Less than $500
Completely portable permeation tube calibration system for pollution monitoring.
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Figure 4. Underside of spalied c o n c r e t e " f l a k e " that originally extended a c r o s s three masonry blocks. Section is about 1 / 4 -in. thick. Opposite side is painted
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dosages was prepared, a n d this partic ular combination proved synergistic— over 15% air h a d b e e n e n t r a i n e d , a n d 50% loss in s t r e n g t h h a d r e s u l t e d . U n fortunately, t h e r e was no way to save t h e m i l e of c o n c r e t e p a v e m e n t ( a b o u t 10 m i l l i o n l b ) t h a t h a d b e e n p l a c e d , b u t succeeding p a v e m e n t set satisfac t o r i l y b y c o n t r o l l i n g t h e a m o u n t s of t h e a d m i x t u r e in t h e c o n c r e t e .
J -r H '303
CIRCLE 158 O N READER SERVICE CARD
Concrete Scales
ORTEC MAKES YOUR PHOTONS COUNT! In physics . . . optics . . . laser systems . . . ion experiments . . . astronomy . . . molecular studies . . . luminescence . . . fluorescence Raman . . . mass spectroscopy . . . wherever critically accurate light measurement is required. The Ortec 5C1 is the most advanced photon-counting system money can buy. And the most practical. It has a dual-channel pulse height analyzer, for example, that provides first-order pile-up correction at high counting rates ano" window-mode dis crimination of high and low pulses. At counting rates where conventional systems " l o s e " 5 0 % of the counts, the 5C1 linearizes to within 5 % . Another unique advantage is spec trum display. Connect the unit to any CRT, and you can visually opti ©ORTEC
mize high voltage, amplifier gain, and discriminator levels. Then dis able the light source and check for rf pickup or spurious signals. You can't do this with any other photoncounting system. For full technical data, contact your nearby Ortec representative or Ortec Incorporated, 110 Midland Road, Oak Ridge, Tenn. 37830. (615) 482-4411.
ORTEC® AN
EG&G
COMPANY
CIRCLE 181 ON READER SERVICE CARD
1232 A · ANALYTICAL CHEMISTRY, VOL. 46, NO. 14, DECEMBER 1974
5979
M a n y o w n e r s of w o o d f r a m e h o u s e s r e c o g n i z e t h a t t h e p e e l i n g of p a i n t is a major economic headache. Concrete m a y experience the same distress. B u t when a concrete block building began l o s i n g n o t o n l y i t s p a i n t b u t a l s o a V4i n . l a y e r of u n d e r l y i n g c o n c r e t e ( F i g ure 4), c o n s t e r n a t i o n really a b o u n d e d . M i c r o s c o p i c a n a l y s i s of t h e r e c e i v e d "scales" revealed thin delamination layers within t h e spalied section re c e i v e d a t o u r l a b o r a t o r y . T h i s e f f e c t is c h a r a c t e r i s t i c of f r e e z e - t h a w d a m a g e to critically s a t u r a t e d concrete. A n a l y s i s of t h e p a i n t b y i n f r a r e d spectroscopy, solvent extraction, and pyrolysis techniques disclosed an a l k y d t y p e of p a i n t . S u c h a p a i n t is classified as " n o n b r e a t h i n g . " W i t h this analytical data, the t e a m speculated that moisture entering the building walls was p r e v e n t e d from es caping by the paint. T h e concrete near t h e p a i n t surface b e c a m e s a t u r a t e d a n d d u r i n g w i n t e r f r o z e b e c a u s e of i t s exposure at outside temperatures. A site visit revealed a flashing detail e r r o r t h a t a l l o w e d e n t r a n c e of r a i n w a t e r into t h e walls. T h e corrective measures suggested were the elimina t i o n of t h e f l a s h i n g d e t a i l e r r o r b y properly redoing the flashing a n d t h e r e p l a c e m e n t of t h e n o n b r e a t h i n g p a i n t with a breathing paint.
