Underwater Concrete—Impact of Fine Particles in Cement …
135
Table 4 Test results for
concrete mixes [21]
Mix Flow diameter d
(cm)
Flow time t 500 (s) Washout (%)
M1
56
10
2.8
M2
48
–
1.6
A feature common for both chemical additives used, SP and AWA, is a presence of long polyoxyethylene chains in their structure, which decide of their mutual
compatibility.
5.2 Washout of Concrete Mixes
Results of testing for M1 and M2 concrete mixes are shown in Table 4. Concrete
mix M2 containing the addition of nanoparticles shows the lowest slump-flow and
clearly higher resistance to washout. Introduction of 0.5% of SiO 2 nanoparticles
causes reduction of washout by over 40%. Test results confirmed the relation found
in papers [9, 15], i.e. increased resistance to washout of the mix along with reduction
of its flowability.
Results of concrete mixes washout tests (M, MC20, MC50, MF50 and MF60) are
presented in Fig. 2. The highest washout is demonstrated by the mix (M) made of
CEM I cement equal to 2.7%. Addition of the slag reduces the washout significantly,
and the more fineness of the added slag and the higher it’s content, the higher washout
reduction is (Fig. 2).
Tests of particle distribution of blast furnace slag with various specific surface
areas demonstrated that the slag with larger surface area contains much more fine
particles than the cement. Analysis of fine particles content up to 20 µm is presented
in Table 2.
Addition of the slag (C) with a lower content of fine particles to the cement, in
the amount of 20% and 50% by mass slightly reduces the concrete mix washout
compared to the reference mix, by 0.5% and 0.7% percentage point respectively. A
Fig. 2 Washout of concrete mixes [22]
135
Table 4 Test results for
concrete mixes [21]
Mix Flow diameter d
(cm)
Flow time t 500 (s) Washout (%)
M1
56
10
2.8
M2
48
–
1.6
A feature common for both chemical additives used, SP and AWA, is a presence of long polyoxyethylene chains in their structure, which decide of their mutual
compatibility.
5.2 Washout of Concrete Mixes
Results of testing for M1 and M2 concrete mixes are shown in Table 4. Concrete
mix M2 containing the addition of nanoparticles shows the lowest slump-flow and
clearly higher resistance to washout. Introduction of 0.5% of SiO 2 nanoparticles
causes reduction of washout by over 40%. Test results confirmed the relation found
in papers [9, 15], i.e. increased resistance to washout of the mix along with reduction
of its flowability.
Results of concrete mixes washout tests (M, MC20, MC50, MF50 and MF60) are
presented in Fig. 2. The highest washout is demonstrated by the mix (M) made of
CEM I cement equal to 2.7%. Addition of the slag reduces the washout significantly,
and the more fineness of the added slag and the higher it’s content, the higher washout
reduction is (Fig. 2).
Tests of particle distribution of blast furnace slag with various specific surface
areas demonstrated that the slag with larger surface area contains much more fine
particles than the cement. Analysis of fine particles content up to 20 µm is presented
in Table 2.
Addition of the slag (C) with a lower content of fine particles to the cement, in
the amount of 20% and 50% by mass slightly reduces the concrete mix washout
compared to the reference mix, by 0.5% and 0.7% percentage point respectively. A
Fig. 2 Washout of concrete mixes [22]