Effect of internal curing on behavior of high performance concrete

Dissertant

al-Sad, Ayman Jamil Kazim

Thesis advisor

al-Attar, Tariq Salih
Abd al-Latif, Adil Mahmud

University

University of Technology

Faculty

-

Department

Department of Building and Construction Engineering

University Country

Iraq

Degree

Master

Degree Date

2013

English Abstract

High performance concrete (HPC) requires a low water-to-cementitious materials mass ratio (w/cm) and supplemental cementitious materials with silica fumes in the mixture, and use of a superplasticizer.

Because of the low w/cm and rapid reaction at early ages, it becomes more difficult to provide curing water from the top surface that is an adequate to satisfy the normal curing.

Therefore, there is a need to use internal curing that is supplied via internal materials, such as absorbent lightweight aggregate, which has been presaturated.

The use of internal curing was investigated in this study by two ways.

The first way was through the use of partial replacement of original coarse aggregates (gravel) by crushed bricks and crushed Porcelinite.

The second way was the use of a partial replacement of the original fine aggregate (sand) by Porcelinite, limestone-dust and sawdust.

The following tests were conducted throughout this work: slump of concrete, fresh density, compressive, splitting tensile and flexural strength, static and dynamic modulus of elasticity, ultrasonic pulse velocity, absorption of concrete, autogenous and drying shrinkage, and Los Angeles abrasion for aggregate.

The experimental program had extended to the age of 120 days for most tests.

The results showed that the fine aggregate replacement as internal curing material caused better enhancement in mechanical properties (strength, elasticity) of HPC than coarse aggregate.

The replacement of original aggregate with different internal materials caused an increase in compressive strength at 28 days ranged between 4 and 9.68 percent, for splitting tensile strength from 4.15 to 13.7 percent and for flexural strength from 6.86 to 16.67 percent.

Same trends were recorded for other type of strength and for modulus of elasticity.

A proposed method to measure the autogenous shrinkage was suggested by the present work.

The results of this method were compared to the method of the Japan Concrete Institute (JCI)-1996; it gave a high correlation, which gives significance and reliability to the present method.

The effectiveness of use fine replacement materials was also better than coarse material in reducing the autogenous shrinkage.

Internal curing had caused a reduction in total magnitude of autogenous shrinkage of all mixes with respect to the reference-mix.

The reduction ranged f^om 3 to 225 and from 45 to 300 percent for first and second method respectively.

The internal curing materials caused a reduction in length change (drying shrinkage).

The percentages ranged from 34 to 88 percent, depending on the internal curing material type and size.

Main Subjects

Engineering & Technology Sciences (Multidisciplinary)

Topics

• Concrete

• APA
• MLA
• AMA

Language

English

Data Type

Arab Theses

Record ID

BIM-417620