1. 4.7.5 Non-dispersion Concrete in Water (NDC) Introduction Composites of NDC Properties of NDC

2. Introduction NDC is also called casting concrete in water. It is a new kind of concrete, cast in water and unlike ordinary concrete in which aggregate and cement paste will be separated if they react in water.

3. Instrument sketch map of connecting conduct construction Introduction Fig.4.7.9 Instrument sketch map of connecting conduct construction

4. Composites of NDC The main materials are cement, sand and stone, and some other admixtures (water reducing admixture) Cement: its strength grade is 42.5MPa at least. Aggregate Coarse aggregate. Preferably scree; Continous gradation Fine aggregate Preferably medium sand from Mx-=2.6 ～ 3.1 of fine modulus

5. (NDCA) NDCA is the key material in NDC, whose main composites are water soluble ion and material with high specific surface area, whose main functions are strengthening cohesion and packing ability Packing fine particles Other admixtures High efficiency water reducing, accelerator Composites of NDC

6.  Properties of fresh NDC  Good anti-dispersion  Good mobility and packing ability  Certain retardation ability  Properties of hardened NDC  NDC strength  Its quality and mixture quantity will influence the strength of NDC Properties of NDC

7. Influences on NDC compressive strength by C/W 、 NDCA are shown in Fig.4.7.10 and Fig.4.7.11. Fig.4.7.10 Influences on NDC compressive strength by C/W Fig.4.7.11. Influences on NDC compressive strength by NDCA

8. NDC permeability and resistance to impact are shown in Tab.4.7.7 Properties of NDC kinds of concrete permanent in 1.2MPa compression Weight/g ordinary concrete Total permeable within 5min 20679 NDC with NNDC- 2 Average permeable height of 12.7cm in 24h 60.0 Tab.4.7.7 NDC permeability and resistance to impact

9. Properties of NDC Frost resistance –NDC frost resistance is not as good as ordinary concrete Dry shrinkage and moisture expansion of NDC Compared with ordinary concrete. –NDC has good performance in water retentivity and bleeding. –Its dry shrinkage is larger than ordinary concrete but moisture expansion is smaller.