Influence Of Mineral Additives Research Articles

The Influence of Mineral Additives and Sands on the Performance of Self-Compacting Sand Concretes

Abstract The chosen plan for our case study is a network mixture design consisting of 21 mixtures. The application of this method has proven to be immensely useful in studying the influence of composition parameters (composite design) and the utilization of various types of mineral additives (mixture design). The application of the Design of Experiments (DOE) method, based on a statistical approach, allowed for a better understanding of the effect of formulation parameters, including the proportion of alluvial sand (75%), dune sand (25%), the total amount of sand kept at constant percentages, the dosages of brick powder, limestone filler and ceramic powder (all varying from 0 %, 20 %, 40 %, 60 %, 80 %, and 100 %), while keeping the dosage of superplasticizer and the water/binder ratio constant. This approach helped to understand the interactions between these parameters and their impact on the process. Mathematical models relating the variations of these parameters to the workability and compressive strength of such concrete mixtures have been established. The results obtained show that the workability of SCSC (expressed by slump flow and V-funnel flow) improves with the increase in the dosage of limestone filler (FC), brick powder (PB), and ceramic powder (PC), with element having a different impact, be it alone or in a combination. Moreover, they all improved the behavior of SCSC in both the fresh and hardened states. The experiment shows that increasing the proportions of FC and PC in the mixture, whether linear, binary, or ternary, leads to a significant improvement in compressive strength. Furthermore, better strength is observed in the ternary mixture at 28 days, with a strength of 43 MPa, with the following proportions (FC 70%, PB 20%, PC 10%). Finally, the result at 180 days of 48 MPa confirms the following proportions (PC 60 %, FC 30 %, PB 10 %) The compliance of some SCSC compositions was tested according to the recommendations of the French Association of Civil Engineering.

The Use of Aluminosilicate Ash Microspheres from Waste Ash and Slag Mixtures in Gypsum-Lime Compositions.

The article considered the issues of the modification of gypsum stone to improve its performance properties. The influence of mineral additives on the physical and mechanical characteristics of the modified gypsum composition is described. The composition of the gypsum mixture included slaked lime and an aluminosilicate additive in the form of ash microspheres. It was isolated from ash and slag waste from fuel power plants as a result of their enrichment. This made it possible to reduce the carbon content in the additive to 3%. Modified compositions of the gypsum composition are proposed. The binder was replaced with an aluminosilicate microsphere. Hydrated lime was used to activate it. Its content varied: 0, 2, 4, 6, 8 and 10% of the weight of the gypsum binder. Replacing the binder with an aluminosilicate product for the enrichment of ash and slag mixtures made it possible to improve the structure of the stone and increase its operational properties. The compressive strength of the gypsum stone was 9 MPa. This is more than 100% higher than the strength of the control composition of gypsum stone. Studies have confirmed the effectiveness of using an aluminosilicate additive-a product of enrichment of ash and slag mixtures. The use of an aluminosilicate component for the production of modified gypsum mixtures allows the saving of gypsum resources. Developed formulations of gypsum compositions using aluminosilicate microspheres and chemical additives provide the specified performance properties. This makes it possible to use them in the production of self-leveling floors, plastering and puttying works. Replacing traditional compositions with a new composition based on waste has a positive effect on the preservation of the natural environment and contributes to the formation of comfortable conditions for human habitation.

Influence of mineral additives on the rheological and strength properties of fine-grained concrete

The paper considers 4 types of mineral additives for concrete - metakaolin, silica fume, wollastonite and zeolite - and their influence on the rheological properties and strength of fine-grained concrete, in which part of the cement is replaced by a mineral additive. It is shown that the replacement of 5-10% of cement with active mineral additives with a specific surface area 1.5 times or more greater than the specific surface area of cement (metakaolin, silica fume) leads to a decrease in the flowability of the mixture in proportion to the increase in the amount of additive in the system. When replacing 10% of cement with additives, the specific surface of which relative to cement is in the range of 0.88-1.2 (wollastonite, zeolite), on the contrary, increases the flowability of the mixture. The strength of all samples with mineral additives at 28 days of age was greater than that of the control composition. An increase in strength by 1.7-1.76 times is noted for compositions with the replacement of 10% cement with metakaolin, wollastonite or zeolite.

Influence of Mineral Additions on the Fresh State Properties of Printable Mortars

Influence of Mineral Additions on the Fresh State Properties of Printable Mortars

Influence of Mineral Additives on the Structure and Properties of Heat-Insulating Materials Based on Silica-Containing Raw Material

Influence of Mineral Additives on the Structure and Properties of Heat-Insulating Materials Based on Silica-Containing Raw Material

Influence of Mineral Additives on the Efflorescence of Ettringite-Rich Systems.

Efflorescence is aesthetically undesirable to all cementitious materials products and mainly results from the carbonation of hydrates and salt precipitation. Alternative binders without portlandite formation theoretically have much lower efflorescence risk, but in practice, the efflorescence of ettringite-rich systems is still serious. This study reports the impacts of mineral additives on the efflorescence of ettringite-rich systems and the corresponding microstructural evolution. The effects of silica fume, limestone powder, and diatomite on efflorescence and the capillary pore structure of mortars were investigated from a multi-scale analysis. The composition and microstructure of efflorescent phases were revealed by optical microscope (O.M.), in-situ Raman spectroscopy, and Scanning Electron Microscopy (SEM). Results indicate that the addition of mineral additives can efficiently inhibit the efflorescence of reference, especially with silica fume. Similar to the ettringite-rich system, the efflorescence substances of all modifies are composed of ettringite and CaCO3, indicating that the addition of mineral admixture does not lead to chemical reactions, lower capillary absorption coefficient of mineral additives modified specimen, the denser pore structure and the lower efflorescence degree.

Influence of mineral additives on the packing density of ternary mix

The effect of fly ash, rice husk ash, metakaolin, ultra-fine slag on the packing density of ternary mix was studied in this paper, using Puntke’s method of particle packing. The addition of these mineral additives, whose particle size is lower than that of the Ordinary Portland Cement, improves the packing density of cement, by filling the voids between the cement grains, which results in increased compressive strength of concrete. The main aim of this research was to increase the packing density by replacement of cement with fine materials. Cement replacement was carried out from 10% to 40% in steps of 5%. Many combinations were tested and results showed that a maximum packing density of 0.586 was achieved at 75% cement content along with fl y ash and ultra-fine slag, without addition of the superplasticizer. Addition of superplasticizer further increased the packing at lower water to binder ratio.

Tannery Shavings and Mineral Additives as a Basis of New Composite Materials

This paper analyses the possibility of using tannery shavings as a basis for new composite materials with specified properties. The new material was made by combining tannery shavings with an adhesive medium. Mineral additives, such as dolomite, kaolin and bentonite were used in an amount of 5% and 10% of the total mass of shavings as a filler. In order to point out the influence of mineral additives on the final composite structure, some physico–mechanical properties, such as tensile strength and elasticity were examined with the use of static tensile tests. The second part of the investigation involved the analysis of wetteability by immersion, because this property depends on several aspects, such as surface roughness and the material structure. Thus, changes in wetteability values can provide information about the impact of mineral additives on the material properties of composites. With regard to physico–mechanical and sorption properties obtained on the basis of experimental results, it was possible to define areas of possible applications of these materials in comparison with current methods.

Freeze-Thaw Resistance of Cement Screed with Various Supplementary Cementitious Materials

Abstract This paper describes a study of the effect of partial replacement of ordinary Portland cement (OPC) by various mineral additives in the screed mixtures. Ceramic powder, blast furnace slag and fly ash were gradually employed in increments of 12.5 wt.% up to 50 wt.% to replace OPC. The mixtures were designed to a constant consistency. The influence of mineral additives was evaluated in terms of the air content in the fresh mixtures, the compressive strength, the flexural strength and the freeze-thaw resistance and using non-destructive measurements after 28 and 90 days. The accompanied paste sampleswere analysed using thermogravimetry to monitor the hydration process by means of total bound water content. The decrease in the mechanical properties and the frost resistance of the mixtures with the mineral additives were recorded, because of the necessity for a larger addition of water. According to the valid standards for concrete screed related to the frost resistance, it could be concluded that maximal suitable cement replacement contents are 12.5, 37.5 and 50 wt.% for ceramic powder, fly ash and blast furnace slag, respectively. The freeze-thaw resistance of the studied materials was found to be strongly related to the content of CSH and CAH hydrates.

Influence of mineral additives on the formation of a porous structure in liquid-glass granular heat-insulating materials

Influence of mineral additives on the formation of a porous structure in liquid-glass granular heat-insulating materials

Influence of mineral additions on the microstructure of concrete in chloride environment

In this work we have designed an experimental campaign with four different dosages of concrete to study the influence of the principal additions used in marine environments. The effect of material composition [Sulfate Resistant Portland Cement (SRPC), Blast Furnace Slag Portland Cement (BFSPC), Silica Fume (SF) and Fly Ash (FA) with four different mix designs] was performed by means of differential thermal analysis (DTA), mercury intrusion porosimetry (MIP), gas permeability, chloride diffusion and mechanical properties of concrete. In order to simulate the aggressiveness of the marine environment the concretes were immersed in a sodium chloride solution with a concentration of 1 molar during different times of 182, 365 and 546 days. According to the results obtained, the SRPC and SRPC+FA samples suffered the highest rise in permeability, porosity and chloride diffusion, and the greatest loss in compressive strength

E-Modulus and Creep Coefficient of Self-Compacting Concretes and Concretes with some Mineral Additives

The applicability of a proposed model similar to a well-known Hirsch's model for predicting the E-modulus of concrete and the creep coefficient of concrete depending on the composition of the concrete, the properties of the components of concrete mix and the possible effect of the superplasticizer on the deformation properties of cement stone both under short-term and long-term loading is proved. Value ​​of the E-modulus of self-compacting concrete can be reduced to 20% with respect to the ordinary concrete of equal compressive strength, which is confirmed by the model calculation data and some experimental data. For concretes with mineral additives, the influence of mineral additives on the E-modulus was not established. Both an increase and decrease in the E-modulus is possible. The effect depends on the type of additive. The creep coefficient of self-compacting concrete, obtained by calculation according to the model, due to the increased content of cement stone and the possible influence of superplasticizer on the creep of cement stone, can be from 1.3 to 1.8 of the coefficient of creep of ordinary concrete. This result agrees well with some experimental data. The creep coefficient of concrete with mineral additives (silica fume, white ash and metakaolin), obtained by calculation according to the model, can be from 0.5 to 0.6 of the coefficient of creep of ordinary concrete. This result agrees well with some experimental data.

The influence of the mineral additives on the carbonation of cement composites

In practice, it is usually assumed that the durability of basic structural elements should not be less than the expected durability of the building. Reinforced concrete constructions, designed and made with quality requirements, are durable. However, each reinforced concrete structure, from the moment it is made, is gradually degraded, and one of the reasons for its destruction is often the corrosion of the concrete and hence the reinforcement. For the long-term use of reinforced concrete constructions, the most important thing is that a thin protective layer on the steel surface protects the reinforcing steel from rusting. One of the most common causes of corrosion in the reinforcement is the damage of this layer as a result of the carbonation of the concrete cover. The rate of carbonation depends on many factors, such as concrete compactness, concentration of CO2, concrete moisture, content of free calcium dioxide, content of mineral additives, etc. When the carbonated layer reaches the steel reinforcement layer, protection of steel from corrosion ceases to exist. The aim of the presented research was to determine the influence of mineral additives used as a compound of concrete on the carbonation of concrete and polymer-cement composites.

Study of the pore solution and the microstructure of mineral additions blended cement pastes

In this paper, the influence of mineral additions on the microstructure and the chemical composition of the pore solution of cementitious materials is investigated. For this purpose, hardened cement pastes based on Portland cement CEM I are used. In order to study the influence of the cementitious materials composition on their microstructure and pore solution, a part of the cement is substituted by different mineral additions (limestone filler, fly ash, blast furnace slag and silica fumes). Experimental tests covered measurement of chloride diffusion coefficient by migration test and water and mercury porosimetry. Furthermore, pore solutions are extracted by pressing from cement pastes and analyzed by ionic chromatography. Results show that the substitution of cement by mineral addition modifies the total porosity and the pore sizes distribution of the blended cement pastes tested. Chemical analyses showed that all the tested pore solutions are mainly composed by sodium and potassium. A significant concentration of divalent ions, such as sulfates and calcium, is also noticed. The substitution of cement by mineral addition also significantly modifies the pore solution of cement pastes. In fact, a substitution of cement by 10% of silica fume decreases the alkalis concentrations and increases the sulfates and calcium ones. Thus, the divalent species (Ca2+ and SO42-) should be taken into account for the chloride diffusion modelling unlike the current models of the literature. Results of this chemical investigation could be used as initial and boundary conditions in the modeling of aggressive species transport through porous construction materials.

Detonation combustion of lignite with titanium dioxide and water additives in air

The influence of mineral additives (6.2–70%) and water (15–54%) to lignite on the possibility of its burning in an air flow in a continuous detonation regime in a radial vortex combustor 500 mm in diameter is studied. A syngas with a composition CO + 3H2 is used for transporting the coal mixture and for promoting the chemical reaction. It is shown that regimes of continuous spin detonation, conventional combustion, and pulsed combustion may occur depending on the amounts of the mineral (TiO2) added to coal, water, and syngas. The boundaries between the domains of existence of detonation and combustion are determined in the coordinates of the ratio of the syngas flow rate to the rate of consumption of the combustible portion of coal and the mineral component of coal and water. It is seen that the continuous spin detonation regime persists if the mineral additive fraction in the lignite mixture is up to 65% and the water fraction is smaller than 30%. It is also demonstrated that the syngas flow rate should be increased with increasing mineral additive fraction and increasing coal humidity in order to ensure burning of the combustible component of syngas.

Long Term Leaching Behavior of Antimony from MSWI Bottom Ash: Influence of Mineral Additives and of Organic Acids

The leaching of Sb in alkaline environment is known to be mainly governed by the precipitation of Ca- and Fe-antimonates. To reduce Sb leaching from MSWI bottom ash below the regulatory limit for recycling as construction material, Ca- and Fe-containing chemicals and industrial residues were added to this bottom ash. Short term and medium long term leaching tests were performed by lab batch tests and outdoor field tests. This confirmed that the tested chemicals and industrial residues reduce Sb leaching to below the regulatory limit. Carbonation tests with subsequent leaching were performed to provide information on the long term leaching behavior of Sb from MSWI bottom ash. Upon carbonation, Sb leaching from the bottom ash to which Fe2(SO4)3 or Ca- and Fe-containing industrial residues were added, increased over time, but did not exceed the regulatory limit value after full carbonation. When carbonation progressed, Sb leaching from the untreated bottom ash decreased, which could not be explained by the current state of the knowledge on mechanisms for Sb leaching in alkaline environments. As the leaching of Sb after carbonation was altered similarly as that of Cu, we experimentally checked if Sb leaching could also be influenced by the presence of organic acids,. As a result, we showed that Sb leaching from MSWI bottom ash in alkaline environments is indeed influenced by the presence of organic acids like humic and fulvic acids.

Influence of mineral additions on flexural fatigue performance of steel fibre reinforced concrete

An experimental investigation is conducted to study the flexural fatigue performance of steel fibre reinforced concrete containing fly ash (FA), silica fume (SF), metakaolin (MK) and limestone powder (LP) as mineral additions in terms of theoretical fatigue lives. Seven mix combinations are prepared by replacing 30 % of cement by weight with FA, SF, MK and LP in different proportions to form binary and ternary blend systems. Rectangular corrugated steel fibres at 1.0 % volume fraction are incorporated in all seven mix combinations. Beam specimens are tested at four fatigue stress levels ranging from 0.90 to 0.75. The Weibull distribution is employed to incorporate the failure probabilities into the fatigue life data of all mix combinations. The theoretical fatigue lives of all mix combinations are calculated using single-logarithm fatigue equation. The theoretical fatigue lives of concretes containing mineral additions get enhanced in different extent as compared to control concrete. The concrete containing SF and FA in the amount of 10 and 20 % by weight of binder respectively has shown the best flexural fatigue performance, which is much better than that of the control concrete.

Influence of Mineral Additives on Environmental Resistance of Concrete

Influence of Mineral Additives on Environmental Resistance of Concrete

Influence of mineral additives and environmental conditions on the self-healing capabilities of cementitious materials

The effects of the addition of minerals of various compositions (i.e., silica-based materials, chemical expansive agents, swelling minerals and crystalline components) on the self-healing performances of cementitious materials were investigated. The self-healing capabilities were assessed by performing water permeability tests, quantifying the widths of the surface cracks and studying the water absorption of mortars that were pre-cracked by either splitting or compression. The results showed that the cracks that appeared early on healed more efficiently when they were cured in still rather than flowing water. High pHs and high temperatures accelerate crack healing. The healing efficiency can be further improved by utilizing a combination of minerals rather than a single mineral. A self-healing mechanism was discussed by combining these results with micro-observations. The precipitation of calcium carbonate, which is aided by higher pH values and higher calcium ion contents, was found to be the main contributor to the healing of surface cracks.

Influence of mineral additions and different compositional parameters on the shrinkage of structural expanded clay lightweight concrete

A comprehensive experimental study was carried out on the shrinkage behaviour of structural expanded clay lightweight aggregate concrete (LWC), taking into account different compositions, types and initial wetting conditions of lightweight aggregates (LWA). The influence of different compositional parameters on shrinkage, such as the type and volume of aggregate, the w/c ratio, the binder content and the partial replacement of normal aggregates by LWA was analysed. The shrinkage of LWC depends on how the volume of LWA varies. The influence of different pozzolanic materials was also studied, namely, silica fume, nanosilica and fly ash. Depending on the type, content and reactivity of the pozzolanic additions, the shrinkage was higher or lower than that of LWC without admixtures. The initial wetting condition of LWA had little influence on the long-term shrinkage. The LWC with the most porous aggregates is more affected by the cross-section geometry of concrete in that it is more susceptible to differential shrinkage. Current standard expressions did not properly predict the shrinkage behaviour of LWC. Multiplier coefficients of about 1.3 for the most common structural LWA and about 1.6 for more porous LWA are suggested, to take into account the higher long-term shrinkage of LWC.