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PROJECT WORK
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i DEDICATION I dedicate this work to Almighty God who has been there right from the beginning to this very point. I also dedicate this work to my ever supportive Mum and Family, for their relentless support and compassion towards my pursuit for B.Eng. Degree in Structural Engineering in University of Benin. ii ACKNOWLEDGEMENT I want to say a big thank you to my Mother, Mrs. Patricia Obiagboso, my brothers and sisters for their caring attitude and support from the beginning of my pursuit for B.Eng. Degree in Structural Engineering to this point. I also want to express my appreciation to my project supervisor, Engr. (Dr.) Ebuka Nwankwo for his intellectual support, cooperation and guidance during our work together to achieve a positive result.
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E-Book Available at: https://ekumbh.aicte-india.org/allbook.php
Concrete is the most versatile building material. Its property to get moulded in any shape easily makes it widely used in infrastructure projects including buildings, bridges, dams, silos and pavements. Durability of these structures depends on quality production, testing and maintenance of concrete.
This book is intended to provide students and professionals, a deep understanding of concrete technology. It explains the fundamental concepts, material characteristics and related laboratory experiments on concrete and its ingredients. It also includes relevant provisions of Indian Standards such as IS 456, IS 10262, IS 383, IS 2386 and IS 516.
Unit I details properties of ingredients of concrete, viz., cement, aggregates and water.
Unit II describes the different grades of concrete and properties of fresh concrete.
Unit III outlines the procedure to obtain concrete mix design as per IS 10262. It also explains destructive and non-destructive tests on hardened concrete.
Unit IV provides details of quality control during various concreting operations. It also details formwork for concreting, waterproofing and joints in concrete construction.
Unit V discusses chemical admixtures, special concrete and extreme weather concreting.
Unit VI details laboratory and field experiments to determine properties of concrete and its ingredients.
The book provides latest scientific advances in concrete technology. We hope that students will find it easy to comprehend, and concrete technology fraternity at large will get benefitted. Comments and suggestions to further improve the book are always
welcome, and can be sent to smandal.civ@iitbhu.ac.in, anand.civ@iitbhu.ac.in,
sushilkumar39@gmail.com.
The effect of sugar cane juice, (SCJ) on slump values, setting time and compressive strength of concrete cubes was investigated. A total of 32 concrete cubes of size 150x150x150mm with a mix ratio of 1:2:4 were cast with different percentages of unfermented sugar cane juice replacing some proportion of water in the concrete mix. Water/Sugar Cane Juice/cement ratio was held constant at 0.45. The concrete cubes were prepared by replacing water with SCJ in the following proportions 0, 25, 50 and 100%. The cubes were cured, tested and the physical properties of interest in this study were determined. The slump values of the concrete decreased from 40mm at 100: 0 (water:SCJ) to 18mm at 50:50 (water:SCJ) and to 0mm (collapse) at (0:100) (water :SCJ). The final setting time of concrete increased with increase in proportion of SCJ. The highest final setting time of 42 hours (considered excessive), occurred at 75:25 (water:SCJ) proportion. The compressive strength of the (water:SCJ) concrete decreased as the percentage of SCJ increased up to 25% SCJ. Thereafter, an increase in compressive strength was noticed up till 100% SCJ, with a maximum strength of 13.08N/mm2 occurring at 100% SCJ at 28 days. The early strength reduction is due to quick-setting of the concrete, at 25% SCJ, retardation commences and the strength of concrete increases. The study has been carried out at 0, 25, 50 and 100% replacement by weight of potable water with SCJ. A comparative study has been done between concrete made with potable water and those made with water/sugar cane juice.http://dx.doi.org/10.4314/njt.v34i2.6
Various mechanisms have been proposed to explain how organic admixtures affect the hydration of cement clinker compounds. These are reviewed and discussed critically. Complex formation between the organic compounds and aluminate or silicate ions may enhance the initial reactivity of the anhydrous compounds. Set-retardation may be primarily due to retarding of the hydration of tricalcium silicate through the adsorption of organic admixtures onto calcium hydroxide nuclei. Adsorption onto the initial hydration products of tricalcium aluminate can also retard further hydration.AbstractDiffe´rents me´canismes onte´te´propose´s pour expliquer l'effet des adjuvants organiques sur l'hydratation des composants du clinker de ciment. Dans le pre´sent article, ils sont passe´s en revue et discute´s. La formation de complexes entre compose´s organiques et ions aluminate ou silicate peut accroiˆtre la re´activite´initiale des compose´s anhydres. Le retardement de la prise est peut-eˆtre duˆprincipalement au ralentissement de l'hydratation du silicate tricalcique par adsorption des produits organiques sur les noyaux de chaux hydrate´e. L'adsorption sur les produits de l'hydratation initiale de l'aluminate tricalcique peute´galement retarder la poursuite de l'hydratation.
Sugars retard the hydration of Portland cement. The effectiveness of different sugars is compared from studies of solution analysis, calorimetry, calcium binding ability and alkaline stability. The best retarders, sucrose and raffinose, have a remarkable ability to solubilize cement constituents and in particular give rise to dramatic increases in the amount of silica in solution. However, 13C and 29Si N.M.R. do not reveal the existence of sucrose-silicate complexes. The retarding action of sugars is explained in terms of adsorption onto and poisoning of hydrate surfaces.
While concreting in hot weather, both setting time and compressive strength are adversely affected. To prevent concrete from the adverse effects of hot weather, admixtures are usually incorporated in it. The objective of this paper is to investigate the effects of a retarding admixture (ASTM C 494 Type D) on setting time of cement pastes. The setting time tests were performed under three different curing conditions (temperature & relative humidity). The admixture was added to pastes made from three different types of cements. The test results revealed that the effects of admixture on setting time of cement pastes are dependent upon the type of cement and dosage of the admixture. It caused set retardation of the three different types of cements used, but with one type of cement it accelerated, the initial setting time and retarded the final setting time when dosages higher than 0.25% were used.
Six phosphonates, comprising the three acids aminotri(methylenephosphonic acid) (ATMP), 1-hydroxyethylidene-1,1-diphosphonic acid (HEDP) and diethylenetriaminepenta-(methylenephosphonic acid) (DTPMP) and their corresponding sodium salts Na5ATMP, Na4HEDP and Na6DTPMP, were added to Portland cement in dosages ranging from 0.03 to 0.09%, at a constant water/cement ratio of 0.35 and their conduction calorimetric behaviour was investigated up to 72 h. The induction period, the time to attain the maximum heat effect and the integral heat developed at different times were determined. All phosphonates increased the induction period, from about 3 h to greater than 72 h, with respect to the reference cement with an induction period of 2 h. The acid phosphonates were more effective retarders than their corresponding salts. At a concentration of 0.05% the induction period extended from 10.1 to 21.1 h with the acids and only from 4.1 to 16.2 h with the salts. DTPMP was the most effective retarder among all the phosphonates, a concentration of 0.05% producing an induction period of 21.1 h and an exothermic inflection at 42.4 h compared with values of 2.2 and 7.9 h, respectively, for the reference. The corresponding salt (Na6DTPMP) was the most efficient of all the salt retarders. At a concentration of 0.05%, the induction period was extended to 16.2 h and the exothermal inflection to 31.4 h. In most instances the degree of extension of the induction period increased with the dosage of retarder. Phosphonates appear to be much more efficient retarders than many other retarders used in concrete practice.
The effect of sugar on setting-time of various types of cements
- Bazid
- B Bulent
Bazid, K and Bulent, B., 2002. The effect of sugar on setting-time of various types of cements,
Quarterly SCIENCE VISION 8, (1):
Admixtures for Concrete
- T Y Erdogan
Erdogan, T. Y. 1997. Admixtures for Concrete, Middle East Technical University Ankara
Turkey.