by a proposed closed‑loop process for the valorisation of wood in earlier works. the present work newly focusses on combining agricultural biomass with mineralised co2. Here, the reactivity of selected agricultural biomass ashes with co2 and their ability to be bound by mineralised carbonate in a hardened product is examined. three categories of agricultural biomass residues, including shell, fibre and soft peel, were incinerated at 900 ± 25 °C. The biomass ashes were moistened (10% w/w) and moulded into cylindrical samples and exposed to 100% CO2 gas at 50% RH for 24 h, during which they cemented into hardened monolithic products. the calcia in ashes formed a negative relationship with ash yield and the microstructure of the carbonate‑cementing phase was distinct and related to the particular biomass feedstock. this work shows that in common with woody biomass residues, carbonated agricultural biomass ash‑based monoliths have potential as novel low‑carbon construction products

Flexural Behavior of Reinforced Concrete Beams Made with Recycled Concrete Aggregates

The reuse of Construction and Demolition Waste (CDW) to produce new materials is an effective method for reducing the negative impacts from the inadequate waste disposition, in addition to bringing economic and environmental benefits to the industry. The use of Recycled Concrete Aggregate (RCA) in concrete is a technique widely disseminated, however, using this material for structural applications is a target of distrust among professionals in the construction sector. Therefore, the purpose of this study is to analyze the influence of using RCA to replace 100% of course natural coarse aggregates with size fraction 9.5-19 mm in the flexural behavior of reinforced normal-strength concrete beams (35 MPa). In addition to a reference mixture produced with only natural aggregates, a Recycled Aggregate Concrete (RAC) mixture was designed, according to the well-known Compressible Packing Model (CPM), using RCA from demolition waste. The mechanical behavior of the concrete mixtures was characterized by compressive and splitting tensile tests. A pair of flexural critical beams of each concrete mixture was tested under a supported four-point loading condition at the age of 28 days. All tested beams had 240 cm length and rectangular cross section of 20 x 30 cm(2). The experimental cracking, yielding and ultimate load of the beams were measured. Besides that, the load-strain behavior for concrete was obtained, as well as the load-deflection behavior. The results showed that the flexural behavior of RAC beams was not negatively affected by the presence of RCAs