The High Volume Reuse of Hybrid Biomass Ash as a Primary Binder in Cementless Mortar Block

Abstract

High Calcium Wood Ash (HCWA) and Pulverised Fuel Ash (PFA) are by-products from the wood biomass and coal energy production which are produced in large quantity with combined annual production of 500 million tonnes. This poses a serious problem for disposal of the waste material especially at places where land is scarce. The prescribed study was aimed to examine the mineralogical phases and their respective amount present in the industrial wastes which governs the hydration mechanism towards self-sustained solidification of the ashes when used in combination. Besides, the influence of various forming pressure and hydrothermal treatment temperature on mechanical strength performance of HCWA-PFA cementless mortar blocks was also examined. In the study, the mechanical strength of the HCWA-PFA cementless mortar block produced using various forming pressure and hydrothermal treatment temperature was assessed in terms of compressive strength and dynamic modulus. The results of the study are indicative that HCWA is rich in calcium oxide and potassium oxide content. This enables the hybridization of HCWA with the amorphous silica and alumina rich PFA to form a solid geopolymer binder matrix for fabrication of cementless mortar block. Throughout the study, dimensionally and mechanically stable HCWA-PFA geopolymer mortar blocks were successfully produced by press forming and hydrothermal treatment method. Based on statistical analysis, the hydrothermal treatment temperature has a statistically insignificant effect on the mechanical strength of the HCWA-PFA cementless mortar blocks. The dominant factor which governs the mechanical strength of the HCWA-PFA cementless mortar blocks was found to be the hydraulic forming pressure. Moreover, it was found that hybridized HCWA-PFA can be recycled as the sole binder for fabrication of cementless concrete block which is a useful construction material.

Metakaolin-based inorganic polymer synthesis using cotton shell ash as sole alkaline activator

“…Biomass ashes are usually valorised industrially as an additive in cement, in the neutralisation of acid waste streams, as raw materials in fertiliser and ceramic glazes production [20], and a recent study has shown that their addition in mortars as aggregate can also enhance the absorption of Volatile Organic Compounds (VOCs) [21]. Their alkaline nature and mineralogical content in general have motivated some research teams to investigate their role in the production of inorganic polymers, without the addition of any manufactured chemical activator, as was the case with wood and some agricultural residues [10,22,23].…”

Application of wood biomass ash in cement composites

“…Povećanjem udjela PDB-a raste i električna provodljivost. [20] Kad je 10 % PDB-a u masi veziva, smanjuje se ukupno skupljanje (uslijed sušenja i autogeno), što rezultira manjim naprezanjima unutar elementa u konstrukciji [4].…”

Use of wood biomass ash (WBA) as a cement replacement in concrete

“…Troškovi upravljanja otpadnim pepelom iz biomase iznose između 200 i 500 eura po toni, a u budućnosti se može očekivati povećanje troškova odlaganja u obliku poreza ili naknada na odlaganje, kao i poteškoće u pronalaženju novih odlagališta te strože EU direktive vezano uz odlaganje [13]. Zasad se 70 % pepela iz drvne biomase (PDB) odlaže, 20 % se nastoji primijeniti kao dodatak tlu u poljoprivredi i 10 % za ostale namjene [2,14]. Odlaganje pepela iz drvne biomase bez ikakva oblika kontrole može prouzročiti onečišće-nje zraka sitnim česticama nošenim vjetrom [15], onečišćenje podzemnih voda zbog izluživanja teških metala iz pepela, te ulazak teških metala u prehrambeni lanac [16].…”