Enhancing Off-Spec Limestone Aggregates with Polymer Treatment for Sustainable Infrastructure Construction – A Review

Abstract

The utilization of off-spec limestone aggregates in concrete production presents both challenges and opportunities for sustainable infrastructure development. These aggregates, abundant yet often failing to meet industry standards, remain underutilized despite their potential contribution to construction. The review assesses the characteristics of off-spec limestone aggregates, their implications on concrete performance, and explores polymer modification techniques to enhance their suitability for construction. Off-spec aggregates exhibit diverse physical and chemical attributes, varying from standard specifications, impacting their strength, durability, and composition. Polymer modification methods, including latex modification, silane coupling agents, epoxy and acrylic resin treatments, impregnation, physical modification, etc. offer avenues for improving aggregate properties, yet each technique presents distinct merits and demerits. The impact of polymer treatment manifests in changes to density, water absorption, and mechanical properties, as observed through SEM, FTIR, and BET analyses. Evaluating treated aggregates involves assessing their performance under diverse environmental conditions, including exposure to water, chloride solutions, and thermal stress cycles, revealing improvements in durability and bonding within concrete matrices. Implementing polymer-treated aggregates in construction projects proves feasible, offering enhanced mechanical properties, reduced water absorption, and potential environmental and economic benefits through reduced cement usage and waste generation. This review emphasizes the significance of complying with industry standards for size, strength, durability, and other physical and chemical properties to render off-spec aggregates suitable for concrete production. The amalgamation of various polymer modification techniques, as discussed comprehensively in the manuscript, not only ensures enhanced concrete performance but also contributes to the sustainability of infrastructure construction practices. LITERATURE REVIEWThis section focuses on characteristics of off-spec limestone aggregates, different methods and techniques of polymer modification of the aggregates, effects of polymer treatment on the aggregates, evaluation of performance of treated aggregates, and the application of treated aggregates in the concrete industry. Characteristics of Off-Spec Limestone AggregatesOff-spec limestone aggregates are those that do not meet the standard specifications for use in construction. These aggregates, deviate from standard specifications in size, shape, gradation, strength, and durability, require treatment with polymers due to their inherent deficiencies (Table 1). The aggregates present variations in size, shape, and gradation, impacting concrete properties and workability, potentially leading to reduced strength and durability. Additionally, their susceptibility to weathering, and impurities affecting bond integrity with cement paste, and non-compliance with industry standard...