Effect of Some Additiveson Mechanical and Physical Properties of Cob Building in Iraq

Abstract

Construction materials needs to be low energy consuming and mud construction system is less energy consuming and very successful in different weather conditions. Cob is an old earth building method passed down through the millennia, Cob is a sustainable earth building material with mud soil, coarse sand, straw and water are thoroughly combined and beaten together. This research aims to study the effect of some additives on physical properties (thermal conductivity and water content %) and mechanical property (compression strength) of Cob. These additives are: polymethyl methacrylate (PMMA) grains, hooked end steel fibers (HESF), wood as sawdust (SDW) and goat hair fibers (GHF), with 2 and 4 % by weight as the percentages of additives. Results shows that (PMMA) improves the insulation of Cob to maximum values compared to other additives in both 2 and 4 % followed by (SDW) and (GHF) respectively. All additive materials improve the compressive strength of Cob but with different extents depending on the water content. (GHF) is the best material to improve the compressive strength of Cob followed by (HESF) and (PMMA) respectively while adding (SDW) will lead to reverse effect i.e. decreasing the compressive strength.