M45 CONCRETE MIX DESIGN BY IS METHOD

A-1) Design stipulations

Characteristics compressive strength 28 days              : 45N/mm²

Target mean strength                                                       :f^’_ck = f_ck +1.65 s ( s= 5; from is 10262 table 1)

                                                                                               f^’_ck = 45+1.65 x 5 = 53.25N/mm²

maximum size of aggregates                                            : 20 mm

workability, slump                                                              : 50 to 75mm

Type of exposure                                                                : moderate

Aggregate surface condition                                            :all aggregates are in surface dried   

                                                                                                 condition                                                     

A-2) Test data for materials

Type of cement                                                                  :ACC 43 grade (OPC)

Specific gravity of cement                                                  :3.15

Specific gravity of admixture                                             :1.07

Specific gravity of coarse aggregates                               :2.54

Specific gravity of fine aggregates                                    :2.47

Table for densities of materials used

materials	Specific gravity	X 1000	Specific weight(kg/m3)
Water	1	1000	1000
Cement	3.155	1000	3155
Surface dried fine aggregates	2.47	1000	2470
Surface dried coarse aggregates	2.54	1000	2540
admixture	1.07	1000	1070

A-3) Selection of water/cement ratio

From is 456-2000 table 5 maximum W/C ratio =0.35

Based on trials adopted w/c ratio=0.34<0.35 hence ok

Hence selected W/C ratio is = 0.34

A-4)Estimation of mixing water

a)      Weight of water for 20 mm aggregates and slump 25-50 mm = 186 litre.

b)      Weight of water for 50-75 mm slump (increased by 3% for additional 25 mm slump as per is 10262 clause 4.2) = 191.58 litre.

Note: on adding  super plasticizer @ 0.9% water content reduces by 20%

Net water volume  =191.58X0.8=litre =153.26 litre

A-6) estimation of weight of cement

Wt. of cement=wt. of water/water cement ratio

Wt. of cement=153.26/0.34 =450.76kg/m³

Min. content as per is 456 for moderate exposure =360kg

450.76> 360kg hence ok

A-7) estimation of weight of admixture

weight of admixture @0.9% of weight of cement=0.9x 450.36/100 =4.05kg

volume of admixture(E)=wt. of admixture/specific weight

                                     =4.05/1070 = 0.00378 m³

A-8) calculating proportion of coarse and fine aggregates

From is-10262 table 3

Volume of coarse aggregates corresponding to 20mm size and fine aggregates zone 1=o.60

Volume of fine aggregates =(1-0.60)= 0.40

A-9) mix calculations

a)      Volume of concrete    =1m³

b)      volume of cement      =  (mass of cement/specific gravity)x(1/1000)

                                       = (450.76/3.155)x(1/1000) =0.1428 m³

c)       volume of water          =(mass of water/specific gravity)x(1/1000)

                                              = (153.36/1.00)x(1/1000) =0.153 m³

d)      volume of admixture = (mass of admixture/specific gravity)x(1/1000)

                                       =(4.05/1.07)x(1/1000)   =0.00378 m³

e)      Volume of all in aggregates=  {a-(b+c+d)}

1-(0. 1428+0.153+0.00378) =0.70042

f)        Weight o coarse aggregates  = 0.7057x0.63x specific gravity of coarse aggregates x 1000

                                                    =0.7004x0.60x2.54 x 1000 =1067.44 kg

g)       Weight of fine aggregates    = 0.7004 x0.40x 2.47 x 1000 =691.99kg

A-10) proportion ratio

Cement: coarse aggregates : fine aggregates = 1 : 1.53 : 2.36

A-11) Table of ingredients

Ingredients	Surface dried weights
cement	450.76 kg
Coarse aggregates	1067.44 kg
Fine aggregates	691.99 kg
water	153 litre.
Admixture	4.05 kg
Water cement ratio	0.34