Clinker-free Binder Research Articles

Seawater Mixed with One Part Alkali Activated Material: An Environmental and Cost Evaluation.

Concrete production is associated with extensive energy consumption and significant CO2 emissions. In addition, tremendous amounts of freshwater are used as a mixing agent. Urgency is increasing to develop sustainable cementitious materials and promote freshwater-saving strategies. An environmentally friendly alternative binder, seawater mixed with one part alkali activated material, is studied. In this work, a cradle-to-gate life cycle assessment was applied to study the equivalent CO2 emission and cost properties of the clinker-free binder. The seawater mixed mortar possesses comparable mechanical properties to Portland cement, with 3 d flexural and compressive strengths of 5.3 MPa and 25.2 MPa. In addition, the mortar developed in this work is of similar cost as commercial cement, but reduces CO2 emissions by 44.8%.

Novel activation method of waste concrete powder for sustainable clinker-free binder

This study investigates the environmental and mechanical implications of incorporating silica fume into lime-activated thermo-mechanically treated waste concrete powder (TMWCP) to develop a sustainable clinker-free binder. The novel activation method involves thermo-mechanical treatment of WCP, followed by lime and calcium formate chemical activation. The results demonstrated that incorporating silica fume enhanced the pozzolanic reactivity, which led to the formation of C–S–H, pore refinement, and a dramatic increase in compressive strength. For instance, the incorporation of 20 % and 25 % silica fume exhibited compressive strength of 46 MPa and 43 MPa after 28 days of curing. The developed clinker-free binder with the addition of 20 % silica fume demonstrated a reduction in mineral resource consumption of 99.3 % and CO2 emissions of 13 % and 69.3 % compared to the sample without silica fume and ordinary Portland cement, respectively. This study offers a promising avenue for the widespread utilization of WCP as an environmentally friendly clinker-free binder.

Clinker-free binders based on waste from the extraction and processing of tuff open cast mines in Armenia

The paper is related to the development of clinker-free binders based on Armenian tuff wastes, namely the Artik and Dzhraber deposits, which opencast mines are the most extensively used. Both studied rocks are mutable, which is explained by the high content of the glass phase. On their basis, it is possible to develop thermodynamically active systems that can change the state by thermal and mechanical effects using the energy of both the system itself and the environment surrounding the system, resulting in the formation of new structural bonds through hydration hardening. The compositions of clinker-free binders are given, and methods for increasing the reactivity of selected volcanic aluminosilicate rocks are investigated.

Rheology, mechanical properties, and hydration of synergistically activated coal gasification slag with three typical solid wastes

The utilization of multiple solid-waste-activated slags to prepare clinker-free binders has garnered considerable interest due to their environmental friendliness and low cost. In this study, a novel binder was developed by incorporating multiple solid wastes, namely red mud (RM), carbide slag (CS), phosphogypsum (PG), and coal gasification slag (CGS). RM, CS, and PG were used as activators to synergistically activate two kinds of ultra-fine CGS precursors with median particle sizes of 5.2 μm and 6.1 μm, respectively. The effects of parameters including precursor fineness and activator dosage were systematically investigated. The hydration products were then characterized to elucidate the activation mechanism. The results showed that the rheology of the pastes fitted well with Herschel-Bulkley model, exhibiting shear thinning behavior regardless of the proportion of the activators. The low CGS fineness and high PG dosage reduced viscosity, yield stress, and shear stress of the pastes. Fine CGS particles were found to shorten the hydration dormancy period and accelerate the appearance of the second exothermic peak, thus promoting strength development. CGS with small particles facilitated the formation of ettringite but restricted hydrotalcite generation. This study reported a binder utilizing full solid wastes and confirmed its feasibility as a sustainable alternative in construction applications.

Utilizing granulated blast furnace slag as an alternative cement binder

This study addresses the challenges associated with the accumulation of technogenic waste in the production of ferrous and non-ferrous metals. We present the findings of global research on the utilization of blast furnace slag as a sustainable alternative to traditional cement binders. Our scientific investigation focuses on the laboratory exploration of replacing cement binders with a highly efficient clinkerless alternative based on blast furnace slag. The fundamentals of formulating clinkerless binders from slag were thoroughly examined for binder design. Through an extensive review, we conducted tests to identify an optimal composition, constrained within the ranges of 70-90% blast-furnace granulated slag, 14% lime, 1.5-2% gypsum, 1.5-2% C-3, and 2-25% microsilica. The outcome of these tests resulted in the development of a novel binder that combines the characteristics and properties of a lime-slag binder with the advantages of a low water consumption binder. This clinker-free binder presents a sustainable solution for construction, serving as a viable substitute for traditional cement. Our findings contribute to the ongoing efforts in adopting environmentally friendly practices in the construction industry.

Identifying the influence of expanded clay concrete based on a binder from phosphorus slag on the strength of structures from leaked concrete

The paper presents the results of experimental studies of concrete and compressed reinforced concrete elements from cementless claydite-concrete. An experimental study of reinforced concrete elements with central and eccentric application of forces was carried out to determine their increased sensitivity. The construction material is cementless expanded clay concrete, obtained by a mixture of finely divided granular electrothermophosphorus slag. The tests were carried out on reinforced concrete compressed elements with central and eccentric application of longitudinal force to determine their bearing capacity. According to the test results, the strength and deformation properties of new concrete on a glass-slag binder and the calculation of reinforced concrete structures are checked. The selection of compositions of glass-slag claydite-concrete of various grades has been made. The use of concrete with a clinker-free binder in construction makes it possible to reduce the need for a scarce building material – cement. Studies of the physical and mechanical properties of glass-slag expanded clay concrete grades M50+M150 with a bulk density of 1,000–1,400 kg/m3 were carried out under a short-term static load. At the same time, the strength and deformation properties of glass-slag expanded clay concrete were studied under short-term action of compressive and tensile loads. The use of any new building material must be preceded by a comprehensive study of it – determination of its strength properties, study of concrete in the structure under load, etc. Building codes and regulations are adopted for the standard construction material, the properties of aggregates are not taken into account. Our studies show that the properties of fillers increase the strength properties of the structure when using claydite concrete on a glass-slag binder in reinforced concrete structures

Stabilization/solidification of lead- and cadmium-containing tailings for cemented paste backfill by using clinker-free binders

Clinker-free cementitious materials are essential for both lowering the costs of cemented paste backfill (CPB) and ensuring that the heavy metal leaching meets relevant standards. This study investigated the influence of Pb(Ⅱ) and Cd(Ⅱ) on the hydration and mechanical properties of slag-based low-carbon binders, as well as the solidification/stabilization (S/S) efficiency of Pb(Ⅱ)- and Cd(Ⅱ)-containing tailings. The presence of Pb(Ⅱ) not only retarded the binder hydration but also decreased the compressive strength, while such negative effects were relatively little when adding Cd(Ⅱ); besides, the addition of calcined quarry dust (CQD) reduced these adverse impacts. X-ray diffractometry and thermogravimetric analysis showed that both Pb(Ⅱ) and Cd(Ⅱ) can influence the phase assembles, and hydrocerussite was detected in the composites containing Pb(II). Moreover, a horizontal semi-dynamic surface leaching test revealed that the main mechanism of Pb(Ⅱ) and Cd(Ⅱ) leaching is diffusion and adding CQD reduces their leachability and mean effective diffusion coefficient. The resulting solidified/stabilized tailings fulfilled the heavy metal leachability and mechanical strength requirements for CPB; this demonstrates that low-carbon binders can be effectively used for the sustainable treatment of Pb(Ⅱ)- and Cd(Ⅱ)-containing tailings, for CPB applications.

Structural Formation of Alkali-Activated Materials Based on Thermally Treated Marl and Na2SiO3.

Modern materials science is aimed towards abandoning Portland cement in the production of building materials. The scientific novelty of this study lies in its being the first time a comprehensive study of the structure formation of alkali-activated materials (AAM) based on thermally treated marl and Na2SiO3 is carried out. The tasks for achieving this goal were to characterize the thermally treated marl as a new binder, and to comprehensively research the microstructure, fresh, physical, and mechanical properties of the AAM based on the binder. Received active particles of marl with a smaller size than Portland cement have a specific surface area of 580–590 m2/kg. The mineral composition of heat-treated marl is characterized by calcium silicates, which guarantee good binding properties. The results of X-ray diffraction analysis of the samples based on the clinker-free binder of alkaline activation using opoka-like marl confirmed the presence of calcite, quartz, and feldspar close to albite, micas, and zeolites. The obtained products of the chemical interaction of the components of the binder confirm the effectiveness of the newly developed AAM. As a result of comparing several binders, it was found that the binder “thermally treated marl—Na2SiO3” is the most effective, since for specimens based on it, a maximum compressive strength of 42.6 MPa, a flexural strength of 4.6 MPa, and minimum setting time were obtained (start 26 min, end 32 min) as well as a water absorption of 10.2 wt.%. The research results will be of interest to specialists in the construction industry, since the proposed recipes for clinker-free cements are an alternative to expensive and energy-intensive Portland cement and provide the creation of strong and durable concrete and reinforced concrete composites.

Green clinker-free binders: Simultaneous immobilization and carbonation of ferrous metallurgical residues activated by sulfur wastes

In this work, green clinker-free binders (GCFBs), an alternative cement, were fabricated by recycling sulfur wastes to activate ferrous metallurgical residues for immobilization of solid wastes and carbonation of carbon dioxide synchronously. The results of compressive strength revealed that GCFB-2 activated by thenardite has the highest strength (36.74 MPa) in 3–28 days, and the GCFB-3 activated by ardealite retains a positive growth rate, as well reaches the maximum strength (38.51 MPa) in 120 days. The mineral compositions of GCFBs hardened paste disclosed that ettringite, CSH gels, and portlandite are the main hydrates, which are the strength source of immobilized solid wastes. After the carbonation of carbon dioxide, the compressive strength declines, calcite was the main mineral product, and the net carbonation capacity of carbon dioxide is 2.86–4.75 g/Kg for GCFBs. GCFBs have offered the double benefits of CO2 emission reduction and waste management, and the hardened pastes are a well better alternative aggregate due to the extremely high compressive strength. This study could provide a new perspective on the full resource utilization of industrial solid wastes, while GCFBs are an excellent alternative to cement in the field of environmental immobilization, with outstanding carbon capture and storage capacity in terms of CO2 carbonation.

Obtaining of geopolymer binders based on thermally modified clay rocks of Georgia

Obtaining of geopolymer binders based on thermally modified clay rocks of Georgia. / E. Shapakidze, M. Avaliani, M. Nadirashvili, V. Maisuradze, I. Gejadze, T. Petriashvili. / Nano Studies. – 2020. – # 20. – pp. 43-52. – geo. The production of cement / concrete, which is one of the most ecologically harmful industries, has irreparable damage to the environment. Therefore, much attention is paid to the development of technologies for obtaining alternative types of materials to cement, the so-called clinker-free binders. In particular, such materials are geopolymer binders. The purpose of this study is to develop a technology for producing geopolymer binders based on thermally modified clay rocks of Georgia, for which clay shale, mudstone and low-melting clay rocks were used. As a result of the studies, a heat treatment regime for clay rocks was developed and various compositions of geopolymer binding materials were obtained on their basis. It was found that heat treatment of the geopolymer binders significantly increases their mechanical strength. Fig. 3, Tab. 2, Ref. 30.

MODIFIED CONCRETES BASED ON NON-CLINKER BINDERS

The study of the properties of high-strength concrete on the basis of new binders made from technogen waste is discussed. Theoretical provisions for the hardening of a clinker-free binder, consisting of co-crushed dump steel-smelting slag, cullet, a modifying aluminum-containing additive, and an alkaline component hardening under conditions of heat and moisture treatment, have been developed. The optimal compositions of clinker-free binder and fine-grained concrete based on it have been determined. At 25.0 MPa of the activity of the clinker-free binder, the composition contains (metallurgical waste) slag -52%; cullet - 37%; modifying aluminum-containing additive -11%; alkalis (activator) - 7.4% (by weight of the binder). It has been established that to obtain fine-grained concrete grade M 150, it is necessary: 25% clinker-free binder and 75% mixed aggregate, consisting of 35% steel-smelting waste slag and 65% sand. With a water / binder ratio of 0.33. Keywords: clinker-free cement, waste, modified concrete, metallurgical slag, glass-alkali binder, slag cement.

Physical-Chemical Studies of the Process of Condensation of a Clinker-Free Binder

The possibility of using a clinker-free binder as an alternative to expensive and energy-intensive Portland cement is being considered. The pozzolanizing effect of volcanic rocks is presented, where along with the binding of calcium hydroxide by silica to hydrosilicates, the binding of calcium hydroxide by “free” alumina to hydroaluminates also takes place. In the process of hardening of the clinker-free binder, the phase mineralogical composition of the formed new formations differs from the new formations that are synthesized during hardening of traditional Portland cement, which explains the difference in their properties. The new formations that are formed during the hardening process of clinker-free cements are mainly low-basic hydrosilicates, and alkaline aluminosilicates give the cast-in-place stone water resistance, frost resistance, waterproofing, etc., in a word, durability. Physical and chemical studies of the hardening process of clinker-free lime-igneous cements have been carried out, which indicates the possibility of replacing the energy-intensive Portland cement with cheaper clinker-free cement.

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

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

Industrial experience in the implementation of clinker-free binders of alkaline activation

Objective. Issues related to the search for new, less energy- and material- intensive binders have long been on the agenda of many world environmental forums, since the carbonate technology of Portland cement entails pollution of the surrounding atmosphere and habitat, and the price of this product is unjustifiably growing. In our opinion, alkaline cements could contribute to the construction industry. Within the framework of this work, research results have been obtained that confirm the effectiveness of the development of a clinker-free technology for producing alkaline-mixed binders and composites based on them using aluminosilicate additives, both natural and technogenic origin.Method. The methods of electron microscopy and differential thermal analysis make it possible to study the nature of the components and the processes of formation of the structure of the cement stone. Waste from the cement industry has the appropriate granulometric and chemical composition, the aluminosilicate mineralogy of the studied powders confirms their compliance with the ready-made raw mix of Portland cement clinker, which is the key to the possibility of their effective use.Result. The carried out differential thermal analyzes confirmed the presence of the following phases in the composition of cement stone on binding bonds "cement dust - alkaline activator" of zeolite, calcite, mica type muscovite, montrillonite, magnesium oxide, calcium sulfoaluminates, ettringite structure, calcium hydrochloraluminate, calcium hydrosilicate, calcium hydrosilicate calcium.Conclusion. The obtained regularities of the processes of formation of the structure of the cement binder "waste of the cement industry - Na2SiO3", will transform these developments to create strong and durable artificial building composites competing with concretes on Portland cement.

Mathematical Modelling to Control the Chemical Composition of Blast Furnace Slag Using Artificial Neural Networks and Empirical Correlation

Portland cement additions have been used for many years with the main objective of reducing the amount of clinker. Among the additions, blast furnace slag, resulting from the production of pig iron, that is, reusing this by-product, reduces the emission of carbon dioxide as well as decreases the exploitation of natural limestone and clay reserves, which are raw materials for Portland clinker. In order to reduce these emissions and increase the availability of raw materials, research has been directed to study clinker-free binders, as is the case with activated alkali cements and supersulfated cements. In this way, alkali-activated cements can only involve the reuse of industry by-products and do not require the calcination of the raw material, thus reducing the emission of polluting gases into the atmosphere. Supersulfated cement are composed of up to 90% blast furnace slag, in addition to 10 to 20% calcium sulfate. One of the most important characteristics of blast furnace slag is the ratio of the content of CaO and SiO2, also known as the simplified basicity index (B2). This paper proposes the mathematical modeling of an artificial neural network to predict the final chemical composition of the blast furnace slag to be produced based on the operational parameters of the blast furnace aiming its use in the production of special cements such as alkali-activated cements and supersulfated cements. The high values of (R) associated with low values (RMSE) show the good statistical performance of ANN demonstrating that the mathematical model is efficient to carry out the forecast of the production of blast furnace slag.

Production and Investigation of a Finely Dispersed Fraction of Blast-Furnace Granulated Slag for Use as Components of Clinker-Free Binders

Production and Investigation of a Finely Dispersed Fraction of Blast-Furnace Granulated Slag for Use as Components of Clinker-Free Binders

Reactive MgO-modified slag-based binders for cemented paste backfill and potential heavy-metal leaching behavior

As a binder to replace Portland cement completely for cemented paste backfill, the use of clinker-free binders combined with copper slag is proposed to achieve the purpose of low-cost mine backfilling and safe disposal of copper slag. We studied the influence of reactive MgO on the properties of cemented paste backfill (CPB) samples, including rheological characteristics, setting time, and compressive strength as well as the heavy-metal leaching behavior. The results indicated that the addition of reactive MgO increased the yield stress of the fresh CPB samples, leading to decreased flowability, whereas the compressive strength of the CPB samples was increased. Besides, the release amount of all the investigated heavy metals was decreased in the presence of reactive MgO due to the formation of additional hydrotalcite-like phases with the formation of a more compact structure. These results provide a strategy for the safe large-scale utilization of copper slag.

Research of the features of the formation of the structure and properties of building composites based on clinker-free binders of alkaline activation with the use of unconditional natural and secondary raw materials

The anthropogenic load on the natural resource potential of the planet is growing rapidly. Therefore, special attention is paid to the development of less costly and low energy-consuming technologies for obtaining new building materials. Those materials do not require high-temperature and expensive technological processing, and this will allow the use of local secondary and substandard raw materials. The development of formulations for linker-free binders of alkaline activation based on fine powders of aluminosilicate nature will make it possible to obtain new effective building composites. The work reveals issues related to the theoretical foundations of the structure formation and strength of cement stone based on an alkaline activator. The research results, in our opinion, have a practical importance for the construction industry, since the proposed formulations of clinker-free cements can replace expensive and energy-intensive Portland cement, allowing creating strong and durable concrete and reinforced concrete structures. The results presented in this article were obtained in the framework of research on the implementation of scientific project No. 05. 607.21.0320. “Development of technology for new building composites based on linker-free binders of alkaline activation using substandard natural and secondary raw materials” supported by the Federal Target Program “Research and Development in Priority Areas of Development of the Scientific and Technological Complex of Russia for 2014-2020” The unique identifier for the agreement is RFMTFI60719X0320.

Recipes and Properties of Multicomponent Systems "Aspiration Dust - Mineral Powder - Na<sub>2</sub>SiO<sub>3</sub>"

The paper presents the results of studies of the effect of the concentration of binder components on the properties of cement alkaline stone. Formulations of clinker-free binders of alkaline activation with the level of filling the system of 20 and 40% have been developed, the properties of the cement paste of the binding binder "aspiration dust - mineral powder - liquid glass" have been studied, the dynamics of a set of strength indicators has been studied, both for bending and compressive forces. The received results allow to estimate uniqueness of properties of a binding binder "a mineral powder - Na2SiO3" and to create new materials on resource saving and energy saving technology. The results presented in this article were obtained within the framework of studies on the implementation of scientific project No. 05. 607.21.0320. "Development of technology for new building composites based on clinkerless cement of alkaline activation using substandard natural and secondary raw materials" supported by the Federal Target Program "Research and Development in Priority Areas of Development of the Scientific and Technological Complex of Russia for 2014-2020". The unique identifier for the agreement is RFMTFI60719X0320.

ИССЛЕДОВАНИЕ СВОЙСТВ МНОГОКОМПОНЕНТНЫХ НАПОЛНЕННЫХ ВЯЖУЩИХ СИСТЕМ ЩЕЛОЧНОЙ АКТИВАЦИИ

The anthropogenic load on the planet’s natural resource potential is growing rapidly, therefore, special attention is paid to the development of less costly and low energy-intensive technologies for obtaining new building materials, the implementation of which does not require high-temperature and expensive technological processing, and will allow the use of local secondary and substandard raw materials. The development of formulations of clinker-free binders of alkaline activation based on fine powders of natural and technogenic origin will allow to obtain new effective building composites. The paper reveals issues related to the theoretical foundations of the formation of the structure and strength of cement stone based on an alkaline activator. The research results, in our opinion, undoubtedly are of practical importance for the construction industry, since the proposed recipes for clinker-free cements can replace expensive and energy-intensive Portland cement, allowing you to create strong and durable concrete and reinforced concrete structures.