Effects of an Applied Load on the Chloride Penetration of Concrete with Recycled Aggregates and Recycled Powder

Abstract

Recycled aggregate (RA) and recycled powder (RP) are the primary products of the reclamation of construction and demolition (C&D) wastes, and the question of how to use them to prepare recycled aggregate concrete (RAC) and recycled powder concrete (RPC) has been a hot topic in the construction industry in China. As concrete structures are frequently subjected to the effects of both applied loads and chloride attacks, it is necessary to examine their effects on both RAC and RPC, which have received little consideration in previous investigations. In this study, RAC and RPC were firstly prepared by using RA and RP, respectively, to replace natural coarse aggregate and cement by weight. For each type of recycled concrete, sustained load and repeated load tests were then conducted, followed by a chloride diffusion experiment after unloading. The results indicated that the chloride penetration increased with the loading degree as well as the repeated load cycles. As the RP used in this study has high fineness and activity, the chloride penetration of RPC was lower than that of natural concrete, while the opposite result was found in RAC. Besides, the correlation between the chloride diffusivity and the imposed loading damage was also established in this study.

Using Eco-Friendly Recycled Powder from CDW to Prepare Strain Hardening Cementitious Composites (SHCC) and Properties Determination

“…Attributed to the dilution effect and nucleation of RBP, the addition of RBP promotes the hydration reaction rate of cementitious materials. However, the RBP has higher SiO 2 content and lower CaO content than the cement, and thus, incorporating RBP leads to a reduction in the hydration products when using RBP to partially replace the cement in the paste, and a similar phenomenon is obtained by previous studies [41,42]. When the RBP replacement is 18%, there is no obvious difference for the micro-structure of Paste-0%RBP and Paste-18%RBP, and this may be because the micro-aggregate filling effect of RBP filled the pores and meanwhile the reduction of hydration products in cementitious materials is not obvious.…”

“…The incorporation of RP increases the content of SiO 2 in the paste, while the content of Ca(OH) 2 and CaCO 3 decreases with the addition of RBP. The Ca(OH) 2 and CaCO 3 are the main hydration products of cementitious materials; thus, incorporating RBP reduces the hydration products of cementitious materials [41,45]. Attributed to RBP containing higher SiO 2 content and lower CaO content compared with the cement, the addition of RBP increases the SiO 2 content when using the RBP to replace the cement by weight in the paste.…”

Experimental Study on Diffusion Process of Sulfate Ion in Cemented Gangue Backfill Material

“…Nicola et al used external sulfate to attack concrete structures under partially or fully saturated conditions and established a diffusion model to account for chemical and mechanical damage [15,16]. In order to calculate the chloride diffusion coefficient (D) in concrete, 3 factors (chloride concentration, curing, and environment temperature) were considered and used to predict concrete's life of service [17,18]. Wang et al used Fick's second law to calculate diffusion coefficient of chloride ion [19][20][21].…”

Durability Studies on the Recycled Aggregate Concrete in China over the Past Decade: A Review

“…With the rapid development of construction industry, large amounts of construction and demolition (C&D) wastes are being produced [1,2]. e disposal of such wastes at air storage or landfills inevitably produces some environmental problems (such as soil, water, and air pollution) because C&D wastes may contain some hazardous substances [3][4][5].…”