Embodied Energy & Cost Issues of Tank-Bed-Lime Based Geopolymer Adobes

Abstract

It is well-known that a product or a system is sustainable if it is economically viable, socially acceptable and environmentally friendly. Load bearing masonry is one such example which is quite sustainable, especially if the masonry units are locally available. It is important to quantify the environmental benefits and cost, if an alternative to an existing technology is to be suggested. Of course the issues related to acceptance have to be discussed and addressed. This paper presents the quantification of embodied energy and cost of limepozzolana-cement (LPC) geopolymer based masonry units made using locally available bulk ingredients viz. tank-bed soil (TBS) and brick-powder (BP). The masonry adobe units developed have achieved the target performance in terms of strength, low water absorption and relative ease of production. Simultaneously the issues related to cost are also discussed in this paper. The studies have revealed that the bulk contributor to embodied energy and cost of geopolymer adobes are the alkaline materials viz sodium hydroxide and sodium silicate. However, the embodied energy and cost per unit strength appears to be better than that of conventional table moulded bricks in south India, especially when alkaline solution at 2M concentration is used with LPC.

Use of Vietnamese rice husk ash for the production of sodium silicate as the activator for alkali-activated binders

“…Embodied energy and CO2 footprint of commercially available waterglass were obtained from the literature, although with significant scatter (Jamieson et al, 2015, Fawer et al, 1999, Jyothi et al, 2017, Maskell et al, 2014, Mathew et al, 2013, Turner and Collins, 2013, Habert et al, 2011. EEraw equal to 5 MJ/kg and CFraw equal to 1.5 kg/kg were considered suitable values for waterglass.…”

“…The EE of NaOH was assumed to be 8MJ/kg as recommended in the literature (Jamieson et al, 2015, Fawer et al, 1999, Jyothi et al, 2017, Maskell et al, 2014, Mathew et al, 2013, Turner and Collins, 2013, Habert et al, 2011. This value was then scaled down according to the amount of NaOH in 1 kg of solution (i.e.…”