Madirisha, Musa2021-10-122021-10-122019Madirisha,M (2019) Investigation on suitability of crusher dust to replace natural sand in concrete works A Case Study of Dodoma and Lugoba Quarries,Masters dissertation,University of Dar es Salaam, Dar es Salaam.http://41.86.178.5:8080/xmlui/handle/123456789/15996Available in print form, East Africana Collection, Dr.Wilbert Chagula Library, class mark (THS EAF TA444.T34M234)Concrete is a most usable building material, and is commonly made of natural sand, crushed coarse aggregates, cement and water. Due to development, population growth and rapid growth of construction activities, natural sand sources are becoming exhaustive; hence raise a need of a new material with similar properties for replacement of natural sand in concrete works. In this stud, laboratory tests have been made to find out a suitable mix proportion of desired strength by replacing natural sand with two types of crusher dusts in cement concrete. In laboratory experiments, six numbers of mix samples for each type of crusher dust were prepared by replacing natural sand with crusher dust at 0, 20,40,60,80 and 100%.A mix design proportion of 1:1:8:3:5 by weight for cement, natural sand and coarse aggregates respectively was established by the absolute volume method for concrete grade 30 and water to cement ratio (w:c) of 0.5. Fresh concrete properties were evaluated using slump test and properties of hardened concrete were obtained through compressive, splitting, flexural, bond, temperature resistance (residual) strength and water absorption test .Based on all test results, it was observed that at the age of 28 days, 100% replacement of sand with crusher dust from Dodoma gave increased compressive, splitting, bond, temperature resistance (residual) strength and water absorption tests up to 30.77%,25.54%,35.73% and 2.41% respectively in comparison to the control mix. Flexural strength was reduced with minimum reduction of 0.59% at 80% replacement of natural sand with crusher dust. For the crusher dust from Lugoba, it was observed that at the age of 28days, 40% replacement of sand gave increased compressive strength up to 5.34%, 20% replacement of sand gave increased splitting strength up to 16.44%. At 80% replacement of sand gave increased bond strength up to 15.83%, 100% replacement of sand gave increased temperature resistance (residual) strength up to 17.60% Flexural strength was reduced with minimum reduction of 8.82% at 40% replacement of natural sand water absorption was reduced to the maximum of 16.87% at 100% replacement of sand with crusher dust in comparison to the control mix.The study concluded that it is suitable to replace the natural sand with crusher dust at the specified ratios depending on the loads resisting mechanism and working environment of the structure.enConcrete constructionDust, DodomaSandLugobaTanzaniaThesis