Rice straw ash: A potential pozzolanic supplementary material for cementing systems

Abstract

Biomass waste from rice straw has many management problems, including field firing causing severe air pollution and natural organic decomposition resulting in methane emission. The conversion of this waste to ashes may offer the possibility of reusing them in cementing systems. For the first time ashes from different parts of the rice plant (Oryza sativa) were characterised from the chemical composition point of view: rice leaf ash (RLA), rice leaf sheath ash (RlsA) and rice stem ash (RsA). Microscopic studies on ashes revealed heterogeneity in the distribution of chemical elements in the remaining cellular structure (spodograms). The highest concentration of SiO 2 was found in dumbbell-shaped phytoliths (%SiO 2 > 78%). In the global chemical composition of ashes, SiO 2 was also the main oxide present. According to Vassilev's classification of chemical composition, RLA belongs to the K-MA zone (medium acid), RlsA to the K-zone (low acid) and RsA to the S-zone (high acid). Calcination temperatures ≥550 • C completely removed organic matter from the straw and ashes underwent significant sinterisation by calcining at 650 • C due to the presence of potassium chloride. Here, ashes from global straw (rice straw ash, RSA) are characterised (via X-ray diffraction, Fourier transform infrared spectroscopy and thermogravimetry) and tested from a reactivity point of view (reaction towards calcium hydroxide) in order to assess the possibility for its reuse in cementing systems. Results from pastes made by mixing RSA and calcium hydroxide showed that the pozzolanic reactivity of the ashes is important (hydrated lime fixation of 82% for 7 days and 87% for 28 days in RSA:hydrated lime paste) and cementing C S H gel is formed after 7 and 28 days at room temperature. Compressive strength development of Portland cement mortars with 10% and 25% replacements by RSA yielded 107% and 98% of the strength of control mortar after 28 days of curing. Frattini test confirmed the pozzolanicity of the RSA blended cements. These reactivity results are very promising in terms of the potential reuse of ashes in cementing systems.

An Approach to a New Supplementary Cementing Material: Arundo donax Straw Ash

“…In this diagram, the ashes from different parts of Arundo donax are located in the K zone, which corresponds to low-acid biomass ashes rich in potassium and chlorine. These ashes derived from Arundo donax are very different from those found for rice husk, sugar cane leaf and bamboo leaf [11]. Table 2 summarizes the chemical compositions of the samples determined by EDX.…”

“…These include sugarcane bagasse ash (SCBA), studied in ordinary Portland cement (OPC) mixes [8,9], and sugarcane straw ash (SCSA), studied in geopolymeric systems based on blast furnace slag [10]. Rice straw ash (RSA) has been characterized and used to replace 10% and 25% OPC [11]. Wheat straw ash and corncob ash were studied by Memon et al [12,13] and demonstrated good pozzolanic performance of the ash, aiding in the production of environmentally friendly concrete.…”

Can Common Reed Fiber Become an Effective Construction Material? Physical, Mechanical, and Thermal Properties of Mortar Mixture Containing Common Reed Fiber

“…For example, some ashes derived from agricultural biomass, such as rice husk, biochar, and pam oil fuel ash, have been successfully used in cement or concrete as supplementary cementitious materials (SCMs). It is well-known that the use of rice husk ash in a concrete matrix can improve the strength and durability of concrete due to the pozzolanic reaction between highly reactive amorphous silica from rice husk ash and portlandite from cement hydration [8][9][10][11][12]. Cuthbertson et al [13] used biochar from residual biomass of the bio-ethanol industry as a concrete filler.…”

Comparative Study of Water-Leaching and Acid-Leaching Pretreatment on the Thermal Stability and Reactivity of Biomass Silica for Viability as a Pozzolanic Additive in Cement

“…The major components of RH are organic materials such as hemicellulose, cellulose, and lignin, totaling about 85%, and the remaining ash content is 15–20% [ 4 ]. Of all the residues of edible plants, the ash obtained from the calcined RH has the highest silica content [ 5 ].…”