Open Access

ARTICLE

Study on the Durability of Recycled Powder Concrete against Sulfate Attack under Partial Immersion Condition

by Hualei Bai^1,2, Ying Li^1,2,*, Dahu Dai^1,2

1 School of Civil Engineering, Qinghai University, Xining, 810016, China
2 Qinghai Provincial Key Laboratory of Energy Saving Building Materials and Engineering Safety, Xining, 810016, China

* Corresponding Author: Ying Li. Email:

(This article belongs to the Special Issue: Recycled Concrete Towards a Sustainable Society)

Journal of Renewable Materials 2022, 10(11), 3059-3078. https://doi.org/10.32604/jrm.2022.020148

Received 06 November 2021; Accepted 24 January 2022; Issue published 29 June 2022

Abstract

In order to make full use of waste recycled fine powder (RFP) in concrete and achieve the goal of carbon neutrality in the concrete industry, the durability of sulfate resistance is an important aspect of evaluating the performance of recycled powder concrete (RPC). Therefore, the durability of RPC under partial sulfate immersion was studied to provide theoretical guidance for understanding the erosion mechanism of RPC. The compressive strength, mass loss, and microstructure change patterns of RPC under partial immersion of 5% Na₂SO₄ and MgSO₄ solutions were analyzed by cubic compressive strength, mass loss rate, SEM-EDS, and XRD. The results showed that the surface crystalline matter of concrete in Na₂SO₄ solution was mainly white powders, and that of concrete in MgSO₄ solution was mainly transparent paste, both of which had a little spalling on the outer surface of the concrete. The compressive strength and mass loss rate of concrete with 20% RFP was relatively good, indicating that concrete with 20% RFP had better durability against sulfate. The compressive strength of the lower part of the concrete partially immersed in Na₂SO₄ solution was higher than that of the upper part and the strength of the lower part of RPC-2 was 3.11% higher than the upper part at 180 d; The pattern was reversed in the MgSO₄ solution, where the strength of the lower part of RPC-2 was 19.74% lower than the upper part at 180 d. Microscopic analysis showed that the hydration products of RPC were mainly gypsum and ettringite, while the RPC produced more hydration products with the promotion of magnesium ion in the MgSO₄ solution. The higher the replacement rate of RFP, the more frequent the gypsum-type failures in the concrete.

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