REINFORCED CONCRETE
A Written Report presented to
Engr. Owiedah M. Malawani Jr., RCE
College of Information Technology and Engineering
Philippine Engineering and Agro-Industrial College Inc.
Datu Gonsi St., Lomidong, Marawi City
In Partial Fulfillment of the Requirements for the Course
CE 221e – Construction Materials and Testing – A
Second Trimester
A.Y. 2024 – 2025
Basman, Saharah M.
Decampong, Abdulraffy
Laguindab, Basit S.
Solaiman, Jalaica Mae M.
January 2025
I. Plain Cement Concrete (PCC)
Is an artificial stone made out from the mixture of cement, sand, gravel, and water or
other inert materials.
Though strong in resisting compression, concrete is particularly weak in tension.
II. Reinforced Cement Concrete (RCC)
In real life, concrete structures experience a variety of stresses at the same time, as
opposed to just one specific stress. When applied with loads, beams experience both
compression and tension at the top and bottom portions respectively.
The design of RCC assumes that concrete and steel reinforcements act together in
resisting load and likewise to be in a state of simultaneous deformation, otherwise due
to excessive load, steel bars might slip from the concrete in the absence of sufficient
bond.
The combination of concrete and steel shows the following satisfactory joint
performance:
1. Negligible difference in thermal expansion coefficient that makes it safe from
undue effects of differential thermal expansion.
2. The concrete around steel provides for an excellent protective covering from
corrosion in steel.
3. The strength of steel decreases when exposed to high temperatures but the
concrete covering provides sufficient thermal insulation.
4. While concrete is weak in tension force, steel has high resistance against it.
The use of RCC does not necessarily mean that structures are completely safe from
failure. It simply makes a drastic difference from the safety of PCC and reveals
warning signs in the form of gradual cracks (Ductile Failure) as opposed to
spontaneous breakage (Brittle Failure).
III. Steel Reinforcement / Steel Rebar
Steel is 10 times stronger than concrete in resisting compressive stress and 100 times
stronger in resisting tensile stress.
Up until the 1950’s, engineers incorporated the use of plain steel rods to counter
tension stress experienced by plain concrete. However, this did not solve the problem
and still resulted in disastrous accidents as plain rebars performed badly in
earthquakes.
Steel reinforcing bars with surface deformations were introduced to provide a high
degree of interlocking between the bars and concrete.
Bond of Concrete Reinforcing Bars, a study in 1949, found that the use of deformed
rebars in concrete more than tripled the capacity than that of a plain rebar in resisting
loads.
IV. Types of Tests Performed on Reinforced Concrete
1. Reinforced Concrete Testing
o Compressive Strength tests – measure the resistance of concrete systems to
compressive loads. Cylindrical or cubic samples are compressed until failure, and
peak compressive strength is captured.
o Flexural Strength tests – measure concrete resistance to bending. Rectangular
beams are loaded until failure, and flexural strength and modulus are measured.
2. Rebar Testing – Steel reinforcing bars, or rebar, are used in concrete construction to
enhance tensile strength, complementing concrete's excellent compressive properties.
o Tensile tests – determine the yield strength, ultimate tensile strength, and
elongation of steel reinforcing bars (rebar).
o Bend and rebend tests – assess the ductility of steel reinforcement. The rebar is
bent to a specified angle and then bent back (rebend).
3. Concrete & Steel Bond Testing
o Pull-out tests – measure the bond strength between a steel bar and the
surrounding concrete. A rebar embedded in concrete is pulled out, and the force
required to cause failure is measured.
Popular Standards for Testing Reinforced Concrete
ASTM C39 Compressive Strength of Cylindrical Concrete Specimens
o ASTM C39 test for compressive concrete covers the determination of
compressive strength of cylindrical concrete specimens such as molded cylinders
and drilled cores. ASTM C39 consists of applying a compressive axial load to
molded cylinders or cores at a rate which is within a prescribed range until failure
occurs.
ASTM C78 Flexural Bend Concrete
o ASTM C78 determines the flexural strength of concrete by the use of a simple
beam with third-point loading. This standard is used in the testing of concrete in
the construction of slabs and pavements.
ASTM C469 Compression Concrete Elasticity Poisson Test
o This test method provides a stress to strain ratio value and a ratio of lateral to
longitudinal strain for hardened concrete at whatever age and curing conditions
may be designated.
Conclusion
Though a good structural material on its own, Plain Cement Concrete is not sufficient to
withstand the many and dynamic stresses experienced by structures on a day-to-day basis.
Natural phenomenon such as earthquakes alone pose great dangers to structures made only with
PCC. Since PCC is weak in resisting tensile forces, the incorporation of steel rebars in concrete
provided the best counteraction to this problem. Hence the introduction of Reinforced Cement
Concrete or simply Reinforced Concrete, specifically with deformed steel rods. With the use of
RCC, structures are now safer and more durable, lasting infinitely longer than with PCC.
References
Fajardo, M. (2000). Simplified Methods on Building Construction.
Thakur, P. Plain Cement Concrete. Civil Concept. Retrieved from
https://www.civilconcept.com/plain-cement-concrete/
The Engineering Hub. (2023, June 2). Why does concrete reinforcement have deformations?
[Video]. YouTube. https://youtu.be/KOmS03VnPLM?si=P4DpcPpY3GnbzlWd
Practical Engineering. (2018, April 26). Why Concrete Needs Reinforcement [Video]. YouTube.
https://www.youtube.com/watch?v=cZINeaDjisY&list=LL&index=1&t=331s
Sabins Civil Engineering. (2024, December 31). The Beauty of Reinforced Concrete! [Video].
YouTube. https://www.youtube.com/watch?v=JHuf1Hu7ApU&list=LL&index=3
The Engineering Hub. (2023, June 2). Why does concrete reinforcement have deformations?
[Video]. YouTube. https://youtu.be/KOmS03VnPLM?si=P4DpcPpY3GnbzlWd
Cttp Arkansas. (2022, August 31). ASTM C39 & C1231 - Compressive Strength with Unbonded
Caps [Video]. YouTube. https://www.youtube.com/watch?v=jLIXAzWFl2M
Cttp Arkansas. (2020, May 19). ASTM C78 - Flexural Strength [Video]. YouTube.
https://www.youtube.com/watch?v=TCfQdlriFAQ
Philippine Industry and ASTM International Standards | NEWSROOM. (n.d.).
https://newsroom.astm.org/philippine-industry-and-astm-international-standards
Test Resources. https://www.testresources.net/applications/materials/reinforced-concrete
