Journal of Multidisciplinary Engineering Science Studies (JMESS) ISSN: 2458-925X Vol. 5 Issue 12, December - 2019 www.jmess.org JMESSP13420608 3012 Properties of cow-dung ash blended cement concretes in fresh and hardened states Adekunle Adewuyi* & Gabalaiwe L. Ramahobo Department of Civil Engineering Faculty of Engineering and Technology University of Botswana, Gaborone, Botswana *Corresponding Author: AdewuyiA@ub.ac.bw Abstract—The paper reports the investigation thee properties of cow dung ash and its influence on the fresh and hardened properties of concrete. The utilization of cow dung ash was meant to achieve purposes of waste management, reduction of greenhouse gases and its unhealthy effects on global warming and indiscriminate depletion of natural resources for the production cement. The colour of the sundried cow dung was light grey and while the pulverised CDA was dark grey/black at 900°C in 2 hours. The loose bulk density of CDA was 810 kg/m 3 . The pH of the CDA was 6.9, and the specific gravity was 2.48 g/cm 3 . The CDA was well graded with coefficients of uniformity and curvature of 12.5 and 1.62 respectively. Both the consistency and slump of CDA-blended cement concrete were quadratic and it increased with CDA content up to 20% beyond which it dropped. For a concrete mix of target strength 30 N/mm 2 , 10% CDA content was above the threshold which gave 7.8%, 5.4%, 5.2% and 2.8% strength decline at 7, 14, 21 and 28 days curing ages respectively. The tensile strength of concrete increased by 26.5% and 17.7% for 10% and 20% CDA contents respectively, while 30% CDA content recorded 26.5% tensile strength loss. A gradual increase of water absorption of concrete cubes was recorded from 0% to 10% CDA replacement for all the curing days. Beyond 20% CDA content, water absorption of concrete slowly decreased for all the four curing ages, namely 7, 14, 21 and 28 days. It can be concluded that up to 20% CDA replacement of cement is ideal for acceptable concrete performance in plastic and hardened states. Keywords—concrete, consistency, workability, compressive strength, tensile strength, water absorption, durability. I. INTRODUCTION Building and civil construction industry is one of the leading contributors to the depletion of natural resources and production of greenhouse effects. During the production of concrete, the emissions which cause greatest concern and need to be dealt with are carbon dioxide (CO 2 ) and other air emissions such as nitrogen oxides and sulphur dioxides. Approximately, one ton of CO 2 , a greenhouse gas, is delivered into the atmosphere for each ton of cement production. Worldwide, the cement industry is responsible for about 1.4 billion tons in 1995, which caused the emission of as much CO 2 gas as 300 million automobiles statistically for almost 7% of the total world production of CO 2 [1] . The construction industry is a great resources and materials consuming sector with an enormous potential for the use of waste materials generated by its own activities [2]. The use of such waste materials allows decrease the energy consumption, to preserve non-renewable natural resources, and to reduce the high amount of material that goes to landfills. However, in the cement industry, which has always been among the largest CO 2 emission sources, technical, economic and legal challenges still play as remarkable obstacles against the widespread implementation of procedures to help mitigate this situation [3]. Thus, the increase in demand for construction materials in the recent years as a result of development has called for an alternative way to develop or derive construction materials from different sources. The exorbitant cost of building and construction materials is the greatest challenge confronting housing delivery in low-and-income countries [4]. Unlike the aggregates and water that are locally sourced, the price of cement determines the overall cost of building. Cement is an indispensable material in building and construction works. It is primarily utilized as a binder in the production of sandcrete blocks, concrete and as a stabilizing admixture in soils. In order to ameliorate this problem, alternative materials from a range of widely abundant local materials have been sought to replace the expensive conventional ones, most especially cement. To achieve sustainable development in cement manufacture and building industry, pozzolans such as fly ash, silica fume, rice husk ash and blast furnace slag have been discovered to be viable alternative binders in partial replacement to cement [5, 6]. Other alternatives include recycled crushed glass waste [7- 9], recycled aggregate concrete [10] and agricultural wastes such as corn-cob ash [11], rice husk ash [5, 12] cow bone ash, saw dust ash, palm-kernel shell ash and periwinkle shell [13] have been incorporated as pozzolans in partial replacement of regular cement