A Study on the Pore and Strength Characteristics of an Eco-Friendly Sprayed Ultra High Performance Concrete with Manufactured Sand

Conventional shotcrete systems face critical limitations in adverse geological environments, including a delayed strength development (<5 MPa at 3 h), excessive rebounds (15–25%), and permeable macropore networks (>50 μm), often resulting in support failure for deeply buried tunnels. To addres...

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Main Authors: Zhonghao Wang, Xianjun Tan, Jingqiang Yuan, Chongge Wang, Yubiao Liu
Format: Article
Language:English
Published: MDPI AG 2025-03-01
Series:Applied Sciences
Subjects:
Online Access:https://www.mdpi.com/2076-3417/15/7/3776
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author Zhonghao Wang
Xianjun Tan
Jingqiang Yuan
Chongge Wang
Yubiao Liu
author_facet Zhonghao Wang
Xianjun Tan
Jingqiang Yuan
Chongge Wang
Yubiao Liu
author_sort Zhonghao Wang
collection DOAJ
description Conventional shotcrete systems face critical limitations in adverse geological environments, including a delayed strength development (<5 MPa at 3 h), excessive rebounds (15–25%), and permeable macropore networks (>50 μm), often resulting in support failure for deeply buried tunnels. To address these challenges, this study systematically investigates the mechanical properties and pore characteristics of a manufactured sand-based sprayed UHPC at different spraying positions under simulated tunnel conditions. Our results demonstrate that the high-pressure air (0.8 MPa) driven spraying process optimizes its pore distribution, reducing large pores (>10 μm) and increasing harmless pores (<100 nm). Furthermore, the sprayed UHPC incorporating manufactured sand derived from tunnel slag not only maintains a 28-day compressive strength of 110.9 MPa but also reduces material costs and enhances sustainability. Field tests validate its low rebound rate (<5%) and rapid strength development (achieving a compressive strength of 30 MPa within 1 day), confirming its adaptability to complex geological conditions such as high-stress zones, thereby providing a novel method for support in complex geological conditions.
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spelling doaj-art-0f29b65b4c6a40c880fe3f5d221fa5cf2025-08-20T03:06:32ZengMDPI AGApplied Sciences2076-34172025-03-01157377610.3390/app15073776A Study on the Pore and Strength Characteristics of an Eco-Friendly Sprayed Ultra High Performance Concrete with Manufactured SandZhonghao Wang0Xianjun Tan1Jingqiang Yuan2Chongge Wang3Yubiao Liu4College of Civil Engineering and Architecture, Shandong University of Science and Technology, Qingdao 266590, ChinaState Key Laboratory of Geomechanics and Geotechnical Engineering, Institute of Rock and Soil Mechanics, Chinese Academy of Sciences, Wuhan 430071, ChinaState Key Laboratory of Geomechanics and Geotechnical Engineering, Institute of Rock and Soil Mechanics, Chinese Academy of Sciences, Wuhan 430071, ChinaCollege of Civil Engineering and Architecture, Shandong University of Science and Technology, Qingdao 266590, ChinaState Key Laboratory of Geomechanics and Geotechnical Engineering, Institute of Rock and Soil Mechanics, Chinese Academy of Sciences, Wuhan 430071, ChinaConventional shotcrete systems face critical limitations in adverse geological environments, including a delayed strength development (<5 MPa at 3 h), excessive rebounds (15–25%), and permeable macropore networks (>50 μm), often resulting in support failure for deeply buried tunnels. To address these challenges, this study systematically investigates the mechanical properties and pore characteristics of a manufactured sand-based sprayed UHPC at different spraying positions under simulated tunnel conditions. Our results demonstrate that the high-pressure air (0.8 MPa) driven spraying process optimizes its pore distribution, reducing large pores (>10 μm) and increasing harmless pores (<100 nm). Furthermore, the sprayed UHPC incorporating manufactured sand derived from tunnel slag not only maintains a 28-day compressive strength of 110.9 MPa but also reduces material costs and enhances sustainability. Field tests validate its low rebound rate (<5%) and rapid strength development (achieving a compressive strength of 30 MPa within 1 day), confirming its adaptability to complex geological conditions such as high-stress zones, thereby providing a novel method for support in complex geological conditions.https://www.mdpi.com/2076-3417/15/7/3776sprayed UHPCmechanical propertiespore distributionmicrostructure
spellingShingle Zhonghao Wang
Xianjun Tan
Jingqiang Yuan
Chongge Wang
Yubiao Liu
A Study on the Pore and Strength Characteristics of an Eco-Friendly Sprayed Ultra High Performance Concrete with Manufactured Sand
Applied Sciences
sprayed UHPC
mechanical properties
pore distribution
microstructure
title A Study on the Pore and Strength Characteristics of an Eco-Friendly Sprayed Ultra High Performance Concrete with Manufactured Sand
title_full A Study on the Pore and Strength Characteristics of an Eco-Friendly Sprayed Ultra High Performance Concrete with Manufactured Sand
title_fullStr A Study on the Pore and Strength Characteristics of an Eco-Friendly Sprayed Ultra High Performance Concrete with Manufactured Sand
title_full_unstemmed A Study on the Pore and Strength Characteristics of an Eco-Friendly Sprayed Ultra High Performance Concrete with Manufactured Sand
title_short A Study on the Pore and Strength Characteristics of an Eco-Friendly Sprayed Ultra High Performance Concrete with Manufactured Sand
title_sort study on the pore and strength characteristics of an eco friendly sprayed ultra high performance concrete with manufactured sand
topic sprayed UHPC
mechanical properties
pore distribution
microstructure
url https://www.mdpi.com/2076-3417/15/7/3776
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