Browsing by Author "Ahmed, Redown"

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Influence of Steel Fiber and Superplasticizer on Crumb Rubberized Concrete
(2024-12-15) Abu Hasan; Asadul Howlader, Md.; Ahmed, Redown; Saon, Hasibul Islam
In recent years, the substantial disposal of a large volume of scrap tires has posed a significant environmental solid waste problem. Crumb rubber (CR) generated from these waste tires can serve as a partial replacement of normal aggregates to make crumb rubberized concrete (CRC). Therefore, to investigate the properties of CRC, CR was used as 5%, 10%, and 15% replacement of sand in this study. In addition, steel fiber (SF) by 1% volume fraction of concrete and superplasticizer (SP) by 1% weight of cement were added individually to compare the improvement of concrete strength. Slump, unit weight, compressive strength, and split tensile strength tests were conducted to investigate and compare the properties of CRC. The experimental findings revealed that, as the amount of SF increased, unit weight, compressive strength, and split tensile strength increased. However, SP showed a greater improvement in CRC than SF. The addition of SF increases the compressive strength approximately from 11% to 16% and split tensile strength from 7.6% to 16.3%, while SP showed an increase from 21.1% to 24.5% and 12% to 25%, respectively. Therefore, it can be stated that the 1% SP has better strength improvement quality in comparison with 1% SF.
Mechanical Properties of Fine and Coarse Size Crumb Rubber Concrete
(Daffodil International University, 23-01-18) Howlader, Md. Asadul; Ahmed, Redown; Miah, Md. Al-amin
Disposing of waste tires globally has become a big environmental problem in recent years. Some studies and experiments were conducted on replacement by crumb rubber in concrete and resolve the problem of environmental concern. Waste tires partially replace the fine aggregate and coarse aggregate in regular concrete in crumb rubberized concrete (CRC). Hence, in the concrete mix sand and stone partially replace by crumb rubber both as fine aggregate and coarse aggregate of 0%, 5%, 10% and 15% in this study. To ascertain the behavior of crumb rubber concrete, all mixtures were compared with traditional concrete and also compared between coarse crumb rubber and fine crumb rubber which is replace instead of stone and sand. A total of 78 cylinders with a 100 mm diameter and 200 mm height were cast and put through testing. The M30 concrete mixture underwent testing for twenty days. Slump, the spilt tensile test, and compressive strength were four variables evaluated. The research demonstrates that substituting some crumb rubber for sand and stone degrades concrete over time. According to the tests result, tensile strength, workability, and compressive strength declined as the amount of crumb rubber, both fine and coarse, rose. On the other hand, with increase the amount of coarse crumb rubber (CCR) the tensile strength was increased. Although crumb rubber which is used in concrete decreased compressive and tensile strength, however up to 5% MCR increased the tensile strength 5.30% for 28 days curing. Compared between CRC coarse and fine crumb rubber, the fine crumb rubber provides 48.05% higher compressive than coarse crumb rubberized concrete and 24.1% higher tensile value. So, it is recommended that 5% of MCR is appropriate for application in concrete mixture.