SABS 1200 G-1982 6 [ s t r u c t u r a l ) c o n c r e t e

2.4 2.4.1 2.4.1.1

2.4.1.2

2.4.1.3

2.4.1.4

2.4.2

2.4.3

3. 3 .1

3.2 3.2.1

3.2.2

3.2.3

3.3

3.4 3.4.1

3.4.2

3.4.3

EX P LANATl(il\l CY TEIII.IS Exposure Condi t ions Mild c o n d i t i o n s . a i r . Mndcrate c o n d i t i o n s . Condi t ions under which t h e c o n c r e t e is a) s h e l t e r e d from s e v e r e r a i n and i s n o t s u b j e c t to f r e e z i n g when w e t ; or b) b u r i e d i n non-aggressive so i l . ; or c ) cont inuous ly under f r e s h water. Severe condition?.. a ) Dr iv iny r a i n ; b) a l t e r n a t e w e t t i n g and d r y i n g o u t ; c) f r e e z i n g when w e t ; d ) f r e s h water ( a t t h e w a t e r - l i n e ) ; c ) s p l a s h i n g or s p r a y i y wi th f r e s h water ; f ) c o r r o s i v e fumes or heavy condensat ion of water; g ) aggress ive so i l ; h ) s a l t - l a d e n a i r . very s e v e r e c o n d i t i o n s . a ) Sea-water (below o r a t t h e w a t e r - l i n e ) ; b ) sea-wat.er spray or windborne s a l t s ; c) water c o n t a i n i n g s u l p h a t e s or c h l o r i d e s ; d ) h i g h l y c o r r o s i v e fumes. S t r e n g t h Concrete . A s t r e n g t h c o n c r e t e is d e s i g n a t e d by its spec: i f ied s t r e n g t h fol lowed by t h e s i z e of s t o n e used i n i t s manufacture , e.g. 30 MPa/l9 mm r e f e r s t o a Grade 30 mix made wi th 19 mm s tone . J o i n t s . The l o c a t i o n of j o i n t s is c o n t r o l l e d by des ign requi rements and c o n s t r u c t i o n l i m i t a t i o n s . All j o i n t s a r e " c o n s t r u c t i o n j o i n t s " w i t h i n t h e g e n e r a l meaning of the term. J o i . n t s shown on t h e drawings o r i n t h e schedule are "des igna ted j o i n t s " . The Engineer may, i n c o l l a b o r a t i o n wi th t h e C o n t r a c t o r , approve f u r t h e r j o i n t s b e f o r e t h e c a s t i n g of c o n c r e t e , which j o i n t s w i l l then become "des igna ted j o i n t s " . terms " c o n s t r u c t i o n a l j o i n t s " , "movement j o i n t s " , " c o n t r a c t i o n j o i n t s " , and "expansion j o i n t s " are used to i d e n t i f y v a r i o u s t y p e s of d e s i g n a t e d j o i n t s . formed dur ing c o n c r e t i n g when p l a n t f a i l u r e , inclement weather , or s o m e o t h e r unforeseen e v e n t h a s enforced a h a l t i n t h e p l a c i n g of c o n c r e t e and h a s t h u s c r e a t e d E ! s i t u a t i o n i n which a c o n s t r u c t i o n j o i n t hds to be made i n a l o c a t i o n t h a t was n e i t h e r d e s i g n a t e d nor approved b e f o r e t h e commencement of concre t ing .

MATERIALS APPHGVAL OF MATERIALS. The C o n t r a c t o r s h a l l supply i n good t i m e t o t h e Engineer , f o r h i s approval , samples of t h e aggrega tes (and , i f so o r d e r e d , of t h e water ) that . he proposes t o u s e f o r t h e c o n c r e t e and s h a l l f u r n i s h ev idence t h a t t h e water and aggrega tes comply w i t h t h e requi rements of 3 . 3 and 3.4. Evidence s h a l l b e i n t h e form of e i t h e r a ) a s ta tement frol;, an approved l a b o r a t o r y of t h e r e s u l t s of t es t s , or b ) an a u t h o r i t a t i v e r e p o r t or record of p r e v i o u s exper ience .

CENKNT Appl icable S p e c i f i c a t i o n s . m i l l e d g r a n u l a t e d b l a s t f u r n a c e s l a g (see SABS 626) s h a l l comply w i t h t h e r e l e v a n t requi rements of t h e fo l lowing s p e c i f i c a t i o n s : BS 1370 Low h e a t P o r t l a n d cement SABS 471 P o r t l a n d cement (ord inary , rapid-hardening, and s t J p h a t e - r e s i s t i n g ) SABS 626 P o r t l a n d b l a s t f u r n a c e cement SABS 031 A l t e r n a t i v e l'ypcxs of Cement. when s p e c i f i c a l l y a u t h o r i z e d by t h e Engineer . (See 8.1.3.2 and E.1.3.3.) Sllorage of Cement. S e p a r a t e s t o r a g e f a c i l i t i e s s h a l l b e provideC, on t h e S i t e f o r each type of cement used. Cemant t h a t i s s t o r e d on t h e S i t e s h a l l b e k e p t under cover t h a t p rovides p r o p e r p r o t e c t i o n a g a i n s t mois ture and o t h e r f a c t o r s t h a t may promote d e t e r i o r a t i o n . S t o r a g e of cement i n bulk i n weather-proof si los or s i m i l a r c o n t a i n e r s w i l l b e p e r m i t t e d provided t h a t t h e cement drawn f o r use is measured by mass and n o t by volume.

WATER. Water s h a l l be c l e a n and f r e e from i n j u r i o u s amounts of a c i d s , a l k a l i s , o r g a n i c matter, and o t h e r subs tances t h a t may impair t h e s t r e n g t h or d u r a b i l i t y of concre te .

AGCR)LGATES Appl icable S p e c i f i c a t i o n . Both t h e c o a r s e a g s r e g a t e ( s tone) and t h e f i n e a g g r e g a t e (sand) s h a l l comply wi th the r e l e v a n t requi rements of SABS 1083. use of Plums. Where plums are r e q u i r e d to be used, or are p e r m i t t e d , they s h a l l a ) b e h a r d , c l e a n s t o n e of mass 15 t o 55 kg; b ) c o n s t i t u t e n o t more than 20 % of t h e volume of t h e concre te ; c) have no adher ing f i l m or c o a t i n g ; d ) be such t h a t no plum h a s a dimension g r e a t e r than one- th i rd of t h e smallest dimension of t h e c o n c r e t e member or g r e a t e r than 300 mm, whichever i s less; e ) each be surrounded by c o n c r e t e of depth a t l eas t 80 mm; and f ) have an aggrega te c rush ing va lue a t least e q u a l t o t h a t s p e c i f i e d f o r c o a r s e aggrega te i n SAnS 1.083. S torage of Aggregates . Aggregates of d i f f e r e n t nominal s i z e s s h a l l b e s t o r e d s e p a r a t e l y and i n such a way t h a t a ) segrega t ion i s minimized; and b ) in te rmixing of d i f f e r e n t materials and contaminat ion by foreiyr i m a t t e r i s prevented .

~. _I_

Condi t ions under which t h e c o n c r e t e is p r o t e c t e d from t h e weather and exposed o n l y t o - - __ __

Condi t ions under which t h e c o n c r e t e is expostid o r s u b j e c t t o any of t h e fo l lowing:

Condi t ions under which t h e c o n c r e t e i s exposed to any of t h e fol lowing:

---_-

The

The tenn "unforeseen j o i n t " i s used to i d e n t i f y a j o i n t

S u b j e c t t o t h e p r o v i s i o n s of 3.2.2, cement and b lends of p o r t l a n d cement and

P o r t l a n d cement 15 and rapid-hardening p o r t l a n d cement 15 Any type of cement o t h e r t h a n t h o s e r e f e r r e d t o i n 3.2.1 s h a l l b e used only

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7 SABS 1200 G-1992 Concrete ( s t r u c t u r a l )

3.5 ADMIXTURES 3.5.1 2 p r o v a l of Admixtures Required.

of the Engineer, who may require tests to be made before they a r e used. Contractor s h a l l provide the following information: a) The t rade name of t h e admixture, i ts source, and the manufacturer 's recommended method of use; b) t yp ica l dosage r a t e s and possible detr imental e f f e c t s of under-dosage and overdosage; c ) whether compounds (such a s those containing chlor ide i n any form a s an ac t ive ingredient) l i k e l y t o cause corrosion of the reinforcement o r de t e r io ra t ion of t h e concrete a r e present and, i f so, the chlor ide content (expressed as chlor ide ions o r a s equivalent anhydrous calcium chlor ide) by mass of admixture (see 5.5.1.4); d ) the average expected a i r content of f r e sh ly mixed concrete containing an admixture which causes a i r t o be entrained when used a t the manufacturer's recommended r a t e of dosage.

measurements s h a l l be ca r r i ed out on S i t e by the Contractor, a s and when required by the Engineer, to determine a ) the percentage of a i r entrained i n the concrete; and b) t he densi ty of t h e concrete. The Contractor s h a l l provide equipment t o permit measurement of entrained a i r a t such frequencies a s are required by the Engineer.

Admixtures s h a l l not be used i n any concrete mix without t he approval To f a c i l i t a t e approval, t he

3.5.2 Air-Entraining Agents. I f t he use of an air-entraining agent is permitted by the Engineer, test

3.6

3.7

3 . 8

4. 4.1

4.2

REINFORCEMENT. Reinforcing ba r s s h a l l comply with the r e l evan t requirements of SABS 920. Welded s t ee l f ab r i c s h a l l comply with the relevant requirements of SABS 1074. S t e e l s h a l l be so stacked o f f t he ground a s t o prevent d i s t o r t i o n and s h a l l be protected from aggressive environments and contamination.

STORAGE CAPACITY. The s torage capacity provided and the amount of mater ia l s tored (whether cement, aggregates, s t e e l , or water) s h a l l be s u f f i c i e n t t o ensure t h a t no in t e r rup t ion to the progress of the work is occasioned by lack of mater ia ls .

DETERIORATED MATERIAL. Material t h a t has de t e r io ra t ed , o r t h a t has been contaminated o r otherwise damaged, s h a l l not be used i n concrete. Such mater ia l s h a l l be removed from the S i t e without delay.

PLANT GENERAL.

HATCHING PLANT. The Contractor s h a l l ensure, by regular examination, ca l ib ra t ion , and tests, t h a t the batching s y s t e m funct ions e f f i c i e n t l y and accurately and t h a t hoppers and cement containers a re kept dry and clean. The batching p l an t s h a l l be such t h a t a ) cement may be batched t o an accuracy of within 2 2 of t h e mass required; b) water may be measured, by mass o r by volume, t o an accuracy of within 2 % o f the quan t i ty required; and c) aggregate may be batched t o an accuracy of within 3 % of the mass required. In the case of an automatic p l an t , t he weighing sca l e s s h a l l be so inter locked t h a t a new batch of ma te r i a l s cannot be del ivered u n t i l t he weighing hoppers have been completely emptied of t h e previous batch and the sca l e s a r e i n balance. Where discharge of ma te r i a l s from the hoppers is manually control led, a method of s igna l l i ng s h a l l be employed t o e n s u r e t h a t ingredients a r e not omitted, o r a r e not added more than once, when a batch of concrete is being made up.

All p lan t s h a l l be maintained i n good working order .

4.3 M I X I N G PLANT 4.3.1 General Requirements f o r Mixing Plant . The type and capaci ty of mixing machines s h a l l be such t h a t the

r a t e of output of concrete is su i t ab le f o r t he rate of concreting. Each machine s h a l l be capable of producing a uniform d i s t r i b u t i o n of t he ingredients throughout t h e batch and s h a l l comply with the spec i f i ca t ion t o which t h e manufacturer claims it has been manufactured. s h a l l be replaced. The i n n e r surfaces of the mixer s h a l l be clean and f r e e from hardened concrete. Approval f o r Shor t Mixing P e a . wish to use any p a r t i c u l a r type of mixer i n respect of which a ) it has been establ ished on S i t e , o r b ) the manufacturer has guaranteed, t h a t e f f i c i e n t mixing can be cons i s t en t ly achieved i n mixing per iods sho r t e r than those spec i f i ed i n 5.5.3.1(e).

VIBRATORS. Vibrators s h a l l be capable of f u l l y compacting each l aye r of concrete where compaction by v ib ra t ion i s specif ied. A t l e a s t one standby v ib ra to r s h a l l be avai lable f o r every th ree (or smaller number o f ) v ib ra to r s necessary t o maintain the r a t e of placing.

Worn or bent blades and paddles

The Contractor s h a l l obtain the Engineer 's p r i o r approval should he 4.3.2

4.4

4.5 FORMWORK 4.5.1 Design. Formwork s h a l l be so designed and constructed t h a t t he concrete can be properly placed and

compacted and t h a t , sub jec t t o the tolerances spec i f i ed i n 6.2.3 (a) and ( b ) , t he required shapes, f i n i shcs , pos i t i ons , l eve l s , and dimensions shown on the drawings a r e maintained. The formwork and j o i n t s s h a l l be capable of r e s i s t i n g the dead load, including the pressure exer ted by the w e t concrete, wind forces , and a l l o the r superimposed loads and forces. Where formwork is to be erected over a road, a s t r e e t , o r a railway, t h e Contractor s h a l l so design h i s formwork t h a t the f u l l c learances required f o r the f r e e movement of t r a f f i c are maintained t o the s a t i s f a c t i o n of the au tho r i ty con t ro l l i ng such road, street, o r railway. Where so required i n terms of the p ro jec t spec i f i ca t ion , the Contractor s h a l l , before comencing e rec t ion , obtain the approval of such authori ty f o r t he design of h i s formwork.

4.5.2 Finish. The qua l i t y of formwork s h a l l be such t h a t the f in i shed surface of the concrete is a s scheduled o r shown on the drawings o r a s required i n terms of the p r o j e c t spec i f i ca t ion (see 5.2.1).

4.5.3 U. w i l l not be marred by subsequent corrosion of t he t i e s .

The types of t i e s used and t h e i r pos i t i on s h a l l be such t h a t the required f i n i s h is achieved and

SABS 1200 G-1982 Concrete ( s t r u c t u r a l )

(Sec 2 .4 .1 )

Mild ................ Moderate ............ Severe .............. Very severe .........

8

MPa

20 25 30 tTi

20 20 15 1 5 40 40 30 ;!5

50 40 L O 60

5. 5.1 5.1.1 5.1.1.1 5.1.1.2

5.1.1.3

5.1.1.4

5.1.2

5.1.3

5.1.4

5.1.5

5.2 5.2.1

5.2.2

5 . 2 . 3

5 . 2 . 4

CONSTHIJCTlON RI~INFOIICMENT Bending Reinforcing ba r s s h a l l be bent t o the dimensions shown on the drawings and i n accordance with SABS 82. Except a s allowed i n 5.1.1.3, a l l ba r s s h a l l be bent cold and bending s h a l l be done slowly, a s teady, even pressure being used without j e rk o r impact. Subject to the approval of t he Engineer and provided t h a t t he ba r s do not depend f o r t h e i r s t r eng th on cold working, ba r s of diameter 32 mm o r more may be bent hot. Bars t h a t a r e to be bent ho t s h a l l be heated slowly t o a cherry red hea t (not above 840 "C) and, a f t e r bending, s h a l l be allowed t o cool slowly i n a i r . Hot ba r s shall1 not be quenched with wat.er. Fixing. S t e e l s h a l l , a t t he t i m e of t he placing of the concrete, be f r e e from loose o r powdery r u s t , s ca l e , o i l , and o the r coat ings t h a t may reduce t h e bond between steel and surrounding concrete, a f f e c t the d u r a b i l i t y of the concrete, o r i n i t i a t e corrosion of the reinforcement. wat.er i s used f o r l ub r i ca t ing the formwork, every precaution s h a l l be taken to avoid contamination of the reinforcement by such substance. Reinforcement s h a l l be posi t ioned as shown on the drawings and maintained i n those pos i t i ons within the tolerances given i n 6.2. I t s h a l l be secured against displaceraent by tying a t i n t e r sec t ions with ailnealed w i r e of nominal diameter 1,6 mm or 1,25 nun, o r by the u s e of acceptable c l i p s o r , i f permitted by the Engineer, by welding. hangers o r saddles , and al igned by means of cha i r s and spacers of approved design. Supporting s t e e l t o approved design w i l l be added to the reinforcing schedule by the Engineer. o the r supporting ma te r i a l s s h a l l be subject to p r i o r approval. Cover. Unless otherwise shown on the drawings, t h e cover of concrete over reinforcement (other than over r a i l o r s t r u c t u r a l s t e e l reinforcement) f o r var ious environmental exposure condi t ions s h a l l i n no case be less than a) the appl icable value given i n Table 1, measured from the ou1.side of any ba r o r s t i r r u p , o r b) t he diameter of t he reinforcement or s t i r r u p to which the cover is measured, whichever i s g rea t e r .

I f any substance o the r than

Reinforcement s h a l l be supported i n i ts co r rec t pos i t i on by means of

__

TABLE 1 - M I N I M U M COVER FOR VARIOUS EXPOSURE CONDITIONS

(mm)

Specified s t rength Exposure condi t ions of Concrete, I

Cover over r a i l and s t r u c t u r a l s t e e l reinforcement s h a l l be a t l e a s t 80 mm, unless otherwise showii on the drawings. The cover f o r f i r e protect ion s h a l l be i n accordance with the relevant requirements of SABS 0144. Splicing. Spl ices o r j o i n t s i n re inforcing ba r s s h a l l be made only as and where shown on the drawings or a s otherwise approved. Protect ion of Exposed Bars. I f l e f t exposed f o r fu tu re bondinc of extensions t o the Works, reinforcement s h a l l be protected from corrosi.on as directed.

FOKI4WORK C las s i f i ca t ion of Finishes. Formwork w i l l be c l a s s i f i e d i n accordance with the surface condition required on the f inished concrete. Such surface condi t ions a r e c l a s s i f i e d as follows and w i l l be so scheduled: a ) Rough. formwork. The f i n i s h of t he concrete need not be more accurate than Degree of Accuracy I11 a s defined i n terms of Clause 6. b) Smooth. Imperfections such a s small f i n s , bulges, i r r e g u l a r i t i e s , surface honeycombing, and s l i g h t surface discolorat ions s h a l l be made good and repaired by apprc'ved methods. The f i n i s h of the concrete s h a l l be accurate t o Degree of Accuracy I1 as defined i n terms of Clause 6 (see a l so 5 . 5 . 1 0 . 3 ) . c) Special . Special f i n i shes s h a l l be a s spec i f i ed i n the p ro jec t spec i f i ca t ion . Preparation of Formwork. mortar. Surfaces of forms (regardless of the ma te r i a l of which they a re made) t h a t a r e t o be i n contact with f r e sh (wet) concrete s h a l l be t r ea t ed with a coat of non-staining mineral o i l o r o the r approved mater ia l o r , only i n the case of timber forms, by thorough wetting of t he surfaces with water, so a s t o ensure easy release and prevent adhesion of t he formwork during s t r ipping. Re-use of Formwork. Before re-use, a l l formwork s h a l l be reconditioned, and a l l form surfaces t h a t a r e t o be i n contact with the concrete s h a l l be thoroughly cleaned. Openings. Where necessary f o r the proper placing of the concrete, temporary openings for cleaning, inspect ion, o r placing purposes s h a l l be provided and, subsequently, so closed a s to provide the f i n i s h spec i f i ed and t o conform t o the appl icable tolerances given i n 6.2.3(b).

No treatment of t h e surface of t he concrete w i l l be required a f t e r the s t r i k i n g of t he

Forms s h a l l be erected with j o i n t s t i g h t enough t o prevent leakage of cement