Abstract
New/old concrete interface is usually the weakest zone in repair of concrete substrate, wet-joint of precast elements and overlay of concrete bridge. In this study, superplasticizers with coupled functions of new/old concrete interfacial agent and water reducer were developed by using silane to modify polycarboxylate superplasticizer (PCE). With these highly reactive silane groups, this novel superplasticizer not only had a better water reduction efficiency and fluidity retention ability than commercial PCE, but also can establish a stronger interfacial bond between new and old concrete, i.e. by >35 % at 28 d age. The porosity of the new/old mortar interfacial transition zone at 28 d age was obviously reduced. Raman spectroscopy mapping showed that this novel superplasticizer with a smaller molecular weight can migrate into the old mortar well and the XPS results indicated that the superplasticizer migrated from the new mortar can react with the old mortar substrate. A moderate siloxane group content makes the new superplasticizer have a larger migrating amount, while the more siloxane groups in the new superplasticizer the higher reaction degree with the old mortar was found.
Published Version
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call