WEEK 01

• Concrete - mixture of sand, gravel, crushed rock, or other aggregates held together in a rocklike mass with a paste of cement and water.
• Reinforced concrete - combination of concrete and steel wherein the steel reinforcement provides the tensile strength lacking in the concrete.
• Aggregate - A granular material, such as sand, gravel, crushed stone and iron-blast furnace slag, and when used with a cementing medium forms a hydraulic cement concrete or mortar.
• Balanced Design -A design so proportioned that the maximum stresses in concrete (with strain of 0.003) and steel (with strain of fy/Es) are reached simultaneously once the ultimate load is reached, causing them to fail simultaneously.
• Cementitious materials - Materials with cementing value when used in concrete either by themselves, such as Portland cement, blended hydraulic cement, or such materials in combination with fly ash, raw or other calcined natural pozzolans, silica fume, or ground granulated blast-furnace slag.
• Concrete -Mixture of water, cement, sand, gravel, crushed rock, or other aggregates.
• Dead Load - Loads of constant magnitude that remains in one position.
• Design Load Combinations - Combination of factored loads and forces.
• Design Strength - The nominal strength multiplied by a strength-reduction factor ø.
• Live Load - Loads that may change in magnitude and position.
• Modulus of Elasticity - The ratio of normal stress to corresponding strain for tensile or compressive stresses below proportional limit of material.
• Nominal Strength - The strength of a member or cross section calculated in accordance with provisions and assumptions of the strength design method before application of any strength-reduction factors.
• Over Reinforced Design - A design in which the steel reinforcement is more than what is required for balanced design.
• Under Reinforced Design -A design in which the steel reinforcement is lesser than what is required for balanced design.
• Plain concrete - Structural concrete with no reinforcement or with less reinforcement than the minimum amount specified for reinforced concrete.
• Reinforced concrete- Concrete in which reinforcing bars or other types of reinforcement have been integrated to improve one or more properties of concrete.
• Specified Compressive Strength of Concrete, (f’c) -The compressive strength of concrete used in design of reinforced concrete members in MPa.
• In general, water that is drinkable can usually be used for making concrete.
• NSCP C101-10 - states that water used in mixing concrete shall be clean and free from injurious amount of oils, acids, alkalis, salts, organic materials or other substances deleterious to concrete or reinforcement.
• Admixtures - ingredients other than cement, aggregates, and water that are added to concrete mix immediately before or during mixing.
• Air-entraining admixtures - these admixtures purposely introduce microscopic air bubbles in concrete to improve its durability when exposed to repeated freeze-thaw cycles.
• Superplasticizers - these high-range water reducers that can greatly reduce water demand and cement content without sacrificing workability.
• Corrosion inhibitors - these are usually in parking structures, marine structures, and other structures exposed to chlorides, which can cause corrosion of steel reinforcement in concrete.
• Test on wet concrete

  1. Slump Test
  2. Compacting Factor Test
• Slump Test – standard method in determining the relative consistency of concrete.
• Compacting Factor Test – the degree of compaction achieved by a standard amount of work is measured.
• Test on hardened concrete

  1. Compressive Strength
  2. Tensile Strength
  3. Flexure Test
  4. Test Cores
• Compressive Strength – the most important property of concrete. The characteristic strength is measured by the 28 day cylinder strength.
• Tensile Strength – is about a tenth of compressive strength. It is determined by loading a concrete cylinder across a diameter.
• Flexure Test – a plain concrete specimen is tested to failure in bending.
• Test Cores – cylindrical cores are cut from the finished structure with a rotary cutting tool.
• Non-destructive test

  1. Rebound Hardness Test
  2. Ultrasonic Pulse Velocity Test
• Rebound Hardness Test – in which a metal hammer held against the concrete is struck by another spring-driven metal mass and rebounds.
• Ultrasonic Pulse Velocity Test – pass through a concrete section from a transmitter to a receiver is measured.