Influence of Modified Starch Admixtures on Selected Physicochemical Properties of Cement Composites

Abstract

The conducted research aimed to evaluate the influence of admixtures of various modified starches on the rheological properties of cement composites and their influence on the compressive strength of hardened cement mortars. The study involved 17 different modified starch admixtures. Using a rheometer, the values of viscosity and tangential stresses were determined depending on the shear rate, and were subsequently used to determine the yield point and plastic viscosity of cement slurries. The next parameters tested were the flow of fresh cement slurry and the compressive strength of hardened cement composite. The highest fluidisation was recorded for retentate LU-1420-0.5%Ac-R, an increase of 82%. The conducted tests led to the conclusion that admixing cement composites with modified starches changes the rheological parameters and the compressive strength of cement composites. The highest strength gains occurred for the admixtures of retentate LU-1412-R (increase of 25%). Declines in compressive strength were noticed in the retentate LU-1422-R (decrease by 13%) and the retentate OSA-2.5%-R (decrease of 17%). The admixture of starch hydrolysate significantly decreases the yield point of slurries, which in turn may contribute to the fluidisation of concrete mixes and the reduction of mixing water. The lowest values were obtained for retentates LU-1420-0.5%Ac-R (decrease of 94%), and LU-1412-R (decrease of 93%). It was found that the consistency and compressive strength of cement mortars are affected by both the type of modification and the length of the chemical chain of starch.

A Comprehensive Review of Plant-Based Biopolymers as Viscosity-Modifying Admixtures in Cement-Based Materials

“…For example, in the study, hydrolyzed starch, with a short polymer chain, reduced the yield stress and the plastic viscosity, resulting in larger flow diameters. Meanwhile, unhydrolyzed potato starch thickened the cement mixture and increased the yield stress [43].…”

Performance of potato starch admixture on fresh and hardened behaviours of concrete at varied mix design ratios

“…Their impact varies with the cement type, mix ratio, and quantity. Their applications in engineering works are on the increase due to their edge such as ameliorated workability, better frost and sulfate-retardant, fireproof, cracking-control, acceleration or retardation in setting-time, high concrete strength, increased flow for the equal water-cement ratio, coloring and improved quality [6][7][8]. Admixtures are categorized as either mineral or chemical.…”

“…Sybis and Konował [7] analyzed the impact of the inclusion of restructured starches on rheology and the preferred physicochemical characteristics of cement pastes and mortars. The authors ascertained the feasibility of adopting customized starches as plasticizers.…”

Analysing the Effect of Cassava Flour as a Mixture on the Physical, Mechanical, and Durability Properties of High-Strength Concrete

“…The slump value of the concrete with cassava starch, sawdust, and sodium chloride also decreased, but not as much as the concrete without sodium chloride. Sybis & Konował (2022) [42] the impact of cassava starch on the rheological characteristics of cement and how it influences the compressive strength of cement. This study made use of 17 different types of processed starch.…”