NUMBERS TELL THE TALE

ISSUE 1 : CONCRETE TEXTURE METER 

DECO CRETE has a whole range of concrete surface testing equipment for their Q/C and R&D. In this article we elaborate on a concrete texture meter (CTM) which measures the profile of the surface. (See figure 1)

  Figure 1.  Surface texture of concrete and its measurement by a probe of a CTM.

  Figure 2. Calculation of Average Roughness (RA)

A CTM determines over a set length the profile of the surface and calculates the Roughness Average (Ra) and the Mean Roughness Depth (Rz).

In the United States, a leading country in the field of polished concrete, a CTM is being frequently being used in the polishing industry to analyze a polished concrete surface. The first standard to measure concrete surfaces for their surface texture value is CSDA ST 115 from 2013.

Table 1 from this standard shows the relation between the various polished surfaces, the grit of the cutting tools and the average roughness (RA).  It can be seen that with each consecutive abrasive grit, the RA value should be halved.

Deco Crete has used a CTM to develop the DECOquickcut system, with which 4 grinding steps can be done in 1 step.  In a next article we will elaborate on this game changer in the polishing industry.

  Table 1.  CSDA ST 115 surface texture grades and RA values

Remark; the CSDA committee does not recommend the above method and values to be used in Architectural  Specifications. Measuring the RA value of the surface of a concrete floor is too unpredictable to be used in a contractual context given the nature of concrete with pinholes, micro cracks etc.

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