Assessing the Effect of Accelerators and Retarders on the Early-Age Compressive Strength of Concrete.

Accelerating admixtures affect the rates of reactions between cement and water to give an overall increase in the hydration rate. Retarding admixtures on the other hand slow down the hydration rate. Thus, the use of accelerators in concrete provides a shortening of setting time and/or an increase in...

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Bibliographic Details
Main Author: Gumoshabe, Edgar
Format: Thesis
Language:English
Published: Kabale University 2024
Subjects:
Online Access:http://hdl.handle.net/20.500.12493/2377
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Summary:Accelerating admixtures affect the rates of reactions between cement and water to give an overall increase in the hydration rate. Retarding admixtures on the other hand slow down the hydration rate. Thus, the use of accelerators in concrete provides a shortening of setting time and/or an increase in early strength development and retarders increase the setting time and reduce early strength development. In this project, the issues of slow down and uncontrolled rapid setting and hardening of concrete or addressed by the use of accelerating and retarding admixtures (Calcium Chloride and Citric Acid respectively) in concrete. Calcium chloride and citric acid were added in four samples, with quantities of 1%, 1.5 %, 2%, and 2.5% by weight of cement, which were taken as mix -1 and mix -2. The concrete samples were tested 1, 3, 7, and 28 days of Compressive strength. The concrete specimens were laid for M25 grade of concrete.