Reactive Powder Concrete Essay

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Register to read the introduction… 0.01
0.3
4.2
1.0

88.9
0.6
4.3
1.2
0.1
0.5
< 0.1
0.1
0.3
0.05
n.d.
5.0

21.8
2.2
3.6
n.d.
0.2
0.4
0.9
2.1
65.4
n.d.
n.d.
4.4

2.2.2 Cement
Due to the very high cement factor, the choice of cement can be an important factor in the performance of RPC. Based on published practice, the ideal cement has a high C3S and C2S (di& tri-calcium silicate) content and very little C3A (tri-calcium aluminate). This is understandable because C3A has little intrinsic value as a binding agent and is primarily included in cement due to its role as a flux during the calcination process. Consequently, most
RPC made with commercially-available cement employs an ASTM Type V ‘sulfate-resistant’ blend, which is formulated specifically for low C3A content. Because this variety is not routinely manufactured in New Zealand, standard Golden Bay Type GP cement was substituted instead. As shown in Table 5, the C3A content of this cement is not excessively high, despite not being formulated specifically for sulfate resistance.
Table 5. Bogue composition of Portland cements
Cement

C3S

C2S

C3A

C4AF

ASTM Type V

40

40

4

10

Golden Bay GP

58

21

7

6

2.2.3 Quartz
…show more content…
Sensitivitiy of M ortar Flow to Superplasticiser Dosage
[Simcoa SF : 0.14 w/b]
150

140

ASTM C1437 Mortar Flow (%)

3.2

130

120

110

100

90
0.63%

Figure 9.

0.74%
0.84%
0.95%
Superplasticiser Dosage (% on cement)

1.61%

The effect of super-plasticiser dosage on RPC mortar flow

Similarly, within broad limits the super-plasticiser content has little affect on the ultimate compressive strength of the hardened RPC mixes as indicated by Figure 10, although there is some suggestion of a small peak in performance. As expected, increasing super-plasticiser dose severely retards the rate of initial hardening, with dosages in excess of 1% typically taking more than 24 hours to gain significant strength. Once initial set is achieved, strength gain is observed to be dramatic however.

18

Effect of Superplasticiser Dosage
[Simcoa SF : 0.14 w/b ratio]
1 day strength
200

ultimate strength

Compressive Strength (MPa)

150

100

50

0
0.63%

0.74%

0.84%

0.95%

1.61%

Superplasticiser Dosage (% on cement)

Figure 10. The effect of super-plasticiser dosage on RPC compressive strength

3.3

Influence of curing

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