Research On Carbonation Curing And The Leachate PH Value Testing Methods Of Self-compacting Concrete For Marine Artificial Reef

Concrete for marine artificial reef can meet the requirements of manufacturing technology,structural mechanical properties,and durability of marine artificial reef,which is suitable for the attachment and growth of marine organisms and beneficial to the ecological environment.At present,the concrete for marine artificial reef has the following problems:(1)Because of the concrete for marine artificial reef low working performance,this will not be conducive to the construction of marine artificial reef with complex ecological spatial structure.(2)Because the pore solution of concrete for marine artificial reef with ordinary Portland cement as cementitious material has a pH value of 12-13 and is strongly alkaline,this will affect the surface leachate pH value,and then affect its biological adhesion(3)At present,the test method of pH value of surface leaching solution of concrete for marine artificial reef is not suitable for on-site test.In view of the existing problems of concrete for marine artificial reef,the carbonation curing system of self-compacting concrete for marine artificial reef and the testing method of surface leachate pH value are studied in this paper.The main contents of this paper are as follows:(1)On the basis of the mix proportion of ordinary concrete for marine artificial reef,the self-compacting concrete for marine artificial reef with water-binder ratio of 0.4,0.5 and0.6 was prepared and its working performance indexes and surface leachate pH value were measured(2)The self-compacting concrete for marine artificial reef was cured under the carbonation curing system,and the effect of carbonation curing system on the surface leachate pH value was compared and analyzed.(3)Under the carbonation curing system,the surface leachate pH value of self-compacting concrete for marine artificial reef was determined by the test method of surface static water leachate pH value,surface dynamic water leachate pH value,prefabricated surface static water leachate pH value and prefabricated surface dynamic water leachate pH value.The surface leachate pH value was compared and analyzed to determine the optimal test method of the surface leachate pH value.The main conclusions are as follows:(1)Self-compacting concrete for marine artificial reef with water binder ratios of 0.4,0.5and 0.6 meets the requirements of corresponding performance technical indexes.Under the standard curing system(14d standard curing system and 28 d standard curing system),the surface leachate pH value of the self-compacting concrete for marine artificial reef with the same water-binder ratio is higher than that of the ordinary concrete for marine artificial reef.It may be because the actual amount of cement per unit volume of self-compacting concrete for marine artificial reef with the same water-binder ratio is larger,which will lead to more alkaline substances in pore solution during hydration reaction of cement,resulting in high pH of surface leachate.(2)In view of surface leachate pH value,compared with carbonation system(14d carbonation curing and 28 d half carbonation curing)and standard curing system(14d standard curing and 28 d standard curing).The result of the prefabricated hole surface dynamic leachate pH value showed that,compared with 14 d standard curing system,under 14 d carbonation curing system,self-compacting concrete with the same water-binder ratio for marine artificial reef surface leachate pH value decreased 8%,16% and 28%.(3)Under the carbonation curing system,In view of four surface leachate pH value test methods.Compared with surface static leachate pH value test method and surface dynamic leachate pH value test method,under 14 d carbonation curing system and 28 d half carbonation curing system,prefabricated hole surface static leachate pH value test method and prefabricated hole surface leachate dynamic pH value test method can clearly distinguish self-compacting concrete with the water-binder ratio of 0.4,0.5 and 0.6 for marine artificial reef surface leachate pH value.Compared with prefabricated hole surface leachate static pH value test method,the surface leachate pH value determined by prefabricated hole surface dynamic leachate pH value test method was more consistent with the reality.