Effect of Adding Slag to concrete on Drying Shrinkage crackingavd some mechanical by Haider Mohammed Owaid.

Dissertant

Uwayyid, Haydar Muhammad

University

University of Technology

Faculty

-

Department

Department of Building and Construction Engineering

University Country

Iraq

Degree

Master

Degree Date

2006

English Abstract

The main aim of this work is to study the effect of adding local slag on shrinkage cracking of concrete and give a clear picture of the factors involved and its effect on compressive, tensile and flexural strengths of concrete.

In this study a restrained shrinkage model was used.

End restrained concrete beams were cast and exposed to drying conditions.

Specimens were cast also for the compressive strength and tensile strength determination of slaged concrete.

The experimental program is divided into two parts.

The first part consists of studying the effects of a partial replacement of cement by an equal weight of slag with the following percentages (0, 20, 30 and 40) %.

In the second part, slag was used as a partial weight replacement of sand with the percentages (0, 30, 45 and 60) %.

It was concluded that the effects of adding local slag as a partial replacement of cement or sand on engineering properties of concrete are as follows:- > The drying shrinkage of concrete generally increases with increasing the slag content as a partial replacement of cement, for the same water-cement ratio and the percentages of increase in drying shrinkage at the age of 90 days were about 7.36%, 10.56% and 13.6% with 20, 30 and 40% of slag respectively, compared with the control mix, and the tensile strain capacity of concrete decreases with increasing slag content.

But the drying shrinkage decreases with increasing the slag content as a partial replacement of sand, especially with 30 and 45 percent of slag and the percentages of decrease in drying shrinkage at the age of 90 days were about 5% and 7% respectively, whereas, the tensile strain capacity increases.

> The creep of concrete decreases with increasing the percentage of cement partial replacement by slag.

Whereas, no significant changes in creep were observed when slag is used as a partial replacement of sand.

> The cracking time (age) of concrete decreases with increasing the slag content as a partial replacement of cement, and the crack width increased.

While, cracking time increases when slag is used as a part'mj replacement of sand, and the crack width decreases.

Also, the results indicate that increasing the percentages of cement partial replacement by slag leads to decrease the compressive strength and this reduction significant at ages of (7,28) days.

On the <

Other concrete properties including modulus of rupture and splitting tensile strength show trends similar to that observed in compressive strength.

Finally, two mathematical equations for the prediction of shrinkage strain were proposed and developed in this study.

These equations use multivariate non-linear regression equation to evaluate good correlation coefficient (R=0.9908) with slag replacement by wt.

ol cement, and (R=0.988S) with slag replacement by wt.

of sand with less difference between the observed and predicated shrinkage strain (df ± 56.52x10"6, df= ± 58.09* 10'6) respectively.

Main Subjects

Civil Engineering

Topics

• Cement
• Concrete
• Mechanical properties
• Cracking(Chemistry)

• APA
• MLA
• AMA

Language

English

Data Type

Arab Theses

Record ID

BIM-305445