compressive strength

In the post-war period, Ukraine will need a large number of aggregates to repair and rebuild destroyed and damaged objects of transport infrastructure, including roads, airfields, and parking lots. To expand the raw material base of such construction, in addition to traditional high-quality aggregates from crushed granite, quartz sand and manufactured sand, it is advisable to use some types of waste and secondary products from various industries. They must meet the basic requirements for density, strength, frost resistance. These include a by-product of iron ore mining, quartzite.

The influence of the air-entraining agent (AEA) on a density, the volume of entrained air of mortar mix and compressive strength of hardened mortar was studied in this article. Results show that the addition of AEA results in the reduction of water to cement ratio to provide the targeted flow and the density that depends on the volume of entrained air. The addition of AEA causes the decrease of the density of mortar (C:S=1:2) by 8,2% and the increase of the compressive strength by 13,9% after 28 days of hardening compared to the mortar (C:S=1:2) without AEA.

The article analyzes the experience of using Portland limestone cement for the production of ready-mixed concretes. It is shown that polycarboxylate superplasticizers (PCE) play a decisive role in providing required technological and construction-technical properties of concrete. The data show that the most effective PCEs for maintaining the workability of the concrete mixture over time and obtaining the required strength class of concrete are РСЕ based on modified acrylic polymers.

This article proves the possibility of replacing aggregates in concrete mixtures with rubber, which is obtained by grinding used car tires. It was found that the replacement of crushed coarse aggregate in the amount of 10 vol.% with ground rubber from used car tires increases the bending strength by 23% The compressive strength does not change significantly.

The article considers the possibility of using wastepaper sludge ash (WSA) as a soil reinforcement material for the construction of layers of road wear. Loamy sand, sandy loam, silty clay loam, silty clay were chosen as soils for strengthening. The maximum density of the soil skeleton at optimum humidity was established by the method of Proctor. Wastepaper sludge ash and Portland cement grade 400 were used separately for soil strengthening.

The properties of fine-grained asphalt concrete and its modified by bio based epoxy rape oil (BERO) form were studied. Rapeseed oil epoxide (ROE) obtained from renewable and ecological raw materials, rapeseed oil in a composition with initiators (hardeners) was used as a modifier. It was found that the introduction of BERO in the amount of 3% of the mass. allows to increase indicators of limit of durability of asphalt concrete at compression at a temperature of 20 ° C and 50 ° C.

Particulate composite was prepared from a mixture of cement, gravel and water with additions of a polyepoxide and/or expanded polystyrene in powder. For consolidation, each mixture was poured into a mold, remaining for a short period and then removed. For complete solidification the specimens were cured with water during the final stage. The weight, compressive strength and thermal conductivity of the composite were determined.

This paper presents the investigations of the environmental advantages of low carbon composite gypsum binders for building applications. The impact of ultrafine zeolite additive on the physico-mechanical properties and hydration processes of composite gypsum binders has been investigated. The modification of gypsum pastes by polycarboxylate type superplasticizer results in the radical change in the formed microstructure of composite gypsum binders. The obtained results are essential for further design and development of new types of gypsum composites with an increased water resistance.

Production of foam concrete products and monolithic concreting from them requires foaming agents that have the properties of the obtained foam with a sufficient value of its criteria (multiplicity of foaming, stability of foam for a certain period of time); its compatibility with Portland cement and its hydration products; with hydrated lime, etc. Insufficient properties of the foam can be compensated by the introduction of corrective and stabilizing additives.

In conditions of intensive increasing of urbanized impervious areas, stormwater management became especially relevant. To solve this problem, a number of methods have been developed and investigated, which are based on the retention, detention or filtration of stormwater runoff. Stormwater management by the pervious pavements is an effective method to control surface runoff; it is widely used in foreign practice, allowing to reduce the runoff volume, provides its preliminary treatment, improves the safety on the roads.