strength

DESIGNING OF ALKALINE ACTIVATED CEMENTING MATRIX OF ENGINEERED CEMENTITIOUS COMPOSITES

The development of high-performance materials, which are characterized by high compressive and flexural strength, durability and performance properties, is an urgent problem of modern construction. Engineered cementitious composites are one such material. Improving of properties of composites is achieved by partial replacement of cement with supplementary cementitious materials. The ratio of binder and filler components and superplasticizer consumption were selected.

Effect of Borosilicate Glass Wastes and Synthetic Silica on Cement Products Properties

This paper presents the findings of research study on the effect of borosilicate glass wastes on properties of cement paste and mortar. The borosilicate glass contains three times less alkali than soda-lime glass and about 12 % of boron oxide, so pozzolanic activity of borosilicate glass is three times higher compared to soda-lime glass. In order to increase the pozzolanic activity of glass precipitated synthetic silica was used. Mathematical models were used in order to test the effect of synthetic silica on pozzolanic activity of borosilicate glass.

Modeling of “combined cutter - cone” connection in tricone drill bits

A theoretical analysis of the stiffness of the “cutter-cone” connection was performed. In the article the character and magnitude of the tension at the contact of "cutter-cone" are investigated. An analysis of the surface of the openings for carbide inserts revealed traces of plastic deformation and fretting wear.

STRENGTH AND DESTRUCTION OF BRICK MASASONRY BASED ON MODIFIED CEMENT MORTARS

The article investigates the strength and deformability of brick masonry based on clinkereffective buikding mortars modified by additives of air-entraining action. Comparative studies have determined the physical and mechanical properties of mortar based on composite Portland cement CEM II / B-M 32.5R and masonry cement MC 22.5. It is shown that mortar on the basis of modified low-emission zeolite-containing cement MC 22.5 with additives of air-entraining action provides reduction of stress-deformed state of brick masonry.

INVESTIGATION OF ENGINEERED CEMENTITIOUS COMPOSITES PROPERTIES

Concrete is the most widely used building material due to its versatility, durability and availability of raw materials. With the development of the construction industry requirements to concrete, in particular their strength, are increased. Increasing of the physical and mechanical properties and crack resistance of cementitious composites during the operation of buildings and structures is an actual problem in engineering practice. A special class of fiber reinforced materials – engineered cementitious composites (ECC) has been developed for this purpose.

RESEARCH OF MODIFIED GYPSUM BINDERS PROPERTIES

In the article the analysis of literary sources concerning methods of gypsum binders modification is shown. It is shown that today more and more attention is paid on the ecology of production and the maximum efficiency of the use of natural resources, therefore the development of non-klinker binders, such as anhydrite and gypsum, is relevant.

INFLUENCE OF ELEVATED TEMPERATURES ON THE PERFORMANCE OF NANOMODIFIED FIBER-REINFORCED CONCRETES

Exposure to elevated temperatures has detrimental effects on the properties of concretes based on the Portland cement, leading to irreversible changes, up to total failure. One of solutions to improve resistance of structures after exposure to high temperatures may be the use of cement-based materials modified at the nanoscale.

ROAD CEMENT CONCRETES BASED ON MODIFIED ADDITIVES OF NEW GENERATION

The modified concrete mixes design and cement concrete with the given operational parameters was developed. During the experiment, cement concrete was obtained from concrete mixtures of various compositions with modifying additives of a new generation containing a superplasticizer based on polycarboxylates and an air-absorbent additive. Superplasticizer was injected into a concrete mix with water in a quantity of 0,6; 0,8 and 1,0 % of the mass of cement, and the additive-aeration – in the amount of 0,1 % of the mass of cement in all the components of concrete.

EFFECT OF COMPONENT COMPOSITION ON PROPERTIES OF ENGINEERED CEMENTITIOUS COMPOSITES

The application of engineering cementitious composites (ECC) – a specially developed class of cement-based material reinforced with fibers – allows to enhance the loading capacity, stability under static and dynamic influences, as well as durability of building structures due to controlled cracking process. The design of engineering cementitious composites is based on the concept of micromechanics, which includes the strength and energy criteria of deformation strengthening throughout the wide range from the macro- to the nanostructural level.

INFLUENCE OF DEFECTS OF THE WORKING REBAR ON THE BEARING CAPACITY OF THE REINFORCED CONCRETE BEAMS

Every construction is influenced by different factors during operation. As a result, there are various defects and damage of these elements, which affects their operating condition. One of such defects is the corrosion of the working rebar. Investigation of samples with corrosion is a complicated and labor-intensive process. Instead of corrosive effects, we perform controlled valves of damaged. In this way, we obtained experimental samples with a fixed value of reducing the diameter of the valve.