Sustainable Impact of Coarse Aggregate Crushing Waste (CACW) in Decreasing Carbon Footprint and Enhancing Geotechnical Properties of Silty Sand Soil

Abstract

People are forced to use all types of soil, especially bad soils, as infrastructure demands grow. Different procedures must be used to ameliorate these poor soils, which are fragile during building. Natural resource depletion and the rising costs of available materials force us to consider alternative supplies. For several years, researchers have investigated the use of by-products from industry and associated approaches to improve the qualities of various soils. Coarse Aggregate Crushing Waste (CACW) is a waste product that results from the primary crushing of aggregates. Massive amounts of CACW are produced in the business, posing serious issues from handling to disposal. As a result, the widespread use of CACW for diverse purposes has been recommended in the civil engineering profession to address these concerns. Because some natural resources, such as gravel, are nonrenewable, it is vital to decrease their consumption and replace them with recycled, cost-effective, and ecologically acceptable alternatives. This research aimed to investigate the possibility of reusing CACW to improve the geotechnical properties of silty sand (SM) soil available in the Najran region. In this research, soil samples were collected from Najran city and subjected to a variety of lab experiments to determine their characterization. Mixes were designed for a parent soil with a range of percentages of CACW with/without 2% cement. The designed mixes were examined through a set of lab tests to obtain the optimum design for use in road construction. The findings of the tests showed that the optimum dosage is 10% CACW with 2% cement, raising the undrained shear strength of silty sand soil by 323%, CBR by 286%, and P-wave by 180%. The durability tests show that soil mixed with 10% CACW and 2% cement fulfills the requirements and stays within the 14% weight loss limit imposed by the Portland Cement Association (PCA). The microscopic investigation results confirmed the outcomes obtained by macro tests. As a result, the carbon footprint values decrease when CAWA is added, making this treatment approach almost carbon neutral. This study clarifies the long-term effects of CACW on improving the geotechnical characteristics of silty sand soil in the Najran Region of the Kingdom of Saudi Arabia and other comparable soils globally.