CMT Exam Reviewer 2

Lecture 5 - 7

Concrete Specimens

Sample units of concrete.

Testing ang evaluating the compressive strength, flexural strength, and others.

What are concrete specimens subjected to/created for?

Cylindrical Specimens

Used to determine compressive strength of concrete.

ASTM C39/C39M (AASHTO T22)

Test code for Compressive Strength Test

ASTM C78/C78M (AASHTO T97) and ASTM C293/C293M (AASHTO T177)

Test code for Flexural Strength Test

AmericanSociety of Testing Materials (ASTM)

Responsible for setting the standars in the preparation and curing of concrete test specimens in laboratory and field settings.

ASTM C192/C192M

Test Code for Standard Practice for Making and Curing Concrete Test Specimens in Laboratory

Steel or cast iron or any nonabsorbent material or nonreactive with concrete

Molds for concrete specimens shall be made of what material?

Watertightness

The ability to hold water in molds.

Cylindrical and Beam Molds

What are the two types of molds?

Tamping Rods

Is a round, straight steel rod having a rounded end and a hemispherical tip of the same dia.

3/8 in (10 mm) in dia. and approx. 12 in. (300 mm) long

What is the specification of the Small Tamping Rod?

5/8 in (16 mm) in dia. and approx. 24 in. (600 mm) long

What is the specification of the Large Tamping Rod?

Mallet/s

Used in concrete testing that has a rubber or rawhide head

1.25 + 0.50 lb (0.6 + 0.20 kg)

In testing, how much should the mallet weigh? (lb and kg)

Internal Vibrators

A construction vibrator that operates in the concrete.

At least 7000 vibrations per minute or 115 Hz

What frequency do internal vibrators operate under? (vibrations per min and Hz)

1/4

The diameter of a round vibrator shall be no more than __ of the diameter of a cylinder mold or shall be no more than _ of the width of a beam or prism mold.

3600 vibrations per minute or 60 Hz

What frequency do external vibrators operate under? (vibrations per min and Hz)

Table or Plank

What are the 2 types of external vibrators?

C143/143M (Slump Apparatus)

Test Method for Slump Test

Flat bottom and of heavy-gage metal, watertight, of convenient depth and of sufficient capacity to allow mixing

Specifications for a sampling or mixing pan

C 172 (Wet-Sieving Equipment)

Practice code for wet-sieving

C 231 or C173 (Air Content Apparatus)

Test method code for measuring air content.

Scales

Determines the mass of batches of materials and concrete

w/in 0.3% of the test load

What percentage shall the accuracy of scales be?

C 1064

Test code of Temperature Measuring Device

Concrete Mixer

It thoroughly mixes batches of cement, sand, water, and other materials.

Trowels, Finishing Trowel, Concrete Hand Floats

Three types of Small Tools

68 to 86 deg. F (20 to 30 deg. C)

What room temperature should the concrete materials be before mixing?

850 - um (No.200) or finer sieve

Cement shall pass through what sieve no. ?

C 70 and C 566

Test code for determining moisture content of aggregates

C 70 and C 566

Test code for determining surface moisture in fine aggregates

¼ ft3 (0.007 m3)

Batches for aggregates in material preparation

24 + 8 hrs

When are specimens removed from the molds after casting?

20 + 4 hrs

For concrete w/ prolonged setting time, molds are removed after?

C403/ C403M

Test code for determining setting times

73.5 + 3.5 deg F (23.0 + 2.0 deg C)

What temperature (moist cured )shall all specimens be under from the time of molding to the moment of test.

C 511

Specification code for using water storage tanks or a moist room

C 330

Specification code for curing structural lightweight concrete cylinders

20 hrs

Minimum period of immersion of flexural strength specimens in water sturated w/ calcium hydroxide.

73 + 3 deg F ( 23 + 2 deg C)

Temperature of water saturated in calcium hydroxide.

ASTM C31

Code for the Standard Practice for Making and Curing Concrete Test Specimens in the Field

at least 100 mm (4 in); at most 600 mm (24 in)

In field testing, the length of the tamping rod shall be at least _ greater than the depth of the mold, but not greater than _ in overall length.

2 times; 3 times

For Cylindrical Specimens, the length shall be _ the diameter and the diameter shall be at least _ the nominal maximum size of coarse aggregate.

150 by 300 mm or 100 by 200 mm

What is the accepted dimensions of a cylindrical specimen for testing?

150 mm x 150 mm

What is the standard cross-section dimension of a beam specimen for testing?

C1077

What is the practice code for Field Practitioners?

15 min.

In the field, how many minutes/hrs is required in moving the specimen to the initial curing location after molding operation.

Up to 48 hrs

In the field, how many minutes/hrs should the specimen be cured after molding?

Specimens shall not be transported until at least _ (minutes/hours) after final set.

4 hrs

Transportation time shall not exceed _