The lack of global standardization in the testing methods for Stabilized Rammed Earth (SRE) hinders progress in advancing knowledge of this sustainable construction technique. This review compiles research from the last four years on SRE, focusing on manufacturing parameters, curing conditions, chemical stabilizer kinds, stabilizer dosage, testing methods, and mechanical and durability properties. Based on this analysis, a methodology is proposed to define and standardize SRE manufacturing parameters, curing, and testing conditions. The proposed methodology suggests that soil particle size distribution should be optimized to enhance mechanical strength and durability while reducing stabilizer dosage. The selection and dosage of stabilizers should be determined based on soil characteristics and environmental considerations. The standard proctor test is recommended for assessing manufacturing conditions, while curing should be performed by wrapping samples in plastic at laboratory temperature. Unconfined Compressive Strength is identified as the most relevant mechanical test and should be conducted at 7, 28, and 90 days. For durability assessment, erosion testing and exposure to liquid water are recommended at 28 days. This methodology represents one of the first steps toward the standardization of SRE testing methods, which must be accepted and adopted by researchers and practitioners. By implementing this methodology, comparable results across studies could be achieved, facilitating further research and collaboration among researchers. Such efforts would contribute to enhancing the available knowledge to improve the material's performance and further promote SRE as a sustainable construction technique.

Environmentally persistent free radicals (EPFRs) are produced during biochar pyrolysis and, depending on biochar application, can be either detrimental or beneficial. High levels of EPFRs may interfere with cellular metabolism and be toxic, because EPFR-generated reactive oxygen species (e.g., hydroxyl radicals (center dot OH)) attack organic molecules. However, center dot OH can be useful in remediating recalcitrant organic contaminants in soils. Understanding the (system-specific) safe range of EPFRs produced by biochars requires knowing both the context of their use and their overall significance in the existing suite of environmental radicals, which has rarely been addressed. Here we place EPFRs in a broader environmental context, showing that biochar can have EPFR concentrations from 108-fold lower to 109-fold higher than EPFRs from other environmental sources, depending on feedstock, production conditions, and degree of environmental aging. We also demonstrate that center dot OH radical concentrations from biochar EPFRs can be from 104-fold lower to 1017-fold higher than other environmental sources, depending on EPFR type and concentration, reaction time, oxidant concentration, and extent of environmental EPFR persistence. For both EPFR and center dot OH concentrations, major uncertainties derive from the range of biochar properties and the range of data reporting practices. Controlling feedstock lignin content and pyrolysis conditions are the most immediate options for managing EPFRs. Co-application of compost to provide organics may serve as a postpyrolysis method to quench and reduce biochar EPFRs.