Page 150 - Water Standards
P. 150
narrow topography.
4) Crane swinging concrete tanks should be employed for
gravity dams, and capacious sluices and dams in river
channels.
3 3 6 Concrete temperature controlling measures shall meet the fol⁃
lowing requirements:
1 In the cold season, the requirements of Article 2 7 23 in
this specification shall be complied with. In hot seasons, the require⁃
ments of Article 2 7 24 in this specification shall be complied with,
as well as that in this section.
2 In order to avoid cracking, comprehensive measures shall be
employed regarding structure design, temperature control, rough ma⁃
terials selection, construction plan and construction quality, etc.
Strict temperature control during construction shall be regarded as the
major measure to avoid concrete cracking. Both pouring temperature
and maximum temperature rise of concrete shall meet design require⁃
ments. Otherwise the concrete should not be poured.
3 The construction technology of concrete shall be modified to
improve concrete quality. The concrete shall meet the requirements for
strength guarantee rate, avoid overly surpassing design strength, and
meet the requirements for the construction quality homogeneity
indices. The homogeneity index is expressed as S , the value of the
fcu
standard deviation of the site specimen compressive strength after
curing 28 days. The value should be less than 0 18, and the calcula⁃
tion method is listed in Annex J. When the mix proportion of the con⁃
crete is selected, bleeding problems shall be solved properly, and
during construction, bleeding on bin surfaces shall be strictly con⁃
trolled. During construction crack treatment, all emulsion skin, oil
stains, poorly combined aggregates, and weak layers caused by
bleeding on bin surfaces shall be cleared away.
1 4 3