Use of Processed Garbage in Cement Concrete

Waste Materials

in

Construction.

J.J.J.R. Goumans, H.A. van der Sioot and Th.G Aulbers (Ediiors) 0 1991 Elsevier Science Publishers 8 V. All rights reserved.

643

USE OF PROCESSED GARBAGE I N CEMENT CONCRETE

Z. ZHANG and F. H. WITTMANN I n s t i t u t e f o r B u i l d i n g M a t e r i a l s , S w i s s F e d e r a l I n s t i t u t e of Technology Ziirich ( S w i t z e r l a n d ) SUMMARY

The r e t a r d i n g e f f e c t of p r o c e s s e d garbage on t h e hydration p r o c e s s and on s e t t i n g of cement has been i n v e s t i g a t e d u s i n g s e m i a d i a b a t i c c a l o r i m e t r y . A l k a l i n e h y d r o l y s i s , namely limewash method i s employed t o d i m i n i s h t h e i n f l u e n c e on h a r d e n i n g . Some mechanical a n d p h y s i c a l p r o p e r t i e s of cement c o n c r e t e a r e d e t e r m i n e d a s a f u n c t i o n of c o n c e n t r a t i o n of t h i s admixture. 1.

I NTRODUCTION

A f t e r household s o l i d w a s t e i s t r a n s f o r m e d by a new t e c h n o l o g y i n S w i t z e r l a n d i n t o a r a n g e of p r o d u c t s , t h e u s e of t h e f i n e s t f r a c t i o n i n b u i l d i n g m a t e r i a l s s u c h a s cement c o n c r e t e i s s t u d i e d . I t t u r n e d o u t t h a t a major problem i s s i g n i f i c a n t r e t a r d a t i o n of t h e h y d r a t i o n p r o c e s s of cement. D i f f e r e n t o r g a n i c compounds i n t h e waste a r e b e l i e v e d t o be t h e c a u s e . The a n a l y s i s has shown t h a t t h e s e compounds can be f o r i n s t a n c e c a r b o n h y d r a t e s , f a t s and p r o t e i n s . The mechanism of s e t r e t a r d a t i o n i n v o l v e s t h e a d s o r p t i o n of a t h i n l a y e r of compound molecules on t h e s u r f a c e of cement p a r t i c l e s and on t h e v e r y f i r s t h y d r a t i o n p r o d u c t s . The o r d i n a r y i n t e r a c t i o n s between w a t e r and cement p a r t i c l e s a r e t h u s reduced o r more o r l e s s blocked, and a s a consequence i t makes h y d r a t i o n p r o c e s s d i f f u s i o n c o n t r o l l e d . Sugars, p r o t e i n s and f a t s a r e e s s e n t i a l c o n s t i t u e n t s of o u r food, and t h e b a s i c m a t e r i a l of l i v i n g organisms. The changes i n pH o r t e m p e r a t u r e can l e a d t o loss of b i o l o g i c a l a c t i v i t y . I n t h i s

article

we w i l l p r e s e n t t h e r e s u l t s of a l k a l i n e h y d r o l i z e d household w a s t e s a s an i n g r e d i e n t i n cement c o n c r e t e i n terms of c a l o r i m e t r y a n a l y s i s . 2.

EXPERIMENTS AND RESULTS

Before mixing t h e f i n e f r a c t i o n s of p r o c e s s e d garbage w i t h cement, t h e y a r e exposed t o Ca(OH)2 w a t e r s o l u t i o n , i . e. o r g a n i c compounds undergo limewash. I t has shown t h a t t h i s a l k a l i n e h y d r o l y s i s p r o c e s s i s i n d e p e n d e n t of t i m e i f CaO: H20 up t o 1: 10 by weight. H y d r a t i o n p r o f i l e s f o r P o r t l a n d cement w i t h d i f f e r e n t c o n t e n t of h y d r o l i z e d g a r b a g e a r e r e p r e s e n t e d i n Fig. 1. Although set r e t a r d i n g

644 i s n o t c o m p l e t e l y d i m i n i s h e d , i t c a n be s e e n t h a t it i s s t i l l a c c e p t a b l e i n p r a c t i c e when t h e p r o c e s s e d g a r b a g e c o n t e n t i s n o t more t h a n 1 0 %

of cement i n weight. Cement m o r t a r (cement: sand: w a t e r = l : 2. 5: 0. 5 ) was prepared w i t h 0 % , 5 % ,l o % , 15% p r o 2:cement+5% 3:cement+lO% .?:cement+ 15%

$

40.

3

30;

c 0

+

cessed garbage admixture r e s p e c t ively. be

Specimen s i z e w a s chosen t o

4 0 x 4 0 ~ 1 6 0mm.

... ,

i c a l and p h y s i c a l tested.

10

20 30 Time (hr.)

10

40

properties

are

The r e s u l t s a r e l i s t e d i n

T a b l e 1, where p = d e n s i t y ; h = t h e r m a l

0 ,.,,,(,,,.,.,,,,,.,.,.,.,( 0

A f t e r 28-days of

h y d r a t i o n u n d e r w a t e r some mechan-

conductivity; a,=water

50

adsorption

c o e f f i c i e n t as determined during t h e

Fig. 1 Heat of H y d r a t i o n

f i r s t hour

Profiles

( w a t e r u p t a k e =a*@

w h i l e a,=water

)

adsorption coeff-

i c i e n t f o r w a t e r s u c t i o n a f t e r t h e f i r s t hour; U,=three- p o i n t bending s t r e n g t h ; U,=compreissive s t r e n g t h . T a b l e 1. Mechanical and P h y s i c a l P r o p e r t i e s of Mortars p h a1 a2 ub uc Admixture Content ( % ) g / c m 3 k / m h c " g / c m 2 f i g / c m 2 h N / m m 2 N / m m 2 2. 2 2. 1 1. 9 1. 8

0 5 10 15 3.

2. 1 1. 8 1. 5 1. 4

0. 1 7 1 0. 114 0. 116

-

0. 146 0. 0 4 6 0. 056 -

5. 1 3. 4 2. 0 1. 4

36. 4 19. 9 14. 2 9. 1

CONCLUSIONS Ca(OH)2 a l k a l i n e h y d r o l y s i s

method i s

a

cheap and p r a c t i c a l

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

used

into

cement

concrete.

Compared w i t h

normal

mortar,

the

mortar a r e i t s l i g h t weight,

i t s low t h e r m a l c o n d u c t i v i t y and l o w e r c a p i l l a r y s u c t i o n b e c a u s e of a r t i f i c i a l l y

advantages

of

this

induced p o r e s by t h i s admixture. P o s s i b l e a p p l i c a t i o n s a r e non l o a d bearing s t r u c t u r a l elements. REFERENCES 1 2 3

R. P r e v i t e ,

Cement and C o n c r e t e Research, Vol. l ( 1 9 7 1 ) 301-316 J e n s Akler-Nissen, Enzymic H y d r o l y s i s of Food P r o t e i n s , E l s v i e r Applied S c i e n c e P u b l i s h e r s 1986, 9-52 H. E. G e r t h l e i m , i n C. L. F e r r e r o , M. P. F e r r a n t i , H. Naveau ( E d . ) , Anaerobic D i g e s t i o n and Carbohydrate H y d r o l y s i s of Waste, E l s v i e r A p p l i e d S c i e n c e P u b l i s h e r s 1984, 14-32