Process technology of polymethyl methacrylate mortars and concretes for underwater construction work

This thesis is concerned with recently developed new application techniques of polymethyl methacrylate (PMMA) mortars and concretes for underwater placement and bonding in Japan.; Using PMMA mortars and concretes being placed and bonded underwater, the strength and adhesion properties of these materials were examined from an underwater construction point of view. Specifically the following process technologies of PMMA mortars and concretes were investigated and studied: (1) binder formulations and mix proportions, (2) techniques for improving underwater strength and adhesion properties using white carbon and coupling agents, (3) effects of artificial seawater on strength and adhesion properties, (4) underwater adhesion to cement mortar and concrete substrates using newly developed cement paste primers, (5) effects of water temperature in underwater placing or bonding and curing processes on the strength and adhesion properties, (6) comparison of underwater strength and adhesion properties of PMMA mortar developed for this study with other commercial polymer mortars and (7) bond strength of PMMA concretes to the reinforcing steel (rebars) embedded underwater in consideration of the application of PMMA concretes to the polymer concrete structures reinforced with high-strength rebars or the repair work for deteriorated reinforced concrete structures.; It was concluded that newly developed process technologies of PMMA mortars and concretes give them a high potential to be dominant materials for future underwater construction work. The study shows the outstanding advantages of these materials in comparison to conventional underwater concretes using portland cement and water-soluble polymers. The advantages are that they are completely resistant to segregation and washout, have ease of compaction and show high-early-strength development.