Concrete Mix Designing PDF

Selection of Concrete mixture proportion Concrete Mix Design GARJE RAJESH KUMAR – CE255 CONCRETE TECHNOLOGY – MIX 1 DESIGN  Factors influencing Strength of Concrete ❑ CEMENT – Ty...

Selection of Concrete mixture proportion Concrete Mix Design GARJE RAJESH KUMAR – CE255 CONCRETE TECHNOLOGY – MIX 1 DESIGN  Factors influencing Strength of Concrete ❑ CEMENT – Type of Cement, Dosage of Cement ❑ AGGREGATE – Type of Aggregate, Dosage, Grading, Shape, Surface Texture, Strength of Aggregate, Saturated Surface Dry condition ❑ MINERAL ADMIXTURES – FLY ASH, GGBFS, RHA, SF, MK etc., ❑ WATER – For Hydration - Adequate Workability – Compactability – Strength – Density – Impermeability - Durability ❑ PROPORTION – Plays an important role – C:FA:CA:w/c (1:2.3:3.1:0.4) ❑ COMPACTION – Type of Compaction – Manual, Mechanical etc., ❑ FINISHING – Type of Finishing – Manual, Mechanical etc., ❑ CURING – Type of Curing – Temperature – Relative Humidity etc., ❑ AGE at Testing (28 days strength as the criteria for design) ❑ TESTING – Method of Testing STRENGTH IS A STATISTICAL PARAMETER AVERAGE VALUE AND STANDARD DEVIATION GARJE RAJESH KUMAR – CE255 CONCRETE TECHNOLOGY – MIX 2 DESIGN  SUSTAINABILITY DURABILITY GARJE RAJESH KUMAR – CE255 CONCRETE TECHNOLOGY – MIX 3 DESIGN  CHARACTERISTIC STRENGTH IS 456-2000:The Designation of a concrete characteristic strength is mix- M30 defined as the strength M- Mix of material below which 30 – Characteristic not more than 5 percent compressive strength of the test results are tested on a standard cube expected to fall. (150 mm x 150 mm x 150 mm) as per IS 516 at the end of 28 days of normal curing GARJE RAJESH KUMAR – CE255 CONCRETE TECHNOLOGY – MIX 4 DESIGN SELECTION OF CONCRETE MIX PROPORTIONING 1. Find Target Mean Strength 2. Find Water/Cement ratio (a) Strength (Abram’s Law) (b) Durability 3. Lower of the two is considered 4. Selection of Water & Admixture content (Table 4 & corrections) 5. Cement content can be found using w/c & water content 6. Check cement content w.r.t minimum and maximum requirement 7. Volume of Coarse Aggregate per unit volume of Total Aggregate 8. Apply corrections & arrive at Vol. of CA per unit volume of TA 9. Mix Calculations using Absolute Volume Method 10. Apply local corrections & proceed with Trials GARJE RAJESH KUMAR – CE255 CONCRETE TECHNOLOGY – MIX 5 DESIGN Concrete Mix Design for M50 Grade - DATA Cement – 43 Grade OPC – IS 269-2015 Maximum size of aggregate – 20 mm Slump required = 150 mm Exposure – Moderate Semi angular aggregate is available Specific Gravity of Cement/CA/FA = 3.12/2.8/2.58 Respectively Water absorption of CA/FA = 0.4% / 0.9% Respectively Zone of Sand – Zone III as per IS 383 Well graded Coarse aggregate as per IS 383 GARJE RAJESH KUMAR – CE255 CONCRETE TECHNOLOGY – MIX 6 DESIGN  (1)Target mean strength = fck + 1.65(S) = 50+1.65(5) = 58.25 MPa (2)Target mean strength = fck + X = 50 + 6.5 = 56.5 MPa Maximum of the above to be considered = 58.25 MPa Curve -2 (for 43 G ) of Fig. 1 of IS 10262 = w/c = 0.29 (Strength) Table 5 of IS 456 – Moderate exposure – w/c = 0.5 (Durability) Minimum of the above to be considered w/c = 0.29 Air content – Table 3 of IS 10262 – 20 mm MSA – 1% Water content – Table 4 of IS 10262 – MSA = 20 mm – angular agg – slump = 50 mm – 186 kg/cum For sub angular agg = -10 kg For 150 mm slump = (150-50)/25 = 4x3 = +12% of 186= 22.32 kg Final Water Content = 186 + 22.32 – 10 = 198.32 kg/cum GARJE RAJESH KUMAR – CE255 CONCRETE TECHNOLOGY – MIX 7 DESIGN  For w/c = 0.29 & Water content = 198.32 kg/cum – Cement = 683.86 kg/cum Maximum cement  450 kg/cum, Minimum cement > 300 kg/cum Fix Cement content = 450 kg/cum & water = 130.5 kg/cum Volume of CA per unit volume of TA (From Table 5 of IS 10262) For MSA = 20 mm, w/c = 0.5, Zone-III sand – Vol of CA per unit vol of TA = 0.64 Increase of 0.01 for every decrease of w/c by 0.05 – Actual w/c = 0.29 – (0.5-0.29)/0.05 = 4.2(x0.01) = 0.042 Corrected Vol of CA per unit vol of TA = 0.64+0.042 = 0.682 Therefore Vol of FA per unit Vol of TA = 1-0.682 = 0.318 GARJE RAJESH KUMAR – CE255 CONCRETE TECHNOLOGY – MIX 8 DESIGN Absolute Volume Method – Mix Design Total Volume = 1 cum Entrapped air = 1% = 0.01 cum 𝑀𝑎𝑠𝑠 𝑜𝑓 𝐶𝑒𝑚𝑒𝑛𝑡 450 Volume of Cement = = = 0.144 𝑐𝑢𝑚 𝑆𝑝.𝐺𝑟 𝑜𝑓 𝐶𝑒𝑚𝑒𝑛𝑡 ∗1000 3.12∗1000 𝑀𝑎𝑠𝑠 𝑜𝑓 𝑊𝑎𝑡𝑒𝑟 130.5 Volume of Water = = = 0.1305 𝑐𝑢𝑚 𝑆𝑝.𝐺𝑟 𝑜𝑓 𝑊𝑎𝑡𝑒𝑟 ∗1000 1∗1000 Volume of Total Aggregate = 1-(0.01+0.144+0.1305) = 0.7155 cum Volume of CA = 0.7155 *0.682 = 0.487971 cum Volume of FA = 0.7155 * 0.318 = 0.227529 cum Mass of CA = Vol of CA * Sp. Gr of CA * 1000 = 1366.32 kg/cum Mass of FA = Vol of FA * Sp. Gr of FA * 1000 = 587.02 kg/cum GARJE RAJESH KUMAR – CE255 CONCRETE TECHNOLOGY – MIX 9 DESIGN Mix Proportion before correction (By Weight) (kg/cum) CEMENT 450 1 When the aggregates are in FINE AGGREGATE 587.02 1.304 SSD conditions COARSE AGGREGATE 1366.32 3.036 WATER 130.5 0.29 TOTAL 2533.85 GARJE RAJESH KUMAR – CE255 CONCRETE TECHNOLOGY – MIX 10 DESIGN Corrections due to Water absorption Coarse Aggregate absorbs 0.4% water (By weight) 1366.32 𝑘𝑔 Actual mass of CA = 0.4 = 1360.87 1+100 𝑐𝑢𝑚 Fine Aggregate absorbs 0.9% water (By weight) 587.02 Actual mass of FA = 0.9 = 581.78 𝑘𝑔/𝑐𝑢𝑚 1+ 100 Total water absorbed by CA & FA = (1366.32-1360.87)+(587.02- 581.78) = 10.69 kg/cum Therefore Actual water to be added to the mix = 130.5+10.69 = 141.19 kg/cum GARJE RAJESH KUMAR – CE255 CONCRETE TECHNOLOGY – MIX 11 DESIGN Mix Proportion after correction (By Weight) (kg/cum) CEMENT 450 1 FINE AGGREGATE 581.78 1.293 TRAIL MIXES TO BE CAST & TESTED COARSE AGGREGATE 1360.87 3.024 BEFORE FINAL CONCRETING WATER 141.19 0.31 TOTAL 2533.84 GARJE RAJESH KUMAR – CE255 CONCRETE TECHNOLOGY – MIX 12 DESIGN Quantities required to cast a beam Beam dimensions – 500 x 600 x 5000 mm Volume = 0.5x0.6x5 = 1.5 cum Increase the volume by about 20% = 1.8 cum Cement = 450x1.8=810 kg (16.2 bags) FA = 581.78 x 1.8 = 1047.2 kg CA = 1360.87 x 1.8 = 2449.6 kg Water= 141.19x1.8=252.14 kg GARJE RAJESH KUMAR – CE255 CONCRETE TECHNOLOGY – MIX 13 DESIGN Quantities required to conduct slump test To determine the slump of the concrete - 1:1.293:3.024:0.31 unit Wt. of concrete is 2400 to 2500 kg/cum 100 Wt. of Cement = 2500x(1/5.627)=444.3kg/cum 𝜋𝑟 2 (ℎ) Volume of cone = 300 3 𝜋(1002 )(600) 𝜋(502 )(300) Volume of slump cone = - 3 3 Volume of slump cone = 0.0055x 1.2= 0.0066 cum 200 Wt. of cement = 444.3x0.0066 = 2.93 (3kg) FA = 3.88 kg, CA = 9.072 kg, Water = 0.93 kg GARJE RAJESH KUMAR – CE255 CONCRETE TECHNOLOGY – MIX 14 DESIGN Testing of Hardened Concrete IS 516 – 2019 – Draft code IS 516 – 1959 Destructive Testing & Non Destructive Testing Non Destructive Testing for human beings – X-ray, MRI, BLOOD PRESSURE, temperature by thermometer Destructive Testing for human beings – blood testing , biopsy, While purchasing mangoes – Non Destructive testing – shape, size, color, smell – not fool proof Destructive testing – tasting a piece of mango For already constructed building – Non destructive testing or partially destructive testing GARJE RAJESH KUMAR – CE255 CONCRETE TECHNOLOGY – MIX 15 DESIGN Destructive Testing of hardened concrete Concrete is strong in compression – Compressive Strength – as per IS 516 – 150 mm x 150 mm x 150 mm or 100 mm x 100 mm x 100 mm Compressive strength as per ACI – Cylinder of 150 mm dia & 300 mm height. Tensile strength – Indirect method – (1) Split tensile strength or (2) Modulus of rupture GARJE RAJESH KUMAR – CE255 CONCRETE TECHNOLOGY – MIX 16 DESIGN GARJE RAJESH KUMAR – CE255 CONCRETE TECHNOLOGY – MIX 17 DESIGN  COMPRESSIVE STRENGTH = P/A GARJE RAJESH KUMAR – CE255 CONCRETE TECHNOLOGY – MIX 18 DESIGN Flexural Strength – Modulus of Rupture CONCEPT OF PURE BENDING Theory of Bending - 𝑀 𝑓 𝐸 = = 𝐼 𝑦 𝑅 Bending Stress - 𝑀𝑦 𝑀 𝑓= = 𝐼 𝑍 GARJE RAJESH KUMAR – CE255 CONCRETE TECHNOLOGY – MIX 19 DESIGN  P Size of the specimen as per IS 516 P/2 P/2 100 mm x 100 mm x 500 mm OR 150 mm x 150 mm x 700 mm 50 mm L/3 L/3 L/3 50 mm I = BD3/12 = D4/12, y = D/2 Z = BD2/6 = D3/6 P/2 P/2 𝑀𝑦 𝑃𝐿 When the Crack occurs in middle third portion M =PL/6 - 𝑓 = = 𝐼 𝐷3 𝑀𝑦 𝑃𝑎 6 3𝑃𝑎 When the Crack occurs at ‘a’ from support M =Pa/2 -𝑓 = = = 𝐼 2 𝐷3 𝐷3 When a is less than 170 mm (for 150 mm specimens) or 110 mm (for 100 mm specimens) the results shall be discarded GARJE RAJESH KUMAR – CE255 CONCRETE TECHNOLOGY – MIX 20 DESIGN  Split Tensile Strength CYLINDER 150 mm DIA & 300 mm HEIGHT GARJE RAJESH KUMAR – CE255 CONCRETE TECHNOLOGY – MIX 21 DESIGN SPLIT TENSILE L=300 mm, STRENGTH = D=150 mm 2P/LD GARJE RAJESH KUMAR – CE255 CONCRETE TECHNOLOGY – MIX 22 DESIGN Young’s modulus of Concrete – IS 516- 1959 COMPRESSOMETER GARJE RAJESH KUMAR – CE255 CONCRETE TECHNOLOGY – MIX 23 DESIGN  Seasoning of concrete specimen to determine the Modulus of Elasticity as per IS 516-1959 Note initial extensometer reading = zero Load up to Stress = (C+5) Kg/cm2 at @ 140 kg/cm2/min C= (1/3)* Avg comp. Strength of concrete This stress is maintained for 1 minute and gradually reduced to 1.5 kg/cm2 – Extensometer reading shall be noted & compared with initial reading. Second cycle – load up to a stress of (C+1.5) kg/cm2- maintain for a minute and decrease to 1.5 kg/cm2- again record the extensometer reading- compare with the previous reading. Third cycle – load up to a stress of (c+1.5) kg/cm2 – maintain for a minute and decrease to 1.5 kg/cm2 – record the extensometer reading – compare with the previous reading – repeat this until the previous reading matches with the present reading. Then it is assumed that the concrete is fully dense and the internal voids are minimised. GARJE RAJESH KUMAR – CE255 CONCRETE TECHNOLOGY – MIX 24 DESIGN  LINEAR – STRESS IS PROPORTIONAL TO STRAIN STRAIN ELASTIC – SAME STRESS STRAIN CURVE DURING LOADING AND UNLOADING LINEAR – ELASTIC STRESS = P/A - ANALYSIS LINEAR – NON ELASTIC A = P/STRESS - DESIGN NON LINEAR – ELASTIC NORMAL CONCRETE – LESS STRENGTH NON LINEAR – NON ELASTIC GARJE RAJESH KUMAR – CE255 CONCRETE TECHNOLOGY – MIX 25 DESIGN Preference of HSC or NSC & other alternatives For Multi-storeyed building – HSC to reduce the size of the column HSC has limited ductility Ductility pays a major role in the event of earthquake Ductility saves many lives in the event of an earthquake Multistoryed buildings – HSC – size of columns will be limited – but ductility is compromised Multistoryed buildings – NSC – size of columns will be large – but have adequate ductility. Zones of high seismicity – use Fibre reinforced high strength concrete GARJE RAJESH KUMAR – CE255 CONCRETE TECHNOLOGY – MIX 26 DESIGN GARJE RAJESH KUMAR – CE255 CONCRETE TECHNOLOGY – MIX 27 DESIGN Testing by partial destruction – core samples This is preferred for constructed & finished structure/ road/bridge Sample is extracted by core cutting Sample is cylindrical shape of different H/D ratio Capping is done and tested in compression. Correction factor using Fig. 1 (Pg. No. 13) of IS 516-1959 Corrected cylinder strength is multiplied by 5/4 to equivalent cube strength H/D ratio of the core is 1.6 – Compressive strength for core is 22 MPa Corrected cylindrical strength = 0.95 x 22 = 20.9 MPa Equivalent cube strength = (5/4) 20.9 = 26.125 MPa. GARJE RAJESH KUMAR – CE255 CONCRETE TECHNOLOGY – MIX 28 DESIGN GARJE RAJESH KUMAR – CE255 CONCRETE TECHNOLOGY – MIX 29 DESIGN  ULTRASONIC PULSE VELOCITY TEST IS 516 (Part 5/Sec 1) 2018 Time in micro seconds & Distance in mm – Velocity in mm/ sec = km/sec Higher Velocity is obtained when the quality of concrete in terms of homogeneity, density and uniformity is good – Indirect measure of strength Lower Velocity means more voids, less density, honey combed concrete or existence of cracks Calibration curves for a particular type of aggregate and cement is to be established. Calibration curves are not universally valid GARJE RAJESH KUMAR – CE255 CONCRETE TECHNOLOGY – MIX 30 DESIGN GARJE RAJESH KUMAR – CE255 CONCRETE TECHNOLOGY – MIX 31 DESIGN GARJE RAJESH KUMAR – CE255 CONCRETE TECHNOLOGY – MIX 32 DESIGN