Portland Cement CEM Research Articles

Environmental and technical assessment on the application of slate waste in Portland-composite cement CEM II

Large volumes of waste are generated from the manufacture of slabs, roofing, and tiles using slate stone. The use of waste in the construction industry is prevalent due to the environmental advantages associated with the implementation of circular economy standards. This paper examines the production of Portland cement CEM II using heat-treated slate waste. The fineness index results were 10.95 % for the 75-μm sieve and 23.53 % for the 45-μm sieve. Assessment of reactivity using mechanical methods showed that mortars produced with 20 % slate waste (SW) achieved a strength of 42.35 MPa and a mechanical index of 84.93 %. Direct measurement (FTIR), along with chemical methods (Frattini Test and Saturated lime test), confirm the pozzolanic activity of the slate waste. The environmental impact assessment demonstrated a reduction in the carbon dioxide emission rate by 21.49 % (6.54E+02 kgCO2-eq/t) with the use of Portland cement CEM II/CSW. The valorization of slate waste can contribute to the availability of an alternative source of raw material and the reduction of natural resource consumption. However, further studies on mechanical performance and durability are necessary for this waste to be applied in structural cementitious matrices.

CEMENTITIOUS SYSTEMS FOR HIGH-PERFORMANCE CONCRETES WITH IMPROVED CORROSION RESISTANCE

The article presents the results of research on cementitious systems "Portland cement CEM I 42,5 R - active mineral additives - microfillers - superplasticizer - hardening accelerators" for high-performance concrete with improved corrosion resistance. The resistance of concrete to corrosion caused by the influence of chemical substances was investigated - sulfate corrosion (class XA), which combines the processes of formation and accumulation of sparingly soluble salts in concrete, which are accompanied by internal stresses and destructive phenomena in concrete. The increase in corrosion resistance of high-performance concretes based on modified cementitious systems is explained mainly by the creation of a fine-crystalline microstructure with the formation of C-S-H phases, which contribute to the pores colmatation with age of hardening.

Mechanical properties of cement pastes containing plasma-treated silicon-based materials

The study delves into the impact of waste silicon-based materials on the mechanical characteristics of the resulting cement pastes. The investigation uses Portland cement CEM I 42.5R in conjunction with silicon-based waste materials sourced from the packaging industry, specifically from Recifa, a.s. Variations between the sample groups arise from differences in the concentration of silicon-based materials and the method of surface treatment. The inquiry seeks to assess the effects of two distinct levels of Si-based material incorporation, namely 10 wt. % and 20 wt. %, along with plasma treatment involving two different gases: oxygen (O2) and hydrogen (H2). The mechanical attributes under scrutiny encompass compressive and flexural strengths. The evaluation of mechanical properties is carried out on samples aged 28 days, with dimensions measuring 20 × 20 × 100 mm.

Experimental and operations viability assessment of powder-to-powder (P2P) mixture of graphene and cement for industrial applications

Studies have demonstrated that a minute quantity of graphene is sufficient to boost cement characteristics, but the attainment of good dispersion and uniformity of the resultant graphene-cement mixture remains a challenge. To alleviate these challenges, this study proposes a low-energy powder-to-powder homogeniser for dispersing reasonably large quantities of graphene powder into cement powders. Microscopic analysis of graphene dispersion from two samples (1% and 0.02% graphene) at 5x, 10x and 20x objectives revealed that graphene accounts for 1.3% and 0.09% over the cement area respectively, which is relatively uniform across all selected samples. Furthermore, four different dosages of graphene were used to validate the impacts of various proportions of graphene, i.e., 0%, 0.02%, 0.04% and 0.06% (by mass of cement) on two types of cement (i.e., Portland cement CEM I 52.5 N and Portland cement CEM II 42.5 N) which also revealed compressive strength increases up to 25% at 7 and 28 days.

Experimental Investigation and Classification of Wastewater Treatment Sludge as Pozzolan for Cement

This paper presents an investigation conducted to evaluate wastewater treatment sludge for potential use as a cement extender or pozzolan. Two varieties comprising the digested wastewater sludge (DWWS) and activated wastewater sludge (AWWS) materials, were finely ground then calcined at 750 °C for 30 min. Subsequently, the calcined sludge waste materials were blended with ordinary Portland cement CEM I 52.5 N at 0, 10, 20, 30% DWWS or AWWS, and used to prepare mortar mixtures at proportions of 1:3:0.61 cement to sand to water. Various tests were conducted including workability, compressive strength, pozzolanic activity with lime, drying shrinkage and alkali-silica reaction. It was found that both varieties of the sludge waste materials, once blended with CEM I at 20% DWWS or 20% AWWS, satisfied the ASTM C618 criteria for Class C pozzolan, and may be classified as CEM II /A-P 32.5 N,R cement type of EN 197-1/SANS 50197-1. The overall performance of DWWS was relatively better than that of AWWS.

DURABILITY OF RIGID PAVEMENT CONCRETE REINFORCED WITH BASALT FIBER

The purpose of the work is the development of fiber-reinforced concrete compositions for rigid pavements with properties of high strength, frost resistance and wear resistance due to the use of polycarboxylate type superplasticizer and dispersed reinforcement. The experiments were conducted according to an optimal 3-factor 15-point plan. The following composition factors were varied: the amount of Portland cement CEM I 42.5 R (from 290 to 350 kg/m3); the amount of basalt fiber BAUCON®-bazalt (from 0.9 to 1.5 kg/m3); the amount of polycarboxylate superplasticizer STACHEMENT 2570/5/G (from 0.6 to 1 % by weight of cement). The workability of all developed mixtures was S1, which corresponded to a cone slump 2...3 cm. Research results shows when increasing the amount of cement and the amount of superplasticizer to 0.9 – 1.0 %, the W/C of the mixtures decreases. The amount of basalt fiber practically does not affect the W/C of the mixture. Due to increase in the amount of Portland cement, the strength of fiber-reinforced concrete is increases, as expected. With an increase in the amount of basalt fiber to 1.3 – 1.4 kg/m3, the tensile strength in bending of concrete increases by 12 – 21 %, while the compressive strength changes insignificantly. Fiber concrete with a superplasticizer content of about 0.9 % has the highest compressive and tensile strength in bending. Moreover, due to increase in the amount of Portland cement from 290 to 350 kg/m3, the frost resistance of concrete increases to about 100 cycles. Due to the increase in strength of that composition, the wear resistance of concrete was increased. With an increase in the amount of basalt fiber from 0.9 to 1.3 – 1.4 kg/m3, the wear resistance of concrete increases by 11 – 16 %, and frost resistance increases to approximately 50 cycles. The change in the amount of superplasticizer has little effect on the wear resistance of concrete. However, with an increase in the amount of additive STACHEMENT 2570/5/G from 0.6 to 0.9 % by weight of cement, the frost resistance of fiber-reinforced concrete increases to about 50 cycles. Fiber concretes with a rational amount of dispersed reinforcement (1.3 – 1.4 kg/m3) and superplasticizer (0.9 %), depending on the amount of cement, have compressive strength from 43 to 60 MPa; tensile strength in bending from 4.9 to 6.4 MPa; wear resistance from 0.31 to 0.37 g/cm2 and frost resistance from F200 to F300. This ensures the high durability of the developed fiber-reinforced concrete for rigid pavements.

Investigations on the Suitability of Alternative and Supplementary Cementitious Materials to produce High Performance Aerogel Concrete

AbstractHigh Performance Aerogel Concretes (HPAC) are produced by embedding silica aerogels in high‐performance matrices, which were previously based on finely ground Portland cement CEM I 52.5 R and microsilica. On the one hand, this ensured a comparatively high compressive strength, but on the other hand it was associated with large shrinkage strains and a high global warming potential (GWP). In the following, approaches are presented on how these disadvantages can be counteracted by replacing Portland cement with alternative (ACM) or supplementary cementitious materials (SCM). In the experimental investigations, calcium aluminate cement, calcium sulfoaluminate cement, calcium sulfoaluminate belite cement and a CSH phase binder were used as ACMs; limestone powder, calcined clay, fly ash, glass powder, rice husk ash, brick dust and ground granulated blast‐furnace slag were used as SCMs. Based on extensive fresh and hardened concrete tests, it could be shown that with the (partial) replacement of Portland cement by ACMs or SCMs, High Performance Aerogel Concretes can be produced that have significantly reduced shrinkage deformations and a lower GWP with an unchanged good relationship between compressive strength and thermal conductivity.

Mathematical Modeling of Technological Processes of Concreting Monolithic Structures From Fine-Grained Mixtures

Introduction. The introduction of innovative technologies and materials in the construction industry is constrained by a number of reasons associated with insufficient knowledge of technological processes and the increased cost of highly efficient innovative materials. Therefore, studies in the field of monolithic concrete technology, reflecting the features of concreting structures from self-compacting mixtures and aimed at reducing their cost due to the use of construction waste, are relevant. The purpose of this work is experimental and statistical modeling of rheological characteristics of finegrained self-compacting concrete mixtures and physical and mechanical properties of concretes depending on the influence of two recipe factors — consumption of superplastifying additive and particle size distribution of aggregate including construction wastes.Materials and Methods. For the preparation of fine-grained self-compacting concrete mixtures, portlandcement CEM 0 52,5N, natural quartz sand and crushed concrete sand of a mixture of three fractions of 0.63–5.0 mm and a chemical additive - a superplasticizer based on polycarboxylate esters Polyplast PK were used. Process characteristics of fine-grained self-compacting mixtures (workability, viscosity, fluidity) were determined by standard methods. The shear limits of the mixtures were set by means of an instrument comprising a cylinder with a nozzle and a glass base with circumferential marking. Modeling of rheological and physical-mechanical properties of fine-grained self-compacting concretes was carried out using a two-factor simplex-summed plan on a hexagon inscribed in a circle, which is one of the most convenient for solving technological problems of construction materials science.Results. Experimental-statistical models of rheological characteristics of fine-grained self-compacting mixtures and strength properties of concrete were obtained, adequately describing experimental data.Discussion and Conclusion. The use of mathematical planning methods of the experiment made it possible to comprehensively assess the influence of the two most significant recipe factors on the technological processes of concreting monolithic reinforced concrete structures from fine-grained self-compacting mixtures using aggregate from construction waste. It was established that optimal content of grains from crushed concrete in natural sand is 30–35 %, and dosage of superplasticizer Polyplast PK is 1.2–1.25 % of binder weight.

Influence of the Amount of Conductive Component on the Electrical Resistivity of Fine-Grained Electrically Conductive Concrete

Approaches to the production of electrically conductive concrete and the possibility of its application through the use of electrical properties in various industries are considered. The results of testing the compositions of fine-grained self-compacting concrete based on Portland cement CEM I 52.5 N, sand with a size modulus Mk=2.43 and polycarboxylate plasticizer for changes in electrical resistivity during hardening are presented. The increase in specific electrical conductivity was provided by the introduction of conductive components in various quantities, such as construction soot, carbon black K-354, graphite EUT-2. The positive effect of increasing the amount of the conductive component on the electrical resistivity for 28 days of normal hardening of the samples and on the ability to resistive heating by changing the surface temperature of the samples when passing a direct current with a voltage of 30 V. is shown.

Toward clima-resilient ultra-high performance concrete (UHPC): A survey on high-strength mortars engineered with extra-low dosage graphene-based materials (GBMs)

Latest advances showed that ultra-high performance concrete (UHPC) holds the potential to meet the criteria of future civil infrastructures. Several nanofillers (NFs) proved to enhance the performance of UHPC in terms of economic and environmental sustainability and even assigning novel features. Presently, this promising approach is still in its early stage. In this perspective, mortars based on Portland cement CEM I 52.5 N were engineered with extra-low dosage (0.01% by weight of cement) graphene nanoplatelets (GNPs) or nanographite (nG). An acrylic superplasticizer for high-strength concrete was used as additive. Fresh properties of the cementitious admixtures were characterized by viscosity measurements, flow table and bleeding tests. Prismatic specimens were hardened in water at room temperature for 28 days. Microstructure was observed by Scanning Electron Microscopy, the pore structure and specific surface area (SSA) investigated by Mercury Intrusion Porosimetry (MIP) and nitrogen adsorption-desorption measurements, thermal behavior studied by thermogravimetry, and mechanical strength evaluated by compression and bending tests. Electrical resistivity was determined by Electrochemical Impedance Spectroscopy (EIS). Both 2D-NFs induced a slight lubricant effect that did not significantly affect neither workability nor bleeding. GNPs do not appreciably impact on the mechanical properties of the hardened nano-engineered materials, a decay of bending strength was observed only for nG-loaded samples. The positive impact of the extra-low dosage GNPs on the hardened mortars was clearly detected by MIP and EIS in terms of reduced porosity (−31%), improved bulk density (+5.7%), pore refining (median and average pore diameter −35% and −9%, respectively), increased resistivity (+97%) and lowered predicted intrinsic permeability (−52%). In the same experimental condition, nG-engineered mortars suffered from uneven dispersion that led to increased porosity and pore coarsening.

STRENGTH OF CONCRETE FOR BASES OF ROAD CLOTHES ON DIFFERENT TYPES OF SECONDARY GRAVEL AND SAND

The task of developing of concrete for the bases of road clothing using secondary concrete aggregates is relevant for an economic and ecological reasons. The properties of concrete were compared with different types of coarse aggregate of 8-16 mm fraction: granite river gravel, secondary crushed stone from recycled reinforced concrete structures, secondary crushed stone from recycled brickwork and ceramic tiles. Three types of sand with a fraction of 0-4 mm were also used: quartz, secondary sand from recycled reinforced concrete structures, secondary sand from recycled brickwork. 2 series of experiments were conducted. During the first series of experiments Portland cement CEM II/B-S 32.5 R and superplasticizer Soudal Soudaplast was used (1% from weight of cement). For the second series of experiments Portland cement CEM II/B-S 42.5 R and superplasticizer Berament HT28 was used (1.2% from weight of cement). The mobility of all mixtures was equal to S1. Concretes with Berament HT28 superplasticizer had a lower W/C ratio of mixture than concretes with similar aggregates composition and Soudal Soudaplast superplasticizer. The use of secondary crushed stone requires an increasing of the W/C ratio of the mixture. The simultaneous use of secondary sand additionally increases W/C. Due to the lower W/C, the concretes of the second series have a higher average density than the similar concretes of the first series of the experiment. Concretes based on granite gravel and quartz sand have the highest average density (2369-2465 kg/m3). When using secondary crushed stone from reinforced concrete structures, the average density decreases by 3-5%. When using secondary crushed stone from brickwork and ceramic tiles – decreases by 8-9%. Concretes based on secondary crushed stone and sand from reinforced concrete structures have a 6-9% lower average density compared to concretes on granite gravel. Concretes based on secondary crushed stone and sand from recycled brickwork and ceramic tiles have the lowest average density – from 2015 to 2061 kg/m3. Due to the use of higher grade cement and a more effective superplasticizer, the strength of the concretes of the second series of the experiment at the age of 3 days was 69-190% higher than the strength of similar concretes of the first series, at the age of 28 days – higher by 67 to 147%. When using quartz sand, concrete based on secondary crushed stone from reinforced concrete structures has the greatest strength. At the age of 3 days up to 17.97 MPa and 30.33 MPa, at the design age (28 days) up to 32.07 and 53.41 MPa for the first and second series, respectively. The lowest strength (about 16 MPa in the first series of experiments and 27 MPa in the second) had concretes using only low-strength secondary aggregates from recycled brickwork and ceramic tiles. In general, all the studied concretes on secondary aggregates were characterized by sufficient strength for their use in the bases of hard road clothes.

Research on the Effect of Fire Thermal Energy on the Microstructure and Properties Mechanical of Fiber-Reinforced Cement Mortars

Cement mortar is made of a combination of cement, sand, and water, mixed in the right proportions. It is ideal for erecting walls and masonry structures, including those that must bear heavy loads. In addition, it is used in places that are exposed to higher humidity and in facilities located below ground level. The potential uses of a mortar are determined by material modification. The aim of the experimental studies was to evaluate the effect of high temperature on the microstructure and mechanical properties of cement mortars modified with polypropylene fiber. The novelty of this study is an attempt to compare the use of different types of polypropylene fibers in mortars heated at different temperatures. Cement mortars based on Portland cement CEM I 42.5 R with a constant content of three types of fibers in the amount of 0.9 kg/m3 were designed. The samples were cured and then heated in an oven at 300, 500 and 700 °C. The functional properties of cement mortars, i.e., density, flexural and compressive strength after 28 and 56 days of maturation, as well as flexural and compressive strength at elevated temperature, were determined using samples of 40 × 40 × 160 mm. By modifying cement mortars with fibers, it is possible to obtain a cement composite with good strength parameters which is, at the same time, resistant to high temperature.

Modification of Concrete Composition Doped by Sewage Sludge Fly Ash and Its Effect on Compressive Strength.

The sustainable development of construction materials is an essential aspect of current worldwide trends. Reusing post-production waste in the building industry has numerous positive effects on the environment. Since concrete is one of the materials that people manufacture and use the most, it will continue to be an integral element of the surrounding reality. In this study, the relationship between the individual components and parameters of concrete and its compressive strength properties was assessed. In the experimental works, concrete mixes with different contents of sand, gravel, Portland cement CEM II/B-S 42.5 N, water, superplasticizer, air-entraining admixture, and fly ash from the thermal conversion of municipal sewage sludge (SSFA) were designed. According to legal requirements in the European Union, SSFA waste from the sewage sludge incineration process in a fluidized bed furnace should not be stored in landfills but processed in various ways. Unfortunately, its generated amounts are too large, so new management technologies should be sought. During the experimental work, the compressive strength of concrete samples of various classes, namely, C8/10, C12/15, C16/20, C20/25, C25/30, C30/37, and C35/45, were measured. The higher-class concrete samples that were used, the greater the compressive strength obtained, ranging from 13.7 to 55.2 MPa. A correlation analysis was carried out between the mechanical strength of waste-modified concretes and the composition of concrete mixes (the amount of sand and gravel, cement, and FA), as well as the water-to-cement ratio and the sand point. No negative effect of the addition of SSFA on the strength of concrete samples was demonstrated, which translates into economic and environmental benefits.

An evaluation of cooling Portland cement mortars exposed to high temperature, by using firefighting foam

The purpose of this study was to investigate the effects of cooling Portland cement mortars exposed to high temperature, with synthetic high-expansion firefighting foam. In this experimental study, mortar samples produced with Portland cement CEM I 42,5R, Rilem-Cembureau sand and tap water were first subjected to water curing for 28, 90 and 180 days and then exposed to 20°C, 150°C, 300°C, 500°C and 700°C for 3 hours, respectively. Cement mortars exposed to high temperatures were cooled with high expansion firefighting foam and the resulting flexural strength and compressive strengths were evaluated according to hydration period and temperature parameters. Subsequently, 180-day cement mortar samples exposed to high temperature were cooled using air, water, and foam cooling methods. It was determined that the air cooling method resulted in a higher compressive strength than water or foam cooling. The flexural strength, compressive strength, ultrasonic pulse velocity, and mass loss percentage values, obtained by the different cooling methods and exposure temperatures employed, were then analysed. It was determined that samples exposed to 500°C, cooling with firefighting foam, yielded a compressive strength of 9% higher, compared to water cooling. SEM images of 180-day Portland cement mortars exposed to 20°C, 300°C and 700°C and subsequently air, water and foam cooled, respectively, were obtained and analysed.

An experimental study investigating the effects of bentonite clay on mechanical and thermal properties of concrete

Concrete is one of the most popular building materials used in civil engineering applications. In order to reach the sustainability goals and produce more environmental construction materials, replacing some amount of cement in concrete with natural or industrial mineral additives is of great importance. In this research, from 0 to 30% by volume Portland cement (PC) CEM II 42.5R was replaced with bentonite clay (BC) and standard mortar samples were prepared in five different series, including control samples. Artificial aggregates (AA) with powder mixture of 90% ground granulated blast furnace slag (GGBFS) and 10% PC by weight were pelletized through cold-bonded agglomeration process in samples containing bentonite with different proportions. Mechanical tests and thermal conductivity tests have been performed on concrete samples at the age of 28 days. The results show that the compressive strength of the samples with 5% BC are 94.7% higher and the thermal conductivity of the same samples are 31.2% lower compared to the control sample. However, it is revealed that, increasing the amount of bentonite more than 15% decreases the mechanical and thermal properties considerably. The study revealed that the use of natural materials with low environmental impacts has increased the mechanical and thermal properties of construction materials which will provide significant benefits for sustainable construction.

The influence of eggshell powder and limestone on the rheological properties of cement pastes

The paper presents the effect of the powders obtained from egg-shells and limestone on the rheological properties of cement pastes. Both powders were added to Portland cement CEM I 42.5 R, 30% by mass. The higher yield stress and plastic viscosity of the cement pastes prepared with the addition of eggshell powder, compared to the cement pastes made with limestone powder, were explained by the influence of the eggshell membrane and its chemical structure. The membrane, which absorbs water and expands in the cement paste, is causing an increase in rheological parameters. The membrane, which absorbs water and swells in the cement paste, causes an increase in viscosity and thixotropy compared to the neat cement slurry and slurry with limestone meal added as a result of particle bonding.

Modifying Water-Frost Resistance and Mechanical Properties of Lime Mortar Using Siliceous and Fluidised Bed Fly Combusted Ashes Activated with Cement.

The research focuses on pozzolanic additives, which are compatible with traditional lime mortars, and enable the modification of the rheological, physical and mechanical properties of tested composites. It was noted that lime mortars with fluidised bed fly ash require sand without impurities to avoid possible ettringite crystallisation. The work presents siliceous fly ash and fluidised bed combustion fly ash to modify the frost resistance and mechanical properties of traditional lime mortars with and without the addition of cement. The results show better effects using fluidised bed ash. Traditional Portland cement CEM I 42.5R was used to activate ash and increase the results. The possibility of a significant improvement of properties is indicated with a hybrid addition to the lime binder of 15-30% ash (siliceous or fluidised bed ash) and 15-30% cement. Changing the class and type of cement provides an additional opportunity to alter the properties of the composites. For architectural reasons relating to colour, the suitability of lighter fluidised bed ash instead of darker siliceous ash and of white Portland cement instead of the traditional grey cement can be used. The proposed mortars can be the basis for future modifications with admixtures and additives, e.g., metakaolin, polymers, fibres, slag, glass powder and impregnating agents.

Evaluation of metakaolin pozzolan for cement in South Africa

This paper presents findings of an experimental study conducted to evaluate the performance of metakaolin (MK) for potential use as a supplementary cementitious material or cement extender in South Africa. In this study, various proportions consisting of 0%, 5%, 10%, 15% MK were incorporated into ordinary Portland cement CEM I 52.5 N, then used to prepare mortar mixtures. Various mechanical and durability properties were measured comprising flowability, compressive strength, pozzolanic activity with lime, drying shrinkage, alkali - silica reaction (ASR) and sulphate resistance. Analytical studies were done using X - ray diffraction and scanning electron microscopy. It was found that incorporation of 10%–15% MK into Portland cement led to improved flowability, compressive strength increase and lower drying shrinkage, while ASR and sulphate attack processes were effectively mitigated. Results showed that the MK extender satisfied ASTM C618 specified criteria for ‘Class N’ pozzolan. Incorporation of 15% MK into Portland cement also met the requirements categorising the blend as CEM II/A–P 42.5 N cement type of SANS EN 50197–1.

Nanomodified Basalt Fiber Cement Composite with Bottom Ash

Directed control of the process of structure formation of a cement composite from modern positions must be carried out taking into account the synergistic effect of its components. In particular, the cement composite, when applied with pozzolanic additives and fiber reinforcement, is transformed into a more complex material with excellent performance. The aim of the article is to study the combined action of nanomodified basalt fiber (NBF) and bottom ash (BA) as structural elements of concrete. To achieve this aim, a number of tasks were performed, including the development of nanomodified-basalt-fiber–bottom-ash–cement concretes, as well as the study of their fresh, physical and mechanical properties (flowability, average density, compressive and flexural strength, elastic modulus and crack resistance) and durability characteristics (water, frost and abrasion resistance). A series of nanomodified basalt-fiber-reinforced concretes (from 0 to 7 wt.% NBF) were developed, in which the economical Portland cement CEM I 32.5 N was replaced by up to 45 wt.% mechanically activated bottom ash residue (400 m2/kg). An economical superplasticizer with a high water-reducing capacity (35%) made it possible to achieve uniform flowability of the mixes (slump 20–22 cm and slump flow 45–52 cm). The combined effect of BA and NBF provides control over the structure formation of cement materials, which ensures the redistribution of internal stresses from shrinkage deformations throughout the entire volume of the composite; under loading, the process of crack formation slows down, the stress concentration near structural defects decreases, and stresses are redistributed in the microstructure of the cement composite between its components. Perfect values of mechanical properties (compressive strength up to 59.2 MPa, flexural strength up to 17.8 MPa, elastic modulus up to 52.6 GPa, critical stress intensity factor 0.507 MPa m0.5) are explained by the complex action of the ash residue and nanomodified basalt fibers. A mix with 30 wt.% BA and 5 wt.% NBF is characterized by water resistance grade W18, frost resistance class F400 and abrasion resistance 0.59 g/cm2, which confirms the high wear resistance of the developed materials.

Combined effect on properties and durability performance of nanomodified basalt fiber blended with bottom ash-based cement concrete: ANOVA evaluation

A control of a cement composite structure formation from modern positions should be carried out taking into account the synergistic effect of its components. The goal of the article is to study the combined effect of nanomodified basalt fiber (NBF) and bottom ash (BA) as structural elements of concrete using a two-factor analysis of variance ANOVA. The tasks for achieving this goal are the development of nanomodified basalt fiber bottom ash-cement concretes, as well as the study of their fresh, physical and mechanical properties (slump, slump flow, average density, compressive and flexural strength, elastic modulus and crack resistance) and durability performances (water, frost, and abrasion resistance). Nanomodified basalt-fiber-reinforced concretes (from 0 to 7 wt % NBF) have been developed, in which the economical Portland cement CEM I 32.5 N is replaced by up to 45 wt % mechanically activated bottom ash (400 m2/kg). Achieving uniform flowability of the compositions (slump 20–22 cm and slump flow 45–52 cm) was carried out by varying the dosage of an economical superplasticizer with a high water-reducing ability (35%). The joint effect of the BA and NBF provides control over the structure formation of cement materials, which ensures the redistribution of internal stresses from shrinkage deformations throughout the entire volume of the composite; during loading, the process of crack formation is retarded, stress concentration near structural defects is reduced, and stresses are redistributed in the microstructure of the cement composite between its components.High values of mechanical properties (compressive strength up to 59.2 MPa, flexural strength up to 17.8 MPa, elastic modulus up to 52.6 GPa, limit stress intensity factor 0.507 MPa m0.5) are explained by the complex effect of bottom ash and nanomodified basalt fibers. For the composition with 30 wt % BA and 5 wt % NBF, W18 water resistance grade, F400 frost resistance grade, and the abrasion resistance of 0.59 g/cm2 were achieved, which characterizes the high durability of the developed materials.