Concrete Binder Research Articles

Experimental Study of Sugarcane Bagasse Ash as Partial Replacement of Cement Based on SEM and XRF Analysis

This research aims to identify chemical composition and it’s leaching from concrete mixed with sugarcane bagasse ash. By manipulating percent of slump flow at 110±5%, sugarcane bagasse ash was employed as a pozzolanic material to partially replace cement at 0, 10, 20, 30, 40, and 50 percent by weight of binder in concrete. Cube specimens were cast and cured in water for 3, 7, 14 and, 28 days, respectively. The patterns of sugarcane bagasse ash morphology were performed by using Scanning Electron Microscope (SEM) to analyze physicochemical characteristics. Results of tests on the X-ray fluorescence (XRF) analysis from the ash and curing water at various times revealed that SiO2 made up half of the components in sugarcane bagasse ash. Al2O3, CaO, Fe2O3, K2O, P2O5, and MgO were the minor components. The calcium content from the 14-day period at 50% by weight of the sugarcane bagasse ash binder was higher than that of the other elements, according to the results of curing water. According to the results of 28-day water curing, potassium outnumbered all other elements in the replacement of sugarcane bagasse ash in every ratio.

Enhancing fire resistance of lightweight high-performance cementitious composites using hollow microspheres

Fire is detrimental to skyscrapers. Lightweight high-performance concrete (L-HPC) developed by combining lightweight microspheres and ultra-high-performance concrete binder is promising for future mega infrastructure projects. This study investigates the fire resistance of lightweight high-performance cementitious composites developed using hollow ceramic microspheres (HCMs) and hollow glass microspheres (HGMs) at different temperatures. Experimental results show that incorporating lightweight microspheres significantly increases the residual compressive strength of L-HPC by maintaining those of HGMs and HCMs groups at 92% and 78%, respectively, at 900 °C. Furthermore, these lightweight microspheres effectively mitigate thermal spalling and crack propagation in L-HPC. Microstructural analysis indicates that the lightweight microspheres facilitate steam-pressure release. The melting of HGMs realizes interconnections in the pore channel, which are subsequently strengthened by HGM and matrix-binder reactions. The HCMs feature perforated shells that provide inert and high-temperature-resistant steam channels. This study confirms that L-HPC developed using the abovementioned strategy exhibits excellent fire resistance.

Use of Various Industrial and Eggshell Wastes for the Sustainable Construction Sector

The alternative composites’ production alleviates the serious problem generated by global warming. Methods to reduce the amount of cement used in concrete production, for example, are being investigated to determine how to reduce carbon dioxide emissions in many applications. Egg shells and various industrial wastes, which are recommended to use in the construction sector at an appropriately high rate, also cause serious environmental damage. Bottom ash (BA) and marble powder (MP) wastes are used today in civil engineering applications. In addition, it is important to increase the use of eggshells due to their rich calcium carbonate content. In this work, BA and MP wastes were blended with eggshells to produce cement paste composites. Two different sets of composites were prepared during this study. The composites were prepared with cement (80%), BA (20%), and MP (20%) wastes by weight with 0.3%, 0.75%, 1.5%, and 2.5% eggshell waste. The fresh (flow table), physical (dry unit mass, apparent specific gravity, and porosity), mechanical (unconfined compressive strength and flexural strength), and durability (water absorption, seawater resistance) tests were conducted. According to the experimental results, the composites can be classified as lightweight construction materials. The test results showed that 0.75% eggshell by weight of cement in bottom ash and marble powder can be used as an optimum value for better performance. The bottom ash mixtures groups are higher water absorption and porosity values when referring to the marble powder mixture groups. The highest compressive strength value was found at 56.03 MPa in the MP mixture group and 52.79 MPa in the BA mixture groups with these optimum eggshell combinations at 56 days. The MP mixture group showed better resistance to seawater when referring to the bottom ash blended mixtures. Laboratory-produced composites are possible candidates for cost-effective and environmentally friendly building materials. The eggshells have a promising alternative binder for concrete in the near future and they are utilized together with industrial wastes such as BA and MP in sustainable concrete construction.

Investigate the Effect of Curing Methods for Different Types of Binder Concrete

Abstract Various curing techniques are typically used to achieve the required concrete strengths. The laboratory results of this study investigate the effects of curing techniques (namely water, air-dry, burlap, membrane, and chemical spray) on compressive strength (Fcu) and indirect tensile strength (Ft) using 200 specimens. To determine the optimum method for concrete curing, two different cement contents were used (350 kg/m3 450 kg/m3) with and without chemical admixture (superplasticizer, SP). Compressive and indirect tensile strengths were determined for the four different concrete mixes. Based on the experimental results, adding superplasticizer and increasing the cement content improved the mechanical properties of the concrete mix, as indicated by both compressive and tensile strength. Additionally, it was found that the longer the curing period of the concrete, the higher the Fcu. Furthermore, adding 1% SP has a more significant impact on Fcu than adding 100 kg of cement.

A hybrid technique adopted for study on the properties of alkali-activated binder concrete by using recycled concrete aggregates

ABSTRACT This manuscript presents a novel hybrid technique for assessing the geopolymer concrete’ properties incorporating recycled concrete aggregates. Named AO-GBDT, this hybrid approach combines the Aquila Optimizer (AO) and the Gradient Boosting Decision Tree algorithm. The primary objective is to reduce errors and predict the optimal strength of RCA geopolymers. The method investigates the interaction of key parameters and prediction values, like sodium silicate and sodium hydroxide to improve the binding materials. AO is specifically utilised for optimising the mixture proportions of RCA geopolymers, while GBDT is used to forecast the compressive strength of the optimised concrete mixtures. Additionally, the effects of fly ash (FA) and ground granulated blast furnace slag (GGBS) on the concrete’s hardened and fresh characteristics are investigated. Performance evaluation conducted in MATLAB demonstrates the effectiveness of the proposed system, which is contrasted to existing strategy. The proposed strategy exhibits a root-mean-square error of 1.8, a correlation coefficient (R) of 0.95 and a mean absolute error of 0.9, indicating its superior predictive accuracy and efficacy compared to existing approaches.

Characterization and Properties of Binder and Nano-Filler in Geopolymer Paste with Graphene Oxide

Globally, current research has developed new cement-based materials to meet increased demands for performance, energy efficiency, and environmental protection. Geopolymer, cost-effective, and high-early strength concrete binder alternative, has grown in popularity. Geopolymer reduces emissions by 80% during production while maintaining strength levels comparable to Ordinary Portland Cement (OPC). In their natural state, geopolymer binders have a microstructure that is cross-linked and significantly more brittle than OPC. To improve the properties of geopolymer, several approaches were adopted. However, recent study suggests that incorporating nanomaterials such as graphene oxide (GO) to geopolymer has shown an improvement in physical and mechanical properties. Graphene oxide is an inorganic nanomaterial that improves the mechanical characteristics of various composite materials by showing substantial filling effects on composite materials that significantly improve composite material integrity. The investigation into the potential of GO to improve the efficacy of geopolymer composite materials in various engineering applications has garnered considerable attention in recent years. The simplified hummer’s method was employed to synthesise the GO. Various characterization techniques involving SEM, XRD, and FTIR were utilized to understand the crystalline structure and microstructure of GO nanoparticles. GO powder were used as 0.05%, 0.10%, 0.15%, 0.20%, and 0.25% by weight of binder that includes fly ash class F and steel slag with an optimum binder modification of 40% fly ash and 60% steel slag. The influence of GO on Bulk density, microstructure, and mechanical strength were determined. The compressive strength results indicated an improvement of compressive strength by 21.48% in geopolymer paste with 0.15% GO after 28 days of curing.

Elucidating the role of recycled concrete powder in low-carbon ultra-high performance concrete (UHPC): Multi-performance evaluation

Reusing recycled powder as an alternative binder for ultra-high performance concrete (UHPC) offers a highly value-added approach to recycling concrete waste. This study shows the multi-performance evaluation of low-carbon UHPC containing recycled powder as a substitution of cement and silica fume. Recycled powder, which includes recycled concrete powder (RCP) and recycled paste powder (RPP), contains massive SiO2, CaCO3 and hydration products. Substituting recycled powder for cement reduces the cumulative hydration heat per gram binder, while increasing the cumulative hydration heat per gram cement of UHPC. Replacing high-volume cement and silica fume with recycled powder negatively impacts the micro-characteristics, increasing the drying shrinkage and transport properties. When using recycled powder as cement replacement, incorporating a moderate dosage of recycled powder has negligible impact and can even confer some beneficial effects on the mechanical strength. Substituting recycled powder for high-volume cement reduces the mechanical strength, yet the blended UHPC retains good mechanical strength. The compressive strength of UHPC containing RCP as 0 %, 30 %, 50 % and 70 % of cement is 157.6 MPa, 154.6 MPa, 145.0 MPa and 129.9 MPa, respectively. Due to its good dilution and active effects, the replacement of cement with recycled powder causes a significant increase in compressive strength per unit cement, and the mix of 70 % RCP increases the compressive strength per unit cement by 174.7 %. Besides, incorporating recycled powder as silica fume replacement causes a limited reduction in the mechanical strength of blended UHPC. The RCP-UHPC generally has better micro-macro properties than the RPP-UHPC. By optimizing recycled powder type and replacement rate, UHPC with excellent micro-macro performance can be achieved.

CONSTRUCTION AND OPERATIONAL PROPERTIES OF CONCRETE ON MODIFIED BINDER

The most important tasks of science in the field of construction: facilitating reinforced concrete structures, accelerating and reducing the cost of technological processes, in particular, abandoning heat treatment of products, increasing the durability of concrete can only be solved by giving special properties to binders. The way to solve this problem lies through the expansion of the range of complex mineral additives. Natural and man-made substances in a dispersed state, insoluble in water and characterized by grain size less than 0.16 mm, are used as mineral additives for binders and concretes. Despite the different effectiveness, mineral additives have a similar qualitative chemical composition (oxides of silicon, aluminum and others). The differences are in their mineralogical composition, the ratio of components and the degree of dispersion, which determine the predominant mechanism of their action in cement systems. Depending on the properties of the mineral additive, it is possible to obtain multicomponent binders for concretes with special properties: fast-hardening, high-strength, sulfate-resistant and others with significant savings in the cement component. The effectiveness of superplasticizers in dispersed systems can be increased due to a different procedure for their introduction or by combining them with finely ground mineral fillers of various chemical nature. The article presents the possibility of obtaining heavy concretes with specified construction and operational characteristics using a complex mineral additive, which includes waste from the tailings of the Balkhash mining and Processing plant and silica, as well as superplasticizers of various natures: MasterGlenium 305, Master Rheobuild 1000K and Master Air 200.

Modified Bitumen Materials from Kazakhstani Oilfield

The oil bitumen BND 90/130, produced at the “LLP SP Caspi Bitum” with the modifier, which consists of copolymer of ethylene with butyl acrylate and glycidyl methacrylate taken in an amount of 0.5–1.6 wt%, and the tire reclaim (4–20 wt%), which is the destructate of mesh elastomers of different chemical nature, was modified; possibility of using the developed bitumen-elastomer binders in road asphalt concrete was justified. Modification of bitumen with a copolymer of ethylene with butyl acrylate and glycidyl methacrylate leads to an improvement in the properties of road bitumen: the softening point, hardness, deformability at low temperatures, elasticity, and adhesion to metal and mineral filler increase. It was shown that ethylene with butyl acrylate and glycidyl methacrylate chemically interacts with the functional groups of bitumen asphaltenes through the epoxy group of glycidyl methacrylate. Analysis of the spectra and group composition indicates an increased content of high molecular weight asphaltenes in the modified bitumen with a slight increase in structuring resins. It has been established that bitumen modified with rubber crumbs of 0.6–1.0 mm in size has high elasticity. The most effective composition of a bitumen-regenerated composite material based on tire reclaim has been determined. In terms of the totality of physicochemical and operational characteristics and comparative cost, the most acceptable is the bitumen-regenerated composition (with a regenerate content of 20%) and is superior in the complex of properties to bitumen modified with an optimal content of ethylene with butyl acrylate and glycidyl methacrylate (1.6%). The technology for modifying bitumen with tire reclaim is less time-consuming, more economically profitable, and environmentally effective, since it utilizes large-tonnage waste of worn-out tires. The resulting bitumen-polymer compositions have a high positive set of properties: softening point, hardness, elasticity, frost resistance, and low-temperature characteristics.

Harmonizing smart technologies with building resilience and sustainable built environment systems

Given the escalating concerns posed by climate change-related disasters, there is an urgent need for a more sustainable and resilient built environment. The developing digital revolution in recent years has the potential to harness its superior features to achieve sustainable and resilient building sector goals. This paper aims to present a futuristic perspective on the three basic pillars of a more sustainable and resilient built environment. These pillars comprise sustainability, resilience, and the utilization of Artificial Intelligence (AI) for monitoring and managing structural health and performance. This is evident in the context of smart buildings and their ability to enhance energy consumption efficiency, improve quality of life, and strengthen structural health monitoring in terms of reducing damage and facilitating timely maintenance operations. Through comparing the components of the virtual city designed from two types of alkali-activated binder concrete (AABC) and ordinary Portland cement (OPC) concrete, all components of the city designed from AABC showed a reduction in the amount of emitted CO2. The highest decrease was observed in the schools designed from AABC, where the reduction was about 25 %, while the lowest decrease was for the villas and infrastructure; about 11 % and 10 % respectively, compared to those designed from OPC concrete. The results also indicated that the utilization of sustainable concrete instead of traditional varieties has the potential to decrease CO2 emissions by up to 25 %. The importance of this work resides in establishing a basis for forthcoming research that combines intelligent, environmentally friendly, and resilient building practices.

Experimental investigation of dynamic bond behaviors between LRS-FRP and concrete

The dynamic bonding behaviour at the interface between a large-rupture-strain fibre-reinforced polymer (LRS-FRP) and concrete was investigated via drop weight impact tests of notched beam specimens. The main experimental variables included the concrete strength grade, number of LRS-FRP layers, and loading rate. With increasing loading rate, the location of the peeling damage at the interface between the LRS-FRP and concrete shifted from the interior of the concrete layer to the concrete–binder layer interface, binder layer, and even binder layer–FRP interface. The ultimate debonding load of the LRS-FRP strips increased with increasing strain rate, reaching more than 1.7 times the static value at a strain rate of approximately 4/s, while the effective bond length did not show a clear increasing or decreasing tendency with increasing strain rate. For the local bond-slip relationship, both the peak interfacial bond stress and interfacial fracture energy increased with increasing strain rate, and the influences of the concrete strength and number of FRP layers on the strain rate sensitivity were insignificant. Based on the experimental results, improved models to predict the ultimate debonding load and effective bond length at the LRS-FRP–concrete interface under both static and dynamic loading conditions were proposed. Furthermore, dynamic increase factor (DIF) formulas for the peak interfacial bond stress and interfacial fracture energy for bond-slip modelling of the interface between a polyethylene naphthalate (PEN)-FRP and concrete were established.

Comparative study of different machine learning approaches for predicting the compressive strength of palm fuel ash concrete

Nowadays, the challenge of industrialising concrete is to produce economical, ecological and efficient concrete. As a result, cementitious additions are increasingly used in concrete binders with proportions conferring the desired properties, particularly compressive strength. Palm oil fuel ash (POFA) from palm trees is one of these additions and introduced by substitution of cement in concrete. Although laboratory tests applied to concrete samples are expensive and time-consuming, considerable research is directed towards modelling approaches and machine learning (ML) applications. The purpose of this study is to explore different ML techniques, including artificial neural network (ANN), ANN with combined inputs (ANNX), particle swarm optimisation (PSO) and genetic algorithm (GA). These techniques are used to predict the compressive strength of POFA concrete derived from a dataset consisting of 249 samples with regard to 6 input parameters, namely, cement and POFA contents, aggregate ratio, water-to-binder ratio, superplasticiser dosage and curing duration. The performance of these techniques is evaluated using six performance indices: correlation coefficient, Willmott index of agreement, Nash–Sutcliffe efficiency, root mean squared error, mean absolute error and mean squared relative error. The comparison shows that ANN and ANNX have better predictive accuracy than PSO and GA, and ANNX performs relatively better than ANN. Results are presented using a 3D surface response plot which visually depicts the relationship between predicted outcomes and influential parameters. The comparison made between ANNX and other models in the literature demonstrated that the present model is reliable to predict CS of POFA concrete with high precision in a wide range of data.

A multi-criterial optimization of low-carbon binders for a sustainable high-strength concrete using TOPSIS

The objective of this study is to focus on "low carbon binders," given the adverse environmental impacts resulting from the extensive emission of greenhouse gases. In the current context, the term "geopolymer concrete," often referred to as "low carbon binders," is gaining prominence as a means to develop an eco-friendly binding material. Furthermore, this study focuses on creating high-strength geopolymer binders using ambient curing conditions. Numerous factors are involved in determining the mix ratios for geopolymer concrete. Nonetheless, the reluctance to apply it in practical scenarios arises from an insufficient understanding of how to select the appropriate mix proportions based on these parameters. Therefore, utilizing Multi-Criteria Decision-Making presents the best choice for evaluating the geopolymer parameters. Among several MCDM methods, TOPSIS has been selected for this research. Geopolymer binders are produced using Ground Granulated Blast furnace Slag (GGBS), a by-product from the steel industry and metakaolin (MK), a product from the calcination of clay. A total of thirty-two combinations of geopolymer mortar mixes were created by varying the percentage of metakaolin, the ratio of alkaline activators (sodium silicate to sodium hydroxide, SS/SH), and the concentration of sodium hydroxide (NaOH). The assessment of these mixtures involves nine response factors, encompassing flow characteristics, initial and final setting time, compressive strength (7 and 28 days), initial drying shrinkage, energy consumption, CO2 emission, and financial expenses. A study of the microstructure is carried out to explore the impact of MK presence on geopolymers using GGBS as a base precursor. Hence, techniques for optimizing multiple responses were employed to attain the desired attributes while maintaining all measurable factors within an acceptable range. This approach to optimization holds significant importance, particularly when dealing with geopolymer concrete, as it can enhance its utilization compared to traditional cement-based concrete.

A sustainable treatment method to use municipal solid waste incinerator bottom ash as cement replacement

This paper studies the use of municipal solid waste incinerator bottom ash as a supplementary cementitious material in concrete products using an innovative chemical treatment approach. The primary objective is to address emissions associated with waste-to-energy facilities and the heavy reliance on ordinary Portland cement as the primary binder in concrete. The proposed method involves the removal of metallic aluminium from the bottom ash and the subsequent use of the treated bottom ash as a partial cement replacement to produce concrete. Concrete specimens were produced with varying proportions of treated or untreated municipal solid waste incinerator bottom ash, replacing 20%, 35%, and 55% of ordinary Portland cement according to EN 197 European standard for common cement. Moreover, class F fly ash was incorporated in equivalent percentages as a reference supplementary cementitious material, and a control mix was prepared using solely Portland cement. The evaluation encompassed multiple visual and analytical techniques, including scanning electron microscopy, X-ray diffraction, X-ray fluorescence, and setting time analyses on pastes made with Portland cement, fly ash, and bottom ash. All specimens were evaluated in terms of mechanical performance, namely compressive strength. The chemical treatment process facilitated the release of a significant quantity of hydrogen, a by-product of aluminium oxidization. Consequently, this resulted in significantly reduced formation of gas bubbles in concrete in the fresh state and, therefore, diminished expansion during the setting process. As the proportion of cement replacement with bottom ash increased, a decline in strength was observed. However, this decline was less pronounced when using treated bottom ash, particularly with lower levels of incorporation.

Mechanical and Microstructural Investigation of Geopolymer Concrete Incorporating Recycled Waste Plastic Aggregate.

The effective use of waste materials is one of the key drivers in ensuring sustainability within the construction industry. This paper investigates the viability and efficacy of sustainably incorporating a polylactic acid-type plastic (WP) as a 10 mm natural coarse aggregate (NA) replacement in geopolymer concrete. Two types of concrete (ordinary Portland cement-OPC and geopolymer) were produced for completeness using a concrete formulation ratio of 1:2:3. The ordinary concrete binder control was prepared using 100% OPC at a water/binder ratio of 0.55, while the geopolymer concrete control used an optimum alkaline activator/precursor-A/P ratio (0.5) and sodium silicate to sodium hydroxide-SS/SH volume ratio (1.2/0.8). Using the same binder quantity as the control, four concrete batches were developed by replacing 10 mm NA with WP at 30 and 70 wt% for ordinary and geopolymer concrete. The mechanical performance of the developed concrete was assessed according to their appropriate standards, while a microstructural investigation was employed after 28 days of curing to identify any morphological changes and hydrated phases. The results illustrate the viability of incorporating WP in geopolymer concrete production at up to 70 wt% replacement despite some negative impacts on concrete performance. From a mechanical perspective, geopolymer concrete indicated a 46.7-58.3% strength development superiority over ordinary concrete with or without WP. The sample composition and texture quantified using automated scanning electron microscopy indicated that adding WP reduced the presence of pores within the microstructure of both concrete types. However, this was detrimental to the ordinary concrete due to the low interfacial zone (ITZ) between calcium silicate hydrate (CSH) gel and WP, resulting in the formation of cracks.

To Study the Strength Characteristics of Concrete Using Mineral Admixture

Aside from the combustion of fossil fuels, the cement making business emits carbon dioxide. The global cement industry accounts for around 7% of greenhouse gas emissions into the earth's atmosphere. To address the environmental impacts connected with cement manufacturing, alternative concrete binders must be developed. Another important environmental concern is the extraction of natural resources such as sand from river bottoms. As a result, substantial study into the use of cement substitutes, including several waste materials and industrial byproducts, is continuing. Bamboo leaf ash was utilised as a partial replacement for cement and fenugreek as an addition in this study, and it was compared to standard concrete. The considered bamboo leaf ash was 5%, 10%, 15% by weight of cement for M25 grade concrete and 5% of fenugreek powder as additive for every mix [1]. Additionally, an experimental investigation of the effects of using bamboo leaf ash in place of some of the cement and fenugreek powder as an additive on the performance of concrete in terms of compressive strength and flexure strength. Concrete is cast for the experimental study, and cement is partially substituted with bamboo leaf ash by weight of cement and fenugreek powder as an addition. Because the inclusion of bamboo leaf ash and fenugreek powder works as a binding ingredient in the concrete, the compressive and flexural strength increases. Finally, the compressive and flexural strengths for the combination of bamboo leaf ash as a partial replacement and fenugreek powder as an addition powder in concrete are investigated for the best results obtained from the aforementioned experiment.

Influence of Aggressive Environment in Macro and Microstructural Properties of Bottom Ash Geopolymer Concrete

India generates 759.02 million metric tons of coal ash annually. Part of that quantity is successfully utilized, and the remaining portion of the ash is discarded into a landfill. There also is a need to address pollution. Cement industries are responsible for 7% of global warming. Cement has been replaced entirely by thermal power plant waste, and bottom ash is used as a binder to overcome those issues. A few researchers have carried out strength characterization, but an extensive study needs to be carried out under different environmental exposures. Therefore, the present study investigated macro and micro properties of bottom ash geopolymer concrete (BAGPC) subjected to aggressive ecological exposure conditions such as acid, salt, and sulfate attack. Sodium silicate (Na2SiO3) and sodium hydroxide (NaOH) of eight molarities were used as activators for the bottom ash geopolymer concrete (BAGPC) binder. Further bonding between steel and conventional concrete BAGPC mixes was investigated. The durability of conventional concrete (CC) was taken as the control mix to compare the durability of the optimized mix (B4) of bottom ash geopolymer. The test samples were cured for 28 days under ambient temperature and tested for the effect of MgSO4, NaCl, and HCl. The strength loss and weight loss of the BAGPC B4 mix after 7, 28, 56, 90, and 180 days under aggressive conditions showed better performance than CC. It has been observed that geopolymer concrete has good bonding in nature, and the bond strength results indicate excellent bonding between steel and concrete. Microstructure studies revealed that the BAGPC B4 mix had a strong microstructure and not as much of a porous structure. It is concluded that BAGPC has potential value in the construction industry based on all aspects of the experiment.

KARAKTERISTIK MORTAR GEOPOLIMER BERBASIS FLY ASH KELAS C DENGAN PENAMBAHAN BORAKS

Cement has been widely utilized as a primary material in the construction of structural and architectural elements. The cement factory industry can contribute to 30% of global carbon dioxide emissions. Geopolymers were first introduced by Davidovits in 1979 to represent inorganic polymers produced from geochemistry. Geopolymer materials make use of waste materials such as fly ash as a substitute for concrete binders. In this study, Class C (high calcium) fly ash from the Paiton Power Plant was used. The mix design for geopolymer mortar in this study employed the absolute volume calculation method. Absolute volume calculations are based on the absolute volume proportions of each constituent material within 1 m3. The compressive strength of geopolymer mortar with the addition of 5% borax to the molarity value, the alkali/cementitious ratio showed good performance in the mechanical properties of geopolymer mortar. Alkali/cementitious ratios of 0.3, 0.35, and 0.4 in Class C-based geopolymer mortar with 5% borax addition exhibited good workability, making it suitable for use as a base material in architectural material production.

ИССЛЕДОВАНИЕ ФАЗОВОГО СОСТАВА КОМПОЗИЦИОННЫХ ВЯЖУЩИХ ДЛЯ ГИДРОТЕХНИЧЕСКОГО БЕТОНА

The article studies production of composite binders for hydraulic concrete. Vitreous perlite from the Mukhor-Tala deposit of the Republic of Buryatia was used as an active mineral additive for the composite cement binder. Pozzolanic activity of vitreous and crystallized perlites was determined. Assessment of physical and mechanical properties and phase composition of autoclave-cured lime-perlite binders were carried out for subsequent assessment and identification of the hydrate phases of the composite cement binder. An X-ray phase analysis of Portland cement and a composite binder with vitreous perlite with a specific surface area of 600 m2/kg was carried out. The study established that use of active mineral additive based on glassy perlite leads to increase in amount of low-basic calcium hydrosilicates in cement stone. Electron microscopic analysis of composite binders for concrete hydraulic structures was carried out.

Experimental study on the effect of colloidal nano silica in high strength self-compacting concrete containing ground granulated blast furnace slag

Self-compacting concrete (SCC) is profusely utilized in building construction due to its unique design and mechanism of flow without segregation by occupying the corners and preventing the voids to achieve better compaction and mechanical strength. This work addresses the effect of colloidal nano-silica (NS) of size 5-40nm with an active nano solids content of 32% on the high-strength SCC containing Ground Granulated Blast Furnace Slag (GGBFS) and Ordinary Portland Cement as binders in addition to NS. The liquid content of 68% in NS was added to the water content in the mix. The ratios of NS were evaluated at 0%,0.5%,1%,1.5%, 2% and GGBFS as 20% by weight of binder in concrete. The water to binder ratio was 0.33 with a water and binder content of 184kg/m3 and 557.58 kg/m3. The optimum mix was 1.5% NS based on the concrete’s slump and compressive strength at 28 days. The slump was reduced with a rise in NS beyond 1.5% due to the accumulation of NS particles causing the reduction in flowability. The density of SCC for all the mixes was satisfactory. The compressive strength of optimum SCC, M21.5NS20G was decreased by 5.88% and increased by 0.49% and 2.45% at 7, 28 and 91 days to that of the reference mix whereas its split tensile strength was risen by 31.13%, 9.27%, and 12.41% and flexural strength was risen by 5.8% and reduced by 8.17% and 4.06% to that of the reference mix at aforementioned durations. The SEM and XRD analyses were conducted on the optimum hardened SCC mix at 28 days in which the presence of Calcium silicate hydrate compounds of different crystalline structures, viz., Ettringite, and Portlandite were observed. The SCC designed in the work can be used for structural applications such as beam-column joints.