Girma Zerayohannes (PhD)Fitsum Reda2024-09-032024-09-032024-05https://etd.aau.edu.et/handle/123456789/3447This study aims to investigate crushed sandstone sand (CSS) in Concrete and hollow concrete block (HCB) properties as replacement of RS material. It was conducted by taking samples of CSS from Idaga Hamus, and RS from Gereb Giba quarry sites. The significance of blending CSS with RS materials using several laboratory tests were investigated. Total 36 samples of 15cmx15cmx15cm cubic concrete at 7th, 14th, and 28th days of curing period for compressive strength of concrete, 9 samples 50cmx15cmx15cm beams for flexural strength of concrete with mix ratio of 1:2:3, and water to cement ratio 0.50 for 0% and 50% replacement of CSS and 0.55 for 75% and 100% replacement of CSS, and 24 samples of HCB at 7th day curing period were prepared and tested. The test results on the specimens showed that the concrete and HCB manufactured using CSS as a partial and full replacement of RS have all strength, and density requirements specified in Ethiopian Standard ES 596:2001. It can be concluded from the study that CSS can readily to be used as a replacement for RS, in Concrete and HCB as far as the quantity and procedures in this study are followed. Commercial sand production from the sandstone could also be taken as a potential solution for RS shortage. The RS replaced by 100% of CSS greatly improves the physical and mechanical behaviors of concrete and HCB. The amount in percentage of silt content, and clay content in CSS and RS has been widely investigated. The significance of the replacement of CSS to RS concrete with the characteristic strength of concrete C-25 and HCB were studied in mixtures prepared with constant workability. Compared to RS, CSS has better quality consistency and higher Strength in concrete. The manufactured CSS that is available in Idaga Hamus is well-graded. The strength properties of concrete were investigated with 0%, 50%, 75%, and 100% replacement of RS by CSS for C-25 mix proportion of concrete and 40cmx20cmx20cm, dimension of HCB. There is a 15.4927% increment in the relative compressive strength of concrete, and a 13.226% increase the relative flexural strength of concrete with 100% replaced of CSS at the 28th day of curing period compared with conventional concreteen-USRiver SandHamus Crushed SandstoneConcrete Block ProductionReinforced ConcreteThesis