Improving the technical properties of modified gypsum binder-based materials

Abstract

The article addresses the enhancement of the performance properties of gypsum binder-based materials through targeted structural modification and reinforcement, and aims to quantitatively assess the synergistic effect of the combined use of a polycarboxylate superplasticizer, an organosilicon hydrophobizing agent, and basalt fiber on strength, water resistance, and crack resistance; building gypsum G-5 B II was used, a series of laboratory mixes was prepared in accordance with GOST regulations with the water-to-gypsum ratio adjusted to equal workability, tests were performed on beam and cube specimens with control of density, compressive and flexural strength, water absorption, and softening coefficient, and microstructural analysis was conducted by SEM followed by regression data processing; it is shown that the optimal superplasticizer dosage of 0,3% reduces water demand by~30%(W/G from 0.62 to 0.42), increasing density to~1520 kg/m³ and raising compressive strength 3,5-fold(to~22.6 MPa) and flexural strength by more than twofold, after which further dosage increases do not yield economically meaningful gains; the introduction of 0,7% hydrophobizer reduces water absorption nearly fivefold(to~5,1%) and increases the softening coefficient to 0.88-0.89 with minimal influence on dry strength, thereby placing the material in the water-resistant category; dispersed reinforcement with 1,5% basalt fiber increases flexural strength by approximately 50% and more than triples impact toughness by arresting crack growth, while showing a moderate(5-7%) decrease in compressive strength due to increased structural heterogeneity, and further increases in fiber content are accompanied by agglomeration and property regression; the resulting optimized composition(0,3% superplasticizer+ 0,7% hydrophobizer+ 1,5% fiber) provides a combined improvement: compressive strength>20 MPa, flexural strength>9 MPa, density~1530 kg/m³, softening coefficient~0.9, which expands the application of gypsum composites under moisture and impact loading, reduces dependence on cement systems, and provides a basis for designing water-resistant, strong, and crack-resistant products.