Factor Affecting Work Ability and Strenth of Concrete
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FACTOR AFFECTING WORKABILITY AND STRENGTH OF CONCRETE GONZALES, MEL HARVEY A. COLLEGE OF ENGINEERING DLSU
WORKABILITY A general term to describe the properties of fresh concrete. • Consistency (or fluidity) --describes the ease of concrete flow • Cohesiveness --describes the ability to keep concrete uniformity (no concentration of a single component) • Homogeneity refers to stable distribution of cement, aggregate, and water and resistance to segregation
Workability -Factors Affecting Workability: Water Content • Extra water can lubricate the particles in mixture: the more the water, the easier the flowing. However, too much water will cause segregation • W/C increase • Fluidity increase
Workability -Factors Affecting Workability: Aggregate • • • •
Aggregate/cement ratio �Fine aggregate/Coarse aggregate �Maximum aggregate size �Aggregate shape and texture
Workability -Factors Affecting Workability: Cement • Fineness Fluidity decrease With fineness increase • �Cement Content: Lubrication effect of paste
Workability -Factors Affecting Workability: Admixtures • Air entraining agent • -Pozzolanic admixtures • Superplasticizers • --release water; retarding, air entraining effect
Workability -Factors Affecting Workability: Temperature
• Can influence the hydration rate and water loosing rate • Temperature increase • Workability decrease
measures yield stress and plastic viscosity
FACTOR AFFECTING STRENGTH • CONCRETE POROSITY • WATER CEMENT RATIO • SOUNDNESS OF THE AGGREGATE • AGGREGATE – PASTE BOND
DUCTAL • is an innovative technology which covers a family of ultra-high performance concretes with exceptional characteristics in terms of mechanical resistance (compressive strengths up to 200 MPa, flexural tensile strength beyond 40 MPa), durability, abrasion resistance, and resistance against chemical and environmental attack (freeze and thaw, salt water, etc.). • This new technology permits the development of innovative solutions which are competitive, offer faster construction, require less maintenance, and have a reduced impact on the environment.
DUCTAL • it is significantly stronger than normal concrete. Compressive strengths range between 20,000 to 30,000 psi (150 to 200 MPa) compared to 3,000 to 7,000 psi (20 to 50 MPa) for normal concrete and flexural strengths range between 3,000 to 7,000 psi compared to 500 to 1,000 psi (3 to 7 MPa) for normal concrete.
REFERENCES: • WORKABILITY AND QUALITY CONTROL OF CONCRETE BY : G. H. TATTERSALL • M. Lepech and V.C. Li, "Bridge Decks in Michigan Go Jointless" in Civil & Environmental Engineering Newsletter for Alumni and Friends, University of Michigan, Ann Arbor,