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Figure 16.9 Flexural strength of concrete prepared with NRCAs.
Figure 16.10 Image of one NRCA in new concrete.
Source: Reprinted from Xuan, D.X., Zhan, B.J., Poon, C.S., 2016a. Assessment of
mechanical properties of concrete incorporating carbonated recycled concrete aggregates.
Cem. Concr. Compos., 65, 67 74, with permission from Elsevier.
surface of the old mortar attached to the NRCA. Each reported value was from the
average of five measurements. For the old mortar and the new mortar, eight mea-
surements were made randomly on the cement paste in the mortar. The test load of
the Vickers tester was 10 g with a 10 s contact time.
The Vickers microhardness distributions on the new ITZs around the carbonated
and non-carbonated NRCAs are shown in Fig. 16.11. In addition, the Vickers
microhardness of NAs (as shown in Fig. 16.10) in the NRCAs measured was
704 6 98. In Fig. 16.11, the point at 0 μm means the microhardness of the cement
paste in the old mortar of the NRCAs. It can be noticed that the microhardness of
