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David Axt, AIA, CCS, CSI
Senior Member
Username: david_axt

Post Number: 1177
Registered: 03-2002


Posted on Thursday, April 21, 2011 - 01:48 pm:   Edit PostDelete PostPrint Post

When is it best to specify sharp sand as opposed to rounded sand?
Mark Gilligan SE,
Senior Member
Username: mark_gilligan

Post Number: 385
Registered: 10-2007
Posted on Friday, April 22, 2011 - 01:15 am:   Edit PostDelete PostPrint Post

For what purpose?
John Bunzick, CCS, CCCA, LEED AP
Senior Member
Username: bunzick

Post Number: 1316
Registered: 03-2002
Posted on Monday, April 25, 2011 - 06:49 pm:   Edit PostDelete PostPrint Post

Using rounded sand in mortar, for example, produces a more workable mix than sharp sand because the grains slip past each other more easily. Per Mark, what's your context?
Mark Gilligan SE,
Senior Member
Username: mark_gilligan

Post Number: 391
Registered: 10-2007
Posted on Monday, April 25, 2011 - 07:40 pm:   Edit PostDelete PostPrint Post

I am not aware of a standard that can be used to specify rounded sand.

If the problem has to do with workability of the mix why not leave it to the contractor to chose the source of the sand as long as he meets the requirements in the code?
Brian E. Trimble, CDT
Senior Member
Username: brian_e_trimble_cdt

Post Number: 40
Registered: 08-2005
Posted on Monday, April 25, 2011 - 08:12 pm:   Edit PostDelete PostPrint Post

Here's a section from a paper (DEVELOPMENT OF NORTH AMERICAN GUIDELINES FOR PREQUALIFICATION OF BEDDING SAND FOR USE IN SEGMENTAL CONCRETE PAVEMENTS IN VEHICULAR APPLICATIONS) on sands for segmental pavements:

4.3 Particle Shape
Other studies have also shown that bedding sand particle shape plays a role in performance. [Knap-ton, 1993] noted that rounded or cubical grains lead to stable sands, whereas more angular grains are frequently associated with sands that fail. The same sands tested by ICPI showed that eight of the nine “good to excellent” performing sands had a predominance of sub-angular to sub-rounded particle shapes when tested according to ASTM D 2488 Description and Identification of Soils (Visual-Manual Procedure) [ASTM, 2000](see Table 3).
Specifiers and contractors should consider bedding sand angularity using Figure 2 as a guide. Figure 3 shows a photograph of one of these sands at high magnification. Table 4 suggests as a secondary property, that a combined percentage of sub-angular to sub-rounded particles should be a minimum of 60%.

Hope this helps.

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