TANG Xianyuan, HU Xiansong, LUO Jie, MA Jieling, ZHOU Changhong

(School of Architecture and Traffic Engineering, Guangxi Key Laboratory of Intelligent Transportation, Guilin University of Electronic Science and Technology, Guilin 541010, China)

Abstract

Objective Ultra-high performance concrete ( UHPC) exhibits remarkable properties such as high compressive strength, high toughness, and excellent durability, making it with broad application prospects. Despite its outstanding features, the high cost of UHPC has promoted research into the addition of modified materials with a certain content. This approach can effectively reduce the cost under the premise of ensuring mechanical properties. By studying the influence of different contents of steel slag powder,river sand, coarse aggregate and steel fiber on the compressive strength of UHPC and analyzing the damaged form of modified UHPC, the optimum modified material formula is determined, and the purpose of producing UHPC with low cost and good mechanical properties is realized.

Methods Steel slag powder, river sand, coarse aggregate and steel fiber were selected as four kinds of modified materials. The particle size of steel slag powder, river sand and coarse aggregate were analyzed, and the micromorphology of steel slag powder and silica fume were analyzed. Using four-factors and three-levels orthogonal tests, nine kinds of specimens were prepared and the curing ages of the specimens were set as 3, 7 and 28 days, respectively. Moreover, the compressive strength tests of the specimen were carried out, focusing on the influences of the dosage and curing age of each modified material on the compressive strength. The optimum formula of modified material was determined by the range analysis method. The damaged form of UHPC was analyzed by destructive experiment, and the toughness of the modified specimen was verified.

Results and Discussion The compressive strength range analysis shows that the compressive strength of UHPC first increases and then decreases with the increase of steel slag powder content when the addition of steel slag powder is 193, 210, 228 kg / m³ respectively. Similarly, varing the addition of river sand at 855, 1 045, 1 140 kg / m³ indicates a slowly decreasein compressive strength with the increase of river sand content. For coarse aggregate with the addition of 320, 640, 1 280 kg / m³ , the compressive strength of UHPC exhibits an intial increase followed by a subsequent decrease with the increase of coarse aggregate content.Conversely, the volume fraction of steel fiber at 1. 5%, 2. 0% and 2. 5% demonstrates a slight increase in the compressive strength with increasing steel fiber content. The range values of steel slag powder, river sand, coarse aggregate and steel fiber are 7. 60, 7. 57, 7. 77 and 0. 84, respectively. This indicates that coarse aggregate, steel slag powder and river sand have a greater influence on the compressive strength of UHPC, while steel fiber has less influence. The orthogonal test results show an optimal configuration for modified UHPC. Specifically, when the addition of steel slag powder, river sand and coarse aggregate is 210,855, 640 kg / m³ respectively, with the volume fraction of steel fiber at 1. 5%, and a curing age of 28 days, the compressive strength of the modified UHPC reaches 134. 4 MPa. Importantly, the lateral binding force provided by the steel fiber within the UHPC enhances its structural integrity, avoiding instantaneous bursting under pressure, and maintaining an intact overall shape.

Conclusion The addition of steel slag powder and coarse aggregate reduces the manufacturing cost of the modified UHPC. However,

the reduction of compressive strength of UHPC is small after optimizing the content of four modified materials, but the toughness is

enhanced and the mechanical properties are guaranteed.

Keywords: ultra-high performance concrete; orthogonal test; compressive strength; steel slag powder; steel fiber

Get Citation:TANG X Y, HU X S, LUO J, et al. Effects of modified materials and its contents on mechanical property of ultra-high performance concrete[J]. China Powder Science and Technology, 2024, 30(1): 153-160.

Received: 2023-06-13,Revised:2023-12-07,Online:2023-12-13。

Funding Project:国家自然科学基金项目,编号 :42067044;广西研究生教育创新计划项目,编号:YCSW2021171。

First Author:唐咸远(1973—),男,教授级高级工程师,博士,硕士生导师,研究方向为桥梁工程及高性能材料。 E-mail: thy1188@126.com。

Corresponding Author:胡贤松(2000—),男,硕士生,研究方向为桥梁工程及高性能材料。 E-mail: 18484635906@163.com。