It can't get much more fun than this! This has come up enough that we need to have a good, wonkish discussion of definitions for pervious concrete.
With the publication of ASTM C 1747-11, ASTM now has an official definition for Raveling:
raveling, n—the wearing away of a pavement surface due to dislodgement of aggregate particles.
Also included in C 1747 is a definition for Design Density:
design density, n—the mass of a unit volume of pervious concrete based on the theoretical mixture proportions and void content and where the unit volume includes the volume of the solids and the voids.
Other definitions unique to pervious concrete can be found in other publications.
C 1688 contains the definition of Pervious Concrete:
concrete, pervious, n—hydraulic cement concrete with distributed, interconnected macroscopic voids that allow water to pass through the material with little resistance.
ACI 522R-10 has the definition for Void Content:
void content—The ratio of the volume of voids to the total volume expressed as a percentage. Voids include both entrapped and entrained air voids.
Looking through the above list of definitions, there are a few missing that we need to include in future documents. I throw these out there for the community to discuss and debate. We might want to consider formalizing the following:
Paste Drain, v-the downward movement of cementitious paste within a fresh pervious concrete mass.
An Example of Paste Drain in a Cast Specimen
Paste Bridge, n-the mass of hardened cementitious material connecting adjacent aggregate particles in pervious concrete.
The Arrow Shows the Paste Bridge Between Two Adjacent Aggregate Particles
Design Void Content, n-the percentage of voids of a unit volume of pervious concrete based on the theoretical mixture proportions and design density and where the unit volume includes the volume of the solids and the voids.
Raveling Potential (Potential Resistance to Raveling), n-The qualitative relationship between related pervious concrete mixtures expressed inversely to the mass loss reported when tested in accordance with ASTM C 1747-11.
In This Example the Mixture With Medford 8 Coarse Aggregate Showed the Lowest Raveling Potential.
Also worth mentioning is new terminology recently balloted in ASTM on Calibration vs. Standardization.
calibration, n—of measuring instrument, a process that, under specified conditions and following a standard procedure,establishes metrological traceability by determining: (1) the relationship between the quantity values provided by measurement standards or certified reference materials and the corresponding indications from a measuring instrument or system; and (2) the estimated uncertainty of measurements made subsequently with the instrument or system. (2011)
DISCUSSION—Calibration takes into account systematic error (or bias) of the measuring instrument or system as well as random error that is associated with the use of the measurement instrument or system and error associated with the measurement standards or certified reference materials. Calibration should not be confused with an adjustment of a measuring instrument or with verification of a measuring instrument. Sometimes the first step alone is mistakenly called calibration, but performing only the first step is the process of standardization. In tests of concrete and concrete aggregates, standardization of measuring
instruments or systems is often sufficient.
standardization, n—of measuring instrument, a process that, under specified conditions and following a standard procedure, establishes: (1) the relationship between the quantity values provided by reference standards or reference materials and the corresponding indications from a measuring instrument or system; or (2) the adjustment to be applied to test equipment when its performance is compared to that of an accepted standard or process. (2011)
DISCUSSION—Standardization in case (1) is a simplified form of calibration that accounts for systematic error (bias) but does not evaluate random error. Standardization, therefore, does not address all of the elements of uncertainty of measurement and does not lead to traceable measurements. An example of case (2) standardization is adjusting the number of blows of a mechanically-operated hammer so it applies the same energy as a specified number of blows of a manually-operated hammer.
