INVESTIGATION OF STRENGTH GAIN OF HEAVY CONCRETE IN AN AGGRESSIVE ENVIRONMENT. USING SULPHATE-RESISTANT CEMENT

Abstract

Experimental data are presented on changes in the compressive strength of heavy concrete using sulfate-resistant cement, Crimean aggregates and additives based on polycarboxylate ethers when kept in an aggressive environment - liquid from water treatment facilities in an urban-type settlement Gvardeiskoe, Simferopol district, Republic of Crimea. Compositions of heavy concrete have been developed using hyperplasticizing (polycarboxylate) additives that are capable of increasing their physical and mechanical characteristics over time when operating in aggressive environments. It is relevant to further develop the theoretical and experimental foundations for the production of cement concrete using the latest generation of superplasticizing additives based on polycarboxylates for wastewater treatment and recreational facilities. The durability of cement concrete is a key issue when using it in wastewater treatment and recreational facilities. Cement concrete can be susceptible to sulfate corrosion. Sulfates have a complex mechanism of action on the chemically active component of concrete - cement stone. Sulfates have a complex mechanism of action on the chemically active component of concrete - cement stone. The corrosive effect can increase or decrease depending on the concentration of aggressive components, with varying levels of exposure to salt solutions on the concrete structure, periodic drying, and partial immersion. This is due to the fact that the chemical processes of interaction between an aggressive environment and cement stone in concrete are influenced by physical processes of mass transfer of soluble components and crystallization of corrosion products or soluble components, which can accelerate or inhibit chemical processes. The parameters of the strength characteristics of the optimized compositions at different periods of strength gain have been established, and the average density and water resistance of the optimized concrete compositions have been established.

Subject. heavy concrete using sulfate-resistant cement, Crimean aggregates and additives based on polycarboxylate esters.

Materials and methods. The research was carried out on specially selected compositions of concrete mixtures with mobility P3 on the most common raw materials in Crimea with and without a polycarbosylate plasticizing additive.

Characteristics of concrete mixture components:

The aggressive medium was liquid taken from a water treatment plant in the urban settlement of Gvardeyskoye, Simferopol district, Republic of Crimea.

Results: 1. The use of Hidetal-GP-9 additive means a 15% reduction in water consumption, while the moisture content decreases from 0.65 to 0.55 and the mobility of the P3 grade is maintained. 2. As a result of the study, it was found that concrete compositions using carboxylates showed the best results in increasing strength, especially in an aggressive environment. Thus, composition No. 4 showed the compressive strength of concrete after storage in an aggressive environment for 745 days Rcom = 475 kg/cm2 (47.5 MPa). 3. After long-term storage in an aggressive environment, in particular for 2,920 days, composition No. 4 showed a compressive strength of 519 kg/cm2 (51.9 MPa) of concrete. 4. When examining the appearance of cube samples stored in an aggressive environment for 2,920 days, it was found that the condition of the samples was satisfactory. There were no signs of concrete corrosion on the surface of the samples; there were no cracks or chips of concrete stone. 5. The average density of the studied concretes corresponds to heavy concretes according to the general classification. On average– the density of concrete stone corresponds to the limits of 2350-2450 kg/m3.4. When examining the appearance of samples of cubes stored in an aggressive environment for 2920 days, it was found that the condition of the samples was satisfactory. There were no traces of concrete corrosion on the surface of the samples; there were no cracks or chips of the concrete stone.

1. The average density of the studied concretes corresponds to heavy concretes according to the general classification. On average, the density of concrete stone corresponds to the limits of 2350 – 2450 kg/m3.