Issue 50

M. Papachristoforou et alii, Frattura ed Integrità Strutturale, 50 (2019) 526-536; DOI: 10.3221/IGF-ESIS.50.44

Results of the measurements of restrained shrinkage according to ASTM C1581 are given in Figs.(10,11). Mixtures with FA showed the best results since they lasted longer before crack formation occurs. For 830 kg/m³ binder, the mixture with FA cracked after 7.64 days while the mixture with no SCMs only after 4.88 days. Mixtures with LFS had again better performance compared to one with no SCMs as binder, but not as good as FA based mixtures. Use of LF as aggregate improves the time at cracking compared to mixtures with no LF. Similar results were obtained from the stress rate calculation. Mixtures with no SCMs induced higher stress to the ring compared to the other mixtures.

70.2 0 10 20 30 40 50 60 70 80 Cement/LF Cement/FA/LF Cement/FA Cement/LFS/LF Cement/LFS 830 kg/m3 500 kg/m3 Compressive strength (MPa) Figure 7 : Compressive strength of mixtures with different binder content and materials used. 54.13 61.3 55.66 57.16 47.97 32.95 33.06 31.86 38.06

10 12 14

12.16

830 kg/m3 500 kg/m3

9.71

8.83

8.81

8.72

8.32

7.2

0 2 4 6 8

6.92

6.67

6.62

Flexural strength (MPa)

Cement/LF Cement/FA/LF Cement/FA Cement/LFS/LF Cement/LFS Figure 8 : Flexural strength of mixtures with different binder content and materials used.

90

y = 0.0577x - 199.55

60

30

0

Compressive strength (MPa)

3750

4000

4250

4500

4750

UPV (m/s)

Figure 9 : Ultrasonic Pulse Velocity versus compressive strength of mixtures.

533