Monitoring the Whole Cycle Length Change of Cement Mortar Incorporated with SRA by CMOS Image Sensor

Abstract

This paper introduces a new method to measure whole cycle length change non-destructively and continuously using a digital image analysis system. The macroscale length changes of mortars containing different shrinkage-reducing admixture (SRA) dosages (0%, 1%, 2% and 5% by cement weight) were first determined using a complementary metal oxide semiconductor (CMOS) image sensor under alternating dry and wet curing conditions. After that, the length change was calculated using developed digital image processing technology (DIPT) software. After that, several significant conclusions could be drawn by combining with the results of systematic tests of the macroscopic and microscale physical properties of the cement mortar using X-ray diffraction, scanning electron microscopy, mercury intrusion porosimetry (MIP) and nuclear magnetic resonance (NMR) methods. The test results indicated that SRAs exhibited significant effects on the shrinkage inhibition of cement mortars, whereas the shrinkage reduction behaviour was also affected by varying the curing conditions. The MIP and NMR analyses demonstrated that SRAs reduced the irreversible shrinkage of the cement mortars by decreasing the volume percentage of the 3–50 nm pores and promoting the conversion of calcium silicate hydrate gel from an oligomeric to a high polymerization state thereby improving the volume stability of cement mortars.

Properties and Performance of Novel Mg(OH)2-Based Coatings for Corrosion Mitigation in Concrete Sewer Pipes

“…However, the adhesion of the respective coatings onto the concrete surface is a crucial property that also needs to be examined carefully. There are many factors that can be studied, in order to evaluate the performance of coatings and the protection of the concrete’s surface against corrosion/degradation problems, such as the adhesion ability [ 22 ], the thickness change [ 23 ], the surface characteristics [ 13 ], the concrete properties [ 24 ], the mass change [ 25 ], etc. In this study the factors selected to be examined are the adhesion properties of the coating, the water and acid resistance, the mineralogical changes, the change in roughness and hardness of the concrete substrate after acid spraying, and the surface characteristics of the coatings.…”