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Highway Concrete (HWYCON)E x p e r t S y s t e m

J u n e 1 9 9 5 Te c h n ic al Brie f # 4

On e o f t h e o b je c t ive s o f SHRP r e -

s e a r c h c o n d u c t e d i n t h e c o n c r e t e

a n d s t r u c t u r e s t e c h n i c a l a r e a w a s

t o im p r o ve c on c r e t e t e ch n o lo gy,

p r i m a r i ly f or p a v e m e n t s . Co n t r a c t

C -2 0 6 , O p t im i za t io n o f H ig h w a y

C on c r et e Te ch n o lo gy, in c lu d e d

t h e d e v e l o p m e n t o f a n e x p e r t s y s -

t e m fo r h i gh wa y c o n c r e t e a c t iv i-

t ies . Th e effor t r es u lt ed in

H WYC O N (S H RP p r o d u c t 2 0 3 9 )

w h i c h i s a n o p e r a t i o n a l a n d c o m -

p u t e r ize d k n o w le d ge -b a s e d s y s -

t e m . Th i s b r i ef is in t e n d e d t o h e lp

in t e r e s t ed p r a c t it io n e r s e va l u a t e

t h e s ys t em , a n d it in c lu d e s s o m e

c om m e n t s o n t h e s o ft wa r e w it h

excerpts from the HWYCON docu-m e n ta t ion , Us e rs Gu id e to th e

Highw a y Concrete (HWYCON) Ex-

pert Sys tem (SHRP-C-406 ).

To in s t a l l t h e s o ft wa r e , p r o vid e d

o n d i s k e t t e s wi t h SHRP r e p o r t C-

4 0 6 , a 3 8 6 o r 4 8 6 c om p u t er w it h

a m in im u m of 4 m ega b yt es of

m e m o r y a n d 2 0 m e g a b y t e s o f f r e e

d i s k s p a c e a r e r e q u i r e d . A m o u s e

a n d Win d ow s 3 .1 a r e n e ed ed t o

run HWYCON.

SUMMARY

H WYC ON is d e s ign e d t o a s s is t

h i g h wa y d e p a r t m e n t s t a f f i n t h r e e

m a i n a r e a s a n d t h e s e a r e :

1 ) d ia g n o s t ic s : d is t r e s s id e n t ifi-

ca tion a n d ca u s es of d is -

t r es s (e s ) in h igh w a y p a ve -

m e n t s a n d s t r u c t u r es ,

2 ) m a t e r ia l s s e le c tio n : t h e s ele c-

t ion o f m a t er ia ls for c on -

s t r u c t io n a n d r e co n s t r u c t io n

a n d

3 ) r e p a ir a n d r eh a b ilit a t io n : r e c-

o m m e n d a t io n s o n m a t e ria lsa n d p r o ce d u r e s fo r c o n c r e te

p a ve m en t r ep a ir a n d r eh a -

bilitation.

Figure 1 HWYCON Subsystems and Users

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To a c com p lis h t h is , t h e e xp er t

s y s t e m is o r ga n i ze d in five m o d -

u l e s o r s u b s y s t e m s , a n d t h e s e a r e

d e p ic t ed in F ig u r e 1 , a l on g w it h

t h e t a r g e t a u d i en c e f or e a c h . M or e

d is c u s s io n o f t h e in d i vid u a l s u b -

s ys tem s is p rovid ed in a s u b -

s e q u e n t s e c t i o n .

All five m odu les follow a qu est ion-

a n d - a n s w er fo rm a t in w h ic h t h e

s ys t em p r om p t s t h e u s e r fo r a n -

s wer s t o a s er ies of q u es tion s

a b ou t m a t er ia ls , c on s t r u ct ion

t yp e , o r d is t r e s s c h a r a c t e r is t ic s .

In m a n y ca ses , t h e u s er ca n

c h oos e t o view p h ot ogr a p h s o r

d r a win g s t o a s s is t in a n s w e rin g

t h e q u e s tion s . E xp la n a t io n s a r eo ffe re d in s o m e c a s e s a s t o w h y

t h e r e qu e s t e d in fo r m a t io n is im -

p o r t a n t . F in a l ly, t h e s y s t em p r o -

vid e s a fin a l r e co m m e n d a t i on o r

d i a g n o s i s b a s e d o n t h e r e s p o n s e s

t o t h e q u es tion s . It s h ou ld b e

n o t e d t h a t t h e q u e s t i o n s a n d a n -

s w er s a r e p u r e l y d e s c r ip t ive a n d

n o n u m e rica l a n a lys is is con -

d u c t e d b y t h e s y s t e m . I n t h e a b -

sence of sufficient information the

s ys t em m a y r ec om m e n d fu r t h e rt e s t s b e c o n d u c t e d b e f o r e a c o n -

c l u s i o n c a n b e r e a c h e d .

HWYCONs menu-driven format is

e a s y t o fo llo w a n d u s e , h o w eve r ,

t h e d o cu m e n t a t io n p r o vid e d w it h

t h e s o ft wa r e is n o t ve r y we ll wr it -

t e n . Al t h o u g h t h e m a n u a l i s t i t l e d

a Us e r s Gu i d e , n o t u t o r i a l s o r i n -

s t r u c t io n s fo r u s e b e y o n d i n s t a l la -

t io n a r e in c lu d e d . No n et h e le s s ,

t h e s y s t e m i s s e l f- e xp l a n a t o r y a n dlargely self-teaching.

Th e e xp e rt s ys t em is e a s y t o u s e

b u t t h e s u b j e c t m a t t e r m a y h a v e

b e e n o ve r - s im p l ifie d . Th e a u t h o r s

of t h e wor k a ck n owled ge t h a t

H WYC O N w ill b e m o s t u s e fu l t o

b e gin n in g e n g in e e r s a n d in s p e c -

t or s wh ich s u gges ts t h at th e

scope of the software is l imited. It

i s q u e s t i o n a b l e w h e t h e r t h e c o m -

p u t er ize d s ys t em p r ovid es a n y

gr e a t b e n e fit s b e yo n d t h a t w h ic h

c ou l d b e p r o vid e d b y a s e r ie s o f

flow ch a r ts or t ree d ia gr a m s.

However, the use of digitized pho-

t o gr a p h s a n d d r a w in g s in H WY-

CON is attr active an d in forma tive.

F in a l ly, it s h o u l d b e n o t ed t h a t

HWYCON is sti ll in th e p rototype

s t a g e a n d i t i s n o t w i t h o u t m i n o r

p r o g r a m m i n g f l a ws . Fo r e x a m p l e ,

w it h in C ONS TR UC -D (B r id ge

D ec k s ) it is p os s ib le t o e n t er a n

e n d l e s s l o o p b e t we e n t wo s c r e e n s

fr o m wh i ch t h e r e is n o le git im a t e

e xit . No n e t h e le s s , t h e s y s t em iss u f f i c i e n t l y e a s y a n d q u i c k t o u s e

t h a t a b or tin g fr om s u c h p r oc e-

d u r es d oe s n o t r e p re se n t a t re -

mendous loss of t ime or effort .

Th e fo llo win g p a r a g r a p h s a r e e x -

c er p t s o f r e le va n t in fo rm a t io n

from the HWYCON documentation

a b ou t t h e s ys tem m od u les a n d

k n o wle d g e d o m a in .

KNOWLEDGE DOMAIN

A fu n d a m e n t a l c om p o n e n t o f a n

e xp e rt s ys t e m is t h e k n o wle d ge

d o m a i n , o r w h a t i s k n o w n a b o u t

t h e s u b j ec t a r e a . Th e k n o wle d ge

ba se for HWYCON was developed

u s i n g w h a t w a s c o n s i d e r e d t o b e

t h e b e s t s o u r c e s a v a i l a b l e d u r i n g

t h e d e ve lo p m e n t p e r i od . Eve r y e f-

for t wa s m a d e t o in c or por a te

SHRP-developed technology in theH WYC O N s y s t em . In s o m e c a s e s

t h i s w a s d iffic u l t b e c a u s e t h e d e -

velop m en t of t h e ot h er S HRP

p r od u c ts a n d t h e e xp er t s ys t em

wer e t a kin g p la ce a t t h e s a m e

t i m e . I n t h e a b s e n c e o f SHRP- d e -

ve lo p ed k n o w le d ge , k n o w le d ge

fr o m le a d in g in d u s t r y o r ga n i za -

t ion s a n d s t a te d ep a r tm e n t s of

t r a n s p o r t a t io n (D O Ts ) w a s u s e d .

In e a ch c a s e t h e k n o wle d ge w a s

t es t ed b y t h e d e ve lo pm e n t t ea m

a n d o t h e r e xp e r t s t o e n s u r e t h a t i

r e p r es e n t e d t h e m o s t r e lia b l e a n d

a p p lic a b l e in f or m a t i on a v a il a b le

The process of knowledge acquisi-

tion consisted of the following ac-

tivities:

1 ) lit er a t u r e s e a r ch e s ,

2 ) in t e r vie ws w it h c on c r e t ee x p e r t s ,

3 ) in t e r vie ws w it h s t a t e d e p a r t -m e n t s o f t r a n s p o r t a t i o n ,

4 ) S H RP E x pe rt Ta s k G r ou p(ETG) meetings,

5 ) r e vie w o f p u b lis h e d gu i d e -

lin e s , s t a n d a r d s , a n dp r a c t i c e s , a n d

6 ) in t e r vie ws w it h S H RPproject investigators .

An i m p o r t a n t f a c t o r i n d e v e l o p i n g

a n y e x p e r t s y s t e m i s t h e n e e d t o

lim it it s s c op e . E xp e rt s ys t e m s

o ft e n fa i l b e ca u s e t h e s c o p e o f t h e

s y s t e m i s t o o b r o a d . A m o r e s u c -

c es s fu l a p p r o a c h is t o d e ve lo p a

s y s t e m t h a t a c c om p lis h e s we ll- d e -

fined goals initially and allows fort h e a d d i tio n o f n e w k n o wle d ge a s

it b e c o m e s a v a il a b le o r a s t h e s y s -

t em m a t u r e s . H WYC ON w a s d e

velop ed wit h t h es e b a s ic

p r in c ip le s in m in d . Th e s ys t em

t e n d s t o h a v e m o r e b r e a d t h t h a n

d e p t h i n s o m e a r e a s . T h e s u b s y s -

t e m o n m a t e r i a l s s e l e c t i o n i s c o n -

s i d e r e d t o b e c o m p r e h e n s i v e i n i t s

s c op e . H o w eve r , o t h e r a r e a s m a y

l a c k d e p t h b e c a u s e m o r e d e t a i l e d

k n owle dge on a t op ic wa s n ot

readily available.

H WYC O N is n o t in t e n d e d t o r e

p la c e t h e h i gh - le ve l e xp e r t . It is

c on s id er ed a d ec is io n -m a k in g

t oo l, a n d t h e r e w ill b e s o lu t io n

s e t s t h a t i t c a n n o t h a n d l e . I t w i l

b e u s e fu l fo r s t a f f wit h k n o wle d g e

levels for beginner to mid level. A

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c on s e n s u s d e ve lo p ed d u r in g t h e

review of the HWYCON prototypes

t h a t t h e s y s t e m w o u l d b e p a r t i cu -

la r ly u s e fu l fo r n e w in s p e c to rs

a n d e n g i n e e r s .

SUBSYSTEMS

The primary focus of HWYCON is

on con cr et e p avem en ts , a n d

k n o w le d ge o n t h a t s u b je ct is r e p -

r es en t ed in t h ree s u b s ys tem s ,

CONPAV-D, CONMAT, a n d CON-

PAV-R. Knowledge related to high-

wa y con cr et e s tr u ct u res is

represented in CONSTRUC-D (one

m o d u l e f o r b r i d g e d e c k s a n d o n e

for s u b s t ru c t u r a l e le m en t s in -

c lu d in g b r id ge c olu m n s , p ie rs ,a n d p a r a p e t wa lls ).

Ea c h o f HW YCONs fi ve s u b s y s -

t e m s i s d e s i g n e d t o b e u s e d s e p a -

r a t e l y , b u t i t i s s u g g e s t e d t h a t i n -

f o r m a t i o n o b t a i n e d f r o m o n e s u b -

s ys t em ca n b e u s ed in a n o th e r.

For example, information from the

d i a g n o s t i c s m o d u l e s c a n a s s i s t i n

t h e d e s i g n o f d u r a b l e r e p l a c e m e n t

m a t e r i a l o r t h e p r o p e r r e h a b i l i t a -

t i o n m e t h o d .

DIAGNOSTICS

Th e CONPAV-D an d CONSTRUC-

D s u b s y s t e m s r e p r e s e n t t h e d i a g -

n o s t ic c om p o n e n t o f H WYC O N.

Th e y a r e d e s i g n e d t o i d e n t i f y d i s -

t res s es a n d m a k e con clu s ion s

a b ou t t h e ca u s e(s ) of t h e d is -

t r e s s es . F ig u r e s 2 t h r o u g h 4 s h o w

t h e t y p e s o f s t r u c t u r e s a n d p a v e -m e n t s c o v e r e d b y e a c h o f t h e s u b -

s ys t em s a s well a s t h e

in f or m a t io n r e q u i r e d t o d i a gn o s e

t h e d i s t r e s s e s .

T h e a p p r o a c h t a k e n b y t h e e x p e r t

s ys t em m im i cs t h a t o f a n e xp e rt

in d ia g n os in g a d is t r es s . H WY-

CON q u e r i e s t h e u s e r f o r i n f o r m a -

t io n o n t h e t yp e o f s t ru c t u r e a n d

d i s t r e s s (i .e . , c r a c k i n g i n a p a v e

m e n t , s p a l lin g o f a b r id g e d e ck )

t h e lo ca t io n o f t h e d is t r es s a n d

e xp o s u r e c on d it io n s . A s e s s io n

m a y in v olve q u e s t io n s r e la t e d t o

t h e c o n s t i t u e n t s a n d c o m p o s i t i o n

o f t h e c o n c r e t e , t h e t y p e o f a g g r e -

g a t e in v o lve d o r t h e a g gr e ga t e s

h i s t o r y i n r e l a t i o n t o k n o wn c a s e s

of r ea c tivit y. E xa m p le s of t h e

q u e s tio n s a n d fie ld in s p e ct io n

s h e e t s a r e i n c l u d e d i n Ap p e n d i x A

o f t h e U s er s Gu i d e . At t h i s t im e

HWYCON e v a lu a t e s d i s t r e s s e s in -

d ivid u a l ly a n d t h e r e is n o p r o vi-

s ion t o m a ke con clu s ion s in

s it u a t ion s t h a t in v olve m u lt ip le

Figure 3 Diagram o f the CONSTRUC-D

S u b s y s t e m f o r S u b s t r u c t u r e sFigure 2 Diagram o f the CONSTRUC-D

S u b s y s t e m f o r B r i d g e D e c k s

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c a u s e s o r d is t r e s s es t h a t o cc u r s i-

m u lt a n e o u s l y a t o n e l oc a t io n .

SELECTION OF MATERIALSFOR CONSTRUCTION AND

RECONSTRUCTION

D es ign in g c on c r et e t o p e rfo rm

s a t i s fa c t o r ily in a d v e r s e e n v ir o n -

m e n t s r e qu i r es k n o w le d ge a b o u t

t h e a n t ic ip a t ed e xp os u r e c on d i-

t io n , a c ce p te d a n d p r ove n m e t h -

o d s f o r s p e c i f y i n g t h e a m o u n t a n d

p e r f o r m a n c e o f c o n s t i t u e n t s , a n d

s p e c ifi ca t i on s fo r t h e p r o d u c t io n

a n d p la c em e n t of t h e c on c re te ,

s u c h a s d es ir ed op en in g t im e s.CONMAT gives recomm end ations

o n t h e d e s i g n o f c o n c r e t e f o r f o u r

a r e a s o f d u r a b i lit y a n d in c lu d e s

k n o wl e d g e o n t h r e e m e t h o d s . Th e

d u r a b i lit y a r e a s i n c lu d e :

1 ) c o r r os i on o f r e in f or c in g s t e e l,

2 ) s u lfa t e a t ta ck ,

3 ) fr e ez in g a n d t h a w in g a c t io n s ,a n d

4 ) a l k a li- a gg re ga t e r e a c tio n s .

Th e m e t h od s r ep r es e n t ed in t h e

k n o wl e d g e b a s e i n c l u d e r e c y c l i n g

c on c r et e, p e rm e a b le b a s e s , a n d

fa s t t ra ck con c ret e. Th e se a r e

s h o wn i n Fi g u r e 5 .

Materials durabili ty knowledge in-

clu ded in CONMAT closely pa ral-

lels t h e Gu i d e t o Du r a bl e

Figure 4 Diagram of the CONPAV-D Subsystem

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C o n c r e t e p u b l is h e d b y t h e Am e r i -

c a n Co n c r e t e I n s t i t u t e . Th i s d o c u -

m en t s er ved a s t he b as is for

d e ve lo p in g t h e k n o w le d ge . Ne w

k n o wle d g e fr o m o t h e r SHRP p r o -

ject s on free zin g a n d t h a win g a c-

t ion s a n d a lk ali-a ggr ega te

r e a c t ivit y wa s a l s o i n c lu d e d i n t h e

s u b s y s t e m , a l o n g wi t h k n o wl e d g e

from high-level experts in the field

of concrete du rab ili ty.

REPAIR AND REHABILITATION

OF CONCRETE PAVEMENTS

Th e H WYC O N s u b s y s t em C O N-PAV-R gives recommendations on

t h e s e le c t io n o f m a t e r i a ls a n d p r o -

c ed u r e s fo r t h e r ep a ir a n d r e h a -

b i lit a t i on o f c on c r e t e p a v e m e n t s .

Th e p rogr a m a s su m e s t h a t t h e

p r oc ed u r e h a s a lr ea d y b e en c h o-

s e n . Th e p r oc ed u r e s c ove r ed in

C O NP AV- R in c lu d e b o n d e d a n d

u n b o n d e d o v e r l a y s , f u l l a n d p a r -

t ia l d e p t h r ep a ir s , a n d d ia m o n d

g r i n d i n g a n d m i l l i n g , a s s h o wn i n

Figure 6. CONPAV-R gives recom-

m en d at ion s on m a ter ia ls a n d

s t ep s fo r p e rfo rm i n g t h e p r oc e-

dure. The operation of CONPAV-R

in volves t h e u s er s p ecifyin g

wh e t h e r i n f o r m a t i o n i s n e e d e d o n

p r o c e d u r e s o r m a t e r i a ls .

CONCLUDING REMARKS

It s h ou ld b e n ot ed t h a t H WY-

C ONs c on c lu s i on s a n d r ec om -

m e n d a t io n s a r e m e a n t t o b e u s e d

a s a d e cis io n -m a k in g t oo l. Th e

r ec om m e n d a tio n s a r e b a s ed on

t h e r e s p o n s e s f r o m t h e u s e r a n d

t h e f i n a l r e s p o n s i b i l i t y f o r t h e d e -c is i on s t i ll l ie s wit h t h e u s e r . Al-

t h ou gh t h e s ys tem con ta in s

high-level in forma tion, i t is imp or-

t a n t t o u n d e r s t a n d t h a t v a r i a t i o n s

c a n o c c u r i n t h e p e r c e p t i o n o f t h e

s t r u c t u r e s p e r f o r m a n c e a n d c o n -

d it io n . Th e m i s st a t em e n t of t h e

o bs e r ve r o r a b s e n c e o f i n fo rm a -

Figure 6 Diagram of the CONPAV-R Subsystem

Figure 5 Diagram of the CONMAT Subsystem

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t io n m a y m a k e a r e co m m e n d a t i on

invalid.

The object oriented architecture of

t h e s ys t e m a n d t h e d e ve lo p m en t

t o ols a llo w n e w k n o w le d ge t o b e

a d d e d . M o d i f i c a t i o n s c a n b e m a d e

t o t h e s ys t em s o pe r a tio n m o r e

e a s i l y t h a n w i t h m o s t e x p e r t s y s -

t em s t h a t h a v e b e e n d e ve lo p ed .

Th i s is im p o r t a n t t o p r e ve n t e x-

p e r t s y s t e m s fr o m b e c om i n g o b s o -

le te . S p ec ific it em s fo r fu t u r e

e n h a n ce m en t s w er e id en t ifie d

t h a t w ou l d m a k e H WYC O N m o r e

com p reh en s ive a n d u s efu l t o

h i g h wa y d e p a r t m e n t s t a f f.

F or e xa m p le , c a u s e s o f d is t r es s

o ft e n in v olve n o n - m a t e r ia l s r e -

l a t e d f a c t o r s . Ot h e r d i s t r e s s t y p e s

c ou l d b e a d d e d t o i n c lu d e t h o s e

d e a l in g wit h in t e r a c t io n s b e t we en

c o n c r e t e a n d t h e s o i l , a n d s t r u c -

t u r a l l y i n d u c e d c r a c k s i n c o n c r e t e

p a v e m e n t . Ne w k n o wle d g e d e ve l-

op ed in ot h er S HRP p roject s

w h ic h a d d r e s s e d t h e c or r os io n o f

r e in fo r cin g s t e el in b r id g e d e ck s

m a y b e im p or ta n t a d d it ion s t o

HWYCON.

Ot h e r k n o wle d g e d e ve lo p e d i n t h e

S H RP p r oje ct o n h igh p e rfo rm -

a n c e c on c r et e c ou l d b e in c lu d e d

in the CONMAT selection of mate-

r ia l s m o d u le . Als o , i n t r i n s i c m a t e -

r ia l s -r e la t e d p r o b le m s , in c lu d i n g

p la s tic s h r in k a ge a n d t h er m a

c r a c k i n g , c o u l d b e a d d e d t o CON-

MAT. The CONPAV-R su bs ystem

a ss u m es t ha t t he u s er h a s a l-

r e a d y s e l e c t e d t h e p r o c e d u r e t o b e

u s e d . Th is s u b s ys t em c ou ld b e

e n h a n ce d t o give r ec om m e n d a

t io n s o n t h e s e le c t io n o f t h e r e p a i r

m et h od b a sed on t h e c a u s e a n d

t h e d en s it y of t h e d is t re ss , a n d

t h i s wou ld b e a ve r y p o we r fu l fe a -

t u r e .

For full details of this research see:

SHRP-C-406Users Gu ide to th e High way Concrete (HWYCON)Ex p e r t Sy s t e mAuthors: L.J . Kaetzel, J .R. Clifton, K. Snyder,Na t io n a l I n s t i t u t e o f St a n d a r d s a n d Te c h n o l og y,

Ga i t h e r s b u r g , MD.Strategic Highway Research ProgramNa t io n a l Re s e a r c h Co u n c ilWa s h in g t on , D C 1 9 9 4

SHRP reports are available for sale at reasonableprices ($5 to $35 USD):

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