Effect of Metakaolin on Concrete Produced with a Pozzolan

The physical and mechanical properties of Portland Cement containing metakaolin or combination of metakaolin and pozzolan ((Palm Bunch Ash (PBA)) and the compatibility between such materials were investigated in this study.  A mix proportion of 1:2:6:4.1 with water/cement ratio of 0.4 were used.  The percentage replacement of ordinary Portland Cement (OPC) with a pozzolan (Palm Bunch Ash) (PBA) and Pozzolan/metakaolin used were 0%, 5%, 10%, 20%, 30% and 40%.  Concrete cubes were cast and cured at different days. Similarly, the setting time was also determined.  At the end of each hydration period, the concrete cubes were crushed and their compressive strength determined.  Similarly the setting time of Ordinary Portland Pozzolan and Ordinary Portland Cement/Pozzolan and Metakaolin was also determined.  The result of the compressive strength of 5-40% replacement cement with the Pozzolan (PBA) ranges from 5.87 – 35.50 N/mm2 as against 14.10 – 36.22N/mm2 for the control test. Similarly, the result of the compressive strength of 5-40% replacement of cement with pozzolan and metakaolin ranges from 6.40 – 35.90N/mm2 as against 14.10 – 36.22N/mm2 for the control test. The setting time of cement with 5-40% replacement of cement with pozzolan (PBA) ranges from 57 – 109 mins for the initial setting time and 608 – 731mins for the final setting time as against 50 mins and 585 mins respectively for the initial and final setting time of the control test.  Similarly, the setting time of cement with 5-40% replacement of cement with the pozzolan (PBA) and metakaolin ranges from 54-98 mins for the initial setting time and 590 – 692 mins for the final setting time as against 50mins and 585 mins respectively for the initial and final setting time of the control tests

Effect of Salt Water in the Production of Concrete

In this research work, the effect of salt water in the production of concrete was investigated. A total of ninety (90) concrete cubes were cast for compression strength test i.e. forty five cubes were cast using fresh water and the other forty five cubes were also cast using salt water. Similarly, a total of ninety (90) concrete beams were cast for flexural strength test i.e. forty five beams were cast using fresh water and the other forty five beams were also cast using salt water. The concrete cubes and the beams were cured at 7,21,28,60 and 90 days respectively. The result of the average compressive strength of concrete obtained using fresh water  of mix ratio (1:1.51:4.01), water cement ratio (0.47) ranges from 27.35-42.34N/mm2 while that of salt water ranges from 25.24-38.81N/mm2 for the hydration period of 7,21,28,60 and 90 days. The flexural strength of concrete obtained using fresh water of the same mix ratio and water cement ratio ranges from 6.60 – 11.20N/mm2 for 7,21,28,60 and 90 days hydration period while that of salt water ranges from 5.98-11.04N/mm2 for the same hydration period. For the mix ratio (1:1.61:4.03) and water cement ratio (0.55), the average compressive strength of concrete obtained using fresh and salt water ranges from 27.26-40.80N/mm2 and 24.68 – 39.13N/mm2 respectively while the flexural strength ranges from 6.55-11.13N/mm2 and 6.26-10.76N/mm2 for fresh and salt water respectively. For the mix ratio (1:1.66:4.24) and water cement ratio (0.50), the average compressive strength of concrete obtained using fresh and salt water ranges from 25.05 -38.13N/mm2 and 23.58-36.03N/mm2 respectively while the flexural strength ranges from 6.18-9.88N/mm2 and 6.15 – 10.39N/mm2 for fresh and salt water respectively. The initial and final setting time of cement using fresh water is 50mins and 587mins while that of salt water is 55mins and 605mins respectively

Technical Note: Effect of Incorporating Expanded Polystyrene Aggregate Granules in Concrete Matrix

Incorporating expanded polystyrene granules in concrete matrix can produce lightweight polystyrene aggregate concrete of various densities. Workability which is an important property of concrete, aects the rate of placement and the degree of compaction of concrete. Inadequate compaction leads to reduction in both strength and durability of concrete. In this research work, the effect of incorporation of expanded polystyrene aggregate granules in concrete was studied. The polystyrene aggregate granules was used to replace 0-40% of coarse aggregates. A mix proportion of 1:1.8:3.7 with water cement ratio of 0.47 were used. Concrete cubes of 150xmmx150mmx150mm of coarse aggregate/polystyrene granules were cast and cured at 3, 7, 28, 60 and 90 days respectively. At the end of each hydration period, the three concrete cubes for each hydration period were crushed and their average compressive strength recorded. A total of ninety (90) concrete cubes were cast. The result of the compressive strength tests for 5-40% replacement of coarse aggregates with polystyrene granules ranges from 5.05-31.75N/mm2 as against 23.59-36.08N/mm2 for the control test. The workability for 5-40% replacement of coarse aggregates with polystyrene granules ranges from 15-63mm as against 10mm for the control test (0% replacement). The incorporation of the expanded polystyrene aggregate granules as concrete matrix results in the decrease in strength of concrete produced.Keywords: polystyrene aggregate granules, coarse aggregates, compressive strength, workabilit

The effect of bagasse ash on the compressive strength of concrete

In this research work, the effect of bagasse ash in the production of concrete was investigated. A mix proportion of 1:1.8:3.7with water-cement ratio of 0.47 was used. The percentage replacement of Ordinary Portland Cement (OPC) with bagasse ash is 0, 5, 10, 20, 30 and 40%. Concrete cubes of 150 x 15 x 150 mm of OPC/bagasse ash were cast and cured at 3, 7, 28, 60 and 90 days respectively. At the end of each hydration period, the three concrete cubes for each hydration period were crushed and their average compressive strength recorded. Ninety (90) concrete cubes were cast. The result of the compressive strength test for 5-40% cement replacement, with bagasse ash ranges from 3.11 – 32.57 N/mm2 2 for the control test. Similarly, the setting time of 5-40% cement replacement with bagasse ash ranges from 1.50 – 14.20 hours for the initial setting time and 39.60 – 110.06 hours for the final setting time as against 0.8 hour and 9.80 hours for the initial and final setting time respectively for the control test (0% replacement). Keywords: Bagasse, ash, compressive strength, Seeting time, concrete International Journal of Natural and Applied Sciences, 7(1): 32 - 36, 2011 ISSN: 0794 – 471