ASTM is or isnt comparable to single point loading

Is not; lower strengths

Modulus of Rupture

R; ultimate strength

Sawing and specimen prep will affect results

True

Smaller specimens will have higher or lower strengths

Higher

Span length

Distance between bottom rollers; three times depth

Support blocks height

2.5 inch (65mm)

Support block planeness

0.002 inch

Supports should arc at least how many degrees

45 degrees (0.8 rads)

Span length shall not vary by more than ____

0.05 inch

Bigger aggregates

Bigger beams; lower strength

Surface drying

Reduces strength; microcracks from

Which face propagates

Tension side (bottom)

The point of max load

Form crack from tensile side

Finished face should face which way during testing

To the side

Apply intial load to ___ % of expected max load

3-6%

Use a large ___ in feeler gauge

0.015 in Grind or cap if it passes through

Use a small ___ in feeler gauge

0.004 in Use leather strips if it passes through Test as is if it doesnt pass through

Leather shims dimensions

0.25 in thick 1in - 2 inch wide cover entire specimen Use on all 4 locations

Capping beams

if 0.015 in feeler gauge passes though Cover entire face Include on depth calulations Gysum or neat cement

Load rate per min

125 - 175 psi/min 0.9 - 1.2 MPa/min

Load Rate per sec

2-3 psi/min 0.015-0.02 MPa/min

How to calculate "a"

Take average of three measurements from support line to crack

Which side is used to calulate "a"

tensile side

a > L/6

In middle third

What percent is acceptable to off middle third

5%

Depth vs Breadth

Depth is top to bottom Breadth is left to right

Calculate b and d

Take average of three measurements after testing: choose smaller end

Formula for crack whichin middle third

PL/(b)(d^2)

Formula for crack which 5% of middle third

3Pa/(b)(d^2)

Report MOR to what psi

5 psi

Report avg breadth and depth to what inch

0.05 inch

T or F During first half test speed can be increased

False