A Study on the Effect of Time Duration by Vibrating or Tamping Fresh Concrete on the Compressive Strength of C-25 Concrete
Afework Achalu,
Emer Tucay Quezon,
Gerry Bangayan Macarubbo
Issue:
Volume 3, Issue 6, November 2017
Pages:
72-79
Received:
29 January 2017
Accepted:
23 February 2017
Published:
28 November 2017
Abstract: Many years ago, consolidation accomplished by laborers wielding a variety of spades, tampers, and similar tools. In Ethiopia, there is no enough knowledge by the laborers, while the site engineers ignored the correct application due to some constraints. The agreement of acceptable vibration level in fresh concrete to which tamping time duration is optimum is an issue to obtain the desired specific compressive strength. This research study aims to evaluate the maximum time length and techniques used to the Vibrating or Tamping fresh concrete and its effect on the compressive strength of C-25 Concrete through internal Rodding. Therefore, to study the effects of the period by vibrating or tamping, the needle type internal vibrator was used to test new concrete cubes based on ACI309R-96. The quality of concrete is important to make physical tests on materials used before any actual experiments to perform. The fresh concrete samples tested by using internal vibration methods and techniques of compaction with different time duration of 1sec, 2sec, 3sec, 4sec, and 5sec. These tests performed by using steel rod in fresh concrete to know the Optimum time of compaction by internal vibration on the cube test of new concrete. Laboratory experiments had been conducted to check the methods and techniques applied to construction sites, as well as site observation on the effects of the vibration time of fresh concrete on the compressive strength and flexural strength of C-25 Concrete with varying vibration time duration and steel rod tamping. Based on the results of cube tests of compressive strength of Concrete Samples have been checked at 3rd day, 7th day and the 28th day. This research study found out that the Optimum period of compaction was 3sec to produce an acceptable right quality of the concrete mix. Likewise, the flexural strength of Concrete Sample, when it tested in the laboratory at 7th day and 28th day, the results revealed that the flexural strength improved when vibration time increased, but the amount of water has to be reduced to obtain the desired strength. Finally, Tamping is needed to place fresh concrete in the mold correctly. Furthermore, new concrete produced should match the properties and avoid improper tamping or vibration applications. This situation must not cause differences in compressive strength of concrete.
Abstract: Many years ago, consolidation accomplished by laborers wielding a variety of spades, tampers, and similar tools. In Ethiopia, there is no enough knowledge by the laborers, while the site engineers ignored the correct application due to some constraints. The agreement of acceptable vibration level in fresh concrete to which tamping time duration is ...
Show More
Factors Affecting the Self-Healing Efficiency of Cracked Concrete Structures
Meseret Getnet Meharie,
James Wambua Kaluli,
Zachary Abiero-Gariy,
Nandyala Darga Kumar
Issue:
Volume 3, Issue 6, November 2017
Pages:
80-86
Received:
5 July 2017
Accepted:
18 July 2017
Published:
28 November 2017
Abstract: Self-healing concrete is the ability of concrete to repair its cracks autogenously or autonomously. Since some years ago, several studies have been conducted towards the improvement of self-healing efficiency of cracked concrete structures through various methods for the betterment of its application. However, there is a need to prepare a thorough review report on the factors that affect self-healing efficiency of concrete. This paper focusses a review on several factors that affect the self-repairing efficiency of self-healing smart concrete from the extant recent literature. Based on the review carried out, it can be concluded that formation of CaCO3 or Ca (OH) 2 in natural process, the dosage of capsule and type of healing agent in chemical process, and the type of bacteria and precipitation of CaCO3 in biological process of self-healing are the most vivid factors. It can also be summarised as better self-healing efficiency is achieved during early age of concrete, with narrower cracks, higher concentration of Ca2+ ions, optimum thickness of capsule shell and dosage of capsule.
Abstract: Self-healing concrete is the ability of concrete to repair its cracks autogenously or autonomously. Since some years ago, several studies have been conducted towards the improvement of self-healing efficiency of cracked concrete structures through various methods for the betterment of its application. However, there is a need to prepare a thorough ...
Show More
The Effect of Extraction Method, Bleaching and Clarification Processes on Quality Second Grade Siwi Date Dibs
Hanafy A. Hashem,
Hasan H. Abd El-Daym,
Gamal A. A. El-Sharnouby,
Salwa M. A. Farghal,
Hossameldin A. Badr
Issue:
Volume 3, Issue 6, November 2017
Pages:
87-93
Received:
7 March 2017
Accepted:
29 March 2017
Published:
30 November 2017
Abstract: Second grade Siwi date palm fruits in Baharia Oasis were used forproduction of high quality date syrup (Dibs). Physical and chemical characteristics of Siwi date fruits (second grade) as well as quality parameters of Siwi date extract as affected by bleaching and clarification treatments were investigated. Also, quality parameters of the obtained dibs by different methods and treatments were examined. Physical and chemical characteristics of Siwi date illustrated that, fruit weight, flesh/pit ratio, fruit length, fruit diameter, T.S.S, total and reducing sugars, crude protein, ash, soluble pectin and tannins were 10.0g, 6.40, 3.46 cm, 2.22 cm, 81.40%, 91.41%, 86.78%, 2.76%, 0.83%, 1.55% and 0.27%, respectively. Granular activated charcoal (G.A.C) is more effective bleaching treatment than powder activated charcoal (P.A.C), Also, liming phosphatation is more effective clarification treatment than centrifugation with filtration. Quality dibs results indicated that, the highest values of T.S.S, total and reducing sugars and date syrup yield were recorded for the dibs samples extracted at 75°C and 96°C and concentrated under vacuum while the lowest values were recorded for commercial sample(except yield), also, clarification processed sample recorded the lowest browning index, ash and pectin contents, while the highest values of these parameter were recorded for commercial sample. Sensory quality parameters demonstrated that, the highest taste and flavor scores were recorded for the extracted sample at 96°C with bleaching by GAC then concentrated under vacuum while the extracted sample by blender at room temperature (with or without clarification treatment) had the highest color scores. In relation to microbial quality, results showed that, microwave extraction followed by concentration at 100% power level recorded the highest microbial quality (the lowest counts of bacteria, yeast and mould, and coliform group) followed by sample extracted at 96°C and then concentrated under vacuum.
Abstract: Second grade Siwi date palm fruits in Baharia Oasis were used forproduction of high quality date syrup (Dibs). Physical and chemical characteristics of Siwi date fruits (second grade) as well as quality parameters of Siwi date extract as affected by bleaching and clarification treatments were investigated. Also, quality parameters of the obtained d...
Show More
