Mechanical properties of geopolymer concrete sleepers based on digital image correlation

The sleeper is an important part of track structure, among which concrete sleepers are the most widely used in China. The use of geopolymer concrete rather than conventional concrete can assist in saving energy and minimizing carbon emissions while using solid waste resources such as slag and fly ash. In the current research on the use of geopolymer in railway sleepers, the research on the geopolymer concrete sleepers mixed with cement, fly ash, and slag were still limited. Geopolymer concrete with two mixture were designed and manufactured into sleepers. Using Digital Image Correlation, the stiffness, crack and crack width extension regulation of the sleeper under the two mixes were analyzed under the three-point bending test of the rail seat section. The results show that among the two sleepers, the geopolymer concrete sleeper with the mix of Geo100 has higher stiffness under lower static load, but yields faster in the later stage. Geopolymer concrete sleepers with the mix of Geo50 have lower stiffness under low static load, but the stiffness loss of the sleeper is smaller with the increase of load. The microcracks appeared with similar loads of 120 kN and 130 kN respectively. Under the lower load, the crack extension of the two kinds of sleepers is not much different. Under the higher load, the crack development of the geopolymer concrete sleeper with the mix of Geo100 is accelerated, and the width and increasing rate are greater than those of Geo50. The geopolymer concrete sleepers with the mix of Geo100 are mainly damaged by bending, and those of Geo50 are mainly damaged by diagonal tension failure. In summary, the geopolymer concrete mixed with cement, slag and fly ash can make the sleeper maintain higher stiffness and slower crack extension speed under a higher load. © 2024, Central South University Press. All rights reserved.