Cow dung ash (CDA): A sustainable conductive filler for enhancing electromagnetic shielding property of cement mortar

Abstract

Cow Dung ash (CDA) is a wide spread farm by-product, generated by burning dry cow-dung. Cement mortar, the work horse of construction industry inherently possesses significant electrical conductivity, thereby providing considerable electromagnetic shielding property. CDA is investigated as novel sustainable conductive filler, as sand replacement, for enhancing electromagnetic shielding property of cement mortar. The electromagnetic properties of CDA are determined employing standard wave guide techniques, in X band, and electrical conductivity around 10-2 S/m is observed. The electrical loss tangent is observed around 0.2–0.3. Cement mortar slabs with CDA as sand replacement are prototyped. Sand replacement till 15 % by volume is investigated. Considerable reduction in compressive strength is reported in literature for sand replacement beyond 15 %. After 28 days of curing, the prototyped slabs are subjected to electromagnetic shielding effectiveness determination, as per ASTM 4935 two antenna standard, in the X band of frequencies centred around 10 GHz. Shielding Effectiveness (SE) around 7 dB is observed for 3 % CDA as sand replacement, around 10 dB for 10 % replacement, and around 20 dB for 15 % CDA. Compressive strength measurement employing Universal Testing machine presented significant reduction in compressive strength as CDA replacement tend towards 15 %. Employing CDA loaded cement mortar for plastering, is a low cost, easy deployable solution for realizing customized electromagnetic shielding levels in buildings housing critical electrical and electronic infrastructure including servers and data centres. Realizing low cost, easy deployable customized shielding solutions is an upcoming research domain, primarily due to the anticipated increase in ambient electromagnetic field levels in our surroundings caused by the rampant deployment of communication technologies including 5G and IoT. Apart from providing positive environmental impact, acting as sand replacement, enhanced CDA utilization by engineering sectors can lead to good revenue generation model for rural economic development.