Hydrophysical and mechanical properties of fine-grained concrete based on gypsum cement pozzolanic binder

Introduction. The most important indicators of fine-grained concrete based on gypsum cement pozzolanic binder, allowing to expand the possibilities of its application in load-bearing building structures, are strength and hydrophysical properties. This is especially relevant for structures that are used in the hot tropical climate of the Republic of Yemen and will be in a complex stress-strain state. On the other hand, the low ability of gypsum cement pozzolanic concrete to withstand the effects of moisture penetrating into the “body” of concrete together with aggressive substances from the environment will obviously lead to the loss of its original properties.Materials and methods. To prepare the gypsum cement pozzolanic binder, we used gypsum binder grade G-5 and cement binder grade CEM I 42.5N, as well as two types of pozzolanic additives: natural zeolite and microsilica. Basalt fibre was used as a fibrous material. Superplating agent grade Master Glenium 112 and crystallization water repellent grade Flocrete WP Crystal were used as chemical modifiers. To prepare the gypsum cement pozzolanic concrete, unfractionated natural quartz sand and two types of sand dispersed by fractions were used as fine aggregate. The water permeability of gypsum cement pozzolanic concrete was studied using the method of water penetration depth under pressure. The mobility was determined by the diameter of the gypsum-cement-pozzolanic mixture flow — according to GOST 23789–2018 using the Suttard device; compressive strength was assessed after 28 days of hardening in accordance with GOST 10180–2012; water absorption — according to the method of GOST 23789–2018; water resistance was assessed by the softening coefficient.Results. As a result of the experiments, an optimal composition of gypsum-cement-pozzolanic concrete with high strength and hydrophysical properties was obtained due to the optimal granulometric composition of fine aggregate, reinforcement with fibre and the use of various complex chemical additives.Conclusions. The study yielded the following results: compressive strength 60 MPa, water absorption 2.8 %, softening coefficient 1.17, water resistance W10.

gypsum-cement-pozzolanic binders, water absorption, mobility, strength, water resistance, water impermeability, water penetration depth