Feasibility of Using Selected Addis Ababa Basaltic Crusher Dust as Partial Cement Replacement Material in Concrete Production
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Date
2018-01
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Addis Ababa University
Abstract
The production of coarse aggregates generates up to 25% Crusher by-product. Crusher by-product contains 15% to 25% fine materials called crusher dust. In most of aggregate production plants found in Ethiopia, dry screening to separate the excess fines from crusher by-product is not adopted. Hence crusher by-product containing high amount of fines becomes controversial to be used as manufactured sand, on the other hand there are economic and environmental issues speculated in relation to the use of River sand and Portland cement products.
Consequently Efforts have been made in the concrete industry to use crusher dust as partial replacement of fine aggregates and cement. This research work examines the feasibility of using raw basaltic crusher dusts as a partial replacement of OPC and PPC cement in concrete production. Here OPC and PPC were partially replaced by Basaltic Crusher Dust as 5%, 10%, 15% and 20% to prepare blended cements and produce commonly used C-25 and C-30concretes. Then tests were performed to examine the effects of basaltic crusher dust replacements on consistency and setting time of cement paste; compressive strength of cement mortar; workability of fresh concrete and compressive strength and water permeability of hardened concretes. Additionally it was attempted to survey the possible economic and environmental advantages derived from using basaltic crusher dust as a partial cement replacement material.
From the results obtained, it was noticed that basaltic crusher dust can replace 5% of PPC and 10% of OPC with comparable concrete compressive strength and water penetration resistance. However, basaltic crusher dust containing up to 20% clay shows higher loss in compressive strength of cement mortar and concrete compressive strength. Furthermore it was observed that partial replacement of basaltic crusher dust with OPC or PPC is more favorable in C-25 than C-30 concrete. Replacing crusher dust were also found to reduce environmental and related problems created in lesser use of crusher by-product and crusher dust produced during aggregate production. Finally it was able to observe that using basaltic crusher dust as partial cement replacement material by 5% and 10% results in saving 2.7% to 6.4% cost of concretes with comparable properties.
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Keywords
Basaltic crusher dust, Blended cement, Crusher By-product, Concrete