Page 154 - Water Standards
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be inspected and treated in time. If concrete strength or internal
                       quality is suspected, non⁃destructive testing methods such as rebound
                       apparatus and ultrasonic⁃rebound method or core drilling, water⁃pres⁃
                       sure tests, etc. may be employed for inspection.
                           12  For in⁃situ concrete quality inspection, priority shall be
                       given to compressive strength. Concrete specimens are mainly
                       randomly sampled at batching machine outlets, and three concrete
                       specimens of each group shall be sampled in the same storage hopper
                       or transportation cabin. The specimen tsampling quantity at the
                       pouring site should be 10% of that at batching machine outlets.
                           13  Specimens sampling quantity of same strength grade shall
                       meet the following requirements:
                             1) Compressive strength: for mass concrete, one group is
                                                                  3             3
                                 needed for the age of 28 days per 500m and per 1000m
                                 for design age; for no⁃mass concrete, one group is for the
                                                     3              3
                                 age of 28 days per 100m , and per 200m for design age.
                             2) Tensile strength: one group is for the age of 28 days per
                                      3               3
                                 2000m , and per 3000m for design age.
                             3) Frost resistance, anti⁃permeability or other main special
                                 requirements: proper sampling and inspection shall be
                                 carried out during construction, and the quantity shall be
                                 1⁃2 groups for main structures in each season.
                           14  Inspection and evaluation of concrete strength shall be im⁃
                       plemented according to Annex C of SL 176.
                           15    For built concrete structures, core drilling and water⁃
                       pressure tests shall be properly carried out. For mass concrete, core
                       drilling and water⁃pressure tesst may be carried out by drilling holes
                                                3
                       for 2-10m depth per 10000m , and the evaluation standards for the
                       actual drilling site, inspection items, water⁃pressure test sites and
                       water absorption shall be determined according to the actual situation
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