Since 1919 Robinson Flagstone has been the preferred supplier of Pennsylvania flagstone (Bluestone) servicing the needs of architects, landscape architects, designers and the construction industry in general. Our full cooperation is given for each job whether that requires technical information, budgeting, samples, or design concepts.

Our years of accumulated knowledge and continued research is complimented by our fully trained staff in sales, design and drafting, right down to the actual craftsmen who cut each individual stone. We are constantly studying and experimenting with our products to secure architectural effects for residential, institutional and commercial applications. Specify us by name for full cooperation and quality controlled source.

Shop drawings are provided with most jobs so review of the design is available prior to any fabrication.

Robinson Flagstone is a specially selected Pennsylvania bluestone (not slate). The stone itself is only quarried in a small region of Pennsylvania and lower state New York formed during the Devonian age. Bluestone is composed of fine grained silica sand cemented together by very strong binder materials. Fossilized sediments plus minerals present during formation contributed to the various shades of blue, gray, green, lilac and the combination of these tones. With a natural cleft surface texture, the stone has slight variations which while true to one plane offer a relatively smooth surface without the annoyance of an overly rough stone. This material is one of the toughest known stones to abrasion (approximately seventy percent quartzite) making it virtually non-slip whether wet or dry. The stone is very resilient and stable, resisting cracking and disintegration.

PENNSYLVANIA BLUESTONE ASTM QUALIFICATIONS

ASTM C 616: CLASSIFICATION OF SANDSTONE--TYPE II QUARTZITE SANDSTONE

 

Composition

 

Silicon Dioxide - 72.8%

Aluminum Oxide - 12.2%

Iron Oxide (Ferric) - 1.92%

Calcium Oxide (Lime) - .70%

Iron Oxide (Ferrous) - 2.50%

Magnesium Oxide - 1.20%

Sodum Oxide - .85%
Titanium Oxide - 1.16%


Acid Resistance: N/A
Edge Detail: Sawn, Thermal (flamed), Rocked, Rubbed, Bullnosed, ½” Radius, ¾” Radius, DuPont, Cove DuPont, Honed
(Please note that these edge details are only applicable to thermal bluestone, not natural cleft)
Texture: Thermal, Natural Cleft, Honed
Thickness Range: 3/8” to 30” thick
Lippage/Warpage: Quality Controlled
Flaking: Quality Controlled
Sealer Recommendation: N/A
Percentage Breakage: Quality Controlled
Approximate Crate Size: 42” x 48” pallet, Approximately 3,600 lbs.
Recommended Areas of Usage: Interior or Exterior
Peculiar Characteristics: Only quarried in Northeast Pennsylvania and Southern New York

 


ASTM QUALIFICATIONS OF SANDSTONE

 

 

ASTM C-97: ABSORPTION & BULK SPECIFIC GRAVITY

SAMPLE ID

ABSORPTION SPECIFIC GRAVITY

#1
#2
#3
Average

1.09%

1.04%

1.11%

1.08%

2.810 (162.86 pcf)

2.607 (162.68 pcf)

2.608 (162.74 pcf)

2.608 (162.74 pcf)

 

ASTM C-99: MODULUS OF RUPTURE

SAMPLE ID

PARALLEL TO BED PERPENDICULAR TO BED

#1
#2
#3

#4

#5
Average

2093 psi

2268 psi

2188 psi

2209 psi

2213 psi

2194 psi

2901 psi

2842 psi

2755 psi

2951 psi

2832 psi

2856 psi

 

 

ASTM C-170: COMPRESSIVE STRENGTH DRY CONDITION

SAMPLE ID

PARALLEL TO BED PERPENDICULAR TO BED

#1
#2
#3

#4

#5
Average

14235 psi

13960 psi

14891 psi

15124 psi

14200 psi

14482 psi

18523 psi

18910 psi

18546 psi

17953 psi

17997 psi

18386 psi

 

ASTM C-170: COMPRESSIVE STRENGTH WET CONDITION

SAMPLE ID

PARALLEL TO BED PERPENDICULAR TO BED

#1
#2
#3

#4

#5
Average

13120 psi

12900 psi

13006 psi

12854 psi

12910 psi

12958 psi

17424 psi

17019 psi

16841 psi

16420 psi

17283 psi

16988 psi

 

ASTM C-241 ABRASION RESISTANCE TO FOOT TRAFFIC

SAMPLE ID

THERMAL FACE NATURAL CLEFT

#1
#2
#3
Average

26.8

27.4

26.9

27.0

9.2

8.8

8.6

8.9