Project on Concrete Mix Design for various grades of Concrete

  Mix design for M35 grade concrete with fly ash 

 Aim : Mix design for M 35 grade concrete with fly ash

INTRODUCTION:

Concrete mix design is the method of finding the precise proportion of cement, sand and aggregates for concrete to achieve the target strength in structures, therefore concrete mix design can be stated as concrete mix in terms of cement: sand: aggregates. The design is done according to the requirements of concrete strength. So, we can achieve the desirable properties of concrete either it is in fresh stage or in hardened stage. The fresh concrete properties like workability, setting time and hardened concrete properties like compressive strength, durability etc. are attained surely by this method. Use of additives like admixtures, retarders etc. other than basic ingredients are used to improve the properties of mix. This project consist of two parts, the first part deals with the design of M35 grade cement with fly ash as a part of it and second part is the design of M50 grade concrete without fly ash.

OBJECTIVE:

The objective of this project is to produce a mix design for M35 grade concrete containing fly ash and M50 grade concrete. The mix will be prepared as per IS METHOD: Concrete mix proportioning guidelines from IS 10262:2009 and recommented guide lines from IS 10262:1982.

 Procedure:

     Step :1

      Stipulations for proportioning

      a. Grade designation : M35

      b. Type of cement : OPC 43 grade conforming to IS 8112

      c. Type of mineral admixture: Fly ash confirming to IS 3812 ( Part 1)

      d. Maximum nominal size of aggregates : 20mm

      e. Minimum cement content : 320 kg/m^3 (Table :5 IS 456-2000,based on exposure condition)

      f. Maximum water-cement ratio : 0.45 (Table :5 IS 456-2000,based on exposure condition)

      g. Workability :100mm slump value of pumpable concrete

      h. Exposure condition : Severe ( for reinforced concrete)

      i. Method of concrete placing : Pumping 

      j. Degree of supervision : Good

     k. Type of aggregate: Crushed angular aggregate

     l. Maximum cement content : 450 kg/m^3.

     m. Chemical admixture type : Superplaticizer.

    Step :2

    Test data for materials       

     a.  Cement used : OPC 43 grade confirming to IS 8112

     b. Specific gravity of cement : 3.15

     c. Fly ash : Conforming to IS 3812 part 1

     d. Specific gravity of flyash : 2.2

     e. Chemical admixture : Superplaticizer conforming to IS 9103

     f. Specific gravity of :

           Coarse aggregate : 2.74

           Fine aggregate : 2.74

    g. Water absorption :

           Coarse aggregate : 0.5%

           Fine aggregate : 1%

    h. Free surface moisture 

           Coarse aggregate : Nil

           Fine aggregate : Nil

    i. Seive analysis 

            Coarse aggregates:   

IS seive size (mm)	Analysis of coarse aggregate fraction		% of different fraction			Remarks
	I	II	I	II	Combined
20	100	100	60	40	100	Confirming         to
10	0	71.2	0	28.5	28.5	Table 2
4.75		9.4		3.7	3.7	of
2.36		0				IS 383

      Fine aggregate : Conforming to grading Zone 1 of table 4 IS 383.

   Step :3

     To find target mean strength for mix proportioning

      Target mean strength f'ck = fck +1.65s

                                           = 35 +1.65*5 =43.25 Nmm2">Nmm2���2     

        fck- Characteristic compressive strength

        s- Standard deviation                

   Step:4

      Selection of water-cement ratio

      Maximum water-cement ratio =0.45 (for severe condition ,from table 5 of IS 456-2000)

      On experience water- cement ratio =0.4

        0.4 <0.45, Hence OK.

  Step :5

    Calculation of water content

   Maximum water content for 20mm aggregate  =186 litres ( Table 2 of IS 1026:2009) for 25mm to 50mm slump range

   For 100 mm slump ,= 186+(6/100)*186 =197 litres

   As superplaticizer is used, the water content is reduced upto 30%

   Based on trials water content reduction of 29% is achieved with plasticizer

   Hence arrived water content = 197*0.71 = 140 litres

  Step :6

   Calculation of cement content

    Water - cement ratio = 0.4

    Cementatious material ( Cement +flyash ) = 140/0.4 =350 kgm3">kgm3���3

    In table 5 of IS 456-2000,  the cement content for severe exposure =320 kgm3">kgm3���3

      350 kgm3">kgm3���3  > 320kgm3">kgm3���3  

   Hence OK.

 To proportion the mix containing flyash the following steps are suggested :

  a. The percentage of flyash need to be decided based on project requirement and qualityof materials.

  b. In some cases increase in cementatious materials can be warrned . Increase in cementatious material content and its percentage may be based on experience and trial

      In this increase of 10% cementatious material content is considered.

      Cementatious material content = 350*1.1 =385kgm3">kgm3���3

      Water content = 140kgm3">kgm3���3

      So, water- cement ratio = 140/385 =0.364

      Fly ash at 30% total cementatious material content = 35-30% =115kgm3">kgm3���3

      Cement (OPC) =385-115 =270kgm3">kgm3���3

      Saving of cement while using flyash = 350-270=80kgm3">kgm3���3

      Fly ash beign utilized = 115kgm3">kgm3���3

   Step: 7

    Proportion of volume of coarse aggregate and fine aggregate content

      From table 3 of IS 1026:2009 ,volume of coarse aggregate corresponding to 20 mm size aggregate and fine aggregate (Zone 1 ) for water- cement ratio =0.6

      In present case the water - cement ratio is 0.4

      Therefore the volume of coarse aggregate needs to be increased to decrease the fine aggregate content .

      As the water- cement ratio is lowered by 0.1 ,the proportion of volume of coarse aggregate is increased by 0.02( at the rate of +/- 0.01 for every +/- 0.05 change in water- cement ratio)

      Hence the corrected value ofcoarse aggregate for the water-cemnt ratio = 0.64

      ( If coarse aggregate is not of angular type, then also the volume of coarse aggregate may be required to be increased suitably ,based on experience)

     For pumpable concrete, these are reduced by 10 %

      Volume of coarse aggregate = 0.64*0.9 = 0.576

      Volume of fine aggregate = 1-0.576 =0.424

 Step :8

    Mix calculations

    Mix calculation per unit volume of concrete:

    a. Volume of concrete = 1 m^3.

    b. Volume of cement = (Mass of cement / Specific gravity of cement ) *1/1000

                                   = (270/3.15 )*1/1000  =0.086 m3">m3�3

    c. Volume of flyash = (Mass of flyash / Specific gravity of flyash )*1/1000

                                =  (115/2.2) *1/1000  = 0.052m3">m3�3

    d. Volume of water = ( Mass of water / Specific gravity of water)*1/1000

                                = (140/1)*1/1000 =0.140 m3">m3�3

    e. Volume of chemical admixture = ( Mass of admixture / specific gravity of admixture)*1/1000

                                                    =( 7.6/1.14)*1/1000  =0.006 m3">m3�3

   f. Volume of aggregate ( Fine and coarse)  = a- (b+c+d+e)

                                                                 = 1-(0.086+0.052+0.140+0.006) =0.716 m3">m3�3

  g. Mass of coarse aggregate = f* Volume of coarse aggregate * Specific gravity of coarse aggregate *1000

                                           = 0.716*0.576*2.74*1000  =1130kgm3">kgm3���3

  h. Mass of fine aggregate = f* Volume of fine aggregate* Specific gravity of fine aggreate*1000

                                       = 0.716*0.424*2.74*1000= 831kgm3">kgm3���3

  Step :9

   Mix proportion

      Cement = 270 kgm3">kgm3���3

      Fly ash = 115 kgm3">kgm3���3

      Water  = 140kgm3">kgm3���3

      Fine aggregate = 831 kgm3">kgm3���3

      Coarse aggregate = 1130 kgm3">kgm3���3

     Chemical admixture = 7kgm3">kgm3���3

      Water- cement ratio = 0.364

   Mix ratio  1: 2.15: 2.94

Step : 10

   The slump shall be measured and the water content and dosage of admixyure shall be adjusted for achieving the required slump on trial . The mix proportion shall be reworked for the actual water content and checkedd for durability requirements.

Step :11 

 Two or more trials having variation of 10 % of water-cement ratio in Clause 10( Step 10) shall be carried out and a graph between three water -cement ratios and corresponding strengths shall be plotted to work out the mix proportions for the given target strength for feild trials .However durability shall be met.

 Result : The mix design for M 35 grade of concrete with flyash is 1: 2.15:2.94

Aim : Mix Design for M50 grade concrete without Fly ash

INTRODUCTION:

Concrete mix design is the method of finding the precise proportion of cement, sand and aggregates for concrete to achieve the target strength in structures, therefore concrete mix design can be stated as concrete mix in terms of cement: sand: aggregates. The design is done according to the requirements of concrete strength. So, we can achieve the desirable properties of concrete either it is in fresh stage or in hardened stage. The fresh concrete properties like workability, setting time and hardened concrete properties like compressive strength, durability etc. are attained surely by this method. Use of additives like admixtures, retarders etc. other than basic ingredients are used to improve the properties of mix. This project consist of two parts, the first part deals with the design of M35 grade cement with fly ash as a part of it and second part is the design of M50 grade concrete without fly ash.

OBJECTIVE:

The objective of this project is to produce a mix design for M35 grade concrete containing fly ash and M50 grade concrete. The mix will be prepared as per IS METHOD: Concrete mix proportioning guidelines from IS 10262:2009 and recommented guide lines from IS 10262:1982.

M50 grade concrete without Fly ash
STEP 1: Stipulations for Concrete design mix
Grade designation	M50
Type of cement	OPC 53 Grade confirming to IS BIS 12269 - 1987
Maximum nominal size of aggregate	20 mm
Minimum cement content	320 kg/m3 (Table 5 of  IS 456:2000- Exposure condition)
Maximum water-cement ratio	0.45 (Table 5 of IS 456:2000 Exposure   condition)
Workability	100 mm (slump value for pumpable concrete)
Exposure condition	Severe (For Reinforced Concrete)
Method of concrete placing	Pumping
Degree of supervision	Good
Type of aggregate	Crushed Angular Aggregates
Maximum cement content	450 kg/m3
Chemical admixture type	Super Plasticizer
STEP 2: TEST DATA FOR MATERIALS
Cement used	OPC 53 Grade conforming IS 12269-1987
Specific gravity of cement	3.15
Chemical admixture	Super Plasticizer conforming to IS 9103
Specific gravity of coarse aggregate	2.74
Specific gravity of fine aggregate	2.64
Water absorption of coarse aggregate	0.5%
Water absorption of fine aggregate	1.0%
Free surface moisture of Coarse aggregate	Nil
Free surface moisture of  Coarse aggregate	Nil
Sieve analysis: Coarse aggregate	Conforming to Table 2 of IS 383
Sieve analysis: Fine aggregate	Conforming to Grading Zone II of Table 4 of IS 383
STEP 3: TARGET STRENGTH FOR MIX PROPORTIONING
f’ck =fck + 1.65s Where ·        f’ck = target average compressive strength at 28 days ·        fck = characteristics compressive strength at 28 days, and ·        s = standard deviation From Table I of IS 10262:2009, Standard Deviation, s = 5 N/mm2.	50 + 1.65 x 5 = 58.25 N/mm2
Target mean strength = 58.25 N/mm2
STEP 4: SELECTION OF WATER-CEMENT RATIO
The maximum water-cement ratio to design M50 grade concrete can be found from Table 5 of IS 456-2000 for severe exposure.	Maximum W/C ratio =0.45
Based on experience adopted water cement ratio is .44 0.44<0.45, hence ok
Adopted W/C ratio=0.44
STEP 5: SELECTION OF WATER CONTENT
From Table 2 of IS 10262:2009, maximum water content for 20 mm aggregate	186 litre (for 25 to 50 mm slump range)
Clause 4.2 suggests increasing of 3% of water content for every extra 25mm slump from 50mm slump. So a 6% is to be added to it Estimated water content for 100 mm slump	186+ (6/100)*186 = 197 litre.
(Note: If Super plasticizer is used, the water content can be reduced up to 20% and above.) Based on trials with Super plasticizer water content reduction of 20% has been achieved, Hence the arrived water content	197 X 0.8 = 158 litre
Water required 158 litres
EP 6: CALCULATION OF CEMENT REQUIRED
Adopted w/c Ratio	0.44
Cement Content	158/0.44 = 359 kg/m3
From Table 5 of IS 456, Minimum cement content for ‘Severe’ exposure conditions	320kg/m3
359 kg/m3 > 320 kg/m3 hence ok.
Cement required is  359 kg/m3
STEP 7: VOLUME OF COARSE AGGREGATE AND FINE AGGREGATE CONTENT
From Table 3 of (IS 10262:2009) Volume of coarse aggregate corresponding to 20 mm size aggregate and fine aggregate (Zone II) for water-cement ratio of 0.50 is	0.62.
In the present case water-cement ratio is 0.44. Therefore, volume of coarse aggregate is required to be increased to decrease the fine aggregate content. As the water-cement ratio is lower by 0.06. The proportion of volume of coarse aggregate is increased by 0.02 (at the rate of -/+ 0.01 for every ± 0.05 change in water-cement ratio).
Therefore, corrected proportion of volume of coarse aggregate for the water-cement ratio of 0.44	0.632
For pumpable concrete these values should be reduced up to 10%. Therefore, volume of coarse aggregate	0.632 x 0.9 =0.568.
Volume of fine aggregate content	1 – 0.576 =0.431
Volume of fine aggregate and coarse aggregate is 0.431 and .568 respectively
STEP 8: MIX CALCULATIONS
The mix calculations per unit volume of concrete shall be as follows:
a) Volume of concrete	1 m3
b) Volume of cement = [Mass of cement] / [Specific Gravity of Cement] x 1/1000	(359/3.15) X (1/1000) =0.114m3
c) Volume of water = [Mass of water] / [Specific Gravity of water] x 1/1000	(158/1) X (1/1000) = 0.158m3
d) Volume of chemical admixture = [Mass of admixture] / [Specific Gravity of admixture] x 1/1000	(7.6/1.145) X (1/1000) =0.006 m3
e) Volume of all in aggregate =  [a-(b+c+d)]	[1-(0.114+0.158+0.006)] = 0.722m3
f) Mass of coarse aggregate= e x Volume of Coarse Aggregate x Specific Gravity of Fine Aggregate x 1000	0.722x 0.568 x 2.74 x 1000 = 1123 kg/m3
g) Mass of fine aggregate= e x Volume of Fine Aggregate x Specific Gravity of Fine Aggregate x 1000	0.722x 0.431x 2.64 x 1000 = 821 kg/m3
STEP 9: MIX PROPORTIONS
Cement	359 kg/m3
Water	158 l/m3
Fine aggregate	821 kg/m3
Coarse aggregate 20mm	1123 kg/m3
Chemical admixture	7.18kg/m3
Water-cement ratio	0.44
Mix Proportion By weight	1:2.28:3.12
STEP 10: The slump shall be measured, the water content and dosage of admixture shall be adjusted for achieving the required slump on trial. The mix proportion shall be reworked for the actual water content and checked for durability requirements
STEP 11: Two more trials having variation of 10% of water-cement ratio shall be carried out and a graph between three water- cement ratios and corresponding strengths shall be plotted to work out the mix proportions for the given target for field trials.

RESULTS:

Mix Proportion by weight of M35 grade of concrete with fly ash is 1:2.08:2.72 and its water-cement ratio was found to be 0.4.

Mix Proportion by weight of M50 grade of concrete without fly ash is 1:2.28:3.12 and its water-cement ratio was found to be 0.44.