Synthesis Of Polymer-modified Fly Ash And Its Effects On Properties Of Cement Based Composite Materials

Cement based composite materials have the characteristics of high compressive strength, good durability, low price, so it is widely used in highway, railway, bridge, tunnel, construction and other fields, while at the same time they have the problem of brittleness. The polymer is usually used to solve the brittleness problem, but the physical mixing by increasing the molecular interactions has no much contribution to structure improvement of interface transition zone, besides, the compatibility between polymer and aggregate and cementitious materials is not good, this has largely hindered the flexural performance improvement of cement based composite materials. Fly ash is a kind of ideal concrete mineral admixture, in this study, we prepare polymer-modified fly ash by chemical means (grafting the highly hydrophilic polymer directly on the surface of fly ash), in this way we can improve the flexural strength of cement based composite materials.Specific methods and contents are as follows:(1) By alkali solution treatment, we can introduce hydroxyl groups on the surface of fly ash, then treat it with organic silane coupling agent KH-570, at last modified it with MPA (homemade), by using it we aim to improve the flexural strength of cement based composite.(2) By Piranha solution (20%H2O2,98%H2SO4) treatment, we can introduce hydroxyl groups on the surface of fly ash, then treat it with organic silane coupling agent KH-570, at last modified it with acrylamide, by using it we aim to improve the flexural strength of cement based composite.(3) By alkali solution treatment, we can introduce hydroxyl groups on the surface of fly ash, then treat it with organic silane coupling agent KH-566, at last modified it with acrylic acid, by using it we aim to improve the flexural strength of cement based composite.