scholarly journals Concept of Evaluation of Mineral Additives’ Effect on Cement Pastes’ Durability and Environmental Suitability

Materials ◽  
2021 ◽  
Vol 14 (6) ◽  
pp. 1448
Author(s):  
Robert Figmig ◽  
Adriana Estokova ◽  
Miloslav Luptak
Keyword(s):  
Natural Zeolite ◽  
Holistic Approach ◽  
Cement Composites ◽  
Cement Pastes ◽  
Supplementary Cementitious Material ◽  
Environmental Suitability ◽  
Evaluation Approach ◽  
Mineral Additive ◽  
Mineral Additives ◽  
Positive Effect

This experimental study focuses on the assessment of mineral additives and their incorporation into cement composites (CC). The assessment was based on a holistic approach to the performance of the durability properties of CC. Environmental suitability was also taken into consideration. In the experiments, cement pastes with w/c ratios of 0.3, 0.4, and 0.5, respectively, were prepared. Natural zeolite (NZ) and densified silica fume (SF) at doses of 7.5 and 15.0 wt.% of cement were used as the investigated (replacement) materials. Their effects (including development over time) on density, strength (flexural and compressive), porosity by water absorption, permeability by rapid chloride penetration (RCP) test, phase content by thermal analysis, and hydration progression, were observed. The results were then used to propose an evaluation approach. Natural zeolite was used for its known pozzolanic activity and classification as a supplementary cementitious material (SCM). In contrast SF acted as a filler in cement pastes, and thus did not have a direct positive effect on durability. The concept of comprehensive analysis for unknown additive classification is proposed to expressly differentiate between SCM, inert, and improving mineral additive. This concept could be applied to the assessment of mineral additives with regards to the durability and suitability of cement composites.

scholarly journals Increasing the crack resistance of high-strength self-compacting concrete

2021 ◽  
Vol 1 (1(57)) ◽  
pp. 17-24
Author(s):  
Vyacheslav Troуan ◽  
Bogdan Kindras
Keyword(s):  
Stress Intensity Factor ◽  
Stress Intensity ◽  
Silica Fume ◽  
Critical Stress ◽  
High Strength ◽  
Critical Stress Intensity Factor ◽  
Self Compacting Concrete ◽  
Mineral Additive ◽  
Mineral Additives ◽  
Positive Effect

The object of research is high-strength self-compacting concrete, which does not require additional vibration during laying. One of the most problematic issues of high-strength self-compacting concretes is increased cracking, associated with large shrinkage deformations of such concretes and their fragile destruction. A decrease in shrinkage deformations of concrete was established when part of the cement was replaced to mineral additives. This effect is explained by a decrease of the cement content and, accordingly, a decrease of the chemical component of the autogenous shrinkage of concrete, and an increase of the adsorptive binding of capillary moisture by mineral additives, with reduces the physical drying shrinkage of concrete. In this case, the type and dispersion of the used mineral additive can affect to the shrinkage deformations of concrete. A significant decrease in shrinkage deformations when using metakaolin is explained by an increase the amount of ettringite as a result of the reaction of active metakaolin Al2O3 with two-water gypsum of cement. It was found that the replacement of cement to 10 % of mineral additives leads to a decrease in the value of the critical stress intensity factor (SIF), which is compensated by a decrease of the fragility of concrete fracture (an increase of the area of microplastic deformations). At the same time, the type of mineral additive used does not affect to the value of the critical stress intensity factor, but significantly affects to the fragility of fracture of concrete samples. The introduction of 10 % mineral additives (to replace cement) had a positive effect on the retention of flow of self-compacting concrete mixes; the best results according to this criterion were observed when using silica fume, fly ash and limestone. All mineral modifiers, except for silica fume, led to a decrease of the compressive strength of high-strength concretes on all terms of hardening. In the case of the tensile strength of concrete at bending and splitting, with the introduction of silica fume, metakaolin and fly ash, a positive effect was observed compared to the base composition without additives. Comprehensive accounting of the results obtained will allow a reasonable approach to the design of high-strength self-compacting concretes with increased crack resistance.

scholarly journals Improvement of Strength Parameters of Cement Matrix with the Addition of Siliceous Fly Ash by Using Nanometric C-S-H Seeds

Energies ◽  
2020 ◽  
Vol 13 (24) ◽  
pp. 6734
Author(s):  
Bartosz Szostak ◽  
Grzegorz Ludwik Golewski
Keyword(s):  
Negative Influence ◽  
Cement Matrix ◽  
Negative Effects ◽  
Strength Parameters ◽  
Cement Pastes ◽  
Cement Production ◽  
Early Stages ◽  
Strength Tests ◽  
Mineral Additives ◽  
Positive Effect

Modification of a cement matrix using additives and admixtures has been a common practice for many years. The use of some mineral additives as substitutes for the cement, e.g., the siliceous fly ashes (FAs), has a positive effect on reducing the energy used in cement production. On the other hand, such activities may have negative effects due to the lowering of strength parameters of composites in early stages of curing. In order to solve this problem, over the last few years, thanks to the patented "seedings" technology, a branch of industry connected with the production of admixtures that accelerate the binding process has developed significantly. Therefore, the paper presents the results of research aimed at analyzing the parameters of FA cement matrix with the nanoadmixture containing the nanometric C-S-H seeds (nanoadmixture (NA)). By using the modern NA, an attempt was made to neutralize the negative influence of the used industrial waste on the structure of the cement matrix in the early stages of its curing. The paper presents the results of strength tests for the FA cement pastes modified by NA in seven test periods, i.e., after 8, 12, 24 and 72 h, and 7, 14 and 28 days. Additionally, hydration heat tests were carried out on the analyzed material in the first 24 hours of curing.

scholarly journals Biopolymer-Based Hybrids as Effective Admixtures for Cement Composites

Polymers ◽  
2020 ◽  
Vol 12 (5) ◽  
pp. 1180
Author(s):  
Agnieszka Ślosarczyk ◽  
Izabela Klapiszewska ◽  
Patryk Jędrzejczak ◽  
Łukasz Klapiszewski ◽  
Teofil Jesionowski
Keyword(s):  
Hybrid Materials ◽  
Weight Ratio ◽  
High Energy ◽  
Cement Composites ◽  
Cement Pastes ◽  
Colorimetric Data ◽  
Physical Interactions ◽  
Ratio Of Components ◽  
Positive Effect ◽  
Satisfactory Plasticity

In the framework of this publication, silica-lignin hybrid materials were designed, obtained, characterized and then used as admixtures for cement composites. High-energy mechanical grinding of individual components was used to produce the systems that allowed ensuring adequate homogeneity of the final products. As a result of the analysis of Fourier transform infrared spectroscopy, it has been confirmed that weak physical interactions occur between the components. This allowed classifying the resulting systems as I class hybrid materials. In addition, the efficiency of obtaining final products was also inferred on the basis of obtained porous structure parameters and colorimetric data. The achieved bio-admixture with different weight ratios of silica and lignin was added to cement pastes in the amount ranging from 0.5 to 1 wt.%. The study showed that increasing the ratio of lignin in the admixture from 0.15 to 1 wt.% had a positive effect on the rheological properties of the pastes, while the mechanical properties of the composite were deteriorated. In turn, a higher amount of silica in the admixture acted in reverse. The most favorable results were obtained for a silica-lignin bio-admixture with a weight ratio of components equal to 5:1 wt./wt. A significant increase in compressive strength was gained at satisfactory plasticity of the paste.

scholarly journals Rheology of Cement Pastes with Siliceous Fly Ash and the CSH Nano-Admixture

Materials ◽  
2021 ◽  
Vol 14 (13) ◽  
pp. 3640
Author(s):  
Bartosz Szostak ◽  
Grzegorz Ludwik Golewski
Keyword(s):  
Fly Ash ◽  
Modern Technology ◽  
Heat Of Hydration ◽  
Hydration Heat ◽  
Cement Composites ◽  
Standard Samples ◽  
Cement Pastes ◽  
Positive Effects ◽  
Calcium Silicates ◽  
Positive Effect

The use of fly ash in cement composites adversely affects its mechanical properties during the first days of mixture curing. Modern technology, in the form of an admixture containing the hydrated calcium silicates, allows to accelerate the hardening and binding process of concrete. In this paper, studies on the influence of the admixture on properties of concretes with the ordinary Portland cements (OPC) containing the addition of siliceous fly ash (FA) have been carried out. As part of the experimental research, the authors conducted a series of studies for cement pastes modified with the addition of FA and the CSH nano-admixture (NA). In order to compare the mixtures, the following tests of cement pastes were carried out: the compressive and flexural strength, heat of hydration, SEM and rheological shrinkage. The mechanical parameters were tested after 4, 8, 12 and 24 h. The hydration heat test and microstructure analysis were carried out during the first 24 h of the concrete curing. All tests were carried out on the standard samples. On the basis of the heat of hydration test, much higher hydration heat was found in mixtures modified with the NA. During the shrinkage test, a positive effect of the NA was observed—the shrinkage during the first 28 days of mixture curing was lower than in the reference samples. The application of the CSH nano-admixture to cement pastes with the addition of FA has brought positive effects. Apart from a significant increase in strength in the first 24 h of mixture curing, a reduction in the rheological shrinkage was observed. The admixture can be successfully used in the ash concretes, in which a higher early strength is required.

scholarly journals The Influence of Cement Substitution by Biomass Fly Ash on the Polymer–Cement Composites Properties

Materials ◽  
2021 ◽  
Vol 14 (11) ◽  
pp. 3079
Author(s):  
Beata Jaworska ◽  
Dominika Stańczak ◽  
Joanna Tarańska ◽  
Jerzy Jaworski
Keyword(s):  
Fly Ash ◽  
Building Materials ◽  
Raw Materials ◽  
Combustion Process ◽  
Biomass Combustion ◽  
Cement Composites ◽  
Cement Mortars ◽  
Mineral Additive ◽  
Biomass Fly Ash

The generation of energy for the needs of the population is currently a problem. In consideration of that, the biomass combustion process has started to be implemented as a new source of energy. The dynamic increase in the use of biomass for energy generation also resulted in the formation of waste in the form of fly ash. This paper presents an efficient way to manage this troublesome material in the polymer–cement composites (PCC), which have investigated to a lesser extent. The research outlined in this article consists of the characterization of biomass fly ash (BFA) as well as PCC containing this waste. The characteristics of PCC with BFA after 3, 7, 14, and 28 days of curing were analyzed. Our main findings are that biomass fly ash is suitable as a mineral additive in polymer–cement composites. The most interesting result is that the addition of biomass fly ash did not affect the rheological properties of the polymer–cement mortars, but it especially influenced its compressive strength. Most importantly, our findings can help prevent this byproduct from being placed in landfills, prevent the mining of new raw materials, and promote the manufacture of durable building materials.

Study of the pozzolanic activity and hydration products of cement pastes with addition of natural zeolites

Clay Minerals ◽  
2011 ◽  
Vol 46 (2) ◽  
pp. 241-250 ◽  
Author(s):  
V. Lilkov ◽  
O. Petrov ◽  
V. Petkova ◽  
N. Petrova ◽  
Y. Tzvetanova
Keyword(s):  
Surface Area ◽  
Cement Paste ◽  
Chemical Reactions ◽  
Natural Zeolite ◽  
Early Stage ◽  
Pozzolanic Activity ◽  
Large Surface Area ◽  
Natural Zeolites ◽  
Hydration Products ◽  
Cement Pastes

AbstractThis paper presents results from comparative thermogravimetric, calorimetric and pozzolanic activity analyses of five natural zeolite samples from Bulgaria, Slovakia, Philippines, USA and North Korea. The zeolites actively participate in the hydration processes of cement. Their activity in the early stage of hydration is based mainly on the large surface area of the particles while, in the later stages of activation, chemical reactions occur between the products of the hydration of cement and the soluble SiO2 that is present in the bulk of the zeolites. It has been shown that in all cement pastes which contain zeolite additives, the quantity of portlandite is lower than that in pure cement paste or is even totally absent. The amounts of hydration products are greater when 30% zeolite is used than when 10% zeolite is added (excluding the sample with chabazite). The lowest pozzolanic activity is shown by chabazite, which possessed the lowest SiO2/Al2O2 ratio.

scholarly journals DESIGN OF CEMENT COMPOSITES WITH INCREASED IMPERMEABILITY

Vestnik MGSU ◽  
2016 ◽  
pp. 72-81
Author(s):  
Roman Sergeevich Fedyuk
Keyword(s):  
Composite Materials ◽  
Cement Composite ◽  
Vapor Permeability ◽  
Cement Stone ◽  
Cement Composites ◽  
Hydrated Cement ◽  
Body Density ◽  
Scale Levels ◽  
Positive Effect ◽  
Improved Characteristics

The paper deals with the development of composite binders for producing concrete with improved characteristics of gas, water and vapor permeability. The authors investigate the processes of composite materials formation in order of decreasing scale levels from macro to nanostructures. The criteria for optimization of the volume of dispersed additives in concrete are offered. The authors theoretically studied the technological features of the formation of hydrated cement stone structure. A positive effect of nanodispersed additives on the structure and physico-mechanical properties of cement composite materials are predicted. Thanks to its improved features, such as good ratio of strength and body density, high density and lifetime, the modified concrete may be used when solving various practical tasks of the construction branch.

Cement Composites’ Biostability

2020 ◽  
Vol 1011 ◽  
pp. 171-178
Author(s):  
Alexander Rodin ◽  
Sergej Karpushin ◽  
Vasiliy Smirnov
Keyword(s):  
Species Composition ◽  
Sodium Sulfate ◽  
Sampling Methods ◽  
Sea Water ◽  
Cement Clinker ◽  
Cement Stone ◽  
Cement Composites ◽  
Portland Cement Clinker ◽  
Mineral Additive ◽  
Surface Modified

The studies to establish the species composition of micro-mycetes inhabiting the surface of cement composites after aging in sea water have been carried out. Cement stone made on the basis of Portland cement clinker, a mineral additive and a fungicidal preparation was considered as the studied material. To determine the materials’ fouling by microorganisms, their species composition, imprints and sampling methods were used. A change in the species composition of mycobiota isolated from the cement composites’ surface modified with sodium sulfate and sodium fluoride depending on the amount of active filler, gypsum, and biocidal additives was experimentally revealed. The effectiveness of using the biocidal cement composites with an active mineral additive has been confirmed. It was found that the composites on the developed compositions showed higher resistance compared to the materials on ordinary cement. The compositions modified with biocidal additives showed a fungicidal effect.

scholarly journals Nanoparticles of activated natural zeolite on textiles for protection and therapy

2009 ◽  
Vol 15 (4) ◽  
pp. 203-210 ◽  
Author(s):  
Ana Grancaric ◽  
Anita Tarbuk ◽  
Ivancica Kovacek
Keyword(s):  
Small Molecules ◽  
Natural Zeolite ◽  
Catalytic Properties ◽  
Antioxidant Effect ◽  
Healing Wounds ◽  
The Common ◽  
Living Organisms ◽  
Positive Effect ◽  
Agriculture Water ◽  
Protective Textiles

Activated natural zeolite clinoptilolite is microporous hydrated aluminosilicates crystals with well-defined structures containing AlO4 and SiO4 tetrahedral linked through the common oxygen atoms. It is to point out that zeolites act as strong adsorbents and ion-exchangers but having many other useful properties. Due to its cationexchange ability, zeolites have catalytic properties and, for that, multiple uses in medicine and industry, agriculture, water purification and detergents. Zeolites are nontoxic substance, excellent for UVR and microbes protection, for proteins and small molecules such as glucose adsorption. In this paper its positive effect on the metabolism of living organisms and its anticancerogenic, antiviral, antimetastatic and antioxidant effect. The activity of natural zeolite as natural immunostimulator was presented as well as its help in healing wounds. Therefore, the present paper is an attempt to modify cotton (by mercerization) and polyester (by alkaline hydrolysis) fabrics for summer clothing with addition of natural zeolite nanoparticles for achieving UV and antibacterial protective textiles.

scholarly journals Effect of Graphene Oxide on Mechanical Properties of Cement Mortar and its Strengthening Mechanism

Materials ◽  
2019 ◽  
Vol 12 (22) ◽  
pp. 3753 ◽  
Author(s):  
Yahui Wang ◽  
Jiawen Yang ◽  
Dong Ouyang
Keyword(s):  
Mechanical Properties ◽  
Graphene Oxide ◽  
Cement Hydration ◽  
Strengthening Mechanism ◽  
Cement Composites ◽  
Working Mechanism ◽  
Cement Pastes ◽  
Cement Mortars ◽  
Binder Ratio ◽  
Growth Space

The effects of the water–binder ratio and different graphene oxide (GO) sizes on the mechanical properties of GO-cement composites were systematically studied by preparing GO-cement mortars. The scanning electron microscopy observation (SEM) of the surface and fracture surface of cement pastes was carried out to study the morphology of cement hydration crystals in GO-cement systems under different space conditions. It was found that GO nanosheets significantly improved the compressive, flexural, and tensile strengths of cement mortars. When the dosage of GO nanosheets was 0.03% by weight of cement, the compressive, flexural, and tensile strengths at 28 days increased by 21.37%, 39.62%, and 53.77%, respectively, but GO was not found to be able to regulate the formation of flower-like cement hydration crystals. It was only shown that the growth space had an important influence on the morphology of hydrates. A possible working mechanism was proposed by which GO nanosheets prevented the expansion of microcracks in the cement pastes via a shield effect, thus enhancing the strength and toughness of the cement composites.

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