Effects of silicon fume and latex on properties and hydration of modified mortars
Polybutadiene-graft-polystyrene (PB-g-PS) latex with a weight ratio of 50/50 was used to modify cement mortar. This study examines the effects of silicon fume content and the polymer-cement ratios (P/C) on the flow, compressive and flexural strength and water absorption rate of PB-g-PS latex modified cement mortar. The experimental results show that the flow of modified mortar is increased with increasing polymer-cement ratios, and it is decreased with increasing silicon fume content, PB-g-PS latex and suitable silicon fume content can markedly reduce capillary water absorption rate. PB-g-PS latex can marked influences much on the mechanical properties of modified mortars. The compressive of the polymer modified mortar decreased, and the flexural strength of a portion of polymer modified mortar increased. The suitble silicon fume can improve mechanical properties of modified mortats. The effect of PB-g-PS latex and silicon fume content on cement hydration was explored by XRD, the analysis results showed that the cement hydration was influenced by silicon fume content and P/C.
Mechanism of the Effect of Styrene-Butadiene Latex on the Water Absorption and Carbonization of Cement Mortar
The effect of styrene-butadiene latex(SBL) on the water absorption ratio and the carbonization depth of cement mortar were studied.The prediction models of water absorption ratio,carbonization depth correlating with many factors were proposed.The micro-pore parameters,included open porosity,close porosity and total porosity,pore size distribution and characteristic pore diameter of cement mortar modified by SBL were tested.The microstructure of cement mortar was studied by SEM.The results show that with the additive of SBL,the water absorption ratio and the carbonization depth of cement mortar decrease greatly.When the content of SBL exceed 3%(the ratio of total styrene-butadiene latex to cement),the pores with size below 20 nm increase markedly,while the pores with size exceed 50 nm decrease markedly.The mean pore diameter,mode pore diameter and median pore diameter decrease in large degree with the increasing of SBL.The open porosity decreases and the close porosity increases markedly,while the total porosity changes little with the content of SBL exceed 6%.
A Study on Technology Embedded English Classes Using QR Codes
The development of information and technology has brought plenty of changes to the educational environment. The prevalence of smart phones is particularly playing a huge role in shaping learning methods. Smart phones provide the opportunity to scan QR codes, which can greatly ease access to information. Due to a high recognition speed, recognition rate, and restoration rate, they can be useful tools for English teachers to use in their class. In this study, we suggest using QR codes for writing and picture descriptions. Based on this study, more research should invest in Technology Embedded English teaching models to create better English classes for students.