Cement Tests
Tests on portland cement and concrete: fineness, setting time, soundness, specific gravity and loss on ignition, and the compressive, flexural and tensile strength of the hardened material.
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Compressive Strength
PCC is most often known by its compressive strength. This is because PCC is much stronger in compression than it is in tension and thus, is often used in compression.
Early Age Behavior
The service life of PCC pavements is highly dependent upon their early-age behavior. Rigid pavements are significantly affected by temperature and moisture changes during the first 72 hours following placement.
Portland Cement Compressive Strength
The most common strength test, compressive strength, is carried out on a 50 mm (2-inch) cement mortar test specimen. The test specimen is subjected to a compressive load (usually from a hydraulic machine) until failure.
Portland Cement Fineness
Fineness, or particle size of portland cement affects hydration rate and thus the rate of strength gain.
Portland Cement Flexural Strength
Flexural strength (sometimes called the modulus of rupture) is actually a measure of tensile strength in bending. PCC flexural strength testing is carried out on a 40 x 40 x 160 mm (1.57-inch x 1.57-inch x 6.30-inch) cement mortar beam.
Portland Cement Loss on Ignition
Loss on ignition is calculated by heating up a cement sample to 900 - 1000°C (1650 - 1830°F) until a constant weight is obtained. The weight loss of the sample due to heating is then determined.
Portland Cement Setting Time
Cement paste setting time is affected by a number of items including: cement fineness, water-cement ratio, chemical content (especially gypsum content) and admixtures.
Portland Cement Soundness
When referring to portland cement, "soundness" refers to the ability of a hardened cement paste to retain its volume after setting without delayed destructive expansion (PCA, 1988).
Portland Cement Specific Gravity
Specific gravity is normally used in mixture proportioning calculations.
Portland Cement Tensile Strength
Although PCC is not nearly as strong in tension as it is in compression, PCC tensile strength is important in pavement applications.
Air Content of Fresh Concrete
Why air is entrained in paving concrete and how it is measured in the field with the pressure meter, the volumetric meter and the gravimetric method.
Concrete Batch Tickets and the Water–Cementitious Ratio
Reading a ready-mixed concrete batch ticket, checking time and drum revolutions, and working out the w/cm and the water that may still be added on site.
Field Testing of Fresh Concrete
The routine tests on fresh concrete at the truck or paver: sampling, temperature, slump, air, unit weight and strength specimens, and their timing.
Making and Curing Concrete Test Specimens
Making cylinders and beams in the field, initial curing on site, transport and final curing, and the handling errors that most often cause low strength results.
Sampling Freshly Mixed Concrete
How to take a representative composite sample of fresh concrete from truck mixers, agitators, dump trucks and pavers, and the time limits that follow.
Unit Weight and Yield of Fresh Concrete
The fresh concrete density test and what it tells you: yield, relative yield, actual cement content and gravimetric air, with worked equations.