2019-04-03_REVISION - M1980244

• Permit No: M1980244
• IBM Index Class Name: REVISION
• Doc Date: 4/3/2019
• Doc Name: Adequacy Review Response
• From: CC&V
• To: DRMS
• Email Name: TC1
• Media Type: D
• Archive: No

Choosing the water/cement ratio 70 Fig 1.17
An appropriate w/c ratio will depend primarily upon E influence of the w/c
environmental exposure and the loads the concrete ratio on 28-day
p ? 60
construction will be carrying (Fig 1.17). r compressive
o, strength of
Recommended maximum w/c for different exposure C
E so concrete
conditions are given,for example, in the EN 206 or d
in ACI 318. 40
E
Minimum cement content in concrete 30
With sufficient cement in concrete, enough calcium
hydroxide is formed during hydration that the high 20
alkalinity and low porosity achieved in the concrete
io
will reliably protect the steel reinforcement from 0,3 0,4 0,5 0,6 0,7 0,8 0,9 1
rusting.On the other hand,overly large amounts of Water/cement ratio
cement in concrete increases the possibility of cracks normal application range(0,45-0,60)
due to shrinkage and increased heat of hydration. unusual applications
According to EN 206, reinforced concrete with a Fig 1.18
maximum aggregate size of 32mm should normally Poor filling of
void spaces,high
contain at least 300kg cement per m3 compacted permeability
concrete.The dosage may be reduced to 250 kg/m3 /� �� concrete with
only if the constructed element is permanently / only one size of
protected from environmental action and other aggregate
forms of attack. \ 1 (schematic)
TCXDVN 327:2004 - Concrete and Reinforced j
Concrete Structures Requirements of Protection
from Corrosion in Marine Environment requires:
Minimum cement
Fig 1.29
Good filling of
No direct contact 350 o void spaces,low
Q� ° ° permeability
Direct contact — 400 O o 0 o concrete with a
smooth grading
Table 1.3-Minimum cement content depend on curve(schematic)
environmental exposure(TCXDVN 327) o
1
°
The European standard EN206 increases the
minimum cement content to the environmental o �J
conditions(refer chapter IV.C)
Low porosity in concrete
A well-designed aggregate mix with a smooth
grading curve produces concrete with good
workability and high cohesion, with a high
resistance to segregation. The hardened concrete
will have low permeability, which gives it good
durability(Fig 1.18 and 1.19).