1 / 24

CONCRETE CLASSIFICATION (IS-456)

CONCRETE CLASSIFICATION (IS-456). PRESCRIPTIVE (Nominal mix concrete)- Proportions and Characteristics of ingredients specified. PERFORMANCE BASED ( Design mix concrete) - Requirements of properties specified. Choice and proportioning of ingredients left to producer

destiny-espinoza
Télécharger la présentation

CONCRETE CLASSIFICATION (IS-456)

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. CONCRETE CLASSIFICATION (IS-456) • PRESCRIPTIVE (Nominal mix concrete)- Proportions and Characteristics of ingredients specified. • PERFORMANCE BASED ( Design mix concrete) - Requirements of properties specified. Choice and proportioning of ingredients left to producer • CONCRETE CAN BE CLASSIFIED SITUATION SPECIFIC ALSO e.g. LIGHT WEIGHT CONCRETE ETC.

  2. PROPERTIES OF CONCRETE • Fresh concrete - workability • Hardened concrete • STRENGTH • COMPRESSIVE • TENSILE • FLEXURAL • BOND • DURABILITY • CONCRETE IN FRESH AND HARDENED STATE HAS CONFLICTING DESIGN REQUIREMENTS.

  3. WORKABILITY • From the stage of mixing, transportation and placement upto compaction, concrete should be - • stable - No segregation or bleeding • cohesive and mobile • for proper placement • casting in required shape • amenable to compaction & • should give satisfactory surface finish • WORKABILITY IS THUS THE PROPERTY WHICH DETERMINE THE EASE WITH WHICH IT CAN BE MIXED, PLACED COMPACTED AND FINISHED.

  4. FACTORS AFFECTING WORKABILITY • Water - enough cement paste • Aggregates - • Size - sp. Surface area • shape - particle interference round flaky angular elongated • For a fixed water content, there is one optimum combination of coarse & fine aggregates giving highest workability if w/c ratio is constant. • Time - loss of water • Temperature

  5. REQUIREMENT OF WORKABILITY • TO BE DECIDED ON THE BASIS OF • CROSS SECTION OF THE MEMBER • REINFORCEMENT CONGESTION • AMOUNT OF AVAILABLE COMPACTION EFFORT • SPECIAL TRANSPORTATION OR PLACEMENT • TEMPERATURE AND TIME LAG • METHODS OF TESTING • SLUMP TEST • COMPACTION FACTOR TEST • VEE-BEE TEST

  6. COMPRESSIVE STRENGTH • Factors affecting: • W/C RATIO - S=K1/K2w/c • CEMENT CONTENT - OPTIMUM VALUE • CEMENT CHARACTERISTIC • AGE OF TESTING • PLACING, COMPACTION AND CURING

  7. DURABILITY • ABSENCE OF DURABILITY DUE TO • External factors • WEATHERING • ATTACK BY NATURAL/INDUSTRIAL LIQUIDS • Internal factors • ALKALI - AGGREGATE REACTION • NON COMPATIBLE THERMAL PROPERTIES • PRESENCE OF SULPHATES, CHLORIDES • CORROSION OF REINFORCEMENT DUE TO PRESENCE OF MOISTURE AND AIR

  8. DURABLE DESIGN • DURABILITY ENSURED BY PRESCRIBING • MAXM. W/C RAIO • TO CONTROL PERMEABILITY • MINM CEMENT CONTENT • COVER THICKNESS • TYPE OF CEMENT • AMOUNT OF SULPHATES • > 4% BY MASS OF CEMENT • AMOUNT OF CHLORIDES IN MOIST ENVIRONMENT • > 0.15% BY MASS OF CEMENT (RCC) • 0.06 % BY MASS OF CEMENT (PCC)

  9. REQUIREMENTS OF DURABILITY IS:456-1978 BUILDINGS ETC. • CEMENT REDUCED BY 10 PERCENT IF MAXM W/C RATIO STRICTLY CONTROLLED • THE MINIMUM CEMENT BASED ON 20 MM AGGREGATE. FOR 40 MM REDUCE BY ABOUT 10%; FOR 12.5 MM INCREASE BY ABOUT 10 %

  10. DEGREE OF Q.C. EXPECTED UNDER DIFFERENT SITE CONDITIONS

  11. VALUES OF STANDARD DEVIATION

  12. INPUT DESIGN PARAMETERSIS 10262 • CHARACTERISTIC STR. FCK =20 N1mm2 • WORKABILITY IN C.F. =0.90 • EXPOSURE CONDITION (MILD/MODERATE/SEVERE)= MILD • TYPE OF CONSTRUCTION ( PCC/RCC/PSC)= RCC • DEGREE OF QC EXPECTED =V.GOOD/GOOD/FAIR STANDARD DEVIATION = • TYPE OF CEMENT (A/B/C/D/E) =48 N/mm2/D • MAXM. SIZE OF C.A. = 20 mm • GRADING ZONE OF F.A. = ZONE III • SP. GR. OF C.A. = 2.6 • SP. GR. OF F.A. = 2.6 • SP. GR. OF CEMENT = 3.15. • TYPE OF AGG. (ROUND/ANGULAR)= ROUND

  13. APPROX SAND AND WATER CONTENT PER CUM. OF CONCRETE + SAND CONFORMING TO ZONE II 383-1970 * WATER CONTENT CORRESPONDING TO SATURATED SURFACE DRY. * WORKABILITY - COMPACTING FACTOR = 0.8 * USING ANGULAR AGGREGATES.

  14. PERCENTAGE ADJUSTMENTS IN WATER CONTENT AND SANDIS:10262 - 1982

  15. IS : 10 262 - 1982 • WHERE, • V = ABS. VOL. OF FRESH CONCRETE • W= MASS OF WATER PER m3 OF CONC. • C = MASS OF CEMENT PER m3 OF CONC. • Sc = SPEC. GRAVITY OF CEMENT • p = RATIO OF FA/TOTAL AGG. BY ABS. VOL. Fa, Ca - TOTAL MASSES OF FA AND CA IN KG/m3 OF CONC. Sfa, Sca - SPEC. GRAVITIES OF SATURATED SURFACE DRY FA AND CA.

  16. RAPID MIX DESIGN • DESIGN REFERENCE CONCRETE MIX W/C = 0.35 CF = 0.8 MSA = 10 mm FA = Zone II • DETERMINE ACCELERATED STRENGTH OF REFERENCE MIX USING BOILING WATER METHOD ( IS: 9013) • CHOOSE W/C FROM CURVES AT APP. B TO IS: 10262

  17. RAPID MIX DESIGN

  18. FREQUENCYOFSAMPLING • RANDOM • REPRESENTATIVE • SPREAD OVER ENTIRE PERIOD OF CONCRETING • COVER ALL MIXING UNITS QTY OF WORK M3NO. OF SAMPLES 1-5 1 6-15 2 16-30 3 31-50 4 51 & ABOVE4+1 FOR EACH 50 m3 OR PART THERE OF NOTE : AT LEAST ONE SAMPLE FROM EACH SHIFT SHALL BE TAKEN. TEST SPECIMEN: 3 FROM EACH SAMPLE ADDITIONAL FOR 7 DAY STRENGTH, PRESTRESSING.

  19. ACCEPTANCE CRITERIA (CONTD.) • CONCRETE OF EACH GRADE ASSESSED SEPARATELY • CONCRETE ASSESSED DAILY • CONCRETE LIABLE FOR REJECTION IF • POROUS, HONEY COMBED • PLACING INTERRUPTED WITHOUT CONSTRUCTION JOINT • REINFORCEMENT DISPLACED BEYOND TOLERANCES • CONSTRUCTION TOLERANCES NOT MET • HOWEVER HARDENED CONCRETE MAY BE ACCEPTED AFTER CARRYING OUT SUITABLE REMEDIAL MEASURES : • CORE TEST • LOAD TEST • NDT

More Related