CONCRETE TESTINGCONCRETE TESTING

Dr. Sophia Hassiotis

In This PresentationIn This Presentation

Strength Testing Compressive Testing Tensile Testing

Beam Split Cylinder

Durability Testing Chemical Attack Freeze-Thaw

StrengthStrength

Concrete is most often known for its compressive strength

Flexural strength is of importance when used in rigid pavements.

Most often, 28-day strength is specified although other strengths such as 1-day, 7-day, 56-day and 90-day strength can be used as well.

Concrete continues to gain strength over time Curing methods can pay a major role in Concrete strength gain and a standard curing method has to be observed for repeatable test results.  

Compressive StrengthCompressive Strength

Compressive Strength of Cylindrical Concrete Specimens (ASTM C39)

Apparatus: Forney Hydraulic Universal Testing Machine 200,000 lbs Tension,400,000 lbs Compression

Accuracy is approximately 10% of the maximum load.

Compressive Strength — Testing Procedure

Compressive Strength — Testing Procedure

Maintain the specimen in a water storage tanks and controlled temperature of 73.5 +- 3.5 °F [23.0 +- 2.0 °C] up to the time of compression testing.

Testing Procedure (cont)Testing Procedure (cont)

Carefully align the axis of the specimen with the center of thrust of the spherically seated upper platen.

Bring the upper platen to bear on the specimen, adjustingthe load to obtain uniform seating of the specimen, no more than 50% of the ultimate load.

Center the specimen on the lower platen of the testing machine.

Testing Procedure (cont)Testing Procedure (cont)

Apply the load at a loading rate of 35 psi/s (within a range of 28 to 42 psi/s). Maintain this loading rate at least for the last half of the anticipated loading phase.

Make no adjustment in the rate of movement till the end of the test

Apply the compressive load until the load indicator shows that the load is decreasing steadily and the specimen displays a well-defined cracking pattern. Record the maximum load (lb)

Types of Concrete Fracture (ASTM C 39)

Types of Concrete Fracture (ASTM C 39)

Tensile StrengthTensile Strength

Concrete is not nearly as strong in tension as it is in compression.

Concrete flexural strength is important in some applications. For example, flexural strength is typically used as a Concrete performance measure for pavements because it best simulates flexural stresses at the bottom of the Concrete surface course as it is subjected to loading.

Tensile Strength Testing — Flexural strength

Tensile Strength Testing — Flexural strength

The standard flexural strength test is: AASHTO T 97 and ASTM C 78:

Flexural Strength of Concrete (Using Simple Beam with Third-Point Loading)

AASHTO T 177 and ASTM C 293: Flexural Strength of Concrete (Using Simple Beam with Center-Point Loading)  

Tensile Strength Tesing — Split Tension Test

Tensile Strength Tesing — Split Tension Test

The standard split tension test is:AASHTO T 198 and ASTM C 496: Splitting Tensile Strength of

Cylindrical Concrete Specimens

Compressive to Tensile Strength RelationshipsCompressive to Tensile Strength Relationships

In absence of flexural or tensile testing, the ACI Concrete Code gives some rough rules-of-thumbfor converting compressive strength:

Durability of ConcreteDurability of Concrete

Durability is a measure of how Concrete performs over time. 

Two major factors that affect Concrete durability are freeze-thaw cycles and chemical attack. 

Durability Testing—Chemical AttackDurability Testing—Chemical Attack

Some standard tests for chemical attack are:

AASHTO T 259: Resistance of Concrete to Chloride Ion Penetration

AASHTO T 277 and ASTM C 1202: Electrical Indication of Concrete's Ability to Resist Chloride Ion Penetration

AASHTO T 303 and ASTM C 227: Accelerated Detection of Potentially Deleterious Expansion of Mortar Bars Due to Alkali-Silica Reaction  

Durability Testing — Freeze/Thaw

Durability Testing — Freeze/Thaw

Standard freeze-thaw tests are: AASHTO T 161 and ASTM C 666:

Resistance of Concrete to Rapid Freezing and Thawing

AASHTO T 121: Mass Per Cubic Meter (Cubic Foot), Yield, and Air Content (Gravimetric) of Concrete

ASTM C 671: Critical Dilation of Concrete Specimens Subjected to Freezing

LAB REPORTLAB REPORTEach one of you will write and submit his/her own lab report (no

group reports)Your lab report should be typed and all figures should be

professional looking. A big percentage of your grade will be dedicated to the degree of professionalism of your report.

DUE: One week after cylinder breaking

Report the following information: Cover page with Name, Lab group, Group members, Date Calculations for concrete mixing, Procedure for mixing concrete in the lab. ASTM test

number Procedure for Slump Testing, ASTM test number Procedure for setting cylinders, size of cylinders, ASTM

test number When do you remove the cylinders, how do you cure and

for how long Compression testing. Record testing machine and

procedure for compression testing Record Compressive strength ,type of fracture, Defects in

specimen and, Age of specimen.

Example of Report (2013)Example of Report (2013)