Effect of highly efficient substrate modifier, super-absorbent polymer, on the performance of the green roof

Mo Yang; Wenyi Dong; Ruirui Cheng; Hongjie Wang; Zilong Zhao; Feng Wang; Yaowu Wang

doi:10.1016/j.scitotenv.2021.150638

Effect of highly efficient substrate modifier, super-absorbent polymer, on the performance of the green roof

Sci Total Environ. 2022 Feb 1;806(Pt 2):150638. doi: 10.1016/j.scitotenv.2021.150638. Epub 2021 Sep 27.

Authors

Mo Yang¹, Wenyi Dong², Ruirui Cheng³, Hongjie Wang², Zilong Zhao⁴, Feng Wang⁵, Yaowu Wang¹

Affiliations

¹ School of Architecture, Harbin Institute of Technology Shenzhen, Shenzhen 518055, PR China.
² School of Civil and Environmental Engineering, Harbin Institute of Technology Shenzhen, Shenzhen 518055, PR China; Shenzhen Key Laboratory of Water Resource Utilization and Environmental Pollution Control, Shenzhen 518055, PR China; State Key Laboratory of Urban Water Resource and Environment, School of Environment, Harbin Institute of Technology, Harbin 150090, PR China.
³ Shenzhen Branch, Northwest Design Institute of China Municipal Engineering, Shenzhen 578055, PR China.
⁴ School of Civil and Environmental Engineering, Harbin Institute of Technology Shenzhen, Shenzhen 518055, PR China; Shenzhen Key Laboratory of Water Resource Utilization and Environmental Pollution Control, Shenzhen 518055, PR China; State Key Laboratory of Urban Water Resource and Environment, School of Environment, Harbin Institute of Technology, Harbin 150090, PR China. Electronic address: berthillon@hotmail.com.
⁵ School of Civil and Environmental Engineering, Harbin Institute of Technology Shenzhen, Shenzhen 518055, PR China.

PMID: 34592276
DOI: 10.1016/j.scitotenv.2021.150638

Abstract

Green roofs are commonly used in sponge city construction. However, the limitations of substrate thickness and strong sunlight have caused water retention to become the primary problem in the promotion of this technology. Super-absorbent polymer (SAP) is a material with excellent water absorption capacity that is expected to improve the substrate to solve the problem of the insufficient water storage capacity of green roofs. In this study, the basic performances of two types of SAPs, namely polyacrylate sylvite and acrylic acid-attapulgite hybrid (P-SAP and A-SAP, respectively), were evaluated on a bench-scale. The results showed that both SAPs had good water absorption, reusability, and fertilizer protection ability. These SAPs could maintain high water absorption within a certain range of salinity, pH, and temperature. Although water absorption of P-SAP was higher than that of A-SAP, the latter showed a significant advantage in substrate modification. After adding A-SAP (application rate: 0.6%, particle size: 12 mesh), the water storage capacity of the substrate was significantly improved, with an increase in the saturation moisture content of 23.8% and a decrease in the infiltration rate of 48.5%. A simulator of green roof was constructed with A-SAP under optimal conditions. The enhancement of the water retention capacity increased the drought resistance of the plants, which improved their growth; in particular, the fresh weight was 98% higher than that of the control group. A-SAP increased the rate of building up the lawn by 25%. The average soil moisture of the A-SAP group was 63.3%, which was 10.0% higher than that of the control group. An increase of more than 26% in the runoff control capacity was found in the green roof with A-SAP. Overall, our study indicates that A-SAP is a practical and efficient modifier for green roofs.

Keywords: Green roof; Plant growth; Runoff control; Substrate modifier; Super-absorbent polymer; Water retention.

MeSH terms

Conservation of Natural Resources*
Plants
Polymers
Rain*
Water Movements

Substances

Polymers