Pozzolanic Test Research Articles

Investigating the performance and durability of high mechanical milling nano pulverised refused SCMs

This study investigated the performance and durability of high-mechanical-milling nano-pulverized industrial reject supplementary cementitious materials (SCMs). The research utilized industrial reject (IR-1), specifically Ground Blast Furnace Slag (GBFS), as the SCM. As-received IR-1 GBFS was milled for 90 minutes to achieve nano-sized particles, and its properties were compared with the un-milled, or before-milled (BM) material. Three pozzolanicity tests were conducted to compare the before milled (BM) and after-milled (AM) materials. Additionally, M30 grade concrete mixes were developed with cement partially replaced by 30 %, 35 %, and 40 % using both BM and AM IR-1 materials. Mechanical performance, including compressive strength, flexural strength, and split tensile strength, along with durability tests such as water absorption, sorptivity, and rapid chloride penetration, were conducted for the BM and AM IR-1 blended concretes. The results showed that AM IR-1 blended concrete achieved the required design strength at a 30 % cement replacement level. Furthermore, the AM IR-1 blended concrete exhibited 40 % higher compressive strength, 39 % higher flexural strength, and 29 % higher split tensile strength compared to the control concrete. Durability testing also revealed significant improvements in AM IR-1 blended concrete, with reductions of 19.65 % in water absorption, 24.71 % in sorptivity, and 38 % in chloride penetration. This study demonstrates that industrial waste, such as GBFS, can be effectively utilized as a sustainable alternative to traditional materials in the construction industry. Additionally, nano-pulverization treatment significantly enhances the pozzolanicity and overall performance of materials that may not meet the physicochemical standards specified in IS 3812-(Part 1):2017 and ASTM C618–19.

New Discovery of Natural Zeolite-Rich Tuff on the Northern Margin of the Los Frailes Caldera: A Study to Determine Its Performance as a Supplementary Cementitious Material.

The release of Neogene volcanism in the southeastern part of the Iberian Peninsula produced a series of volcanic structures in the form of stratovolcanoes and calderas; however, other materials also accumulated such as large amounts of pyroclastic materials such as cinerites, ashes, and lapilli, which were later altered to form deposits of zeolites and bentonites. This work has focused on an area located on the northern flank of the San José-Los Escullos zeolite deposit, the only one of its kind with industrial capacity in Spain. The main objective of this research is to characterize the zeolite (SZ) of this new area from the mineral, chemical, and technical points of view and establish its possible use as a natural pozzolan. In the first stage, a study of the mineralogical and chemical composition of the selected samples was carried out using X-ray diffraction (XRD), scanning electron microscopy (SEM), X-ray fluorescence (XRF), and thermogravimetric analysis (TGA); in the second stage, chemical-qualitative and pozzolanicity technical tests were carried out at 8 and 15 days. In addition, a chemical analysis was performed using XRF on the specimens of mortars made with a standardized mixture of Portland cement (PC: 75%) and natural zeolite (SZ: 25%) at the ages of 7, 28, and 90 days. The results of the mineralogical analyses indicated that the samples are made up mainly of mordenite and subordinately by smectite, plagioclase, quartz, halloysite, illite, and muscovite. Qualitative chemical assays indicated a high percentage of reactive silica and reactive CaO and also negligible contents of insoluble residues. The results of the pozzolanicity test indicate that all the samples analyzed behave like natural pozzolans of good quality, increasing their pozzolanic reactivity from 8 to 15 days of testing. Chemical analyses of PC/SZ composite mortar specimens showed how a significant part of SiO2 and Al2O3 are released by zeolite while it absorbs a large part of the SO3 contained in the cement. The results presented in this research could be of great practical and scientific importance as they indicate the continuation of zeolitic mineralization beyond the limits of the San José-Los Escullos deposit, which would result in an increase in geological reserves and the extension of the useful life of the deposit, which is of vital importance to the local mining industry.

Bentonite Clays Related to Volcanosedimentary Formations in Southeastern Spain: Mineralogical, Chemical and Pozzolanic Characteristics

The volcanism that took place during the Neogene in the southeastern Iberian Peninsula caused a large accumulation of volcanosedimentary materials, which were subsequently altered and transformed into bentonite deposits. The mineral composition and technical quality of these deposits have been demonstrated and established in this work. The main object of this research is the mineral, chemical and thermal characterization of the bentonites that lie in the southeastern region of Spain and to demonstrate their technical capabilities to be used as pozzolans. The first phase of characterization of the samples was carried out by X-ray diffraction (XRD), oriented aggregates (OAs), X-ray fluorescence (XRF) and thermogravimetric analysis (TGA). In the second phase, a chemical–technical quality test (CTQT) was carried out, aimed at determining reactive SiO2 and reactive CaO, whereas in the third phase, a chemical pozzolanicity test (CPT) was carried out to establish the pozzolanic behavior of the samples over two test periods: 8 and 15 days. The XRD and OA analyses showed that the bentonite samples are made up of a main phase formed by montmorillonite, quartz, plagioclase-albite and chabazite–Ca. The results obtained by XRF on the bentonite samples indicated that the SiO2 contents are high and vary between 43.33% and 64.71%, while Al2O3 ranges between 15.81% and 17.49%. The CTQT established that more than 80% of the SiO2 and CaO present in the samples are reactive, which was confirmed by the results of the chemical pozzolanicity test (CPT). The results obtained show that the bentonites in this study present technical qualities that are undoubtedly reinforced by their mineral constitution and chemical composition. These tests could become a practical guide for the selection of eco-efficient materials in the production of pozzolanic cements and environmentally friendly ceramic products.

Use of iron ore tailings as partial replacement for cement on cementitious composites production with vegetable fibers

The mining industry has been expanding and consequently increasing the associated environmental impacts, especially regarding this process's high volume of iron ore tailings (IOT) disposal. The best way to solve the problems caused by IOT is to develop large-scale utilization technologies that may consume large quantities of it. This study aims to evaluate the influence of incorporating IOTs on the mechanical, physical, microstructural, and morphological properties of extruded fiber-cement reinforced with eucalyptus cellulose pulp. For its use, IOT was characterized by the inhibition index, pozzolanic test, and granulometric, chemical, morphological, and X-ray diffraction analyses. The fiber-cement flat slabs were prepared by replacing cement using 10%, 20%, 30%, and 40% of IOT and the control treatment, generating specimens measuring 20x30x200mm (height x width x length). The composites were characterized for physical, mechanical, and microstructural properties before and after exposure to weathering by accelerated aging test. This study showed an improvement in fiber durability with the increase in IOT content as a function of the waste’s pozzolanic activity and an improvement in physical properties using 10% cement replaced by IOT. All treatments tested at 28 days presented values within trading standards limits. However, the treatments with 10% and 20% of IOT met the most demanding criteria. Thus, using iron ore waste as a substitute for raw materials in cementitious composites may reduce the difficulties of IOT disposal and save natural resources, leading to more sustainable constructions.

Mineral, Chemical and Technical Characterization of Altered Pyroxenic Andesites from Southeastern Spain for Use as Eco-Efficient Natural Materials

Climate change is already an undeniable reality, and it is a direct consequence of our society’s lifestyle and the indiscriminate use of certain materials, such as Portland cement, which causes the emission of gases and waste that contributes to the greenhouse effect. The object of this work is to present the results obtained from research on pyroxenic andesites that have become altered to zeolite and their use as alternative, eco-efficient materials that improve the quality of cement through a standardized partial substitution. In this work, four samples of pyroxenic andesites altered to zeolites (PAAZ) and two samples of unaltered andesites (UPA) were analyzed. The methods used in this study are as follows: petrography of thin section (PTS), chemical analysis of X-ray fluorescence (XRF) and phase determination by X-ray diffraction (XRD). Other tests were carried out to determine the quality of the PAAZ from a technical and practical application point of view, such as chemical analysis of pozzolanicity (CPT) at 8 and 15 days, as well as mechanical compression tests at 2, 7, 28 and 90 days. Petrographic and phase analyses show that the original mineral components of the samples such as pyroxene, amphibole, plagioclase and mica were leached and replaced by more than 90% with mordenite and smectite. XRF analyses indicates an anomalous rise in SiO2, a drastic reduction in alumina Al2O3 and a significant increase in alkaline compounds over alkaline-earth compounds in samples of altered pyroxenic andesites (PAAZ) with respect to samples of unaltered andesites (UPA). The pozzolanicity test establishes that the samples of unaltered andesites do not behave like pozzolans at 8 or 15 days; however, altered andesites experienced remarkable pozzolanic reactivity in the same periods. The mechanical compression tests carried out on specimens made with PAAZ and Portland cement showed a growing increase in mechanical resistance from 2 days (15.2 MPa) to 90 days (72.1 MPa). These results suggest that pyroxenic andesites altered to zeolite can be an ideal alternative to partially replace Portland cement, which in turn could contribute to the preservation of the environment and a more rational use of traditional resources.

Development of framework in the selection and reuse of concrete waste and brick waste powder as pozzolanic material in cement concrete application using analytical hierarchy process technique

The utilization of construction and demolition waste (C&DW) for sustainability is a promising area. Globally, there is a growing potential interest in the reuse of waste powder from recycled concrete and bricks in concrete applications. In the current study, the pozzolana criteria were evaluated for three materials: Fly ash (FA), Concrete waste powder (CWP), and Brick waste powder (BWP). Chemical, Physical, and Pozzolanic tests, i.e., Frattini test, Lime Saturation test (LST), Strength Activity Index (SAI) and Electrical conductivity test (ECT), were carried out on the raw material. A framework was developed to select and reuse CWP and BWP in cement concrete applications. An Analytical Hierarchy Process (AHP) was carried out to study the priorities of pozzolana materials based on the road map criteria. One-way sensitivity analysis was performed to check the sensitivity of the properties. Microstructural characteristics such as scanning electron microscopy (SEM), X-ray diffraction (XRD), and thermal gravimetric analysis (TGA) were performed to investigate the morphology, amorphous content, and consumption of portlandite in the pozzolana. In addition, chemical activators; Lime, Sodium Silicate, and Sodium Hydroxide were investigated for their ability to enhance the pozzolanic activity of CWP, and statistical analysis was performed to validate the chemical enhancement. CWP and BWP cleared the road map criteria of pozzolanic activity. Adding (5–7.5%) lime improves the later strength, whereas (2.5–7.5%) NaOH & Sodium Silicate improve the early and later mechanical properties of the CWP-based mix.

Volcanic Ash from the Island of La Palma, Spain: An Experimental Study to Establish Their Properties as Pozzolans

The eruption of the Cumbre Vieja volcano on 19 September 2021, resulted in the deposition of large quantities of volcanic ash (VA), causing a great impact on the citizens. This work aims to study the properties of this volcanic ash as pozzolanic raw materials to establish their potential use in the development of sustainable cement. Results of chemical and technical characterization are presented. To achieve this goal, Ordinary Portland Cement (OPC) was replaced with standardized percentages of OPC/VA: 10, 25, and 40%. Characterization studies were carried out using chemical analysis of X-ray fluorescence (XRF), chemical quality analysis (QCA), pozzolanicity test (PT) at 8 and 15 days, as well as determining the mechanical strength (MS) at 7, 28, and 90 days. The results obtained by XRF and QCA established that the chemical composition of the VA corresponds to that of the natural pozzolan typical of pyroclastic genesis. The PT test showed that the analyzed samples have a marked pozzolanic nature, both at 8 and 15 days, showing a significant increase in their hydraulic reactivity. Likewise, the MS tests confirmed a continuous increase in mechanical compressive strength, which increased significantly from 7 to 90 days of curing, reaching more than 58 MPa. On the other hand, mechanical tests showed that the three types of dosages used OPC/VA: 10, 25, and 40% were equally effective, with OPC/VA formulations: 10–25% being the most effective. The results obtained in this research could be used by local industries as a guide for the correct use of the volcanic materials of this island, both for the manufacture of construction materials, such as aggregates, and to produce pozzolanic cement with low CO2 emissions, thus having a positive impact on the environment. Finally, the great natural availability of natural VAs in the surrounding areas of La Palma could cover part of the needs for materials used in the construction and restoration of houses and infrastructures damaged during the volcanic eruption.

Ignimbrites Related to Neogene Volcanism in the Southeast of the Iberian Peninsula: An Experimental Study to Establish Their Pozzolanic Character

The speed at which climate change is happening is leading to a demand for new pozzolanic materials that improve the quality of cements and, at the same time, limit the emission of greenhouse gases into the atmosphere. The main objective of this work is the detailed characterization of an ignimbrite sample (IGNS) to demonstrate its effectiveness as a natural pozzolan. To meet this objective, a series of tests were carried out. In the first stage, mineral and chemical analyses were performed, such as petrographic analysis by thin section (TSP), X-ray diffraction (XRD), oriented aggregate (OA), scanning electron microscopy (SEM) and X-ray fluorescence (XRF). In the second stage, the following technical tests were carried out: chemical quality analysis (QCA), pozzolanicity test (PT) and mechanical compressive strength (MS) at 7, 28 and 90 days, using mortar specimens with ignimbrite/cement formulation (IGNS/PC): 10, 25 and 40% to establish the pozzolanic nature of the ignimbrite. The results of the mineral and chemical analyses showed that the sample has a complex mineralogical constitution, consisting of biotite mica, potassium feldspar, plagioclase, smectite (montmorillonite), quartz, volcanic glass, iron, titanium and manganese oxides, chlorite and chlorapatite. On the other hand, the technological tests revealed the pozzolanic nature of the sample, as well as visible increases in the mechanical compressive strengths in the three proportions, the most effective being IGNS/PC:10% and IGNS/PC:25% at 7, 28 and 90 days of setting. The results obtained could be applied in the formulation of new pozzolanic cements with ignimbrite as a natural pozzolanic aggregate.

Perspectives for the application of bauxite wastes in the development of alternative building materials

Tailings from bauxite extraction are worldwide of environmental concern, due to their open-air disposal in landfill dams. Although numerous studies have been dedicated to the application and reuse of wastes from bauxite processing tailings, there is still an important gap regarding the identification of properties that may, enable its application in the development of materials, especially as construction elements. The objective of this research is to characterize environmentally and microstructurally the bauxite waste from processing tailings produced in the state of Pará, Brazil, aiming at a combined characterization and discussion that evaluates its potential applications, as possible alternative to simple disposal in landfills. Chemical characterization analyzes were performed by X-ray fluorescence (XRF), mineralogical by X-ray diffraction (XRD), morphological by Scanning Electron Microcopy (SEM) and Transmission Electron Microscopy (TEM) combined with Energy Dispersive Spectroscopy (EDS). In addition, physical analyzes were performed by granulometry, surface area measurement (BET) and Luxán pozzolanicity. Environmental analyzes were carried out through solubilization and leaching. The results obtained by chemical and mineralogical analyzes indicate that the material is an aluminosilicate with a high content of amorphous components, which allows it to be used as a pozzolan in either cementitious materials or as a precursor in alkali activated materials or else as a plasticity reducer in red ceramics. The results were confirmed by thermal analysis and by pozzolanicity test. Thus, it is possible to conclude, based on the characterization of the bauxite waste, that the material has potential for use in alternative construction materials, contributing to the sustainable development of civil construction.

Utilization of bioactivated incineration bottom ash in cement binder for mortar harmless treatment and performance improvement

Municipal solid waste incineration bottom ash (IBA) is a common waste containing heavy metals and compounds, and it cannot be recycled until it is treated. This study reports that microbially induced carbonate precipitation (MICP) technology is used to treat a binder of bottom ash with ordinary Portland cement (IBA-OPC, namely IBP), and the IBP after biotreatment is called MTIP. The leaching behavior and splitting tensile strength of IBP and MTIP were investigated. The pozzolanic test was used to analyze the potential of bioactivated IBA as a binder. Additionally, the immobilization efficiency of heavy metals in the samples was studied by microtopography and energy dissipation. The results show that the leaching of Cr, Cu, Zn, Cd, and Pb can be reduced by 70–90% by biomineralization. After biotreatment, the carbonate bound state of heavy metals in IBP increases, while the exchangeable bound state decreases. The strength of MTIP is 10.87% higher than that of IBP at 28 days. By analysis, it also can replace a part of the binder of cement for reducing carbon dioxide emissions. This provides a sustainable idea for the biotreatment of IBA in cement binder.

A New Study on the Eastern Flank of the Loma Blanca Deposit (Cuba) to Establish the Mineralogical, Chemical, and Pozzolanic Properties of Zeolitised Tuffs

The geological nature of the territory of the Republic of Cuba has favoured the formation of large and varied deposits of volcanic tuffs enriched by various species of zeolites. Today, new zeolite deposits continue to be discovered in the country. This work aims to present the results of a study carried out in an unexplored area that is located approximately 1.2 km east of the Loma Blanca deposit, outside the mining operation limits. To carry out this research and to establish a qualitative comparison between both sample populations, four samples were taken from the study area, and another four were taken from the Loma Blanca deposit. The characterisation of the samples was performed by XRD, SEM, and XRF. The pozzolan quality was determined by the pozzolanicity test (PT) and quality chemical analysis (QCA). Finally, a study of the mechanical strength (MST) was performed at 7, 28, and 90 days, using mortar specimens made with PC/ZT: 75–25% and PC/ZT: 70–30%, respectively. The results of the studies using XRD, SEM, and XRF indicated that both groups of samples had a similar complex mineralogical composition, consisting mainly of mordenite and clinoptilolite accompanied by secondary phases such as quartz and amorphous materials in the form of altered glass. The pozzolanicity test showed that both the samples from the study area and those from the Loma Blanca deposit behaved like typical pozzolans, which is a trend that can be seen in the high values of mechanical strength to compression up to 72 MPa for the PC/ZT: 75–25% formulation and 66 MPa for the PC/ZT: 70–30%. The results obtained establish that the zeolite varieties detected in the study area are similar to those of the Loma Blanca deposit, which could have a positive impact on the increase in current reserves, especially for manufacturing pozzolanic cements with properties that contribute to the preservation of the environment.

Performance of Low-Grade Calcined Clays as Supplementary Cementitious Material in Relation to their Geological Characteristics

AbstractCalcined clays are used as a supplementary cementitious material (SCM) because, as hydrated aluminosilicates of the phyllosilicate group, they can be activated thermally, promoting dehydroxylation and structural disorder, i.e. making them reactive. The main effect of using calcined clay as an SCM is that CO2 emissions into the atmosphere are reduced by the reduction in the clinker/cement factor due to substitution of a proportion of clinker by calcined clay. Clays rich in kaolinite (1:1) group minerals offer most promise in terms of thermal activation. However, increased costs caused by demand for kaolinite from other industries means that type 2:1 calcined clays and mixtures of them have begun to be investigated as possible pozzolanic materials. The physical, chemical, and mineralogical characteristics that control the performance of these calcined clays as SCMs are still under discussion. Few in-depth studies of the behavior of these characteristics have been reported. The origin and geological history of raw materials, as well as their impact on the thermal activation and performance as SCM, are not well understood or, in some cases, have not been considered. The objective of the current work, therefore, was to study multicomponent clays from metamorphic rocks with low-grade kaolinite (<50%) from a tropical region of Colombia for possible use as SCMs. The clay deposit was identified by geological exploration techniques and classified in depth according to horizons of the weathering profile. The samples were extracted from the first 50 m of the deposit and characterized physically, chemically, and mineralogically; they were calcined at 650, 750, and 850°C; their degree of alteration was estimated by the Chemical Index of Alteration (CIA); and their performance as an SCM was evaluated by the Strength Activity Index (SAI) and Frattini test. As a main result, a relationship was found between the weathering profile of the deposit and the CIA of raw clays, which confirmed the high weathering and degree of alteration of the parent rock in the deposit (weathered rock and residual soil with a CIA > 80%). Furthermore, pozzolanic (physical and chemical) tests demonstrated the potential use of calcined clays from this deposit as SCMs, as well as their thermal activation at low temperature (≤750°C). In addition, the pozzolanic activity increased with the kaolinite/(muscovite+illite+vermiculite) ratio mainly, and, in turn, the thermal activation temperature increased with the mica and type 2:1 clay content.

Pozzolanic Reactivity Test of Supplementary Cementitious Materials

Pozzolanic Reactivity Test of Supplementary Cementitious Materials

Microstructural Analysis of the Reactivity Parameters of Calcined Clays

Four (04) different types of clays from Burkina Faso were studied for their potential applications in the production of calcined clays as substitution materials for Portland cement. The study aimed at analyzing the factors affecting their reactivity. The untreated clays were subjected to various tests to highlight the intrinsic properties that can influence their reactivity. After the treatment by calcination, the clays were subjected to various pozzolanicity tests and microstructural analysis in order to evaluate their influence on the microstructure of the cement paste. The results showed that the reactivity of calcined clays is strongly related to the intrinsic properties of the raw clays, such as the content and the structure of kaolinite: disordered kaolinite reacts better than ordered kaolinite. After the calcination, the reactivity depends on the amorphous phase (amorphous content) of the clays, which influences the strength activity index. This study established a correlation between different parameters to easily identify the main properties of calcined clays that can influence their pozzolanic reactivity. All the results showed that the kaolinite content is a determining factor in the reactivity of clays before calcination. However, the study showed that the amorphous content of kaolinite is the determining parameter of the reactivity of calcined clays, as calcination can lead to the recrystallization of kaolinite.

A New Study of the Lower Levels of the Los Frailes Caldera (Spain) for the Location and Characterisation of Pozzolans as Construction Materials

Over the last two decades, there was been intensive study of pozzolans on the surface of the Los Frailes Caldera (Spain) for possible use as construction materials; however, research into the deepest underlying horizons has not yet been done. The main object of this paper is to present the results of the research carried out at different levels of depth, down to 30 m, to locate and demonstrate the presence of pozzolans in the depths of the Los Frailes Caldera. To achieve this, a series of analyses were carried out to classify the samples extracted from the various levels of depth, starting at the surface and continuing down to 30 m, which consisted of XRD, XRF, and SEM. Other technological tests were also performed such as chemical analysis of pozzolanic quality (CAQP) and pozzolanicity (PT) tests, at 8 and 15 days. Lastly, a geophysical study using electrical resistivity tomography (ERT) was developed to define the thickness and physical properties of the horizons of pozzolanic materials at depth, as well as to establish the depth of the deposit. The results obtained by XRD, XRF, and SEM confirmed the presence of pozzolans consisting of strongly zeolitized and bentonitised tuffs (ZBVT) in the lower levels of the Los Frailes Caldera, indicating that these horizons continue uninterruptedly beyond 30 m deep. The results of the CAQP and PT established that the ZBVTs that lie in the depths have pozzolanic qualities. On the other hand, the ERT study showed that ZBVT levels continue into the depths, thus proving that the lower limit of the deposit is even deeper. The results obtained in this work could have a positive impact on an increase in the reserves of pozzolanic raw materials in the researched area and could be used in the manufacture of light aggregates for mortars, concretes, and pozzolanic cements, consistent with the environment and effective in reducing CO2 emissions during the production process.

Natural Fluorite from Órgiva Deposit (Spain). A Study of Its Pozzolanic and Mechanical Properties

This work presents the results of the partial substitution of Portland cement (PC) by natural fluorite (NF) and calcined fluorite (CF) in mortars, at 10%, 25% and 40%. To meet these objectives, a sample of fluorite was initially studied by XRD, SEM and Raman Spectroscopy (RS). A chemical quality analysis (CQA) and a chemical pozzolanicity test (CPT) at 8 and 15 days were carried out in a second stage to establish the pozzolanic properties of the investigated sample. Finally, a mechanical compressive strength test (MCST) at 7, 28 and 90 days was carried out on specimens made up with PC/NF and PC/CF mixes, at a ratio of 10%, 25% and 40%. XRD, SEM and RS results indicated fluorite as the major mineralogical phase. The CPT and CQA showed an increase in the pozzolanicity of the samples from 8 to 15 days. The MCST showed an increase in compressive strength from 7 to 90 days for both PC/NF and PC/CF specimens. The results obtained establish that fluorite produces positive effects in the mortar and contributes to the gain of mechanical strength over time, being a suitable material for the manufacture of cements with pozzolanic addition with a reduction of CO2 emissions, and by reducing the energy costs of production.

Use of clay from a local source for calcination and subsequent preparation of the mixed cement

This paper deals with the use of calcinated clay and micronized limestone as supplementary cementitious materials (SMCs) for preparation of blended Portland cement CEM II/B-M (Q-LL). Clay used in this study was calcinated at 700°C and pozzolanic activity after calcination was assessed using accelerated R3 pozzolanic test and modified Chapelle test. The influence of calcinated clay and limestone addition on mechanical properties and hydration process was investigated and an optimal ratio for 35% clinker replacement was found. Initial decrease of mechanical strength at early ages, caused by SCM addition, was almost compensated during maturation of the binder.

Altered Volcanic Tuffs from Los Frailes Caldera. A Study of Their Pozzolanic Properties.

This work presents the results of the study of the physical, chemical, mineralogical and pozzolanic properties of the altered volcanic tuffs (AVT) that lie in the Los Frailes caldera, south of the Iberian Peninsula, and demonstrates their qualities as pozzolans for the manufacturing of mortars and pozzolanic cements of high mechanical strength. The main objective of this research is to show to what extent the AVTs can replace portland cement (PC) in mortars, with standardised proportions of 75:25% and 70:30% (PC-AVT). To achieve these objectives, three AVT samples were studied by a petrographic analysis of thin section (PATS), DRX, FRX and MEB. The pozzolanic properties were determined by three methods: electrical conductivity (ECT), chemical pozzolanicity tests (CPT) at 8 and 15 days and mechanical strength tests (MS) of the specimens at 2, 7, 28 and 90 days. Studies of a PATS, DRX, FRX and MEB showed that the AVT samples’ constitutions are complex where smectite (montmorillonite), mordenite, quartz, halloysite, illite, kaolinite, volcanic glass and lithic fragments coexist. The results of the ECT and CPT tests confirmed the pozzolanic properties of the samples analysed and proved an increase in mechanical strength from 2 to 90 days of testing.

Characterization of Supplementary Cementitious Materials and Fibers to Be Implemented in High Temperature Concretes for Thermal Energy Storage (TES) Application

Six supplementary cementitious materials (SCMs) were identified to be incorporated in concrete exposed to high-temperature cycling conditions within the thermal energy storage literature. The selected SCMs are bauxite, chamotte, ground granulated blast furnace slag, iron silicate, silica fume, and steel slag. A microstructural characterization was carried out through an optical microscope, X-ray diffraction analysis, and FT-IR. Also, a pozzolanic test was performed to study the reaction of SCMs silico-aluminous components. The formation of calcium silica hydrate was observed in all SCMs pozzolanic test. Steel slag, iron silicate, and ground granulated blast furnace slag required further milling to enhance cement reaction. Moreover, the tensile strength of three fibers (polypropylene, steel, and glass fibers) was tested after exposure to an alkalinity environment at ambient temperature during one and three months. Results show an alkaline environment entails a tensile strength decrease in polypropylene and steel fibers, leading to corrosion in the later ones.

Physical and Mechanical Properties of Sustainable Hydraulic Mortar Based on Marble Slurry with Waste Glass

This paper aims to propose and characterize a sustainable hydraulic mortar entirely obtained by the reuse of waste materials, with marble slurry coming from quarries in the north-western Sicily and glass powder coming from a waste collection plant in Marsala (Province of Trapani). The first was used as raw material to produce the mortar binder by a kilning and slaking process, while the second was used as a pozzolanic additive. The chemical and morphological characterization of the marble slurry was done by XRD, FTIR, STA and SEM analyses. Glass powder was analyzed through particle size distribution measurements, XRD and standard pozzolanic tests. Hydraulic mortars constituted by slaked lime from kilned marble slurry and waste glass powder (LGS) were prepared beside commercial Natural Hydraulic Lime (NHL) based mortars (NGS) and air-hardening lime (LSS)-based mortars. Mechanical and absorption properties of the mortars were investigated as a function of the grain size of the glass powder by means of three-point bending and compressive strength tests, capillary uptake, helium pycnometry and simultaneous thermal analysis. The results demonstrated that the formulation LGS exhibits significantly improved mechanical and absorption properties compared to air-hardening mortars (LSS). It confirms the possibility of producing a more sustainable hydraulic mortar exclusively from waste materials for civil engineering.