Behavior of Biochar-Modified Cementitious Composites Exposed to High Temperatures

Abstract

In this study, the effect of biochar on the high temperature resistance of cementitious paste was investigated using multiple experimental methods. The weight loss, cracks, residual compressive strength, and ultrasonic pulse velocity (UPV) of biochar cementitious paste with 2% and 5% biochar exposed to 300, 550 and 900 °C were measured. The products and microstructures of biochar cementitious paste exposed to high temperatures were analyzed by X-ray diffraction, Fourier transform infrared spectroscopy, thermogravimetric analysis, and scanning electron microscopy. The results showed that the cracks of specimens exposed to high temperatures decreased with increasing biochar content. The addition of 2% and 5% biochar increased the residual compressive strength of the specimens exposed to 300 °C and the relative residual compressive strength at 550 °C. As the exposure temperature increased, the addition of biochar compensated for the decreasing ultrasonic pulse velocity. The addition of biochar contributed to the release of free water and bound water, and reduced the vapor pressure of the specimen. The addition of biochar did not change the types of functional groups and crystalline phases of the products of cementitious materials exposed to high temperatures. Biochar particles were difficult to observe at 900 °C in scanning electron microscopy images. In summary, because biochar has internal pores, it can improve the high-temperature resistance of cement paste.

Impact of biochars fabricated with typical feedstocks on soil environment and crop productivity: A case study with D. rubrovolvata

“…Figure 3c shows the FTIR spectra of SDBC, RSBC and CSBC. The broadband at 3430 cm −1 indicates phenolic hydroxyl groups or carboxylic acids in biochar (Liu, Ye, et al, 2022), and the absorption peak near 3640 cm −1 is the stretching vibration of ‐OH in CH (Yang et al, 2021). The prominent peak at 1050–1100 cm −1 corresponds to the ‐OH vibration of cellulose, with higher absorption observed in RSBC and CSBC (Liu et al, 2020).…”

“…Figure 3c shows the FTIR spectra of SDBC, RSBC and CSBC. The broadband at 3430 cm −1 indicates phenolic hydroxyl groups or carboxylic acids in biochar (Liu, Ye, et al, 2022), and the absorption peak near 3640 cm −1 is the stretching vibration of -OH in CH (Yang et al, 2021).…”

Toward Carbon-Neutral Concrete through Biochar–Cement–Calcium Carbonate Composites: A Critical Review

“…The application of both biochar and calcium carbonate in cement has been explored. For the application of biochar in cement, two conclusions can be drawn from the many research findings available [9][10][11][12][13][14][15][16][17][18][19][20][21][22][23][24]. First, biochar can be effectively used as an additive and as a replacement for cement in cement mortars.…”

Carbon Peaking and Carbon Neutrality in the Cement-Based Materials

“…Their results found that the combined use of early Portland cement and granulated blast furnace slag significantly improved the concrete’s early strength and chloride ion resistance. Yang et al [ 4 ] used various experimental methods to study the high-temperature resistance of cement-based materials added with biochar. Their research showed that as the biochar content increased, cracks in samples exposed to high temperatures decreased.…”