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Properties
Table 5: Properties of basic concretes at the fresh state
70%CAC+20%S
F+10%FA
Short Plug
(aggregate from the excavation)
60%OPC+40%SF 35%OPC+35%SF
+30%FA
Unit weight (t/m 3 ) 2.23 2.23 2.25 2.27
Slump (cm) 17 12 13 15
Cohesion Good Good Good Good
Aspect Good Good Good Good
Comp. Strength (MPa)
40
35
30
25
20
Basic concretes
15
70CAC/20SF/10FA sp
10
60OPC/40SF sp
5
0
35OPC/35SF/30FA sp
60OPC/40SF lp
0 20 40 60 80 100
Curing time (days)
283
Long Plug (conventionalaggregates)
60%OPC+40%SF
Figure 1: Evolution of compressive strength over curing time (sp: short plug; lp: long plug)
pH
12,2
12
11,8
11,6
11,4
11,2
11
10,8
10,6
Basic concretes
70CAC/20SF/10FA sp
60OPC/40SF sp
35OPC/35SF/30FA sp
60OPC/40SF lp
10,4
0 20 40 60 80 100
Curing time (days)
Figure 2: Evolution of pH vs. curing time. (sp: short plug; lp: long plug)
Other properties of the low-pH concrete
The hydraulic conductivity of the low-pH concrete was determined using granitic water from Äspö
in order to simulate the real conditions of an underground repository. The mean value obtained
from cored shotcrete samples was 1.03·10 -10 m/s, which is similar to that of the surrounding rock
(which is in the order of 1·10 -10 m/s) and this value does not increase with time [2]. Besides, the pH