Effect of soaking sample cubes on concrete compressive strength: The case of Ethiopian Construction Industry

Concrete is a major component of construction work composed of fine and coarse aggregates bound together with a cement-water solution paste produced with hydration process. Concrete is best characterized by its compressive strength and relatively low in cost as well as the availability of ingredients that makes it the most favorable component of construction compared to other materials like steel. However, this characteristic of concrete is greatly affected by how it is cured after casting. This study is primarily conducted to assess and compare the compressive strength of concrete that has been cured through two curing mechanisms: Soaked – placing concrete cubes in a curing tank to be continuously hydrated and Un-soaked – placing the cubes along the in-situ concrete structure to get equivalent curing condition. In addition to this, an assessment on curing concrete cast with and without the use of admixtures was made. Furthermore, the study also examined the distinction in compressive strength of concrete made out of OPC cement from two different manufacturing companies which produce cement types 42.5 R and 42.5 N grades. The study was conducted at Gerji Federal Housing Corporation (GFHC) site for 500 units of housing construction project which is being undertaken by OVID Construction PLC in which the project has a total consumption of 59,966.46 m 3 of concrete. For this study, 24 sets of representative samples each having three concrete cubes were taken from different concrete batches that were prepared for the actual structural work as per the method of sampling stipulated under ASTM C172 that the project technical specification also specifies. The 28thday test result revealed that the highest compressive strength was obtained from the soaked sample having 46.5 MPa while the un-soaked sample had 41.5 MPa. The test also revealed soaked samples prepared by the cement type with 42.5 R grade exceeds that of the one with 42.5N grade. SP60 admixture used in soaked samples prepared using cement type with grade 42.5R gives a higher value in comparison with concrete produced without admixture.