Concrete Mix Design – M 20 Grade Of Concrete
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1. REQUIREMENTS
a) Specified minimum strength = 20 N/Sq mm
b) Durability requirements
i) Exposure Moderate
ii) Minimum Cement Content = 300 Kgs/cum
c) Cement
(Refer Table No. 5 of IS:456-2000)
i) Make Chetak (Birla)
ii) Type OPC
iii) Grade 43
d) Workability
i) compacting factor = 0.7
e) Degree of quality control Good
2. TEST DATA FOR MATERIALS SUPPLIED
a) CEMENT
i) Specific gravity = 3.05
ii) Avg. comp. strength 7 days = 46.5 more than 33.0 OK
28 days = 55.0 more than 43.0 OK
b) COARSE AGGREGATE
i) 20mm Graded
Type Crushed stone aggregate
Specific gravity = 2.68
Water absorption = 1.46
Free (surface) moisture = 0
c) FINE AGGREGATE (Coarse sand)
i) Type Natural (Ghaggar)
Specific gravity = 2.6
Water absorption = 0.5
Free (surface) moisture = 1.4
3. TARGET MEAN STRENGTH (TMS)
a) Statistical constant K = 1.65
b) Standard deviation S = 4.6
Thus, TMS = 27.59 N/Sqmm
4. SELECTION OF W/C RATIO
a) As required for TMS = 0.5
b) As required for ‘Moderate’ Exposure = 0.55
Assume W/c ratio of 0.5
5. DETERMINATION OF WATER & SAND CONTENT
For W/C = 0.6
C.F. = 0.8
Max. Agg. Size of 20 mm
a) Water content = 186 Kg/cum
b) Sand as percentage of total aggregate by absolute volume = 35 %
Thus,
Net water content = 180.42 Kg/cum
Net sand percentage = 33 %
6. DETERMINATION OF CEMENT CONTENT
W/c ratio = 0.5
Water content = 180.42 Kg/cum
Thus, Cement content = 360.84 Kg/cum Adequate for moderate exposure Say 360 Kg/cum
7. DETERMINATION OF COARSE AND FINE AGGREGATE CONTENT
Assume entrapped air as 2 %
Thus,
0.98 cum = [180.42+360/3.05 + {1/0.33}*{fa/2.6}]/1000
& 0.98 cum = [180.42+360/3.05 + {1/0.67}*{Ca/2.68}]/1000
Hence,
fa = 584 Kg/cum
Ca = 1223.8 Kg/cum
The final mix proportions of M-20 grade of concrete become:-
Note: 1 The above recommended mix design must be verified, by actual cube tests.
2 The mix design is based on the quality and grading of the materials actually supplied, by the client.
Any variation in quality and gradation will result in changes in the mix design.
This mix design was submitted by a regular contributor to this site. We are thankful to him for his excellent service.
what is the exact difference between the RCC Girder and PSC Girder
the main difference btn RCC and PSc is,
In case of rcc we will cast the structure in site how ever we need it. but in case of psc part of the structure will cast sumwhere else and it will conducted to Pre stressing to act againest the structural moments and loads. Rcc is Cast in situ and Psc is Precast.
sir can we design M30 class concrete using cement grade 32.5
i would like to know how do i go about calculating material amounts and increments for a 15L trial mix, using the c&ci method, i would like some worked example,i hope to here from you soon.
sir,Is it possible to use 43 grade of opc for M30 grade of concrete.can u send the details related to Is code.
I would like to know that how calculate the materials/cum in rcc 1:2:4
Its called volumetric batching, just measure with a measuring box of size(0.3*0.3*0.38)mts. so that u can calculate the amount of material. 50 kg cement bag consists of 0.0342=(0.3*0.3*0.38) cu.mt.
so then 1cft box can fill how many bags or kg’s of cement….??
I would like to know cum to sqm and sqm to cum.
I would like to know that how calculate the materials/cum in M20 grade concrete
Dear Sir/Madam,
If i add plasticizers in M-20 grade of concrete. so how many calculate my w/c ratio.
please solve my miner confusion.
is there any method to stop oozing of water while earth excavation
how to do the rate analysis for 1 cmtr of brick masonry?
What is the cost of Sand per cu m in Hyderabad.
We need Mix Design M 80 Grade Details
Its called volumetric batching, just measure with a measuring box of size(0.3*0.3*0.38)mts. so that u can calculate the amount of material. 50 kg cement bag consists of 0.0342=(0.3*0.3*0.38) cu.mt.