Aim The aim of this experiment was to determine how theworkability of fresh concrete and hardened concrete is effected by the watercontent value.IntroductionConstruction of civil engineering structuresrequire background information on the compressive strength of concrete. Forexample, if a sample of concrete has low tensile strength it would be crucialto reinforce it a material that does have high tensile strength such as, steelrods. Reinforcement of such materials would increase the overall tensilestrength of the concrete allowing it support larger loads (Fanella, 2015,p.274)1.
ExperimentalProcedure In order to determine the workability of freshconcrete the slump test was conducted.The procedure began by placing the aggregates,cement and sand into a bucket after being weighed. To manufacture the concretemix, water was added. The amount of water added varied for each group (refer totable 1).A cone mould (100mm top diameter, 200mm bottomdiameter and 300mm in height) was moistened to allow a reduction of surfacefriction on slump (About Civil)2.The freshly manufactured concrete was then poured and compacted using a metalrod into the mould.
After the mould was filled and excess concrete was scrapedoff, the mould was lifted in an upward steady motion revealing the unsupportedconcrete. Due to the lack of support, the concrete slumped. The decrease inheight of the fresh concrete from before and after the mould was removed isreferred to as slump (refer to table 1).To measure the compressive and tensile strengthvalues, fresh concreted was hardened and compacted using a vibrating table withat a speed of 400hz, in accordance to the BS EN 12390-2:2009(The British StandardInstitute)3.Fresh concrete was hardened into the followingshapes; 100mm cubes, 100mmx100mmx500mm beam and 100mm in diameter by 200mmheight cylinder (The British Standard Institute)4.The concrete moulds were left to cure at 20ºC underwater and were tested 14days after curing. The beam was used to determine the flexural tensilestrength of the concrete sample.
The Zwick Rowell Z350 universal testingmachine was used. The beam sample experienced a loading rate of 0.5kN/s until afracture appeared on the specimen (refer to table 3).The cube samples were used to test the compressivestrength of concrete.
The cubes were singularly placed in the ELE ADR- Auto 2000KNcompression testing machine (refer to table 2). The same machine was used onthe cylinder sample (refer to table 3). All samples experienced a 0.3kN/s loadingrate.
The duration of both tests were dependent on when a fractured appeared onthe surface of the samples.1 David A. Fanella.
(2015). Reinforced Concrete Structures: Analysis andDesign, Second Edition. McGraw Hill Professional. Original workpublished 2015.
2 Aboutcivil.org, Concrete Slump TestProcedure, Applications & Types of Slump. Retrieved from: https://www.aboutcivil.org/concrete-slump-test.html. Date accessed: 25/01/2018 3British Standards Institute.
(2009). BS EN 12390-2: Testing Hardened Concrete.Part 2- Making and curing specimen for strength tests. Retrieved from https://bsol.bsigroup.com/ 4British Standards Institute.
(2009). BS EN 12390-3. Compressive strength oftest specimens.
Retrieved from https://bsol.bsigroup.com/Search/Search?OriginPage=Biblio%2Bsearch&facets=IcsCode_91¤tPage=1&pageSize=50&sortingOption=RelevanceDesc.Date Accessed: 09/01/2018