Effect of Methylene Blue （MB）-value of Manufactured Sand on the Durability of Concretes

• Published in: 武汉理工大学学报：材料科学英文版 2012, Vol.27 (6), p.1160-1164
• Main Author: WANG Jiliang NIU Kaimin TIAN Bo SUN liqun
• Format: Article
• Language: English
• Subjects: 亚甲基蓝; 抗压强度; 抗氯离子渗透; 机制砂; 氯离子渗透性; 混凝土耐久性; 石灰石粉; 高强度混凝土
• ISSN: 1000-2413; 1993-0437

The relation between the methylene blue （MB） value of MS and its limestone powder content and clay content was investigated. The effects of MB values ranging from 0.35 to 2.5 on the workability of fresh concrete, the mechanical properties, the resistance to freezing as well as the resistance to chlorine ion permeation of the hardened concrete were all investigated. The experimental results showed that the MB value had no correlation with the limestone powder content of MS, while it was directly related to the clay content. With an increase of MB value, concrete workability decreased, as did the flexural and 7-day compressive strengths, however, the 28-day compressive strength was not affected. Furthermore, influence of MB value on concretes of different strength levels was different. For low-strength concretes, an increase of MB value could improve its impermeability, but this was not the case for high-strength concretes. Instead, their resistance to chloride ion permeability decreased slightly. However, even a slight increase in MB value remarkably accelerated freeze-thaw damage of MS concrete. It was thus concluded that the critical MB value of 1.4 would not cause significant deterioration in the performance of MS concretes.