American Journal of Construction and Building Materials 2020; 4(2): 33-38 http://www.sciencepublishinggroup.com/j/ajcbm doi: 10.11648/j.ajcbm.20200402.11 ISSN: 2640-0022 (Print); ISSN: 2640-0057 (Online) Sustainable Concrete Containing Recycled Aggregates and Pozzolana in Sudan Eltahir Elshiakh 1, * , Salma Mahmoud 2 1 Construction Engineering Department, Sudan University of Science & Technology, Khartoum, Sudan 2 Civil Engineering Department, University of Science & Technology, Omdurman, Sudan Email address: * Corresponding author To cite this article: Eltahir Elshiakh, Salma Mahmoud. Sustainable Concrete Containing Recycled Aggregates and Pozzolana in Sudan. American Journal of Construction and Building Materials. Vol. 4, No. 2, 2020, pp. 33-38. doi: 10.11648/j.ajcbm.20200402.11 Received: July 17, 2020; Accepted: August 3, 2020; Published: August 13, 2020 Abstract: Sustainable trails in the building industry called for preserving the natural resources through the production of green concrete. This is concrete where waste materials are used as at least one of its components, or its production does not lead to environmental destruction through the reduction, reuse or recycling techniques. Experimental results from a study on the potential usefulness of recycled coarse aggregates (RCA) blended with locally available natural Pozzolana are outlined in this paper. Eight concrete mix scenarios were considered: a standard mix with 100% natural coarse aggregates (NCA), 25% RCA, 50% RCA, 75%RCA, 100% RCA and no Pozzolana, 100% RCA and 10% Pozzolana, 100% RCA and 20% Pozzolana, 100% RCA and 30% Pozzolana. Slump test was conducted and the results were all within the specific limits. It was conversely realized that the workability decreased in the cases of replacing NCA by RCA with no Pozzolana while an increase was recognized when the Pozzolana was add in the different percentages with the best results achieved with 100% RCA and 20% Pozzolana. The compressive strength results were consistent for the different curing ages with the highest strength being acquired with the mix that contained 100%RCA and 10% Pozzolana. The results of the durability test revealed better values for the wave length speed value when the NCA was replaced by the RCA. Considering these outcomes, the optimum result was achieved in the case of 100%RCA and 10%Pozzolana. Thus, the experimental results offer good indication for a potential usefulness of RCA proposing a reasonable way for preserving virgin natural materials. Keywords: Compressive Strength, Pozzolana, Recycled Aggregates, Sudan, Workability 1. Introduction Concrete is a heavy, rough building material made from a mixture of cement, fine and coarse aggregates, water and maybe some additives in different proportions produced to meet certain design specifications. For the many negative impacts that the concrete production poses, many researchers classified it as environmentally unfriendly. The fact that concrete production consumes natural resources such as river sand, clays and rocks which will be consumed but not returned back and involves the emission of huge amounts of CO 2 during the production of cement-as one of its major constituents- concerns arise from the associated severe negative impact on the environment. Accordingly, sustainable trails in the building industry called for preserving these natural resources through the production of eco-friendly concrete. This is concrete where waste materials are used as at least one of its components or its production does not lead to environmental destruction through the reduction, reuse or recycling techniques. The call for cement and concrete production sustainability was stressed by [1] with estimated figures on the worldwide production of cement and the associated hazards from the manufacturing process showing how significant is the carbon footprint of the global cement and concrete industry. Being affected by economic and social transformations in societies, urbanization and patterns of population growth has changed entailing consequences of industrialization, globalization and environmental pollution. Global warming is the most important sustainability issue today in the public mind. The World Commission on Environment and Development