Page 145 - Water Standards
P. 145

10m. For special segments which the steel pipe buried for instance, if
                       the limitation is expected to be exceeded, heat preservation measures
                       shall be employed, such as laying mesh reinforcement on the top or
                       reinforcing heat preservation, etc. For construction in summer,
                       curing measures shall be continued until the the upper layer concrete
                       is poured.
                       3   3   3  Layout of the aggregate production system shall meet the fol⁃
                       lowing requirements:
                           1  The aggregate production system consists mainly of the borrow
                       area and the aggregate processing plant.
                             1) The necessary amount of aggregate materials shall be deter⁃
                                mined according to the amount of concrete and other uses,
                                and losses and disposal during quarrying, processing and
                                transportation.
                              2 ) Aggregate processing capacity may be determined
                                according to the monthly average amount of aggregate and
                                other uses during the peak pouring period.
                           2  The quality of aggregate materials shall comply with the re⁃
                       quirements of Articles 2   7   12 and 2   7   13 in this specification. The
                       use of alkali⁃reactive aggregates should be avoided. If tests of low⁃
                       alkali cement or admixtures with such as fly ash certify that no harmful
                       impact on the concrete, the alkali⁃reactive aggregates may be used.
                           3  Aggregate borrow area shall be chosen based on the principles
                       of high quality, low⁃cost, and local sourcing. If there is insufficient
                       qualified natural aggregate near the main works, the possibility and
                       rationality of quarrying and processing artificial aggregate nearby shall
                       be considered; ballast materials that meet quality requirements should
                       be utilized; cultivated land should not be used as borrow areas as less
                       as possible.
                           4  The principles for choosing an aggregate processing plant site
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