Mechanical properties of biopolymer-stabilised soil-based construction materials

Abstract

Soil-based construction materials are of interest as structural building materials due to their green credentials, as well as being present in many historical structures. For effective conservation of the latter, and to motivate greater uptake for new construction, understanding of the mechanical and hydraulic properties of these materials is in need of improvement. Earthen construction materials can be considered to be manufactured unsaturated soils, and advances in understanding can be made by considering them from a geotechnical point of view. This paper presents initial results from a major programme of testing, seeking improved properties for earthen construction materials, where unusual organic compounds have been employed as stabilisers. Two gums (guar and xanthan) used as stabilisers for a soil mixture are shown to have significant effects on certain mechanical properties, some of which can be explained, and other aspects which are in need of further investigation.

Biopolymers as a sustainable solution for the enhancement of soil mechanical properties

“…Splitting tensile strength test. The increase of soil tensile strength with the addition of XG and GG was proven by direct tensile tests performed by Muguda et al 43 . They have found that the tensile strength of soil increases with biopolymer concentration and time.…”

Advances in the Use of Biological Stabilisers and Hyper-compaction for Sustainable Earthen Construction Materials

“…Methodology Stabilisation using biopolymers is achieved through "hydrogels" which are formed through the interaction of soil, biopolymer and water particles. Unlike cementitious bonds formed due to hydration of cement, these "hydrogels" bind soil particles through a combination of chemical bonds and soil suction (Muguda, et al, 2017). As these hydrogels become susceptible to weakening on contact with water, durability tests such as accelerated erosion tests, spray tests, and wire brush tests were considered to be too vigorous and hence an alternative test was chosen, namely the "Geelong" Test (NZS 4298, 1998).…”

“…Recent work reported in Aguilar, et al, (2016) and Nakamatsu, et al, (2017) has investigated the use of biopolymers (namely chitosan and carrageenan) as stabilisers and has reported that the addition of these biopolymers improved mechanical and durability performance of earthen materials. Very recently, the mechanical behaviour of earthen construction materials stabilised with the biopolymers guar gum and xanthan gum was studied by Muguda, et al, (2017) which showed that the addition of these biopolymers improved compressive and tensile strengths. These biopolymers sequester CO 2 during production (Chang et al, 2016;Krishna Leela & Sharma, 2000) in contrast to cement, which leads to the opposite, however energy required in production of the gums may be much greater than for an equivalent amount of cement (e.g.…”

“…For unstabilised earthen construction, the standard tests are immersion, contact, drip and suction tests, while for stabilised materials, accelerated erosion, spray and wire brush tests are conducted to assess durability. Here we examine the durability properties of the materials studied in Muguda, et al, (2017).…”

Bacterial Growth Induced Biocementation Technology, ‘Space-Brick’ - A Proposal for Experiment at Microgravity and Planetary Environments

“…Interestingly, Lambert and Randall [16] have shown that the green brick can be manufactured with the use of human urine as a urea source [17]. Researchers have also explored possible admixtures to strengthen the consolidated samples [18,19] . Bio-based admixtures using additives such as xanthan gum, gellan gum, welan gum lignosulfonates are being explored by researchers for improvement in durability [20].…”