Reinforced Concrete Principles

<p>ASTM D75 (C)</p> Signup and view all the answers

<p>28 days (A)</p> Signup and view all the answers

<p>To determine the forces and deformations within the structure (B)</p> Signup and view all the answers

<p>Concrete with no reinforcement or minimal reinforcement compared to reinforced concrete (A)</p> Signup and view all the answers

<p>Low labor skill requirements for assembly and construction (B)</p> Signup and view all the answers

<p>Compliance of members with strength and serviceability requirements (C)</p> Signup and view all the answers

<p>Has no structural function in a load-bearing system (C)</p> Signup and view all the answers

<p>Requirement for complex formwork (D)</p> Signup and view all the answers

<p>The use of lime mortar mixed with volcanic ash by the Romans (D)</p> Signup and view all the answers

<p>Final decision on the design's optimum status (B)</p> Signup and view all the answers

<p>The reliability of a structural member's performance (B)</p> Signup and view all the answers

<p>Minimizing construction costs (B)</p> Signup and view all the answers

<p>2015 National Structural Code of the Philippines Vol. 1 (C)</p> Signup and view all the answers

<p>Maximizing formwork reuse (A)</p> Signup and view all the answers

<p>Floor and roof systems (A)</p> Signup and view all the answers

<p>Haunched beams and deep spandrel beams for aesthetic value (C)</p> Signup and view all the answers

<p>The total factored load (B)</p> Signup and view all the answers

<p>To simplify formwork (A)</p> Signup and view all the answers

<p>Lower w/c leads to higher compressive strength (D)</p> Signup and view all the answers

<p>Type II (modified) (C)</p> Signup and view all the answers

<p>Improve workability in some cases (B)</p> Signup and view all the answers

<p>Color of the concrete mix (C)</p> Signup and view all the answers

<p>It affects moisture and temperature conditions (C)</p> Signup and view all the answers

<p>Concrete strength increases significantly during this period (D)</p> Signup and view all the answers

<p>Both ASTM C78 and ASTM C496 (C)</p> Signup and view all the answers

<p>Low strain rates (C)</p> Signup and view all the answers

<p>5-7 (10-6)/°F (C)</p> Signup and view all the answers

<p>Maintaining a pH above 11-12 (B)</p> Signup and view all the answers

<p>It creates microscopic voids to relieve pressures. (B)</p> Signup and view all the answers

<p>It improves the bond between concrete and steel. (C)</p> Signup and view all the answers

<p>Utilizing appropriate types of cement (D)</p> Signup and view all the answers

<p>Pressure in water-filled pores (D)</p> Signup and view all the answers

<p>Increased temperature (C)</p> Signup and view all the answers

<p>Pavements (C)</p> Signup and view all the answers

<p>It decreases. (D)</p> Signup and view all the answers

<p>Gray (A)</p> Signup and view all the answers

<p>They significantly increase compressive strength. (C)</p> Signup and view all the answers

<p>Grade 40/300 (A), Grade 60/420 (C)</p> Signup and view all the answers

<p>Steel reinforcement (B)</p> Signup and view all the answers

<p>ASTM A706 (A)</p> Signup and view all the answers

<p>Improved bond and anchorage into concrete. (D)</p> Signup and view all the answers

<p>It shows less significant impact than moist concrete. (B)</p> Signup and view all the answers

Concrete used in structural systems to transfer loads to the ground in a building or structure.

Structural concrete that contains reinforcing steel to increase tensile strength.

Structural concrete with minimal or no reinforcement.

Steps for designing a structure, starting with load application and ending with final design approval.

Modeling and studying a structure's forces and deformations under loads.

Checking if structural members meet strength, serviceability, and design requirements.

Revising the design based on evaluation and client specifications if needed.

A mixture of cement, aggregate, water, and optional admixtures (fibers, etc).

Concrete is strong under compression (squeezing) but weak under tension (pulling). This is why reinforcement is used.

Tiny internal cracks in concrete that form during loading. They help concrete act a bit more ductile (flexible) than it normally would.

Microcracks are called bond cracks when they form between the cement paste and aggregates, and mortar cracks when they form within the cement paste.

Concrete's compressive strength is measured using standard tests with cylinders of specific sizes (6-in or 4-in diameter) and a standard curing time of 28 days.

Concrete under compression fails in stages: first bond cracks develop, then localized mortar cracks, and eventually more mortar cracks form as the load increases.

A factor used to ensure structural safety in design, acknowledging variations in material strength and design assumptions.

The theoretical maximum strength of a structural member calculated without considering variations of actual material or dimensions.

The calculated load on a structure that considers load variability and possible overload scenarios.

A factor applied to load types to account for uncertainties and variations in their actual magnitude.

Differences in material densities and actual load intensities during a structure's usage.

Differences in properties among material samples, including strength and dimensions.

Considering potential consequences of failure, taking into account the variability of both load and strength, and ensuring safety of structures.

Prioritizing cost-effectiveness by avoiding unnecessary complexity in design while employing standard components where feasible, along with cost-effective material selection.

The ratio of water to cement in a concrete mix. Lower ratios generally result in higher compressive strength.

Normal cement used in general construction projects.

Modified cement with lower heat of hydration than Type I, often used in areas with moderate sulfate exposure.

High early strength cement, used when faster setting times are needed. It has higher heat of hydration than Type I.

Low heat cement used for massive concrete structures (dams, large walls) due to its slow heat release.

Sulfate-resisting cement used for underground structures exposed to soils containing sulfates.

Materials like fly ash, silica fume, and ground granulated blast-furnace slag that are added to cement mixtures to improve properties like workability and lower heat of hydration.

The moisture and temperature environment during the initial hardening of concrete. Proper curing helps develop concrete strength.

The change in volume of concrete due to temperature variations. It depends on factors like aggregate type, moisture content, and age.

A measure of how much a material expands or contracts for every degree of temperature change. For concrete, it varies based on the aggregate used (siliceous, limestone, lightweight).

The process of steel reinforcement rusting within concrete, caused by oxygen and moisture. It is prevented by the high pH of fresh concrete, but starts when pH drops below 11-12.

Concrete can withstand fire for a limited time, but high temperatures cause surface cracks (spalling). Spalling gets worse when the surface cools quickly. Concrete's strength and stiffness decrease with rising temperatures.

A thin layer of rust on the surface of steel reinforcement before concrete pouring. It actually helps improve the bond between concrete and steel.

Heated concrete changes color: pink indicates damage, gray means severe damage, and anything beyond gray needs removal.

Concrete gets stronger in cold weather (especially moist concrete). But freezing water inside can damage it.

The breakdown of concrete due to freezing and thawing cycles. Water in the pores expands when frozen, causing pressure that can crack the concrete.

Steel bars, wires, or fibers within concrete that help it resist forces.

Intentionally adding tiny air bubbles to concrete mix during production. These bubbles act as 'pressure relief valves' to prevent freeze-thaw damage.

A chemical attack that weakens concrete when exposed to sulfates (like those in soil or water). It can cause cracks and disintegration.

Common types: hot-rolled deformed bars (for strength and bond), welded wire fabric (for smaller structures), and steel tendons (for prestressed concrete).

A chemical reaction between alkali compounds in cement and silica in aggregates. It causes swelling and cracking in concrete, making it weaker.

Steel bars with bumps (deformations) to create strong bonds with concrete. Used in various grades based on their yield strength (e.g., Grade 40, Grade 60).

The grade number (e.g., Grade 40) indicates the steel's yield strength in ksi/MPa. Higher grade means stronger steel.

Grade 40 and 60 are most common for buildings. Grade 75 is used for large structural members.

Intentionally adding tiny air bubbles to concrete mix during production. These bubbles act as 'pressure relief valves' to prevent freeze-thaw damage.

A chemical attack that weakens concrete when exposed to sulfates (in soil or water). It causes cracks and disintegration.

Using appropriate cement types and checking the source of aggregates to prevent chemical attacks like sulfate attack and ASR.