Strength grade of cement W/C Strength formula of the concrete Factors of aggregate Curing condition Testing condition §4.4.6 Influencing factors

W/C When the types and strength of cement are the same, the concrete strength is determined by w/cWhen the types and strength of cement are the same, the concrete strength is determined by w/c When w/c in a certain range(concrete density) ， W/C ↓→ strength ↑When w/c in a certain range(concrete density) ， W/C ↓→ strength ↑ Excessively small w/c (concrete non-density), W/C↓→ voidage ↑ → strength ↓Excessively small w/c (concrete non-density), W/C↓→ voidage ↑ → strength ↓ I II Excessively small w/c W/C in a certain range W/C Strength W/C Strength

manual operation f 28 W/C mechanic vibration Fig Relationship between f 28 and W/C W/C Relationship between f 28 and W/C is illustrated in Fig.4.4.7

The water needed in normal hydration is 23% of the cement (W/C=0.23) However, in order to have the excellent mobility for the concrete composite,the water should be 40%~ 70% of the cement (W/C=0.4 ~ 0.7) The extra water leaves lots of pores in the concrete, thus reduces the actual loaded area Concentrates the stress Decreases the strength of the concrete W/C

Excluding air completely Lessening the mixing water Density Strength ﹢ The proper method to improve strength through W/C is that lessening the mixing water and excluding air completely at the time.

 The following constructions are used in the current project  velocity mixing  ultrasonic vibration  high frequent vibration  multi frequent vibration W/C