The reasons of the chalking on concrete pavement were discussed according to the project case. The effects of water to cementitious material ratios (W/C ratios), mineral powder contents and construction curing conditions on the concrete chalking were investigated. The technical measures were proposed to prevent or reduce chalking at the concrete surface. The results indicate that the major compositions of chalking material are mineral powder, quartz and part of hydration products of cement. The bleeding of concrete, which mainly caused by lower cement amount, higher surface water to cementitious material ratio and excessive vibration during the construction, is the main cause of concrete chalking. The concrete chalking can be prevented or reduced under the conditions of lower W/C ratios (<0.45), longer wet curing ages (at least 14 d) and good supervisions of construction.
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