Author |
Message |
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: | |
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: | |
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: | |
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: | |
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: | |
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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