1. CONCRETE MIX DESIGN

2. CONCRETE MIX DESIGN ( GACL METHOD)
TO WORK OUT VARIOUS PROPORTIONS OF THE
INGREDIENTS
METHODS OF MIX DESIGN:
IS:10262 METHOD
ROAD NO4 METHOD
MAXIMUM DENSITY METHOD
MINIMUM VOID RATIO METHOD
GUIDELINES TO THE SITE ENGINEER
-- OBSERVATIONS AT SITE
-- QUALITY OF MATERIALS

3. SIMPLIFIED METHOD
ADOPTED IN MUMBAI REGULARLY
PREREQUISITS BEFORE DESIGN:
(a) STUDY THE SPECIFICATIONS OF THE CONCRETE
(i) SPECIFIED MIN. STRENGTH
(ii) MIN. CEMENT CONTENT, MAX W/C RATIO AND
TYPE OF CEMENT - DEPENDS ON ENVIR. AROUND
THE STRUCTURE i.e., EXPOSURE CONDITIONS
AND EXPOSAL OF CONCRETE TO SULPHATE
ATTACK

4. (iii) MATERIALS USED
(iv) CONSTRUCTION METHODS ADOPTED
WORKABILITY:
COMPACTABILITY,MOBILITY AND STABILITY
VERY HIGH,HIGH, MEDIUM,
LOW , VERY LOW AND EXT. LOW
(i) WORKABILITY DEPENDS ON
- CROSS SECTION , DENSITY OF REINFORCEMENT
- EQUIP. USED FOR TRANSPORTATION , PLACING
AND COMPACTING

5. ( c) MAXIMUM SIZE OF AGGREGATE
IN MUMBAI CRUSHED AGG OF MAX. 30mm AND 15mm
MAS - %PASSING 20mm SIZE SIEVE
%PASSING 20mm SIEVE MAS ( mm )
ECONOMICAL CONCRETE:
LARGE MAS SUBJ. TO LIMITATIONS

6. SHAPE OF AGGREGATES
ROUND GRAVEL AGG.
IRREGULAR AGG.
CRUSHED ROCK AGG.
(e) FINNESS OF AGGREGATES
INFLUENCE THE WATER DEMAND , STRENGTH
CLASSIFIED INTO FOUR ZONES
%PASSING 600 mic. Sieve ZONE
ZONE 1 (COARSE SAND
ZONE 2
ZONE 3
ZONE 4 (FINEST SAND)

7. MORE FINES REQ HIGH CEMENT QTY. AND WATER
DOE METHOD’S GRAPHS ARE USED FOR CAL. % FINE
AGG. TO TOTAL AGG. PROPORTIONS.
AGGREGATE TO CEMENT RATIO:
TABLES OF ROAD NO.4 BY RRL OF DEPT. OF Sc. &
Ind. Rea. IN UK ARE USED
TABLES FOR 30 mm & 20 mm ARE DERIVED FROM
40, 20 & 10 mm TABLES.

8. REQUIREMENTS FOR CONCRETE MIX DESIGN:
SPECIFIED MIN. STRENGTH
DURABILITY REQUIREMENT – ENVIRON.CONDITIONS
TYPE, AVG COMP STRENGTH AND STD OF CEMENT
WORKABILITY OF CONCRETE SLUMP IN mm
MAXIMUM SIZE OF AGGREGATES
SHAPE OF AGGREGATES
FINENESS BASED ON % PASSING 600 mic
SIEVE OR ZONE
SPECIFIC GRAVITY OF AGGREGATES

9. ( I ) DETERMINATION OF TARGET MEAN STRENGTH
Fm = F ck+ t * s
s = STD DERIVED FROM TABLE FOR Fck AND DEGREE
OF QUALITY CONTROL EXPECTED AT SITE
t=1.65
( II ) DETERMINATION OF FREE W/C RATIO:
FREE W/C RATIO & CONCRETE STRENGTH AT 28 days
FOR DIFFERENT 28 days CEMENT STRENGTH AS PER
IS:
A( Kg/sqcm) TO G ( Kg/sqcm) CURVES.
COMPARE WITH DURABILITY CONDITIONS & LESSER
OF THE TWO IS TAKEN

10. ( III ) DETERMINATION OF %PROPORTION OF FINE AGG.
DOE METHOD.
DIFFERENT CURVES FOR DIFF. MAS AND DEGREE OF WORKABILITY ARE GIVEN IN FIG.
FIG. ARE DERIVED FOR MAS 15mm and 30mm BY TAKING AVG. VALUS.
BY INTERPOLATING BET. TWO RELEVANT LINES REPR. 15% , 40%, 60%, 80% & 100% ( % PASSING 600 mic SIEVE )
( IV ) CORRECTION FOR OVERSIZE AGGREGATES:
COARSE PARTICLES (RETAINED ON 4.75 mm SIEVE)
IN FINE AGGREGATES

11. (i) BY SIEVING.
ADJUSTING BY CORRECTION
100 * % FA DET. FROM FIG. / % PASSING 4.75 mm SIEVE
(V) DETERMINATION OF COARSE AGGREGATE:
GEN. 40mm & 20mm ARE USED.
MUMBAI - 30mm & 15mm ARE USED
MAS 30mm % & 50 % of 15mm CAI & 30mm CA II AGG.
MAS 20mm % & 67 % of 10mm CA I & 20mm CAII AGG.
MAS 40mm % & 60 % of 20mm CA I & 40mm CAII AGG.
CORRECTIONS ARE DONE FOR FA , CAI & CAII AGG.
(VI) CORRECTIONS FOR FA PROPORTION PRESENT IN CA
- MAINLY CAI CONSISTS OF STONE DUST FOR THE PROPORTINS WORKED ABOVE

12. % OF MATERIAL PASS. 4.75mm SIEVE * % CAI / 100 = COR
FA = FA – COR AND CAI = CAI + COR
(VII) DETERMINATION OF AGG/CEMENT RATIO:
RRL FORMULATED TABLES BASED ON
-- GRADING ZONE OF AGG., DEGREE OF WORKABILITY
-- W/C RATIO, SHAPE OF AGG AND MAS
IF CRUSHED CA OR NATURAL FA IN CONCRETE
AGG/CEMENT RATIO IS ADJUSTED
A/C FOR CRUSHED SAY Aca , A/C FOR ROUNDED AND
IRREGULAR SAY Afa

13. A/C FOR THE MIX = Aca (% of CAI + % of CAII) / 100 +
Afa (% of FAI) / 100 = A’ca + A’fa = A’
( VIII) CORRECTION FOR SPECIFIC GRAVITY:
Sp. GRAVITY OF CA AND FA IS 2.5 & 2.6 RESP.
A’’ = A’ca ( Sp. Gr ACTUAL) /
A’fa ( Sp. Gr ACTUAL) / 2.6 = A’’ca + A’’fa
(IX) CORRECTION FOR FLAKINESS:
FLAKI OR ANGULAR AGG. HAVE HIGH SURFACE
AREA TO WEIGHT RATIO.
MUMBAI REGION 0.95 – 0.98
APPLIED TO FINAL A/C RATIO = A’’ * 0.95

14. (X) DETERMINATION OF CONCRETE DENSITY:
CONC. DENSITY = AVG WT. OF CUBE / VOLUME OF CUBE
DETERMINATION OF CEMENT CONTENT IN
CONCRETE MIX:
(CC) CEMENT CONTENT = DENSITY / ( 1 + A/C + W/C )
IF CC < DURABILITY CONSIDERATIONS THEN NO
CHANGE IS NECESSARY.
( XII ) CONCRETE MIX BY WEIGHT:
WATER CONTENT = W/C * CEMENT CONTENT
TOTAL AGG. CONTENT (TAC) = A/C * CEMENT CONTENT
CAI CONTENT = TAC * % CAI / 100

15. CAII CONTENT = TAC * % CAII / 100
FA CONTENT = TAC * % FAI / 100
(XIII) ADJUSTMENT FOR MOISTURE CORRECTION
% SURFACE MOISTURE IN FA AND CA IS DET. BY
LAB. TESTS. - APPLY NECESSARY CORRECTION

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