In a bid to turn industrial waste into a valuable resource, researchers have been exploring the potential of coal gangue (CG) and ground-granulated blast furnace slag (GGBFS) in creating geopolymers. A recent study, led by Xiaoping Wang from the School of Civil and Transportation Engineering at Guangdong University of Technology in China, delves into how these materials can influence the mechanical properties and microstructure of geopolymers, offering promising insights for the maritime industry.
Geopolymers are inorganic polymers with a structure similar to natural zeolites. They are known for their excellent mechanical properties and durability, making them an attractive alternative to traditional cement. In this study, Wang and his team investigated the effects of different GGBFS/CG mixtures on the compressive strength, setting time, and microstructure of geopolymers.
The results showed that the geopolymer matrix is composed of calcium aluminosilicate (C-(A)-S-H) and sodium aluminosilicate (N-A-S-H) hydrates, which are crucial for enhancing the compressive strength of the specimens. When using 100% GGBFS, the geopolymer matrix sets in just 17 minutes, reaching a compressive strength of 107.55 MPa after 28 days. However, as the CG content increases, both compressive strength and compactness decrease gradually, while the setting time prolongs. For instance, with a GGBFS/CG mass ratio of 1:1, the setting time increases by 64.7% (from 17 to 28 minutes), and the compressive strengths at 3 days, 7 days, and 28 days are recorded to be 46.73 MPa, 53.25 MPa, and 54.59 MPa, respectively. Specimens with 100% CG exhibit a prolonged setting time (122 minutes), but the compressive strength is just 21.80 MPa.
Microscopic analysis revealed that specimens with 50% CG have smaller average pore diameters (22.84 nm) and a compact microstructure. “These findings indicate that the GGBFS content significantly influences geopolymer performance,” Wang noted, highlighting the effective utilization of GGBFS/CG wastes.
For the maritime industry, these findings present several opportunities. The use of geopolymers in marine environments is particularly attractive due to their excellent durability and resistance to sulfate attack, which is a common issue in seawater. Moreover, the ability to use industrial waste products like CG and GGBFS not only reduces the environmental impact but also lowers the cost of raw materials.
The study, published in the journal ‘Buildings’ (translated from Chinese), underscores the potential of geopolymers in the maritime sector. As Wang puts it, “The effective utilization of GGBFS/CG wastes highlights a sustainable strategy for industrial waste recycling.” This could pave the way for more eco-friendly and cost-effective construction materials in the maritime industry, contributing to a more sustainable future.