Performance based evaluation of black cotton soil geopolymer mortar on fresh properties, mechanical strength, durability, and molecular dynamics correlation
摘要
As the construction industry seeks sustainable alternatives, geopolymer concrete emerges as a revolutionary material-redefining strength and durability. This study explores the use of black cotton soil (BCS) as a binder in the production of geopolymer mortar. The binder matrix consists of calcined BCS (750 °C for 6 h) and ground granulated blast furnace slag (GGBS), activated using a 12 M sodium hydroxide solution and sodium silicate at an alkali-to-binder (A/B) ratio of 0.35. Both experimental and molecular dynamics (MD) modeling were studied to gain macro and microscale insights. ASTM standards guided the evaluation of fresh, mechanical, and durability properties across six mix designs. The flow values ranged from 125 to 140 mm, and compressive strengths up to 32 MPa at 28 days of testing. Thermal conductivity ranged from 0.82 to 0.70 W/m·K, while permeability values were observed between 12.5 × 10−10 and 3.1 × 10−10 m/s. MD simulations revealed typical internuclear distances in the BCS precursor: Al-O at 1.73 Å, Na-O at approximately 2.35 Å, and Si-O at around 1.62 Å. Strong N-A-S-H gel formation was indicated by low RDF peak distances (2.7 Å), demonstrating high structural compactness and geopolymer stability. The outcomes of this research study support the development of sustainable infrastructure by demonstrating that BCS-based geopolymer are chemically durable, structurally robust, and suitable for the construction sector. This study advances UN Sustainable Development Goals 9 and 11 by promoting sustainable, low-carbon building materials through geopolymer technology.