ESTUDO DE VIABILIDADE TÉCNICA DA APLICAÇÃO DA ESCÓRIA GRANULADA DE ALTO-FORNO EM SUBSTITUIÇÃO AO AGREGADO MIÚDO NA COMPOSIÇÃO DO CONCRETO

The macro sector of the civil construction industry is a major consumer of natural resources and it generates impacts, identified as social, environmental or economic, and it is necessary to develop studies that aim to rationalize this raw materials consumption and reduce the impacts generated. Since some resources used in the sector are finite, this work’s main objective is to make the concrete more ecological by replacing part of the fine aggregate of its composition for granulated slag from the blast furnace, reducing the need for sand extraction. For this study, tests were carried out with the co-product and with the fine aggregate, evaluating the properties of the concrete in the fresh and hardened states in three mixture types, the first being a reference, the second with 30% replacement and the third with 60% replacement of fine aggregate with slag. Based on the results obtained, it is noted that the granulated blast furnace slag has more similar characteristics to the sand’s; in the fresh state, the concrete showed a similar result in the three mix types; in the hardened state, it was observed that the performance of the concrete in axial compression was satisfactory; while in flexion traction the two proposed mixtures with substitution presented an unsatisfactory result.

Effect of electrolytes with multicharged cations on the strength of stone made of a modified mixed air binder

The possibility of obtaining mixed air binder of high strength and water resistance by using active mineral additives has been considered. In this work, the gypsum binder has been replaced by a combination of hydrated lime with active additives - metakaolin and granulated slag. The ratio effect of the silica component to the binder on the compressive strength of the stone was studied. According to the results of X-ray phase analysis, the presence of tobermorite-like calcium hydrosilicates and the absence of hydrate lime phase were diagnosed in the stone. The influence of electrolyte additives - salts with three-charged cations - on stone hardening kinetics is shown. Increase in the compressive strength of 28-day-old stone from the modified mixed air binder by 5% with the introduction of 1% of the binder mass aluminum sulfate in the mixing water was established. The use of FeCl3 solution for mixing the modified mixed air binder leads to a decrease in the compressive strength of the 28-day-old stone. The mixing of the modified mixed air binder with Al2(SO4)3 solution reduces the time of setting.

Obtaining and investigation of a finely dispersed fraction of granulated blast-furnace slags for use as components of clinker-free binders

A method for obtaining a finely dispersed fraction of ground blast-furnace granulated slag has been developed. The resulting material with the introduction of an alkaline additive can be offered as an alternative to foreign analogous fine-dispersed mineral binders, an example of which can be microcement. A comprehensive study of granular slags of two metallurgical plants was carried out, the physicochemical characteristics of materials were determined. The possibility of obtaining a fraction of ground granular slag with a particle size of no more than 16 microns using vortex electromagnetic homogenization and subsequent air classification is shown.

Sustainable Masonry Mortars with Fly Ash, Blast Furnace Granulated Slag and Wheat Straw Ash

Due to greenhouse gas emissions, the production of cement clinker is considered unsustainable and many attempts are being made to replace cement with alternative materials sourced from agriculture, industry and other urban practices, such as construction and demolition works. The aim of this paper is to analyze the effects of cement substitution by locally available waste materials in Serbia, such as fly ash (FA), blast furnace granulated slag (BFGS) and wheat straw ash (WSA), up to the 50% replacement volume rate in cement–lime mortars. As the effective application of supplementary cementitious materials (SCMs) in cement-based materials requires a comprehensive insight into their properties, a characterization of materials involving all relevant physical, chemical and mechanical tests is conducted. Ten different mortar mixed with ingredients of a volume ratio 1:2:4 (cementitious powder/lime/sand) were designed and their consistency, bulk density, capillary water absorption, flexural strength, compressive strength and thermal analysis (TGA/DTA) results were examined to determine the influence of the abovementioned SCMs on mortar properties. Research findings highlight the possibility of replacing cement with slag (50%), fly ash (30%) or wheat straw ash (30%) while maintaining its performance and improving the economic and environmental impacts of masonry mortar production.

Possibilities of Application Cement By-Pass Dust into the Garden Architecture Elements

This article deals with the possibility of using cement by-pass dust (CBPD) in the garden architecture elements, specifically in curbs for park use. To increase the positive effect on the environment, other secondary raw materials were also used in the research, specifically blast furnace granulated slag and silica fly ash. Mixtures were based on alkali activation, where cement as a binder was 100% replaced by raw materials with waste properties. In the research, properties of used materials and also the basic physical-mechanical and durability properties of prepared mixtures were determined Part of the research focused on the effect of the tested beams on the grassland planted around the beams. Any significant negative impact was not registered, except for low pH increase of soil. Infrared spectroscopy and thermal analysis were performed on selected samples. Testing has shown that the products are in accordance with the Czech standard requirements for concrete curbs in garden architecture. The samples did not pass only the scaling test, which is, however, a condition for concrete curbs used for roads. For garden architecture this test is not required.

Use of Ash after Denitrification as an Additive to Concrete Based on Alcali-Activated Slag

This paper deals with the possibility of using fly ash after denitrification by the SNCR method a partial replacement in alkali-activated concrete based on blast furnace granulated slag. Previous research has verified the use of fly ash after denitrification in alkali-activated materials based on blast furnace granulated slag, and so far no negative effects on the properties of these mixtures have been found. The tests were performed on cement test specimens. As part of the preparation of concrete mixtures, two recipes were prepared. The first reference mixture contained only blast furnace granulated slag activated by sodium water glass with silicate modulus of 2. The second recipe was modified by replacing of 30% slag by fly ash after denitrification by SNCR method. Within the strength characteristics, the reference mixture always achieved better results. Very slow increases in strength were recorded for the mixture with 30% slag replacement by fly ash, when the compressive strength after 7 days of maturation was only 4.5 MPa.

X-ray Diffraction of Alkali-Activated Materials with Cement By-Pass Dust

Alkali-activated materials are alternative building binders, where secondary raw materials are processed. The possibility of using landfilled waste materials in the building industry increases their potential application in construction practice, and they are therefore subject to extensive research, especially in recent years. This paper briefly summarizes the interesting results of an experiment aimed at verifying the possibility of applying cement by-pass dust (CBPD) in the preparation of alkali-activated materials. The research was focused on the possibilities of using these wastes for the preparation of small elements of garden architecture. This work also briefly summarized the interesting results of an experiment aimed at verifying the possibility of applying cement by-pass dust (CBPD) in the preparation of alkali-activated materials. In the experiment, a mixture of blast furnace granulated slag, fly ash and cement by-pass dust was alkali activated with sodium metasilicate.