Influence of Sulphate Attack on Properties of Modified Cement Composites

Abstract

Monitoring the condition of building structures based on composite materials in aggressive environments shows that the deterioration of basic properties occurs under the influence of various factors such as temperature and humidity changes,in addition to changes in the chemical composition of air environment. In addition, the composite materials during the operation must retain not only the mechanical properties laid down at the design stage, but also the electro-physical characteristics, regardless of the type of destructive effects. In the current study, the quantitative assessment of the result of the interaction of an aggressive sulphate-containing medium with composites modified with conductive and dielectric additives was carried out. The effect of sulphateattack on the specific electrical conductivity of cement composites was studied. The nature of the interaction was evaluated by changing the properties of the samples of the developed compositions under the influence of a single-normal solution of sodium sulphate. The analysis was carried out by means of potentiometric titration using the exchange interaction method by fixing the degree of absorption of sulphate ions and determining the concentration of calcium ions in the solution. The measurement of the solution potential allowed determination of the quantitative indicators of the rate of calcium hydroxide leaching from the sample structure,which is necessary to assess the intensity of the destruction process and determine the nature of the change in strength properties.Measurements of the electrical resistivity of samples under the constant influence of sulphate aggression were taken during 28 days of observation. A method for quantifying the effect of a sulphate medium on a cement matrix was proposed that enables the material durability to be predicted. The features of changes in the morphology of structural components after exposure to aggressive solution were determined by physical and chemical methods.

The Study of Metal Corrosion Resistance near Weld Joints When Erecting Building and Structures Composed of Precast Structures

“…We expect to these studies further. Currently, concretes based on multicomponent binders are being developed and used [38,39], which can lead to a change in the pH of the liquid phase in the concrete structure and, accordingly, affect the corrosion of welded joints in the reinforcement [40]. This requires further advanced research of the corrosion processes of welded joints in the concrete thickness.…”

The Present State of the Use of Waste Wood Ash as an Eco-Efficient Construction Material: A Review

“…Despite the advantages of using high concentrations of alkali (NaOH, between 8–10 M) to obtain a high compression strength product of 104.5 MPa and 71 MPa for the paste and mortar, as well as a lower change in length due to temperature and water evaporation that have the lowest shrinkage percentage [ 37 ], it has been proven that the use of ashes from forest biomass (wood) can decrease the requirements of alkaline activators by up to 20% without the loss of properties [ 38 , 39 , 40 , 41 ]. However, when the substitution level of these ashes is higher than 10% by mass, the mechanical properties of the geopolymer are affected [ 42 , 43 , 44 , 45 ], proportionally reducing the compressive and flexural strength of the mortars, for all curing times [ 35 ]. Likewise, it is highlighted that different conditions can be used during the process of obtaining geopolymers, such as the type of curing, humidity control, temperature, concentration and proportions of alkaline activators, type and quantity of raw material or proportions of starting materials (in case of mixtures), which will influence the properties of the final product.…”

Prediction of Splitting Tensile Strength of Self-Compacting Recycled Aggregate Concrete Using Novel Deep Learning Methods

“…Self-compacting concrete, created in Japan in the 1980s to achieve high-performance, long-lasting concrete buildings, is one of the outcomes of improved concrete design technology [4][5][6]. The main distinction between self-compacting concrete and conventional concrete is the mixing proportions of the materials [7][8][9]. SCC is known as the innovative concrete of the era and has the property 2 of 21 of self-settlement in construction areas without vibratory force.…”