Improving the sustainability of lime mortars by reusing cow hair

In many countries, construction, agriculture and livestock sectors produce and emit a large amount of waste and greenhouse gases, accelerating the climate change. For that, new trends and policies for waste management are required due to the high and constant demand for natural resources. The recent activities framed in the green economy are favouring the reuse and recycling of many waste products, in the so-called “Zero Waste” initiatives to reduce the carbon footprint, as well as to the reduction of associated energy expenditure. Among these waste products, those linked to animal by-products not intended for human consumption are usually incinerated for their elimination in Spain, contributing to the emission of CO₂. Consequently, new initiatives are required to promote the reuse of this waste, such as in the development of more sustainable construction products. This paper presents the new results of the SoSCal Project, comparing sets of lime mortar with a proportion of cow hair of 0%, 0.5%, 1%, 2%, 5%, 10% and 12% in weight per kilo of mortar. Some of the advances achieved are that, regardless of the amount of hair added, no cracking process has been observed and the amount of water required can be reduced by 5%, so that extrapolation to larger production quantities would result in significant savings. Although it is necessary to carry out more tests since the workability is compromised, and therefore it will be important to find conditions according to the need for the applicability of the mortar. Another aspect is the increase in the resistance to crystallization of salts with respect to the mortar without fibres, although the durability has been greater in practically all cases, regardless of the quantity of fibres. The addition of hair has affected the thermal properties, specifically the heat transmissivity through the samples, showing a direct relationship between the percentage of added hair and this parameter. The maximum recorded temperatures differed by almost 8°C between the samples without fibres (0%) and those containing 12% of hair after one hour of heating, with the latter also cooling down much faster due to the higher hair content. Based on the results obtained, the addition of animal fibres is showing very positive results compared to the reference mortar. Thus, enhancing the properties of a traditional product, such as lime, compared to Portland cement will also have a very positive effect, since it could reduce the production of this type of cement by having other options, which would also imply reducing the emission of CO₂ into the atmosphere. However, it is necessary to continue with the tests already started and to carry out other tests, especially mechanical and weathering durability tests to evaluate its performance.

 

Acknowledgements: This study was financially supported by the Research Project TED2021-132417A-I00 funded by MCIN/AEI /10.13039/501100011033 and by the European Union NextGenerationEU/ PRTR