Artificial Sand Modified By Polymer And Applied In The Concrete

Since the increasing depletion of river sand and the exploration restrictions, the artificial sand(AS) can be an economic alternative to river sand inconcrete. The artificial sand is an ideal fine aggregate of concrete, however, it is coarser which will weaken the fluidity of the cement-based composites and increase water demand, lead the concrete exhibits large autogenous shrinkage and brittle fractures. The surface modification of inorganic particles by chemically bound polymers has been expanded rapidly. Here in, the artificial sand was modified with polymer, to weaken the influence of the artificial sand on fluidity, to improve flexural strength and workability. The AS particles and water-soluble polymers were linked together through strong chemical bonds, and the water-soluble polymers and concrete paste has a good compatibility. The main investigations are as follows:(1)The surface of the machine-made sands were hydroxylated by a Piranha solution method, and then modified with 3-(methacryloxypropyl) trimethoxy silane (KH-570) obtain target products (AS-MPS). The structure of modified artificial sand particles was characterized by fourier transform infrared spectra (FT-IR), thermogravimetric (TG), X-ray pHotoelectron spectrum(XPS), X-ray diffraction (XRD). The results show that, KH-570 modified the artificial sands were successfully prepared.(2)After reacted with 3-methacryloxypropyltrimethoxysilane, grafted with poly (acrylic acid) and poly (Allyl poly (ethylene glycols)), artificial sand turn into the new artificial sand particles(AS-MPS-PS). Transform infrared spectra (FT-IR), thermogravimetric analysis (TGA), Gel Permeation ChromatograpHy (GPC), and scanning electron microscopy (SEM) were used to characterize the structure, morpHology, and other properties of the products. The workability and pHysical properties of modified artificial sand particles were characterized by cement paste and concrete. The results revealed that the surface-modified artificial sand microfines can significantly improve the workability of cement paste and mortar. The strength experiment of concrete shows that with the increment of the modified-AS from 0% to 100% by mass, the compressive and flexural strengths increase.(3) Sucrose acry late was synthesized by esterification reaction of Sucrose with acrylic acid (AA), finally polymerized with acrylic acid on the surface of AS-MPS to obtain target products. Transform infrared spectra (FT-IR), thermogravimetric analysis (TGA), Gel Permeation ChromatograpHy (GPC), and scanning electron microscopy (SEM) were used to characterize the structure, morpHology, and other properties of the products. The workability and pHysical properties of modified artificial sand particles were characterized by cement paste and concrete. The results revealed that the polymerized Sucrose acrylate chains grafted on AS microfines have a greater effect on the dispersion retention ability? and the compressive and flexural strengths increase.