Epoxy Resins with Concrete - ACS Publications - American Chemical

4 Epoxy Resins with Concrete PHILIP MASLOW

Downloaded by MONASH UNIV on May 4, 2015 | http://pubs.acs.org Publication Date: November 27, 1979 | doi: 10.1021/bk-1979-0113.ch004

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PART A - CHEMISTRY OF EPOXY RESINS

In all the h i s t o r y of the coatings and p l a s t i c s i n d u s t r i e s , more e s p e c i a l l y , since s y n t h e t i c a l l y prepared raw materials have taken t h e i r p r i n c i p a l position in the technology, there has not appeared a r e s i n which has lent i t s e l f to so wide a v a r i e t y of uses, to so wide a v a r i e t y of a p p l i c a t i o n s , and which has been shown to have such a wide field of t e c h n i c a l and economic utility, as does epoxy. Epoxy resins are e s s e n t i a l l y condensation products of epichlorhydrin and diphenylolpropane. The l a t t e r has been known as the usual phenolic compound of "reduced phenolics." E p i c h l o r h y d r i n , c l o s e l y related to g l y c e r o l , i s r e a d i l y obtained from natural g l y c e r o l , or i n the process of making the synthetic product. It i s usually obtained by the l a t t e r method. The epoxies represent a group of resins which range from low v i s c o s i t y , solventless l i q u i d s , to highmelting-point solids. The name f o r t h i s group of resins, "epoxy," has its o r i g i n i n the GreeK. "Epoxy stems from the word "epi", meaning "on the outside of", and "oxygen". The combined words a c t u a l l y describe the p o s i t i o n of the oxygen atom i n the molecular s t r u c t u r e , which i s found at each end of an epoxy molecule. Epoxy resins also contain hydroxyl r a d i c a l s , ether groups and phenolic groups. Each of these contributes highly des i r a b l e p r o p e r t i e s . The high p o l a r i t y o f the molecule and the hydroxyl r a d i c a l s produce excellent adhesion. The long, c h a i n - l i k e structure of the polymer promotes outstanding flexibility. The epoxide groups and hy0-8412-0523-X/79/47-113-039$05.50/0 © 1979 American Chemical Society

In Plastic Mortars, Sealants, and Caulking Compounds; Seymour, R.; ACS Symposium Series; American Chemical Society: Washington, DC, 1979.


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d r o x y l r a d i c a l s a r e the h i g h l y r e a c t i v e p o i n t s o f t h e resins. The e t h e r groups produce e x c e l l e n t c h e m i c a l resistance. F i n a l l y , when p r o p e r l y r e a c t e d , t h e phenol i c groups make the epoxy r e s i n s h i g h l y r e s i s t a n t t o breakdown. Epoxy r e s i n s a r e not u s a b l e by themselves, s i n c e they l a c k adequate m o l e c u l a r s i z e . They must be f u r t h e r p o l y m e r i z e d o r c h e m i c a l l y c r o s s - l i n k e d t o form u s e f u l compounds. There a r e s e v e r a l methods o f m o d i f i c a t i o n which e n a b l e epoxy r e s i n s t o a c h i e v e t h e i r maximum b e nefits. One o f t h e e a r l i e s t methods was t o r e a c t an epoxy r e s i n w i t h an a c i d o f a d r y i n g o i l , g e n e r a l l y c a l l e d a f a t t y a c i d , t o form an epoxy e s t e r . T h i s i s comparable t o an a l k y d r e s i n and t h e c u r i n g mechanism i s by o x i d a t i o n o f t h e d r y i n g o i l , s i n c e the epoxy and h y d r o x y l groups have been e s t e r i f i e d w i t h t h e f a t ~ y acid. These epoxy e s t e r s a r e sometimes c a l l e d "onecomponent epoxy systems". They can a l s o be b l e n d e d w i t h u r e a formaldehyde, melamine formaldehyde and phen o l formaldehyde r e s i n s , t o form b a k i n g c o a t i n g s . Baki n g f i n i s h e s may a l s o be f o r m u l a t e d , u s i n g h i g h - m o l e c u l a r weight epoxy r e s i n s , r e a c t e d w i t h t h e same f o r m a l dehyde r e s i n s . The most w i d e l y used epoxy systems are t h o s e which are b a s e d on pure epoxy r e s i n s , hardened w i t h a c u r i n g agent. C u r i n g o f epoxy r e s i n s c o n t a i n i n g two epoxy groups p e r m o l e c u l e can be r e a d i l y a c c o m p l i s h e d b y the a d d i t i o n o f p r i m a r y polyamines, such as e t h y l e n e d i a mine, d i e t h y l e n e t r i a m i n e , t r i e t h y l e n e t e t r a m i n e , tetrae t h y l e n e pentamine, e t c . A l i p h a t i c polyamines produce cured r e s i n s with the greatest chemical r e s i s t a n c e . However, t h e s e systems have inadequate d u r a b i l i t y , weat h e r r e s i s t a n c e and f i l m - f o r m i n g p r o p e r t i e s . They a r e s e n s i t i v e t o humidity, e r r o r s i n a d d i t i o n rates are q u i t e p o s s i b l e , and t h e c a t a l y s t s a r e r e l a t i v e l y t o x i c . In a d d i t i o n t o p r i m a r y p o l y a m i n e s , secondary and t e r t i a r y amines a r e a l s o u t i l i z e d . The t e r t i a r y amines, such as m e t h y l a t e d a l i p h a t i c a r o m a t i c amines,are most commonly u t i l i z e d . They c a n b e s t be d e s c r i b e d as c a t a l y s t s , r a t h e r than h a r d e n e r s , s i n c e they speed up a r e a c t i o n and c o n t r i b u t e t o c r o s s - l i n k i n g , r a t h e r than e n t e r i n g i n t o the r e a c t i o n i t s e l f . A n o t h e r method o f c u r i n g epoxy r e s i n s i s by the use o f p o l y a m i d e s , which a r e made from polyamines r e -



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Epoxy Resins with Concrete

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a c t e d w i t h ciimerized and t r i m e r i z e d f a t t y a c i d s . These polyamides l e n d themselves t o a wide range o f combina t i o n s w i t h epoxy r e s i n s . They c o n t r i b u t e a g r e a t e r de gree o f f l e x i b i l i t y , b u t s o l v e n t and c h e m i c a l r e s i s t ance i s r e d u c e d . They c o n t r i b u t e b e t t e r h e a t r e s i s t ance and have a minimum d e r m a t i t i c e f f e c t . They a l s o minimize c h a l k i n g tendencies i n outdoor exposure. Even g r e a t e r f l e x i b i l i t y i n epoxy r e s i n systems i s o b t a i n e d by the use o f p o l y s u l f i d e r e s i n s . P o l y s u l f i d e s r e a c t w i t h epoxy r e s i n s t h r o u g h mercaptan groups, b u t v e r y slowly. T e r t i a r y amines a r e u t i l i z e d t o speed the r e action. A l l o f t h e s e systems may be u s e d w i t h h i g h m o l e c u l a r w e i g h t , s o l i d epoxy r e s i n s which must be d i s s o l v e d i n s o l v e n t s , as w e l l as w i t h l i q u i d , low-molecu l a r weight r e s i n s , w h i c h do not r e q u i r e s o l v e n t s and may be u t i l i z e d a t 1 0 0 % s o l i d s . These systems, b a s e d on l i q u i d epoxy r e s i n s , a r e t h e ones most w i d e l y used i n the c o n s t r u c t i o n i n d u s t r y . The p r i n c i p a l c h a r a c t e r i s t i c s o f epoxy r e s i n s , as used w i t h c o n c r e t e , i n t h e c o n s t r u c t i o n i n d u s t r y , i n clude : (a) H i g h s t r e n g t h a d h e s i o n t o most b u i l d i n g ma terials ; (b) V e r y low s h r i n k a g e d u r i n g and a f t e r c u r e ; (c) O u t s t a n d i n g d i m e n s i o n a l s t a b i l i t y ; (d) V o i d f i l l i n g q u a l i t i e s ; (e) T h e r m o s e t t i n g - resistc^nce t o s o f t e n i n g ; (f) Optimum c h e m i c a l r e s i s t a n c e ; (g) F a t i g u e r e s i s t a n c e ; (h) Creep r e s i s t a n c e ; (i) A b i l i t y t o w i t h s t a n d thermocycling; (j) Good e l e c t r i c a l i n s u l a t i o n . PART Β - USE OF EPOXIES IN NEW CONSTRUCTION The b a s i c epoxy r e s i n most o f t e n used w i t h con c r e t e i s a l i g h t , amber-colored l i q u i d , about t h e v i s c o s i t y o f a heavy motor o i l . L i q u i d epoxy r e s i n s a r e g e n e r a l l y made by t h e same p r o c e s s as t h a t u s e d t o make s o l i d epoxy r e s i n s . The r a t i o o f e p i c h l o r h y d r i n t o b i s p h e n o l c o n t r o l s t h e type o f r e s i n p r o d u c e d . The h i g h e r the r a t i o o f e p i c h l o r h y d r i n t o b i s - p h e n o l , t h e lower the v i s c o s i t y o f the f i n a l r e s i n , and the lower i t s mo l e c u l a r weight.



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CAULKING COMPOUNDS

In what ways are epoxy x^esin systems u t i l i z e d i n new c o n s t r u c t i o n ? When i t i s c o n s i d e r e d that c o n c r e t e and s t e e l are v e r y o f t e n welded, i t would seem r e a s o n a b l e to assume t h a t the w e l d i n g would be more e f f e c t i v e i f an epoxy adhesive were u s e d . ~\s an example, composi t e beams o f c o n c r e t e on s t e e l are o f t e n i n c l u d e d i n design s p e c i f i c a t i o n s . I t had been the p r a c t i c e t o weld p r o t r u d i n g l u g s on the s t e e l beam, which would become an i n t e g r a l p a r t o f the p l a s t i c c o n c r e t e p l a c e d on the beam. Today, s t r u c t u r a l e n g i n e e r s are u s i n g s p e c i a l l y f o r m u l a t e d epoxy a d h e s i v e s t o bond c o n c r e t e t o s t e e l w i t h o u t the use of l u g s . F l o o r s and w a l l - o f s t r u c t u r e s are o b v i o u s areas where epoxy systems may be u t i l i z e d t o prevent d e t e r i o r a t i o n from a b r a s i o n and c h e m i c a l a t t a c k . Such systems are now to be found i n o r i g i n a l s p e c i f i c a t i o n s . Wall s u r f a c e s may be c o a t e d w i t h epoxy systems based on s o l i d r e s i n s d i s s o l v e d i n s o l v e n t s and hardened w i t h p o l y amines and/or p o l y a m i d e s . Porous s u r f a c e s , such as c o n c r e t e b l o c k s , are f i r s t p r e p a r e d w i t h f i l l e r s t o p r o v i d e a smooth s u r f a c e f o r a p p l i c a t i o n of c o a t i n g s . These systems are d e s c r i b e d as " t i l e - l i k e " c o a t i n g s . In a d d i t i o n t o f i n i s h i n g w a l l s u r f a c e s on s i t e w i t h epoxy systems, the c o n s t r u c t i o n i n d u s t r y u t i l i z e s c o n c r e t e b l o c k s which are f i n i s h e d i n p l a n t w i t h an epoxy f a c i n g . A r c h i t e c t s r e c o g n i z e t h a t these epoxy f a c i n g s w i l l have a tendency t o c h a l k and y e l l o w when used on e x t e r i o r s u r f a c e s . The problem o f c h a l k i n g and y e l l o w i n g l i m i t s the use o f epoxy r e s i n systems f o r dec o r a t i v e purposes on e x t e r i o r s . The y e l l o w i n g phenomenon i s d i r e c t l y a t t r i b u t a b l e t o the p h e n o l i c base o f the epoxy r e s i n . The c h a l k i n g d e v e l o p s from the comb i n a t i o n o f water, oxygen and u l t r a v i o l e t l i g h t . The c h a l k i n g i s not a d e g r a d i n g c h a l k , b u t , r a t h e r , a s u r f a c e phenomenon w h i c h a c t s as a p a s s i v a t i n g f i l m t o p r e vent f u r t h e r a c t i o n on the u n d e r l y i n g s u r f a c e . Of c o u r s e , f l o o r s i n a s t r u c t u r e r e c e i v e the g r e a t e s t abuse, where d e t e r i o r a t i o n o c c u r s i n such a r e a s , epoxy r e s i n systems have been w i d e l y used f o r r e p a i r s . I n d u s t r i a l f l o o r s are now c o n s t r u c t e d w i t h i n i t i a l spec i f i c a t i o n s c a l l i n g f o r an epoxy mortar, u s u a l l y , 1/4 i n c h i n t h i c k n e s s , t o p r o v i d e a c h e m i c a l l y and p h y s i c a l l y resistant surface. S l i p - r e s i s t a n t aggregates may be embedded i n such epoxy t o p p i n g s . The same t e c h -



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nique i s u t i l i z e d i n p r o v i d i n g s k i d - r e s i s t a n t o v e r l a y s on highways. In such a p p l i c a t i o n s , 100% s o l i d epoxy r e s i n systems are a p p l i e d at t h i c k n e s s e s o f 10-15 m i l s onto which i s b r o a d c a s t sand, emery, pumice o r q u a r t z . In r e c e n t y e a r s , epoxy r e s i n systems have been u t i l i z e d f o r s p e c i a l a p p l i c a t i o n s on the e x t e r i o r s o f buildings. One o f these systems i n v o l v e s the use o f an epoxy p l a s t e r , which i s t r o w e l e d onto the s u r f a c e o f an exposed w a l l , i n t o which are s e t stone a g g r e g a t e s . T h i s s u r f a c i n g resembles a p r e - c a s t c o n c r e t e p a n e l w i t h an exposed aggregate f a c i n g . T h i s method i s u t i l i z e d , not o n l y i n new c o n s t r u c t i o n , but i n r e - s u r f a c i n g d e t e r i o r a ted areas. P r e - c a s t c o n c r e t e has a c h i e v e d a r e c o g n i z e d p o s i t i o n i n the c o n s t r u c t i o n i n d u s t r y . Q u i t e o f t e n , i t i s n e c e s s a r y t o p r o v i d e a d e c o r a t i v e s u r f a c e t o t h e s e panels. A common method i s t o produce an exposed aggregate f i n i s h . Many a r c h i t e c t s now s p e c i f y c o n c r e t e pane l s h a v i n g a v e n e e r o f marble, g r a n i t e , l i m e s t o n e o r other decorative n a t u r a l stone. These veneers are app l i e d i n s e c t i o n s no t h i c k e r t h a n 3/4 inch. Epoxy adh e s i v e s are used t o bond the c o n c r e t e to the v e n e e r . Of c o u r s e , r e i n f o r c i n g anchors are used at the c o r n e r s o f each p a n e l t o p r o v i d e a d d i t i o n a l a s s u r a n c e . The advances i n f o r m u l a t i o n s and a p p l i c a t i o n t e c h n i q u e s , as w e l l as f i e l d e x p e r i e n c e ; have d e v e l o p e d cons i d e r a b l e i n f o r m a t i o n as t o the c a p a b i l i t i e s and l i m i t a t i o n s i n the use o f epoxy r e s i n systems i n c o n s t r u c tion. The a r c h i t e c t and e n g i n e e r must be aware o f the p r o p e r t i e s of these systems and s h o u l d be knowledgeable about p e r t i n e n t s p e c i f i c a t i o n s . PART G - EPOXY RESIN ADHESIVES FOR

BONDING CONCRETE

There are many reasons why e p o x i e s make good adhes i v e s . Among these a r e : (a) Compounds can be i n l i q u i d form and c o n t a i n no volatile solid; (b) They adhere t o most m a t e r i a l s o f c o n s t r u c t i o n ; (c) There are no b y - p r o d u c t s d u r i n g the c u r i n g perios; (d) T h e r e i s l i m i t e d s h r i n k a g e d u r i n g and a f t e r cu re ; (e) Cured e p o x i e s have d i m e n s i o n a l s t a b i l i t y ;


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COMPOUNDS

(f) Cured e p o x i e s have t e n s i l e s t r e n g t h s a n d comp r e s s i v e s t r e n g t h s as h i g h , and h i g h e r t h a n , c o n c r e t e . T a b l e 1 compares the s t r e n g t h c h a r a c t e r i s t i c s o f epoxy compounds w i t h those o f s t r u c t u r a l c o n c r e t e . T a b l e 1 . - S t r e n g t h Comparisons - E p o x i e s v s . C o n c r e t e


Structural Concrete Epoxy Compounds

Flexural (psi)

Tensile (psi)

500-800

100-400

1500-5000

500-5000

Compressive (psi) 3000-10,000

5000-12,000 Structures Publishing Company

The f a c t o r o f t h e r m a l e x p a n s i o n i s most important when c o n s i d e r i n g the use o f e p o x i e s w i t h s t e e l and concrete. S t e e l and c o n c r e t e a r e almost p e r f e c t l y matched. When c o n c r e t e i s bonded t o o t h e r m a t e r i a l s , s t r e s s o f ten o c c u r s . E p o x i e s can e l o n g a t e under s t r e s s t o a c commodate d i f f e r e n c e s r e s u l t i n g from t h e r m a l e f f e c t s . The c o e f f i c i e n t o f t h e r m a l e x p a n s i o n o f an epoxy c a n be e q u a l i z e d t o t h a t o f c o n c r e t e b y the p r o p e r i n c o r p o r a t i o n o f f i l l e r s , such as sand. "/Then the sandrepoxy r a t i o approaches 4:1 up t o 7:1, t h e ^ c o e f f i c i e n t o f t h e r mal e x p a n s i o n w i l l approach 4-6x10 in/in/°F. S h r i n k age o f c o n c r e t e d u r i n g c u r e i s w i d e l y r e c o g n i z e d . Epox i e s show a minimal degree o f s h r i n k a g e , i n the o r d e r o f 0.0010 i n / i n . The p r e p a r a t i o n o f s u r f a c e s t o r e c e i v e epoxy compounds i s as important as the s e l e c t i o n o f the p r o p e r system f o r b o n d i n g . C o n c r e t e s u r f a c e s must be f r e s h l y exposed, f r e e o f l o o s e and unsound m a t e r i a l and s h o u l d be a t p r o p e r s u r f a c e temperatures a t t h e time o f epoxy application. Among the methods f o r p r e p a r a t i o n o f conc r e t e s u r f a c e s are s a n d b l a s t i n g , m e c h a n i c a l s c a r i f i c a t i o n and a c i d e t c h i n g . The same p r o c e d u r e s may be f o l lowed f o r p r e p a r a t i o n o f s t e e l s u r f a c e s . Temperature c o n d i t i o n s f o r ^ e p o x y a p p l i c a t i o n s h o u l d be i n the range of 50 F . t o 90 F . Temperature c o n d i t i o n s w i l l a l s o a f f e c t p o t l i f e o f mixed compounds, as w e l l as c u r i n g time. There are s e v e r a l guide s p e c i f i c a t i o n s f o r epoxy r e s i n b a s e d m a t e r i a l s f o r use w i t h c o n c r e t e , as adhe-



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s i v e s , c r a c k s e a l e r s , p a t c h i n g m a t e r i a l s and n o n - s k i d treatments. One o f t h e v e r y f i r s t s p e c i f i c a t i o n s t o be d e v e l o p e d i s one sponsored by t h e U n i t e d S t a t e s Army Corps o f E n g i n e e r s , and i t i n c l u d e s d e s c r i p t i o n s o f an epoxy r e s i n b i n d e r , and an epoxy r e s i n g r o u t . The spe c i f i c a t i o n s a r e as f o l l o w s : (a) F e d e r a l S p e c i f i c a t i o n MMM-B-350 " B i n d e r a d h e s i v e , Epoxy R e s i n , F l e x i b l e . " (b) F e d e r a l S p e c i f i c a t i o n MMM-G-650 "Grout, Adhe s i v e , Epoxy R e s i n , F l e x i b l e , F i l l e d . " Both s p e c i f i c a t i o n s s p e l l o u t t h e f o r m u l a t i o n s r e q u i r e d , i n complete d e t a i l . They u t i l i z e an epoxy r e s i n w i t h an epoxide e q u i v a l e n t i n t h e range o f 175-210. E p o x i d e e q u i v a l e n t i s t h e weight o f r e s i n c o n t a i n i n g 1 m o l e c u l a r weight o f epoxy g r o u p s . The l o w e r epoxide e q u i v a l e n t , t h e l o w e r t h e v i s c o s i t y o f epoxy r e s i n . The p o l y s u l f i d e r e s i n c a l l e d f o r i n these s p e c i f i c a t i o n s i s a d i c h l o r o e t h y l f o r m a l p o l y s u l f i d e i n the 1000 m o l e c u l a r weight range. The a c c e l e r a t o r s a r e t e r t i a r y amines c o n s i s t i n g o f a b l e n d o f 2, 4, 6 - t r i d i m e t h y l aminomethyl phenol (DKP-30), and d i m e t h y i a m i n o e t h y 1 p h e n o l (DMP-10). T y p i c a l f o r m u l a t i o n s f o r B i n d e r and Grout a r e g i ven i n F i g u r e 1.

Materials

( P a r t A)

L i q u i d epoxy r e s i n Aerated s i l i c a

Materials

Binder (lbs/100 g a l s . )

Grout (lbs/100 g a l s )

630 — 66 g a l s .

450 40 50 g a l s ,

314 — 20 23 33 g a l s .

225 485 14.5 ^6 5_ 50~ g a l s .

( P a r t 3)

P o l y s u l f i d e polymer Silica flour DMP-10 DM Ρ - 3 0

L

Structures Publishing Company

Figure 1.

Binder and grout formulation

F i g u r e s 2 and 3 p r e s e n t t y p i c a l f o r m u l a t i o n s f o r a polyamide :epoxy b o n d i n g agent and a m o d i f i e d c o a l - t a r In Plastic Mortars, Sealants, and Caulking Compounds; Seymour, R.; ACS Symposium Series; American Chemical Society: Washington, DC, 1979.

46

PLASTIC MORTARS, SEALANTS, A N D CAULKING

epoxy r e s i n system f o r s k i d - r e s i s t a n t Materials

overlays. η

(

Ζ^ Λ^/Α 19.

( P a r t A)


L i q u i d epoxy r e s i n Chlorinated biphenyl or Dipropylene g l y c o l dibenzoate Titanium dioxide Magnesium s i l i c a t e C a l c i u m carbonate Asbestos f i b r e Xylol Materials

COMPOUNDS

Gallons

267 106 36 179 13 4 44 649 ^--50 g a l s ,

(Part B)

Polyamide r e s i n (Junine value^350-400) D.MP-30 Magnesium s i l i c a t e Asbestos f i b r e Toluol

267 12 126 5 80 490 =50 g a l s . Structures Publishing Company

Figure 2.

Materials

(Part A)_

L i q u i d epoxy r e s i n Pine o i l Phenol (95% T e c h n i c a l Materials

Polyamide-epoxy bonding agent

Pounds/100

Grade)

Gallons

381 76 19 476 =50 g a l s .

(Part B)

Refined coal-tar o i l Diethylene Triamine

420 64 484 =50 g a l s . Structures Publishing Company

Figure 3.

Epoxy-coal-tar road sealer

There are o t h e r types o f epoxy a d h e s i v e s and bond i n g agents u t i l i z e d f o r s p e c i a l p u r p o s e s , .^mong t h e s e are r a p i d - s e t t i n g a d h e s i v e s f o r use by S t a t e Highway Commissions f o r b o n d i n g t r a f f i c m a r k e r s . S p e c i a l f o r m u l a t i o n s a r e a l s o u t i l i z e d f o r p r o d u c i n g polymer con crete .


4.

MASLOW


47


PART D - REPAIRING OF CRACKED CONCRETE S t r u c t u r e s b u i l t o f c a s t - i n - p l a c e P o r t l a n d cement c o n c r e t e had an u n d e s i r a b l e tendency t o c r a c k , even though p r o p e r p r o v i s i o n i s made f o r e x p a n s i o n and cont r a c t i o n by e n g i n e e r e d j o i n t d e s i g n . On h o r i z o n t a l s l a b s , c r a c k i n g may d e v e l o p because o f a number o f r e a sons, even though e x p a n s i o n j o i n t s have been p r o v i d e d at minimal c e n t e r s . On v e r t i c a l placements, severe s t r e s s e s and s t r a i n s w i l l i n e v i t a b l y r e s u l t i n c r a c k i n g . H e r e t o f o r e , t h e most commonly used method o f r e p a i r i n g c r a c k s i n c o n c r e t e was by i n j e c t i o n o f a cement s l u r r y grout. I t i s obvious t h a t such a g r o u t , based on a cement i t i o u s c o m p o s i t i o n , would s h r i n k and not f i l l the v o i d c o m p l e t e l y . I t i s also h i g h l y l i k e l y that such a g r o u t , a f t e r c u r i n g , would c r a c k a g a i n a t t h e same s t r e s s p o i n t s . L i q u i d epoxy r e s i n systems o f low v i s c o s i t y a r e now b e i n g u t i l i z e d s u c c e s s f u l l y i n f i l l i n g and r e p a i r ing s t r u c t u r a l c r a c k s i n c o n c r e t e members. The u s u a l epoxy r e s i n compounds u t i l i z e d f o r t h i s purpose are the e p o x y : p o l y s u l f i d e type, such as t h e Corps o f E n g i n e e r s B i n d e r , MMM-B-350, o r AASHO S p e c i f i c a t i o n M-200, Type A, or ASTM S p e c i f i c a t i o n f o r "Epoxy R e s i n Base Bonding Systems f o r C o n c r e t e , " Type I, Grade 1 and, g e n e r a l l y , C l a s s A, f o r low temperature use. The v i s c o s i t y o f such compounds g e n e r a l l y runs t o about 2,000 c e n t i p o i s e s . These compounds may be mixed i n s m a l l volumes and i n t r o duced i n t o a s t r u c t u r a l c r a c k , bonding the two s e p a r a t e members w i t h an a d h e s i v e f o r c e which i s h i g h e r t h a n the t e n s i l e s t r e n g t h of the concrete i t s e l f . S i n c e t h e mat e r i a l i s 100% i n s o l i d s and d e v e l o p s no s h r i n k a g e i n curing, the e n t i r e crack i s f i l l e d . Should f u r t h e r s t r e s s be p l a c e d on t h e c o n c r e t e member, c r a c k i n g w i l l i n e v i t a b l y o c c u r at another l o c a t i o n and n e v e r a t t h e epoxy-repaired p o i n t . The epoxy p o l y s u l f i d e f o r m u l a t i o n s a r e comparat i v e l y f a s t s e t t i n g , w i t h a s h o r t p o t l i f e . In f i l l i n g a c r a c k on a h o r i z o n t a l s l a b , t h e c r a c k i s widened by m e c h a n i c a l means t o form a s l i g h t t r o u g h . The mixed compound may t h e n be i n t r o d u c e d i n t o t h e c r a c k b y means of a c a u l k i n g gun, o r d i s p e n s e d t h r o u g h a narrow s p o u t . I f t h e c r a c k i s deep, t h e epoxy b i n d e r may be i n t r o d u c e d i n s t a g e s , t o p e r m i t deep p e n e t r a t i o n . S u c c e e d i n g pours



48

PLASTIC MORTARS, SEALANTS, AND

CAULKING

COMPOUNDS

may be made i n a time sequence t o a l l o w p r e v i o u s l y ap p l i e d m a t e r i a l to begin p o l y m e r i z a t i o n . The r e p a i r of c r a c k s i n v e r t i c a l s t r u c t u r e s may be performed w i t h the same systems. In such s i t u a t i o n s , an i n j e c t i o n p r o c e d u r e i s f o l l o w e d . The c r a c k i t s e l f i s f i r s t s e a l e d on the o u t s i d e f a c e w i t h a f a s t - s e t t i n g epoxy compound f o r m u l a t e d t o have t h i x o t r o p i c p r o p e r t i e s , so as t o p r e v e n t s a g g i n g . T h i s compound i s s p r e a d o v e r the f a c e o f t h e c r a c k t o p r e v e n t the l i q u i d epoxy b i n d e r from o o z i n g o u t . At d e s i g n a t e d i n t e r v a l s a l o n g t h e c r a c k , n i p p l e s made o f m e t a l l i c t u b i n g are i n s e r t e d i n t o the c r a c k and h e l d i n p l a c e by the epoxy mastic. Once t h e m a s t i c has c u r e d , the epoxy r e s i n b i n d e r may then be pumped i n . The b i n d e r may be mixed i n s m a l l b a t c h e s and i n j e c t e d under p r e s s u r e . In l a r g e o p e r a t i o n s , the b i n d e r may be f e d through two s e p a r a t e l i n e s , from s e p a r a t e c o n t a i n e r s , mixed at a s i n g l e noz z l e , and pumped under p r e s s u r e . The b i n d e r may be i n j e c t e d w i t h p r e s s u r e s o f 1000 pounds p e r square i n c h , o r more, as n e c e s s a r y . The b i n d e r i s pumped i n t o one n o z z l e u n t i l i t b e g i n s t o appear at the n o z z l e above it. T h i s procedure i s c a r r i e d out t o t h e f u l l l e n g t h of the c r a c k . A f t e r a c u r i n g p e r i o d , the n o z z l e s are Cut f l u s h t o the c r a c k . T h i s method o f r e p a i r i n g v e r t i c a l c r a c k s may a l s o be used f o r h o r i z o n t a l c r a c k s . The method i n s u r e s a complete f i l l i n g o f the c r a c k i n r a p i d time. C o r e s t a k e n from such r e p a i r s i n v a r i a b l y i n d i c a t e t h a t c r a c k s may be c o m p l e t e l y s e a l e d by t h i s method, and t e s t s run on such c o r e s always r e s u l t i n f r a c t u r e o f the c o n c r e t e a t a p o i n t o t h e r than the r e p a i r e d crack l i n e . PART Ε - PATCHING AND

GROUTING OF

CONCRETE

The v a r i o u s epoxy r e s i n s d e s c r i b e d as u n f i l l e d b i n d e r s , are u t i l i z e d t o make epoxy m o r t a r s and epoxy c o n c r e t e f o r p a t c h i n g and g r o u t i n g P o r t l a n d cement c o n c r e t e , and f o r p r o d u c i n g epoxy m o r t a r s f o r complete o v e r l a y s . The aggregates t o be u s e d s h o u l d be d r y and salt-free. The maximum s i z e o f t h e aggregate t o be u s e d w i l l depend upon the dimensions o f the f i l l . A good r u l e t o f o l l o w i s t h a t the maximum s i z e aggregate s h o u l d not e x c e e d o n e - f o u r t h o f the s m a l l e s t dimensions o f the f i l l . F o r an epoxy c o n c r e t e t o be u s e d where a l a r g e volume o f f i l l i s r e q u i r e d , g r a v e l o r c r u s h e d


4.

MASLOW

49


s t o n e , 1/2 ;:o 3/4 i n c h maximuui s i z e , u n i f o r m l y graded, may be u s e d . F o r most work, t h e aggregate f o r an epoxy m o r t a r shcul-Z conform t o t h e f o l l o w i n g g r a d i n g l i m i t s :


Sieve Size No. No. No. No. No. No.

4 8 16 30 50 100

(4.76 mm) (2.38 ram) (1.19 mm) (595 m i c r o n s ) (297 m i c r o n s ) (149 m i c r o n s )

Percent

Retained,

Cum.

0-5 0-20 15-50 40-75 70-90 90-100

The sand t o meet t h i s s p e c i f i c a t i o n i s a rounded g r a i n type. I t h a s p h y s i c a l p r o p e r t i e s as f o l l o w s : Moh Hardness Specific Gravity Percent S i l i c a

7 Minimum 2.60 Minimum 99.5 Minimum

H i g h e r s t r e n g t h s and b e t t e r w o r k a b i l i t y may be obt a i n e d i f a l l m a t e r i a l p a s s i n g t h e No. 50 s i e v e i s screened out. The more f i n e s , t h e l e s s aggregate may be b l e n d e d i n w i t h t h e epoxy r e s i n . Where i t i s des i r e d t o f i l l shallow s p a l l e d areas, a r e l a t i v e l y f i n e sand o f u n i f o r m g r a d i n g may be u s e d , p a r t i c u l a r l y , where f e a t h e r - e d g i n g i s t o be done. The two components o f t h e epoxy b i n d e r a r e t h o r o u g h l y mixed t o g e t h e r , a f t e r w h i c h t h e s e l e c t i v e a g g r e g a t e i s added, w i t h c o n t i n u e d m i x i n g . The r a t i o o f aggregate t o epoxy b i n d e r may range from 3:1 t o 10:1, by w e i g h t , depending upon t h e mesh s i z e and g r a d a t i o n of the aggregate. P r i m i n g i s o f t e n n e c e s s a r y b e f o r e placement o f the mortar. A s m a l l amount o f the mixed epoxy b i n d e r may be used t o be a p p l i e d t o t h e s u r f a c e on which t h e epoxy m o r t a r i s t o be bonded. The volume o f a b a t c h o f epoxy m o r t a r s h o u l d n o t exceed t h a t which can be p l a c e d w i t h i n one h o u r . Working time o f t h e m i x t u r e may be e x t e n ded by s p r e a d i n g t h e m i x t u r e o u t t o p r e v e n t t h e d e v e l o p ment o f an, e x c e s s i v e exotherm. Areas t o be p a t c h e d s h o u l d be c h i p p e d o u t s o t h a t t h e edges w i l l be e s s e n t i a l l y p e r p e n d i c u l a r t o t h e t o p surface of the f i n i s h e d patch. I t i s advisable to



50

PLASTIC MORTARS, SEALANTS, AND CAULKING COMPOUNDS

avoid feather-edging. Working o f t h e epoxy m o r t a r w h i l e p u t t i n g i t i n p l a c e , s h o u l d be kept t o a minimum t o p r e v e n t t h e b i n d e r p o r t i o n from b e i n g worked up t o the s u r f a c e o f t h e m o r t a r . Where deep p a t c h e s have t o be p l a c e d , i t i s a d v i s a b l e t o i n s t a l l t h e epoxy m o r t a r i n l a y e r s . T h i s w i l l p r e v e n t t h e development o f h i g h exotherm i n e x c e s s i v e t h i c k n e s s e s which c o u l d r e s u l t i n s t r e s s c r a c k i n g o f t h e m o r t a r . A f t e r t h e epoxy mort a r h a s s e t , an epoxy s e a l e r may be a p p l i e d t o the s u r f a c e . T h i s s e a l e r i s p a r t i c u l a r l y recommended i f a h i g h aggregate t o b i n d e r r a t i o i s used and t h e r e s u l t ant m o r t a r i s p o r o u s . The s e a l e r may be t h e same b i n der formulation. PART F - EPOXIES AS FLOORING MATERIALS Epoxy

Mortars, A s a n d - f i l l e d epoxy compound w i l l have lower s t r e s s e s because t h e c o e f f i c i e n t o f t h e r m a l e x p a n s i o n w i l l have been r e d u c e d and w i l l have been b r o u g h t c l o ser t o the c o e f f i c i e n t o f thermal expansion o f P o r t l a n d cement c o n c r e t e . Some o f t h e r e q u i r e m e n t s f o r an epoxy system, based on a p o l y s u l f i d e - m o d i f i e d epoxy b i n d e r , are t y p i c a l l y as f o l l o w s : (a) Pot l i f e i s u s u a l l y between 30 minutes and 2 hours; (b) The b i n d e r , w i t h o u t sand, i s g e n e r a l l y t a c k f r e e i n 8 t o 12 h o u r s . When f i l l e d , t h i s p e r i o d i s shortened c o n s i d e r a b l y . (c) U l t i m a t e t e n s i l e s t r e n g t h i s between 3,000 and 3,500 p s i , and t h e r e i s an e l o n g a t i o n o f a t l e a s t 2 5 % immediately a f t e r c u r e ; (d) The modulus o f e l a s t i c i t y i n t e n s i o n does not e x c e e d 100 p s i . ; (e) The modulus o f toughness g e n e r a l l y runs a t l e a s t 400 i n . l b . p e r c u b i c i n c h ; (f) P e r c e n t weight g a i n i n w a t e r a b s o r p t i o n seldom exceeds 1.0%; (g) T e n s i l e s t r e n g t h o f h e a t - a g e d specimens i s b e tween 200 and 1,500 p s i . E l o n g a t i o n i s l e s s than 10%. T h i s i s an i n d i c a t i o n o f what changes may o c c u r i n an epoxy compound upon a g i n g . (h) Impact s t r e n g t h may r u n as h i g h as 90 f o o t pounds ;


4. MASLOW


51


(i) Bond s t r e n g t h w i l l show a t l e a s t 90% o f t h e f a i l u r e i n the c o n c r e t e ; (j) E l o n g a t i o n a t low temperatures (32°F) i s much lower than a t normal t e m p e r a t u r e s , u s u a l l y , about 5% i n the i n i t i a l stages; (k) T e n s i l e s t r e n g t h may go as h i g h as 1,800 p s i and compressive s t r e n g t h s may r e a c h 15,000 p s i i n t h e f i l l e d systems. R e i n f o r c e m e n t may be u t i l i z e d w i t h epoxy compounds to lower s h r i n k a g e , lower e x p a n s i o n c o e f f i c i e n t , and add s t r e n g t h . The f o l l o w i n g p r o c e d u r e i s a t e c h n i q u e f o r u s i n g f i b e r g l a s s c l o t h w i t h an epoxy m o r t a r . I t i s recommended f o r c o n c r e t e f l o o r s where t h e r e i s e v i dence o f e x c e s s i v e movement, as i n d i c a t e d by c r a c k i n g . C r a c k i n g o f t h e base s l a b w i l l g e n e r a l l y r e s u l t i n c r a c k i n g o f t h e t o p p i n g a t the same l o c a t i o n . Concrete s l a b s , n o t on grade, s u b j e c t e d t o heavy l o a d s , may f l e x . R e t o p p i n g such members r e q u i r e s t h a t t h e epoxy m o r t a r be i n t e g r a l l y r e i n f o r c e d t o f u r t h e r i n c r e a s e r e s i s t a n c e to c r a c k i n g . P r o v i s i o n must, o f c o u r s e , be made t o m a i n t a i n e x p a n s i o n and c o n t r a c t i o n j o i n t s i n t h e base s l a b . These j o i n t s s h o u l d be f i l l e d w i t h an e l a s t o m e r i c s e a l a n t . The epoxy m o r t a r s h o u l d n o t b r i d g e t h e s e j o i n t s , which s h o u l d be c a r r i e d t h r o u g h t h e epoxy mort a r and s h o u l d a l s o be s e a l e d w i t h an e l a s t o m e r i c s e a l ant. A primer adhesive i s f i r s t a p p l i e d t o a p r o p e r l y p r e p a r e d c o n c r e t e s u r f a c e . A t h i n c o a t o f epoxy mort a r i s then a p p l i e d w i t h a t r o w e l . While t h i s t h i n c o a t i s s t i l l wet, a f i b e r g l a s s membrane i s r o l l e d i n t o the m o r t a r . The edges o f t h e membrane s h o u l d be o v e r l a p p e d 2 i n c h e s . The m o r t a r w i l l squeeze up through the v o i d s i n the f i b e r g l a s s mesh, r e s u l t i n g i n a d h e s i v e base t o which t h e f i n a l epoxy m o r t a r w i l l adhere. While t h i s f i r s t a p p l i c a t i o n o f mortar i s s t i l l tacky, the second l a y e r o f epoxy m o r t a r i s a p p l i e d o v e r t h e g l a s s cloth. T h i s second l a y e r may then be s c r e e d e d and l e veled . Expanded m e t a l l a t h e and/or w i r e mesh may be u t i l i z e d i n t h e same way as f i b e r g l a s s membrane, p a r t i c u l a r l y , when a p p l y i n g an epoxy m o r t a r o n t o a wodden floor. I t i s recommended t h a t a p r e l i m i n a r y r e p a i r o f a wood f l o o r be made f i r s t by s e c u r i n g 3/4 i n c h Douglas f i r plywood t o t h e wooden s u b s t r a t e by p r o p e r n a i l i n g .



52

PLASTIC MORTARS, SEALANTS, A N D CAULKING COMPOUNDS

T h i s i s t o i n s u r e a r i g i d i t y i n the wood f l o o r , which may not be p r e s e n t i n the o r i g i n a l s u b s t r a t e . I t also i n s u r e s a c o m p a r a t i v e l y c l e a n wooden s u b s t r a t e f o r t r e a t m e n t . The plywood s h o u l d be f r e e o f p r o t e c t i v e o i l . The l a t h e o r w i r e mesh i s n a i l e d t o t h e wood b a s e , a l lowing a l/16th inch clearance. The epoxy m o r t a r i s a p p l i e d i n the f i r s t pass so as t o p e n e t r & t e the l a t h e o r mesh, and make i n t i m a t e c o n t a c t w i t h t h e wood substrate. The plywood s h o u l d be t r e a t e d w i t h a p r i m e r i n the same way t h a t c o n c r e t e i s f i r s t primed. The epoxy m o r t a r i s compressed t o f i l l a l l t h e v o i d s i n t h e r e i n f o r c i n g mesh. A second a p p l i c a t i o n o f epoxy m o r t a r i s t h e n p l a c e d o v e r the f i r s t , c o v e r i n g the mesh. This system p r o v i d e s maximum a s s u r a n c e o f k e e p i n g the epoxy m o r t a r s e c u r e d t o t h e wooden s u b s t r a t e by c h e m i c a l and p h y s i c a l means. I t a l s o m i n i m i z e s t h e p o s s i b i l i t y o f c r a c k i n g and/or d e l a m i n a t i n g , because o f t h e r e i n f o r c i n g s t r e n g t h s c o n t r i b u t e d by t h e l a t h e and/or mesh. A t y p i c a l f o r m u l a f o r an epoxy m o r t a r i s g i v e n i n F i g u r e 4: Materials

(Part A)

Pounds

L i q u i d epoxy r e s i n Butyl g l y c i d y l ether (reactive diluent) Materials

750 176 926-100 g a l s .

(Part B)

Polyamide r e s i n (amine value-350) T e r t i a r y amine

617

166 733=100 g a l s .

Materials

(Part C) 720 240 40 tint 1,000

F l i n t s h o t s i l i c a sand Emery, 30-80 mesh Titanium dioxide Lampblack


Figure 4.

The

Epoxy mortar topping

epoxy m o r t a r t o p p i n g

i s prepared i n k i t s ,


4.

MASLOW

53


c o m p r i s e d o f t h r e e components, as f o l l o w s : Materials

1 Gallon Kit

P a r t A-epoxy r e s i n P a r t B - c u r i n g agent P a r t C-aggregate

2.25 0.75 14.50 17.50

lbs. lbs. lbs. lbs.

5 Gallon Kit 11.25 3.75 72.50 87.50


Epoxy

lbs. lbs. lbs. lbs.

Terrazzo W i t h t h e development o f epoxy r e s i n systems as t o p p i n g s , i t was o n l y n a t u r a l t h a t these systems would have been adapted i n t e r r a z z o a p p l i c a t i o n s . The advantages o f epoxy-based t e r r a z z o i n c l u d e r a p i d c u r e , as compared t o c o n v e n t i o n a l cement t e r r a z z o , and l i g h t weight o f 1-3 l b s . p e r square f o o t , as compared t o 1020 l b s . p e r square f o o t f o r P o r t l a n d cement t e r r a z z o . There a r e many commercial f o r m u l a t i o n s f o r epoxy t e r r a z z o . Many depend on a p r i m a r y polyamine h a r d e n i n g agent as a means o f o b t a i n i n g the h a r d e s t c u r e d m a t r i x . A l t h o u g h t h i s i s d e s i r a b l e , t h e use o f t h e p r i m a r y p o l y amine may be hazardous because o f i t s p o s s i b l e dermat i t ic effects, o t h e r systems i n v o l v e t h e use o f p o l y amide h a r d e n e r s , w i t h m o d i f i e d a l i p h a t i c amines o r t e r t i a r y amines as c a t a l y s t s . The epoxy b i n d e r i s n o r m a l l y f i l l e d w i t h an e x t e n d e r pigment and c o l o r e d t o p r o v i d e shades which a r e complimentary t o the c o l o r e d marble c h i p s which a r e u s e d . The marble c h i p s and t h e d e s i g n s may be taken from the s t a n d a r d T e r r a z z o A s s o c i a t i o n p l a t e s . The marble c h i p s a r e b l e n d e d w i t h t h e epoxy b i n d e r i n a m e c h a n i c a l m i x e r and a p p l i e d t o t h e divided f l o o r area. S i n c e e x p a n s i o n and c o n t r a c t i o n i s g r e a t e r t h a n f o r a s a n d - f i l l e d epoxy mortar, i t i s adv i s a b l e t o use t h e same b r a s s , z i n c , aluminum o r p l a s t i c d i v i d e r s t r i p s t o c o n t r o l any p o s s i b l e c r a c k i n g , as w e l l as p r o v i d i n g f o r a d e c o r a t i v e d e s i g n system. These s t r i p s a r e p l a c e d w i t h a 1/4 i n c h h e i g h t . The epoxy t e r r a z z o mix i s then s c r e e d e d t o t h e p r o p e r h e i g h t and a d d i t i o n a l marble c h i p s a r e b r o a d c a s t o v e r t h e s u r f a c e at t h e r a t e o f 2 t o 4 pounds p e r square y a r d . The s u r face i s then r o l l e d with a c o n v e n t i o n a l t e r r a z z o r o l l e r . G r i n d i n g may b e g i n 16 hours a f t e r a p p l i c a t i o n , b u t s h o u l d n o t be d e l a y e d more than 48 h o u r s s i n c e g r i n d i n g w i l l become more d i f f i c u l t as cure p r o g r e s s e s . A f t e r the f i r s t g r i n d i n g , t h e s u r f a c e i s g r o u t e d w i t h a


54

PLASTIC MORTARS, SEALANTS, A N D CAULKING COMPOUNDS

b i n d e r , c o l o r e d w i t h the same pigments as i n the epoxy terrazzo. This f i n a l application i s also polished i n the same way as c o n v e n t i o n a l t e r r a z z o . A t y p i c a l formula f o r an epoxy t e r r a z z o i s g i v e n i n F i g u r e 5:


Materials

Pounds

L i q u i d epoxy r e s i n Magnesium s i l i c a t e f i l l e r C o l o r i n g pigments #1 Marble c h i p s T r i e t h y l e n e tetramine (packaged s e p a r a t e l y )

100 50 10 400 10

570 Structures Publishing Company

Figure 5.

Epoxy terrazzo

PART G - SPECIFICATIONS AND TESTS V a r i o u s s p e c i f i c a t i o n s which a r e p e r t i n e n t t o epoxy compounds f o r use w i t h c o n c r e t e have a l r e a d y been listed. There are many o t h e r s which a r e s p e c i f i c w i t h i n d i v i d u a l governmental a g e n c i e s , p r i v a t e a g e n c i e s , a r c h i t e c t u r a l and e n g i n e e r i n g g r o u p s . There a r e a l s o s t a n d a r d ASTM p r o c e d u r e s f o r t e s t i n g t e n s i l e , compress i v e and bond s t r e n g t h s , as w e l l as many o t h e r p r o p e r ties. Some o f these t e s t s a r e , o f c o u r s e , d e s i g n e d f o r concrete, o t h e r s have been d e v e l o p e d p r i m a r i l y f o r t h e p l a s t i c s i n d u s t r y and may be adapted f o r t e s t i n g epoxy compounds. A number o f s p e c i a l t e s t s have been d e v i s e d to a i d i n t h e e v a l u a t i o n o f p a r t i c u l a r epoxy compounds. Some o f t h e t e s t s may be d e s c r i b e d as f o l l o w s : (a) F l e x u r a l Beam T e s t . T h i s t e s t was d e v e l o p e d by the C a l i f o r n i a Highway Department. C o n c r e t e beams, 6 x6"x30", s i m i l a r t o t h o s e d e s c r i b e d i n ASTM C-78, a r e p r e p a r e d as specimens. A f t e r p r o p e r c u r i n g , t h e beams are b r o k e n i n f l e x u r e , u s i n g t h i r d p o i n t l o a d i n g . The two h a l v e s o f one beam a r e cemented t o g e t h e r w i t h an epoxy a d h e s i v e and a l l o w e d t o c u r e . Another broken beam i s c o a t e d w i t h adhesive on t h e b r o k e n end, and f r e s h c o n c r e t e i s c a s t a g a i n s t i t t o r e c o n s t r u c t a new beam. In b o t h c a s e s , a f t e r the adhesive and c o n c r e t e have f u l l y c u r e d , the beams a r e a g a i n s u b j e c t e d t o M



4. MASLOW


55

f l e x u r e , u s i n g t h i r d - p o i n t l o a d i n g . I f t h e beam b r e a k s at p o i n t s o t h e r than a l o n g t h e bond l i n e , i t i s an i n d i c a t i o n t h a t t h e a d h e s i v e bond i s s t r o n g e r t h a n the concrete. (b) Double V e r t i c a l Shear T e s t . T h i s t e s t was dev e l o p e d , p a r t i c u l a r l y , f o r the U.S. Army Corps o f E n g i n e e r s s p e c i f i c a t i o n s MMM-B-350a and MMM-G-650a. The t e s t i n v o l v e s b o n d i n g t h r e e 2 i n c h m o r t a r cubes t o g e t h e r , w i t h t h e c e n t e r cube extended t o 1/2 t h e h e i g h t of t h e a d j a c e n t cubes. The a r e a i n c o n t a c t between t h e cubes i s c o a t e d w i t h an epoxy a d h e s i v e t o a t h i c k n e s s o f 50 m i l s . A f t e r c u r i n g , a t h r e e - p o i n t l o a d i n g i s app l i e d , which t e s t s compressive s h e a r s t r e n g t h . (c) Shear Bond T e s t . T h i s method was d e v e l o p e d i n t h e Bureau o f R e c l a m a t i o n E n g i n e e r i n g L a b o r a t o r i e s . A c y l i n d e r mold, 2 i n c h e s i n d i a m e t e r and 4 i n c h e s l o n g , i s f i l l e d 3 i n c h e s deep w i t h mortar, and the mort a r i s cured. Then one end o f t h e m o r t a r c y l i n d e r i s t h o r o u g h l y c l e a n e d and r e p l a c e d i n t h e mold. An epoxy a d h e s i v e i s t h e n a p p l i e d t o t h e c l e a n e d , exposed end and t h e r e m a i n i n g space i n the mold i s f i l l e d w i t h f r e s h mortar. The r e s u l t i s a c y l i n d e r w i t h a bond l i n e c u t t i n g l a t e r a l l y t h r o u g h i t one i n c h from t h e e n d . The t e s t i s performed by s h e a r i n g t h e end s l i c e from the c y l i n d e r and computing t h e s h e a r bond s t r e s s a t t h e bond l i n e by d i v i d i n g t h e t o t a l f o r c e a p p l i e d by t h e c r o s s - s e c t i o n a l area o f the c y l i n d e r . (d) T e n s i l e S t r e n g t h o f Bonded S t a n d a r d M o r t a r Briquettes. T h i s t e s t i s b a s e d on t h e ASTM p r o c e d u r e for t e s t i n g t e n s i l e strength of p l a s t i c s . The specimen i s a dumbbell-shaped m o r t a r b r i q u e t t e w h i c h i s b r o k e n at t h e narrow p o r t i o n , and the two p i e c e s a r e bonded t o g e t h e r w i t h an epoxy a d h e s i v e . A f t e r complete c u r e , the specimen i s t e s t e d f o r t e n s i l e s t r e n g t h . Normal f a i l u r e i s i n t h e c e m e n t i t i o u s b r i q u e t t e , r a t h e r than at t h e bond l i n e . (e) Composite C y l i n d e r T e s t . C o n c r e t e s t r e n g t h s are n o r m a l l y determined by t h e compression t e s t on t h e s t a n d a r d 6"xl2" c y l i n d e r . When i t i s n e c e s s a r y t o bond new c o n c r e t e t o o l d c o n c r e t e w i t h an epoxy a d h e s i v e , the a d h e s i v e must be a b l e t o t r a n s f e r a l l compressive, s h e a r and t e n s i l e s t r e s s e s which the o r i g i n a l and new concrete are expected t o c a r r y . The specimen used f o r t h i s t e s t i s a s t a n d a r d



56

PLASTIC MORTARS,

SEALANTS,

AND CAULKING COMPOUNDS

6 " x l 2 " c o n c r e t e c y l i n d e r w i t h a d i a g o n a l bond l i n e o f epoxy compound j o i n i n g t h e two p o r t i o n s o f the c y l i n d e r a t a p l a n e o f 30 degrees from t h e l o n g i t u d i n a l a x i s . The composite c y l i n d e r i s t e s t e d i n c o m p r e s s i o n . I f the composite c y l i n d e r has a s t r e n g t h o f 90% o f t h a t o f a s t a n d a r d c o n c r e t e c y l i n d e r , t h e epoxy compound i s adequate f o r use w i t h c o n c r e t e . The composite c y l i n d e r i s made by p l a c i n g a spec i a l l y made dummy s e c t i o n i n t o the c y l i n d e r mold so t h a t i t b i s e c t s the c y l i n d e r e q u a l l y a t an a n g l e o f 30 degrees from t h e l o n g i t u d i n a l a x i s . Concrete i s cast i n t o the mold and c u r e d . The c y l i n d e r i s then removed from the mold, the s l o p i n g f a c e i s a c i d e t c h e d , and the c y l i n d e r i s t h e n s l i p p e d back i n t o the mold, which i s l i n e d w i t h waxed paper. The c y l i n d e r i s t i l t e d so t h a t the s l o p e i s h o r i z o n t a l , the epoxy a d h e s i v e i s a p p l i e d , f o l l o w e d by a l a y e r o f f r e s h c o n c r e t e , t o f i l l up t h e e n t i r e mold. A f t e r complete c u r e , t h e c y l i n d e r i s t e s t e d under c o m p r e s s i o n . This test represents a condit i o n c l o s e r t o t h e a c t u a l use o f t h e epoxy compound i n s t r u c t u r e s , e s p e c i a l l y when compared w i t h t e s t s r e l y i n g on t h e t e n s i l e s t r e n g t h o f t h e c o n c r e t e as a f a i l u r e criterion, i f t h e epoxy compound i s i n a d e q u a t e , f a i l u r e takes p l a c e on t h e bond l i n e . T h i s t e s t may a l s o be used f o r t e s t i n g t h e a d h e s i v e s t r e n g t h of an epoxy compound i n b o n d i n g c o n c r e t e t o s t e e l , b o n d i n g h a r d e n e d c o n c r e t e t o hardened c o n c r e t e , f o r damp o r d r y s u r f a c e s , and a t v a r i o u s temperature c o n d i t i o n s . (f) C r e e p T e s t . T h i s t e s t e v a l u a t e s the c r e e p o f the epoxy r e s i n b o n d i n g system a t low temperatures and at h i g h t e m p e r a t u r e s . The t e s t i n v o l v e s measuring t h e p e n e t r a t i o n o f a s m a l l s t e e l b a l l i n t o a f l a t specimen o f t h e c u r e d r e s i n , and i s measured as a f u n c t i o n o f t i m e . The t e s t u t i l i z e s a c y l i n d e r o f m e t a l o r o t h e r r i g i d m a t e r i a l on t o p o f which i s p l a c e d a f l a t s p e c i men o f c u r e d epoxy compound, c a s t on a s u i t a b l e substrate. B a l l b e a r i n g s , h a v i n g d i a m e t e r s o f 0.25 i n c h e s , may be used as t h e s t e e l s p h e r e s . A m e t a l p l a t e i s used t o b e a r a w e i g h t , and a d i a l i n d i c a t o r i s u s e d t o measure the d e f o r m a t i o n . The e n t i r e u n i t , i n c l u d i n g specimen, i s c o n d i t i o n e d f o r a t l e a s t 8 hours a t t h e s p e c i f i e d temperature, b e f o r e s t a r t i n g t h e t e s t , w i t h out t h e w e i g h t s . An i n i t i a l r e a d i n g i s t a k e n , a f t e r which w e i g h t s a r e p l a c e d on t o p o f the p l a t e . A stop


4.

MASLOW


57

watch measures t h e time a l l o w e d f o r the t e s t , a t which the d i a l i n d i c a t o r i s r e a d a g a i n . The p e n e t r a t i o n o f the s p h e r e s as a f u n c t i o n o f time i s a measure o f the c r e e p o f t h e epoxy r e s i n system.


PART H - HANDLING METHODS AND SAFETY PRECAUTIONS C o n t a c t w i t h epoxy r e s i n systems may l e a d t o a l l e r g i c e p i d e r m a l eczema. The i r r i t a t i n g agent appears to be p r i m a r i l y t h e c u r i n g compound used t o h a r d e n the epoxy r e s i n , r a t h e r than the epoxy r e s i n i t s e l f . The c u r i n g compound may i n v o l v e p r i m a r y polyamines, secondary poiyamines, t e r t i a r y polyamines and p o l y a m i d e s , a l l o f which c o n t a i n amino g r o u p s . The a c t i o n o f t h e i r r i t a n t on t h e s k i n u s u a l l y proceeds as f o l l o w s : After an i n t e r v a l f r e e o f symptoms, w h i c h may l a s t a week, o r l o n g e r , r e d p a t c h e s (erythema) about the s i z e o f a c o i n f i r s t appear. These patches i t c h i n t e n s e l y . T h i s f i r s t stage may h e a l by s c a l i n g o f t h e p a t c h e s a f t e r a s h o r t p e r i o d , and t h e i t c h i n g then d i s a p p e a r s . I f t h e f i r s t s t a g e o f d e r m a t o s i s does n o t h e a l , the second s t a g e c o n s i s t s o f t h e f o r m a t i o n o f a t r u e cutaneous e r u p t i o n w i t h r e d p i m p l e s and t h e f o r m a t i o n of b l i s t e r s . The i n t e n s e i t c h i n g causes t h e p a t i e n t t o s c r a t c h , opening b l i s t e r s , s w e l l i n g the s k i n and c a u s ing t h e i n f l a m e d t i s s u e t o exude f l u i d . W i t h some u s e r s , t h e d e r m a t o s i s n e v e r goes beyond the f i r s t s t a g e ; i . e . , t h e s k i n adapts and i s d e s e n s i tized. I t i s b e s t n o t t o remove a mechanic from h i s job o f u s i n g epoxy compounds a t t h e f i r s t symptoms, so t h a t i t may be seen whether he i s a d a p t i n g , o r d e s e n s i tizing. I f c o n t i n u a t i o n o f work l e a d s t o t h e second s t a g e , i t i s b e s t t o remove such a mechanic from cont a c t w i t h epoxy r e s i n systems c o m p l e t e l y . There a r e a s e r i e s o f p r e v e n t i v e measures i n handl i n g epoxy r e s i n systems: (a) I n s p e c t o r s and foremen s h o u l d be i n f o r m e d o f a l l t h e s e measures which s h o u l d be p a s s e d on t o workmen u s i n g these systems. (b) There s h o u l d be good v e n t i l a t i o n o f t h e work areas. (c) G l o v e s s h o u l d be worn a t a l l t i m e s . The use o f s o l v e n t s s h o u l d be reduced t o an a b s o l u t e minimum s i n c e s o l v e n t s can c a r r y d i l u t e d r e s i n o u s components


PLASTIC MORTARS,

SEALANTS,

AND CAULKING COMPOUNDS

LATEX AND EPOXY ADHESIVES COMPARATIVE

•tear Downloaded by MONASH UNIV on May 4, 2015 | http://pubs.acs.org Publication Date: November 27, 1979 | doi: 10.1021/bk-1979-0113.ch004

Milky Whit*

45 0%

Bonding fresh concrete to old concrete. Concrete admiiture. Thin layer toppings.

Milky White

55.0%

Bonding fresh concrete to old concrete. Concrete admixture. Thin layer

C. ButadieneStyrene

Milky White

480%

Bonding fresh concrete to old concrete. Concrete ad mixture. Thin layer

Milky White Acetate Re-EmulsifiaWt

I. Epoxy — PohrsulMe a. Unfilled Bind b. Filled

II. Epoxya. (Infilled' Bine b Filled

50.0%

Bonding of

Applicatiens

Brush, broom Underlayments spray, roller Stucco as adhesive. Grouting-mortar Terrazzo Trowel as Home Kits topping. Crack Fillers

Brush, spray roller.

Light straw

1:1 by volume Part A and Part Β

Light straw to amber

100%

a. 3040 min. b. 3040

a. 1-3 hours b. 1-3

a. 100 sq. ft per gal. as mortar 25 sq. ft «Λ" thick, contein-

votant Part A and PartB

grease. Wet surface.

Steel trowel, wood float. No excessive trowelling.

a. Bonding hardened con crete and other ma terials to hardened concrete. Setting dow els. Type lb, lib. b. Filling cracks in con crete to bond both sides of crack into an integral member. Type la and lia.

25 sq. ft. VT thick, contain ing sand.

plastic con crete to hardened con crete. Type lb and lib.

b. 100-150 sq. ft per gaf.

d. Preparation of epoxy mortars by adding sand. Types la, Ha, III.

Part A — Light straw

' COTT»

Acids-Fair Alkalis—Very Good Salts—Very Good Solvents—Fair-Good

Acids—Fair Alkalis—Very Good Salts—Very Good Solvents—Fair-Good

MIX-Cement: Sand = 1:3 Latex Solids on Cement = 10-20% Water Cement Ratio = 0:45

b. 25-38 sq. ft. per gal. 95-100%

eof Mwtar ASTM-C2I751T teel trowel, Acids—Fair ood float. Alkalis—Very Good Salts—Very G ο excessive Solvents—fail J


Not used as an admixture.

1:1 by volume Part A and Parte

Preparatit


. 30-50 sq. ft P*r gat

e. Bonding skid-resistant materials to hardened concrete. Types lb, lib, III. between

New Jersey Turnpike Section 4.9.3 Standard Specifications 1965 AASHO Specification Designation M-200-631 Virginia Dept of Highways AASHO Specification Designation M-200-631 III. AASHO Specification Designation M-200431 New Jersey Turnpike Section 4.8.2. Standard Specifications 1965 Ν. Y. State Dept of Public Works Item #6008


solvents, salts with maximum, properties. Also maximum resistance to hydro static water pressure.

4.

MASLOW


AND BONDING AGENTS CHART StTtlftJl : 1"Thiek Iritaettes

Striata : 2" Cabas ASTM-C109-M


3200 psi4100 psi

580 psi615 psi

950 psi1400 psi

Acetate Emulsifiable

NOTE— These 3400 psi3600 psi

350 psi450 psi

3300 psi4000 psi

1000 psi 1250 psi

450 psi580 psi

Strttfth

Strttith

ASTH-C34M1T

do not contain latex, but are applied over the latex film previously applied as an adhesive.

Where Ti Usa

Neat cement 250-300 psi

300 psi

1:3 Ottowa sand mortar 350420 psi

Acrylic

13 Perlite plaster 150-200 psi Finish plaster 30% Gauging plaster

PolyvinylAcetate

70% Lime plaster 120-150 psi 1:3 Cowbay sand mortar 200-290 psi

1250 psi1650 psi

ButadieneStyrene

Accoustical plaster 100-170 psi

May be used as a plas ter bond within 4540 rnin. Not for extreme chemical exposure. Do not use with airentrainers. Not for conditions of high hy drostatic pressure.

Indoor and outdoor exposures. On con crete, steel, wood. Guniting. Thin sec tion topping can be used with accelerators, re tardera, water re ducing agents.

May be used as a plas ter bond within 4540 min. Not for extreme chemical exposure. Do not use with airentrainers. Not for conditions of high hy drostatic pressure.

Indoor and outdoor exposures. On con crete, steel, wood. Guniting. Thin sec-

May be used as a plas ter bond within 45-60 min. Do not use with accelerators. Not for extreme chemical. Not for constant water immersion. Do not use with air-entrainers.

Indoors—ceilings primarily.

Limited use as a con crete bonding agent. Do not use as an ad mixture. Do not use under wet or humid conditions. Do not use at temperatures below 50 F.

1:3 Brown coat 100-150 psi Unmodified mortar. 410 psi Wet cure

Unmodified mortar. 750 psi

VIBRATION TESTS —No failure DETERGENTS & ACIDS —No failure, slight stain

PolyvinylAcetate Re-Emulsifi-

Where Ntt Ta Use

Indoor and outdoor exposures. On con crete, steel, wood. Guniting. Thin sec tion topping.

e

Ceaamshrt StTMft* ASTM-C-1M a. Binder with sand 12,00015,000 psi b. Unfilled 8,00010,000 psi 10,00013,000 psi.

Ttasile StfMgth ASTM-D43I

Teasile Etoagatiea ASTM4-3U

htMM lufrMft

Where Ta Usa 1.

a. 30003500 psi

a. 2.5-15%

b. 3500a. 6-25% 4000 psi

a. 400800 psi

a. 900-1000 psi b. 700-1000 psi

b. Unfilled 6,0004,000 psi

sand 40005000 psi Unfilled 30004000 psi

Ce«ertsshre Deeble Shear

a. 35-40%

a. 400-500 psi b 500-650 psi

a. 300400 psi

a. Generally, on government agency projects. b. Cost is highest. c. For maximum chemical and physical properties. a. Generally proprietary

Where Not Ta Use a. On surfaces treated with rubber or resin curing membranes. b. On dirty surfaces. c. On weak concrete. d. On bituminous surfaces. a. On surfaces treated with rubber or resin curing membranes.

b. Use where longer life is required and b. On dirty surfaces. cost is factor. c. On weak concrete. ι chemical and physical d. On bituminous surfaces. a. For lower cost applications of non-skid membranes. b. On bituminous concrete.

a. Do not use for bonding new wet con crete to old. b. Do not use where black color will be undesirable.

c. For resistance to grease, oil, gasoline and traffic wear.




60

PLASTIC MORTARS, SEALANTS, AND CAULKING

COMPOUNDS

more r e a d i l y t o s k i n a r e a s . (d) P r o t e c t i v e cutaneous ointments are h e l p f u l f o r the back o f t h e hands, the forearms and the f a c e . These ointments are a p p l i e d b e f o r e b e g i n n i n g work. (e) Work c l o t h e s s h o u l d be c l e a n at a l l times, and i t i s recommended t h a t a change o f c l o t h e s be made e a c h day. (f ) Hands s h o u l d be washed w i t h m i l d soap and wat e r b e f o r e and a f t e r work, b e f o r e and a f t e r g o i n g t o the l a v a t o r i e s , b e f o r e and a f t e r l e n g t h y i n t e r r u p t i o n s at work, and each time immediately a f t e r coming inbo contact with l i q u i d r e s i n mixtures. F i n g e r n a i l s should be c u t s h o r t and c l e a n . I t i s sometimes recommended t h a t persons s u b j e c t t o a l l e r g y s h o u l d not be a l l o w e d t o come i n c o n t a c t w i t h epoxy r e s i n systems. T h i s would be an improbably measure t o o b s e r v e . I t must be kept i n mind t h a t exposure t o epoxy r e s i n systems cannot cause a n y t h i n g but s k i n dermatitis. There has been a b s o l u t e l y no e v i d e n c e of any c a r c i n o g e n i c e f f e c t from c o n t a c t w i t h these systems. Where s l i g h t i r r i t a t i o n s o c c u r , d e s e n s i t i z a t i o n s h o u l d f i r s t be attempted. I f eczema o c c u r s , s t a n d a r d m e d i c a l treabment s h o u l d be p r o v i d e d . A n t i h i s t a m i n e drugs may be used o n l y t o reduce i t c h i n g . In s e v e r e c a s e s , such as i n the second s t a g e o f d e r m a t o s i s , c o r t i s o n e o i n b ments have been used s u c c e s s f u l l y t o r e l i e v e the symptoms. I t s h o u l d be kept i n mind t h a t i f p r o t e c t i v e measures are s c r u p u l o u s l y observed, i n c i d e n t s o f dermat o s e s from epoxy r e s i n systems can be kept t o a v e r y low minimum. There i s no r e a s o n f o r any c o n c e r n i n the use o f t h e s e systems i n the c o n s t r u c t i o n i n d u s t r y . Epoxy r e s i n compounds are b e i n g r e c o g n i z e d by a r c h i t e c t s and e n g i n e e r s f o r t h e i r v a r i e d c h e m i c a l and p h y s i c a l p r o p e r t i e s . As t e c h n i c a l p e o p l e become more aware o f the p o t e n t i a l v a l u e s o f t h e s e systems, i n use w i t h c o n c r e t e i n the c o n s t r u c t i o n i n d u s t r i e s , g r e a t e r uses w i l l be made o f a g r e a t e r v a r i e t y o f f o r m u l a t i o n s . However, c a u t i o n s h o u l d be e x e r c i s e d by a l l t h o s e who s p e c i f y t h e s e compounds, t h a t the e p o x i e s are not a c u r e - a l l f o r a l l problems, t h a t e p o x i e s may be d e t r i m e n t a l i n some a p p l i c a t i o n s , and t h a t p r o p r i e t a r y compounds s h o u l d be t h o r o u g h l y e v a l u a t e d b e f o r e they are u s e d . To epoxy o r not t o epoxy - i s a q u e s t i o n t o be thoroughl y a n a l y z e d by the s p e c i f y i n g e n g i n e e r . RECEIVED

April

2,

1979.


Epoxy Resins with Concrete - ACS Publications - American Chemical

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