What is rheology of fresh concrete describe the parameters defining the rheology?
The term rheology may be defined as the study of the science of the flow and deformation of materials. In the concrete study, the concept of rheology may be applied to analyze the hardened concrete deformation, the behavior of cement paste and slurries, handling and placing of mixed concrete in its fresh state.
What are the factors affecting the rheological behavior of concrete?
The rheological properties of concrete are dependent on the factors like mix proportions, consistency, the properties of each ingredient present in the mix, the mixing amount and the admixture amount, the time elapsed after mixing.
What is concrete rheology?
Definitions of Rheology: The Rheological principles and techniques applied to concrete include the deformation of hardened concrete, handling and placing of freshly mixed concrete and the behavior of its constituents parts, namely cement paste and slurries.
What are the rheological parameters?
The rheological parameters were viscosity (cp), torque%, shear stress (dyne/cm2) and shear rate (s-1).
What is the difference between setting and hardening of cement?
Setting describes the stiffening of the fresh cement paste. Onset of rigidity occurs. Then hardening begins, which indicates that a useful and measurable strength is developing. Setting and hardening result from the continuing reaction between the cementitious material and water.
What are the factors affecting strength of concrete?
Factors Affecting Strength of Concrete
- Quality of Raw Materials.
- Water / Cement Ratio.
- Coarse / fine aggregate ratio.
- Aggregate / Cement Ratio.
- Age of concrete.
- Compaction of concrete.
- Relative humidity.
What are the factors affecting properties of concrete?
Concrete strength is affected by many factors, such as quality of raw materials, water/cement ratio, coarse/fine aggregate ratio, age of concrete, compaction of concrete, temperature, relative humidity and curing of concrete.
What are the rheological properties of cement?
The rheological behavior of non-Newtonian fluids such as cement paste, mortar, or concrete is often characterized by two parameters, yield stress, τ0, and plastic viscosity, µ, as defined by the Bingham equation (Eq. (1)).
What are the factors affecting the setting time of cement?
The major factors affecting the time of setting are cement composition, water-cementitious material ratio (w/cm), temperature, and admixtures. When cement hydrates faster, the time of setting is reduced. Increases in the w/cm result in increased time of setting.
What is false setting of cement?
False set is a form of premature stiffening of the paste or concrete, which occurs within 1 to 5 min after mixing. False set can be eliminated by continuous mixing or by reworking and may not be noticed on jobs supplied by truck mixers or with central-mixed concrete that is agitated during delivery to the site.
What is the relationship between aggregate and concrete?
The shape and texture of aggregate affects the properties of fresh concrete more than hardened concrete. Concrete is more workable when smooth and rounded aggregate is used instead of rough angular or elongated aggregate.