,
с
+
W
Where C is lime-sand binder content, kg/m3; W – quantity of
l
water, kg/m3.
188
Content of active calcium oxide in silicate concrete mixture varies depending on
required concrete strength taking into consideration fineness modulus of sand
(Tab.10.1, Fig.10.1, 10.2).
Table 10.1
Content of active СаО, % by mass of compacted silicate concrete mix
Strength of
Sand
concrete,
ultra fine
fine
medium
coarse
MPa
15 6.5 6.2 6 5.8
25
7.5
7.2
7
6.5
30 9 8.5 8 7.5
40
10.5
9.5
8.5
8
189
h, MPa
h, MPa
trengt
trengt
ssive s
ssive s
Compre
Compre
7.5 15.0 22.5 27.5
Content of sand, %
Content of active СаО in mass, %
Fig. 10.2. Relationship between silicate
Fig. 10.1. Effect of active СаО in the
concrete strength and sand content with
mixture on compressive strength of
specific surface:
lime-sand specimens:
1 - 4500 cm2/g; 2 - 2500 cm2/g;
1 – on the basis of quartz sand;
3 - 1500 cm2/g.
2 –on the basis of feldspar sand.
Content of active СаО in the mixture is
12.5%
190
10.2. Slag and fly-ash concrete
Concrete on the basis of lime-slag and lime-ash binders, gypsum-slag,
sulfate slag and slag non-clinker cements can be classified as such concrete.
Slag-alkaline concrete can be referred to a separate group.
Chemical activity of slag is defined by quality coefficient К, calculated
according to following formulas:
- at magnesium oxide (MgO) content up to 10%
CaO + Al O + MgO
К
2
3
=
(10.3)