1. By: Salah Al-Fahad, Ibrahim Nasser, Ali Baslama, Ahmed Alrashed
King Faisal University
College of Engineering
Department of Civil & Environmental Engineering
“Investigation of Strength and Ductility for Engineering Cementitious Composite (ECC)”
By: Salah Al-Fahad, Ibrahim Nasser, Ali Baslama, Ahmed Alrashed
ABSTRACT
In recent years, materials like Engineered Cementitious Composites (ECC) have been in development. ECC is a material designed to be ductile, and to have highly strength, and is referred to as flexible concrete. The components of ECC are similar to normal concrete except no coarse aggregates are used and air entrainment is not necessary. The focus of this paper is to present the results and work performed by students in a construction materials course to develop a type of ductile concrete based on information available in the literature. Students were required to work in teams to perform a literature search; build molds; develop mix designs; cast and test beam specimens; and write a report. This project offered students the opportunity to develop a product that has potential use in the community, and the students really appreciated this aspect.
In some cases, the brittleness as measured by the brittleness number actually increases as the compressive strength goes up. This poses potential danger and limitations of high strength concrete in structural applications. In certain locations, such as where steel and concrete come into contact.
In seismic elements, high ductility in the concrete can make a significant difference in the seismic response of the overall structure. In terms of material constituents, ECC utilizes similar ingredients as fiber reinforced concrete (FRC). It contains water, cement, silica sand, fly ash, fiber, and some common chemical additives. Coarse aggregates are not used as they tend to adversely affect the unique ductile behavior of the composite. A typical composition employs w/c ratio and sand/cement ratio of 0.5 or lower.
RESULTS
Cubic compressive strength test:
This test method covers the determination of unconfined compressive strength of cubic composite specimens. The test method consists of applying a compressive axial load to molded cube at a rate which is within a prescribed range until failure occurs. The compressive strength of the specimen is calculated by dividing the maximum load attained during the test by the cross-sectional area of the specimen Equation (1-1) [ASTM C109].
The compressive strength of any fiber depends upon its own compositions. Also similar fibers may show a variation in strengths when subjected to loading may be due to varied slumps also. Here are the test results for 7, 14, and 28 days in the following figure for deferent mix designs .
CONCLUSIONS
The background and design methodology of ECC has been established. Application of this material is emerging at the present time. The relatively small amount of fibers utilize ensures economic feasibility in practical applications. Some of The unique properties of ECC include: high ductility, high compressive strength, high durability and high resistance to weathering. These properties could make it an ideal material. As compared to plain concrete, ECC material tests show improved performance in shrinkage cracking behavior.
REFERENCES
[1]. “Hillerborg, A., Analysis of One Single Crack, in Fracture Mechanics of Concrete, edited by F.H. Wittmann, Elsevier Science Publishers B.V., Amsterdam, pp ,1983”
[2].” Victor C. Li Engineered Cementitious Composites for Structural Applications”
[3].” Shuxin Wang And Victor C. Li Polyvinyl Alcohol Fiber Reinforced Engineered Cementitious Composites: Material Design And Performances”
MATERIALS / METHODS
The following are the mix designs that we considered in our experiment by making change in the previous mix design CS-MD [Mike Lewis, 2008]:
OBJECTIVES
The objective of this report is to provide a performance summary of a typical ECC using PVA. In addition, we are looking for two important mechanical properties which are strength and ductility using new techniques that Serve the society in an economic and environmental way.
quantity (kg/m3)
Weight percent (%)
Material
583
27.9 %
Portland Cement
467
22.3%
Silica Sand
700
33.5 %
Fly Ash -
Nakheel
OOW
298
14.2%
Water
17.5
0.8%
Admixture
26.0
1.2%
PVA
INTRODUCTION
In the last several decades, concrete with increasingly high compressive strength have been used for structural applications. However, most of these materials remain brittle.
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April 26, 2017