High Performance Composite Cementitious Materials And Products For Offshore Engineering

The increasing demands of modern civil engineering on building structures have promoted the in-depth study of composite cementitious materials and their products.In the marine environment,high-performance composite cementitious materials and related products with high strength levels,good impermeability and frost resistance,low shrinkage,corrosion resistance,and fast construction speed can better adapt to structural requirements and improve service life.In addition,the use of various industrial solid waste residues as admixtures can reduce the consumption of energy and resources and reduce environmental pollution.Therefore,the development prospect of marine high-performance composite cementing materials and their products is inestimable.This study is based on orthogonal experiment and other methods,combined with the test results,to evaluate the degree of influence of various factors on the performance of marine high-performance composite cement mortar and quick-repair mortar,select the appropriate raw material type and dosage,and optimize its mix design,and in-depth study the macro and micro analysis of the working performance,mechanical properties,durability and other macro properties of marine high-performance composite cement mortar and quick-repair mortar,According to the optimum mix ratio parameters,the marine engineering high-performance composite cement mortar and rapid repair mortar are prepared to meet the needs of engineering applications.The results show that: 1)The fluidity of high performance composite cement mortar increases with the increase of water cement ratio and water reducer content,and decreases with the increase of mineral admixture content;With the increase of water reducer,total mineral admixture and silica fume,the mechanical properties and volume stability evaluation index values of composite cement mortar,such as flexural strength,compressive strength,tensile strength,bond strength and dry shrinkage,increase first and then decrease.2)The durability of high performance composite cement mortar with40% mineral admixture and solid water reducer is the best.The number of freeze-thaw cycles can reach more than 200;Compared with ordinary cement mortar,56 chloride ion electric flux decreased by 58.9%,and the impermeability pressure increased by 2.4 times.3)In comprehensive consideration of the standard requirements of working performance,mechanical performance and durability,the solid water-reducing agent content is 0.95%,the water-binder ratio is 0.28,the total content of mineral admixture is 40%,and the proportion of three kinds of admixtures is fly ash: slag powder: silica fume=1:3:0.6 as the optimal composition of composite cement mortar.4)With the increase of the content of sodium aluminate early strength agent,the fluidity of rapid repair mortar gradually decreases;The early flexural strength,compressive strength,tensile strength,and bond strength all show a trend of first increasing and then decreasing with the increase of the amount of early strength agent,and all achieve the best effect when the amount of early strength agent is 1.0%.5)Sodium metaaluminate early strength agent can significantly improve the early mechanical properties and durability of high-performance rapid repair mortar,and its optimum content is 1.0%.6)Through microscopic analysis,sodium aluminate early strength agent can enhance the compactness of hydration products of composite cementitious materials and improve the mechanical properties,durability and other macroscopic properties of cement mortar.