Concrete durability enhancement from nopal (opuntia ficus-indica) additions

Abstract

Durability criteria were used to evaluate concretes containing Opuntia Ficus Indica (OFI, also called nopal) derivatives: exudate nopal mucilage (eNm), cooked nopal mucilage (cNm), and dehydrated nopal powder (dNp). Concrete containing eNm and cNm was fabricated using 4%, 8%, 15%, and 30% concentrations by water mass replacement. The dNp was added at 1%, 2%, and 4% (per cement weight) by sand mass replacement. Concrete’s physical and mechanical performance was monitored for the nopal derivative treatments and the control (without nopal derivatives), to quantify any possible durability improvements.The durability tests included: saturated electrical resistivity (ρS); total voids percentage (TV%), capillary absorption (effective porosity, εEF); compressive strength (fc); rapid chloride permeability (RCP); and SEM micrograph analysis. Because nopal derivatives have an apparently slow reaction time, the tests were evaluated at 30, 90, 180, and 400 days.Addition of dehydrated nopal powder (dNp) did not improve substantially concrete durability performance, except chloride transport: additions <2% decreased RCP index values up to 10%. Exudate nopal mucilage (eNm) exhibited improved durability index values up to 20% (TV%/εEF decrease and ρS/fc increase), and RCP index was improved up to 30%. Cooked nopal mucilage (cNm), at all four tested ages, produced results superior to the control mixture (between 20% and 40% improvements). In summary, nopal derivatives may act as clogging sponge-like biopolymer within the cement matrix pores, stopping water and chloride transport into concrete.