A

B

Fig.1.10. Basic characteristics of silica fume:

A – Particle shape and size; B – Grading curve

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1.7. Mixing water

Mixing water is an active component providing hardening of cement paste

and necessary workability of concrete mix.

Water with a hydrogen parameter рH in the range of 4 to 12.5 is

recommended for making concrete. High content of harmful compounds

(chloride and sulphate, silt or suspended particles) in water retards the

setting and hardening of cement.

Organic substances (sugar, industrial wastes, oils, etc.) can also reduce

the rate of hydration processes and concrete strength.

Magnetic and ultrasonic processing has an activating influence on

mixing water as shown by many researchers.

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A

B

Fig. 1.11. Structure of a molecule of water (A) and types of

hydrogen bonds (B)

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