Shui Zhang

Effect of the Chemical Treated Kevlar Fiber on the Behaviors of Cement Mortars

This work aims to evaluate the effect of Kevlar fibers with chemical treatment on the flexural strength, compressive strength and impact resistance of cement mortar. The experimental results exhibit that Kevlar fiber with a larger percentage can increase the flexural strength and improve the impact resistance of cement mortar, and the reinforcement effect of Kevlar fiber with chemical treatment is more obvious. The surface morphology of Kevlar fiber and the fracture surface of cement mortar reinforced with Kevlar fiber were observed by SEM, and the reinforcement mechanism of the Kevlar fiber on cement mortar was discussed.

Preparation and Properties of Cement Mortar Modified by VAE Latex

The effect of VAE latex modification on the physical properties of cement mortar is investigated. The porosity problem in cement mortar modified by vinyl acetate ester-ethylene (VAE) copolymer emulsion was successfully resolved by reasonable defoaming technique. It is shown that the bond strength and water resistance properties of modified cement mortar are better than unmodified cement mortar. When polymer-cement ratios ranged from 0 to 0.25, the bond strength and anti-permeability increased first and then decreased. The best value appeared at 0.1(polymer-cement ratio). SEM shows that the modified sample has compacted structure, polymeric films wrap the cement body and fill in the gap between cement and sand to improve the interfacial bond.

Properties of the Mortar Modified with the Styrene-Acrylic Emulsion

Styrene-acrylic emulsion was selected to modify the cement mortar which was prepared as the crack mending material for the concrete pavement. The results indicated when the percentage of the styrene-acrylic emulsion was from 15% to 20%, the flexural strength and the bent bond strength increased by 39.00%~48.23% and 45.01%~49.60% respectively at 28 days, compared to the reference mortar. The morphology of the cement mortar modified with styrene-acrylic emulsion was observed by SEM. The modification mechanism of the styrene-acrylic emulsion to the mortar was discussed.

Study on Preparation and Properties of Cement-Based Foamed Lightweight Thermal Insulation Material

A cement-based foamed lightweight thermal insulation material was prepared with cement, industrial waste (fly ash, steel slag) as the main raw materials, by using self-developed composite activator and foaming agent. The influence of foam content on dry density, compressive strength and thermal conductivity coefficient of material was studied, the activation mechanism of composite activator to fly ash and steel slag was discussed. Results showed that, the dry density and compressive strength of material decreased, and thermal conductivity coefficient decreased first and then increased with the increasing foam content.

Performance Properties of Polymer Modified Cement Grouts for Repair and Rehabilitation of Concrete Pavement

This study was conducted to evaluate the groutability and interfacial bond strength of polymer modified cement grouts (PMCG) for repair and rehabilitation of concrete pavement with different polymer/cement ratio. The groutability of grouts was studied through the cone-shaped gap test and the grouted minimum gap width was determined. The interfacial bond strength, such as flexural and shear bond strength were measured. The experimental results indicate that the groutability of grouts modified by vinyl acetate/ethylene copolymer (EVA) improves obviously and the grouted minimum gap width decreases. The flexural and shear bond strength increase 32.41% and 122.92% when the polymer/cement ratio is 10%, at the ages of 28 days respectively. The microstructure of repair interface was observed and analyzed by using scanning electron microscope, and the modification mechanism of EVA latex was discussed.

Modification of Polypropylene Fibers by Acrylic Acid and its Influence on the Mechanical Property of Cement Mortar

The surface of the PP fibers were modified by acrylic acid and grafted by suspension in water medium. The effect of modified PP fibers on mechanical properties of cement mortar was studied. The microstructure of fibers surface, the active functional groups of fibers and the profile of cracked samples were analyzed by SEM and IR. The results show that, crylic acid was grafted on surface of PP fibers after modification; the flexural strength of cement mortar reinforced by modified PP fibers improved markedly, compared with cement mortar reinforced by ordinary PP fibers.

Orthogonal Experimental Study on Properties of Hybrid Fiber Reinforced Cement Mortar

By adopting the method of orthogonal experimental design, the effect of three independent variables, that is steel fiber fraction, polypropylene fiber fraction and silica fume fraction on the compressive strength, flexural strength and shrinkage of cement mortar was studied. The results indicate that steel fiber is one of the most important factors affecting compressive strength and shrinkage, and polypropylene fiber is one of the most important factors affecting flexural strength and shrinkage of cement mortar. By using deviation analysis to analyze the orthogonal experiment results, the optimized mix proportion of hybrid fiber reinforced cement mortar is determined. The hybrid effect of steel fiber and polypropylene fiber on the properties of cement mortar is discussed.