ADMIXTURES to CONCRETE In modern days Concrete without an Admixture Is an exception.
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ADMIXTURES to CONCRETE In modern days Concrete without an Admixture Is an exception
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Transcript of ADMIXTURES to CONCRETE In modern days Concrete without an Admixture Is an exception.
ADMIXTURES to CONCRETE
In modern days
Concrete without an Admixture
Is an exception
Typical Results with Plasticizers
Test Cementkg/m3
DosageLit/50kg
W/C Slumpmm
UCS (N/mm2)7 days 28 days
Control 300 0 0.62 50 25.0 37.0
Workability
increase
300 0.14 0.62 100 26.0 38.0
Strength
increase
300 0.14 0.56 50 34.0 46.0
Cement saving
270 0.14 0.62 50 25.5 37.5
Superplasticiser
Effect of Retarding Superplasticizers at high temp.
Test Temp Concrete Slump (mm)
0-h 1-h 2-h 3-h 4-h 5-h
Control 20 127 89 76 57 38 32
+ Admixture 20 127 127 114 102 70 57
Control 43 114 57 7 - - -
+ Admixture 43 127 70 25 19 13 -
Effect of Accelerating Plasticizers at low Temp.
Temp Mix W/C UCS (N/mm2)
Slump = 25mm
Cement = 300 kg
1 Day 3 Day 7 Day 28 Day
20 CControl 0.65 - 3.6 12.8 26.1
Admixture 0.60 - 7.2 19.2 32.0
50 C
Control 0.65 - 5.4 16.7 30.9
Admixture 0.60 - 8.0 21.0 35.9
180 CControl 0.65 5.6 15.5 28.1 38.6
Admixture 0.60 7.9 19.2 32.9 41.6
• Pozollanic Admixtures
– Metakaolin
– Surkhi
– Fly-ash
• GGBFS
• Silica Fumes
MINERAL ADMIXTURES
Fly- ash
• Lower heat of hydration• Increased water tightness• Lower susceptibility to leaching• Low thermal shrinkage• Reduced alkali aggregate reaction• Improved resistance to sulphate attack• Improved workability• Lower cost
Influence of Fly ash content on strength of concrete
GGBFS
Obtained as a by-product in the making of steel
GGBFS AND PORTLAND CEMENT
• Denser Microstructure • Better long term strength • Slower heat development • Durability is better • Alkali-silica reaction eliminated • Lower slump loss
GGBFS
Silica Fume
A by product in the making of
Silicon / Ferrosilicon
from Carbon or Quartz in
Electric Arc Furnace
Compressive strength of concrete with different contents of Silica
Mix Proportion of Some High Performance Concretes
Ingredients Mix(kg / m3) A B C D EPortland Cement 534 315 513 163 228
Silica Fumes 40 36 43 54 46
Fly ash 59 - - - -
GGBFS - 137 - 325 182
Fine Aggregate 623 745 685 730 800
Coarse Aggregate 1069 1130 1080 1100 1110
Total water 139 150 139 136 138
Water/cementitious 0.22 0.31 0.25 0.25 0.30
Slump (mm) 255 - - 200 220
Strenth (Mpa)
1 day - - - 13 19
7 days - 67 91 72 62
28 days 115 83 119 114 105
90 days - 93 145 126 121
HYDRATION
Compressive strength of concrete
with different contents of GGBFS
