The Influence of a Novel Hydrophobic Agent on the Internal Defect and Multi-Scale Pore Structure of Concrete

Abstract

In high humidity areas, it is necessary to improve the impermeability of concrete to water and other erosion solutions. The internal defect and pore channel of concrete are the main factors affecting the impermeability and durability. In this paper, a novel hydrophobic agent named Yellow River Engineering Consulting (YREC) was prepared. The relative internal defect degree of concrete with different curing ages and YREC contents was evaluated by ultrasonic non-destructive testing as qualitative characterization method, and the effect of YREC on hydration reaction was investigates using X-ray powder diffraction (XRD). Water permeability and contact angle tests were used to analyze the internal and external hydrophobicity induced by YREC addition, respectively. The pore structure changes of concrete mortar matrix induced by YREC were further discussed applying low-temperature liquid nitrogen adsorption (LT-NA) and mercury intrusion/extrusion porosimetry (MIP). The results indicated that YREC not only improves the impermeability of water, but also greatly enhances the mechanical strength. In the case of mixing YREC, the porosity of concrete mortar matrix decreases accompanied with the more advantage pores (micropores and transition pores) developed. Based on the relative internal defect degree and the changes of multi-scale pore structure, the functionality and durability of concrete with 4% YREC addition are the most desirable.

Influence of Old Concrete Age, Interface Roughness and Freeze-Thawing Attack on New-to-Old Concrete Structure

“…It could be seen that the splitting tensile strength of the new-to-old concrete with higher surface roughness was larger than that of specimens with lower surface roughness during the whole F-T cycles. After 60 times of F-T cycles, the specimens in group B lost most of the bonding force, and the splitting tensile strength The mechanical properties of concrete is mainly affected by internal defects, and the relative defect degree D R is characteristic parameter, which can be used to evaluate the strength [36,37]. The relationship considered the influence of surface roughness and old concrete age is further analyzed.…”

“…The relationship considered the influence of surface roughness and old concrete age is further analyzed. The results are shown in Figure 9, where loss rate of splitting tensile strength is defined as Equation (5) [36]:…”

Microstructure Formation of Cement Mortars Modified by Superabsorbent Polymers

“…Despite the fact that the principle of self-healing is relatively well understood and widely discussed in the scientific literature [ 16 , 32 , 33 ], several questions still remain unanswered. Regardless of many research papers aimed at the determination of water’s distribution in cement matrices at various ages [ 34 , 35 , 36 ], the understanding of the effects of SAPs characteristics on the functional properties of cement still has significant gaps. It is of great significance to avoid the undesired phenomena associated with SAPs’ utilization and, concurrently, to elucidate the role of SAPs’ formation of microstructures in cement mortars.…”