Use Of Natural Pozzolan Research Articles

Effect of quaternary binder slag-based geopolymer slurries on mechanical durability and microstructural properties of green prepacked composites

This study conducts a detailed investigation into the effects of slag-based quaternary binder geopolymer slurries on the physico-mechanical properties, high temperature resistance, and microstructural characteristics of prepacked composites. This research employs a strategic combination of aluminosilicate precursors, including metakaolin (MK), pumice powder (Pum), and perlite powder (Per), which are blended with slag in varying mix proportion to identify and optimizing the composite’s performance. In the key finding reveal that samples containing 20 % of MK achieved superior performance, displaying the lowest porosity and water absorption rates. The oven-dry density of the mixtures demonstrated a marked improvement with the inclusion of MK, increasing from a range of 2150–2230 kg/m3 in 0 % MK mixture to 2250–2350 kg/m3 in those with 20 % MK. Post heat curing, the compressive strength peaked at 31.12 MPa in the mixture comprising 20 % MK, 20 % pumice, and 10 % perlite; however, this strength reduced to 11.92 MPa when subjected to a temperature of 600℃. In high temperature resistance tests, the combination of 20 % MK and 10 % perlite resulted in a minimal mass loss of 4 % at 600℃, indicating a robust resistance to thermal degradation. Furthermore, the 24-h water capillary absorption displaying lowest water absorption rates. This study provides a critical advancement in the use of natural pozzolans for developing high-performance, slag based geopolymer slurries. The enhanced high-temperature strength and reduced water absorption underscore the potential of these materials to deliver durable and sustainable solution for the construction industry, particularly in application requiring superior thermal resistance and longevity.

Barthélémy Faujas de Saint-Fond (1741–1819) and his work on pozzolans and lime: A pioneer in sustainable building

Barthélémy Faujas de Saint-Fond (Montélimar, France, 1741–1819) is a renowned scientist whose work on volcanoes influenced the birth of volcanology. In the meantime, he developed a strong interest in the use of natural pozzolan which he recognised as a key ingredient of durable Roman mortars. Indeed, he recognised the similarity of pozzolans from Pozzuoli (the cradle of Roman pozzolan, which gave the name to this product) and newly discovered pozzolans from various places in France. Within 18th and 19th century renowned cement scientists, it is of interest to emphasise the work of Faujas de Saint-Fond. In the current trend to develop sustainable binders based on pozzolans and low-CO2 activators, his work on pozzolan-lime mixes is worth recalling today.

Sulphate-based activation of a binary and ternary hybrid cement with portland cement and different pozzolans

The purpose of this study was the development of a hybrid cement based on ordinary Portland cement (OPC) and different sulfate-based alkaline activated pozzolans using the one-part method dosed in binary and ternary mixtures. The factors evaluated were the percentage and type of pozzolan between fly ash, tepojal and volcanic sand and the use of alkaline activators between sodium and potassium sulfate. The amount of cement in conjunction with the use of alkaline activators benefits the reaction of the pozzolans, reducing the setting time according to isothermal calorimetry due to the consumption of portlandite when reacting with the pozzolans, which can be observed with the derivative of thermogravimetry at approximately 450°C. The shift of the main peaks in FTIR implies the reaction of the cementitious compounds towards the thermodynamically stable phase of C-A-S-H. The ternary mixture of OPC-Fly Ash-Tepojal/Volcanic Sand activated with 4% sodium sulfate are presented as the dosages with the best mechanical performance based on compressive strength due to a synergy effect between pozzolans. Tepojal and volcanic sand are chemically and physically presented as an eco-efficient alternative to natural pozzolan for use as cementitious material.

Mechanical, environmental, and economic assessment of sustainable cement mortar using Afghan natural pozzolan as a partial replacement for cement

Using natural pozzolan to produce cement-based mortar is one of the suitable solutions to reduce cost, energy consumption, and environmental impacts. In this experimental study, the paste replacement methodology (replacement of partial cement wt% with supplementary cementitious material) is used. Natural pozzolan, as vernacular material with high silicate aluminate originating in Afghanistan, is replaced (6, 13, and 20%) with cement in mortar. Various tests such as slump, compressive strength, tensile strength, water absorption, freezing-thawing cycles, relative length change, pull-off test, and microstructure analysis have been performed to study the properties of fresh and hardened mortar. The findings showed that the use of natural pozzolan containing a high level of silicate and aluminate as a replacement of cement in mortar improved 56 days compressive and tensile strength of mortar by 2.2 and 6%, respectively, water absorption was reduced by 1.6%, and the resistance to the freezing and thawing cycles was increased 10.7% as well compared to the reference samples. In addition, the results of economic analysis and sustainable development indicators assessment of mortar showed that using this replacement methodology was economically acceptable and reduced the potential of global warming and energy consumption by 13% of the production of one ton of cement using standard technology. The optimum replacement percentage was selected at 13% without compromising the mechanical properties of mortar.

Calcined Clays from Nigeria-Properties and Performance of Supplementary Cementitious Materials Suitable for Producing Level 1 Concrete.

In this work, four naturally occurring (two kaolinite-rich and two smectite-rich) clay samples were collected from different areas around the Ashaka cement production plant, located in Gombe State, Nigeria and calcined in a laboratory. The mineralogical characterization of the clays was carried out by XRD. The hydration kinetics of the calcined clay-cement systems were monitored by isothermal calorimetry. Workability was determined using the flow table method. The reactivity of the calcined clays was determined from the solubility of Si and Al ions and the strength activity index. All calcined clays studied met the requirements of ASTM C618 for the use of natural pozzolans as a partial replacement for hydraulic cement. The metasmectite clays yielded a higher specific surface area, increased water demand, and less reactive Si and Al ions compared to the metakaolin clays. The two calcined clay groups require the addition of superplasticizer to achieve a workability class similar to the Portland cement mortar system. They can be used to replace Portland cement at replacement levels of up to 45%, in combination with limestone powder to form an LC3 cement, thereby achieving at least a "Level 1" reduction in greenhouse gas emissions.

A comparative study of natural pozzolan and fly ash: Investigation on abrasion resistance and transport properties of self-consolidating concrete

• Potential for use of natural pozzolans in self-consolidating concrete (SCC) was investigated. • Performance of natural pozzolan and fly ash in self-consolidating concrete was compared. • Mechanical and transport properties, drying shrinkage, and abrasion resistance of concrete were investigated. • Natural pozzolans performed at the same level of fly ash showing a proper replacement for fly ash in SCC. This study compared the influence of natural pozzolan with fly ash, as Supplementary Cementitious Material (SCMs), on properties of Self-Consolidating Concrete (SCC) with particular focus on abrasion resistance and transport properties. Natural pozzolan and fly ash replaced a portion of portland cement at the levels of 0, 15, 22.5, 30, and 37.5% by mass. A set of comprehensive experimental program was devised to measure fresh properties (slump flow, J-ring, T 50 and U-box), mechanical properties (compressive strength and modulus of elasticity), drying shrinkage, transport properties (rapid chloride penetration and rapid chloride migration tests, water permeability and absorption, and capillary water absorption) and depth of wear. Overall, the results indicated that replacing 15 and 22.5% of portland cement with SCM, decreased final depth of wear for SCC mixes. However, the observed improvements were diminished with increases in dosage of SCM. Use of SCMs led to similar or improved performance in terms of mechanical and transport properties, specifically at later ages of curing, showing potential for use of fly ash and natural pozzolan in SCC. Considering all the tests carried out, natural pozzolan performed at the same level of fly ash showing its great potential for use in SCC to achieve the same performance. This is of great importance considering the shortage of fly ash in recent years.

Lime-activation of natural pozzolan for use as supplementary cementitious material in concrete

The present work was conducted to examine the beneficial effects of activating natural pozzolan (NP) using hydrated lime (HL) for its efficient utilization in concrete. Optimum dosages of NP and HL determined based on the performance of several trial mixtures to be used in concrete as a partial replacement of ordinary Portland cement (OPC). Three mixtures were finally considered for detailed evaluation of the performance of NP-HL concrete. Activation of NP by HL increased the early- and later-age strength and decreased the depth of water penetration, coefficient of chloride diffusion, depth of carbonation, strength loss due to salt weathering, and reinforcement corrosion. Although the loss of strength due to sulfate attack and shrinkage strain increased due to the inclusion of HL, these values were less than those measured in the concrete prepared using OPC alone. In summary, the results of this study indicate that natural pozzolan can be used as a supplementary cementitious material by activating it using hydrated lime.

Geopolymer Materials Based on Natural Pozzolans from the Moroccan Middle Atlas

The pozzolans of the Moroccan Middle Atlas are derived from a low explosive volcanism, mostly strombolian. They are mainly composed of olivine and pyroxene, presenting a less homogeneous structure (irregular vesicles). The main target of this project is to study the use of natural pozzolans (NP) and metakaolin as precursors for the production of geopolymeric binders. The characterization of raw materials and elaborated geopolymers was carried out to study their mineralogical, chemical, microstructural, and mechanical properties. The studied pozzolans and kaolin were crushed, grinded, and sifted to get a fine grain size diameter of less than 100 µm. Then, they were calcined at 750 °C for 2 h to achieve an amorphous structure, increasing of their reactivity. Geopolymer production consists of mixing pozzolans and metakaolin with different amounts with an alkaline solution of sodium hydroxide and sodium silicates. The mass proportion of metakaolin (MK) used in this study was 10%, 20%, and 30%. In the present work, the amount of metakaolin was added as a source of alumina. The elaborated geopolymers were characterized using XRD, FTIR, TGA, and SEM analyses. The compressive strength was measured at 7, 14, and 28 days. The results showed interesting mechanical proprieties at about 18 MPa at 28 days with the mixture containing 20% MK. The addition of MK showed a significant increase in mechanical properties of the elaborated geopolymer. Meanwhile, the other results confirmed the training of new phases in addition to N-A-S-H gel. All these results indicate that the use of pozzolans in the production of geopolymers could be a great solution for the sustainable management of this mineral resource.

Experimental Optimization of Using Natural Pozzolan in Chloride Ion Exposed Concrete via Taguchi Method

Concrete durability is one of the most important concerns in the field of construction. The environmentally friendly materials that can provide the durability are of great value in the construction of concrete structures. The use of natural pozzolans is one of the cheapest and most efficient methods in this field, which offers a good performance from environmental and economic point of view and satisfies required engineering parameters. In this study, the effect of using natural pozzolan in the manufacture of concrete exposed to sulfate and chloride ion of Oman sea water was investigated. The Taguchi optimization method was used to reduce the number of samples prepared, reduce the cost of experiments and achieve an optimal mix design. The four parameters, namely water to cement ratio, different percentages of natural pozzolan, super-plasticizer and cement grade with different ratios, were considered as problem variables. The Taguchi optimization method proposed 8 mix designs based on the defined levels for the variables. By constructing 96 samples, two parameters of permeability and water absorption from Oman Sea and drinking water were investigated in the samples. By introducing the results of the experiments into the Taguchi method, the final optimal design was presented by this method, and by constructing 12 additional samples and conducting permeability and water absorption experiments, the behavior of this optimal mix design was verified. The appropriate performance of the Taguchi method was demonstrated by obtaining the optimal mix designs from the Taguchi method, constructing this mix design and comparing the results with the regulation limitations. The results showed that it is acceptable to use natural pozzolan under moderate to severe chloride and sulfate ion attacks, but it is not recommended in the extreme environmental conditions.

Use of natural pozzolans in high-performance concrete for the Mombasa–Nairobi railway

Due to the shortage of high-quality fly ash (FA) in Kenya, the successful construction of the Mombasa–Nairobi railway had to rely on the abundant natural pozzolan resources in the country instead. In the work reported in this article, concrete samples produced using 30% FA, 30% fine tuff (FT), 30% fine volcanic slag (FVS), or 10% FA and 20% FVS to replace cement were tested. The hydration activity of the FT was found to be poor. The mechanical properties and durability of the concrete made with FVS were close to those of the FA concrete and optimal performance was obtained from a mixture of FA and FVS. Mercury intrusion porosimetry, X-ray diffraction and differential thermal analysis were used for microanalysis of cementitious systems with 70% cement and 30% FA, 70% cement and 30% FT, and 70% cement and 30% FVS. The results were promising and suggested that the FVS possessed obvious secondary hydration activity and could improve the microstructure of the concrete matrix. It is therefore feasible to use natural pozzolans instead of FA to produce high-performance concrete in railway projects, which would reduce construction costs and help protect the environment.

Facile fabrication of hybrid titanium(IV) isopropoxide/pozzolan nanosheets (TnS-Pz) of high photocatalytic activity: characterization and application for Cr(VI) reduction in an aqueous solution.

This paper presents the synthesis of a hybrid material through the use of natural pozzolan and titanium(IV) isopropoxide using the sol-gel method and its application in the photocatalytic hexavalent chromium reduction. The characterization data indicated a mesoporous material possessing a surface area of 271.7m2g-1. The morphology studies (SEM and TEM) showed nanosheet hybrid structures. The analysis of DRUV, FTIR, XRD, and Mössbauer spectroscopy provides a different electronic structure of the synthetized material when compared with the originals, proving the hybridization process between pozzolan and titanium(IV) isopropoxide. The photocatalytic reduction of Cr(VI) to Cr(III) using the hybrid material showed a better performance than conventional photocatalysts (precursor and TiO2-P25). Operational conditions such as chromium initial concentration (0.02-0.20mM), solution pH (3-6), and type of scavenger (citric or tartaric acid) were evaluated in order to determine the best experimental conditions for the Cr(VI) photoreduction. At their optimum (catalyst load of 15mgL-1, tartaric acid as scavenger, [scavenger]0/[Cr(VI)]0 M ratio = 3:1, pH3, and 25°C), the total photoreduction of 0.20mM Cr(VI) was achieved in 180min. The novel hybrid materials synthesized from pozzolan and titanium(IV) isopropoxide showed to be a potential catalyst for the Cr(VI) reduction in aqueous solution. Graphical abstract.

The potential use of pumice in mine backfill

AbstractThe use of natural pozzolans in concrete applications is gaining more attention because of the associated environmental, economic, and technical benefits. In this study, reference cemented mine backfill samples were prepared using Portland cement, and experimental samples were prepared by partially replacing Portland cement with 10 or 20 wt.% fly ash as a byproduct (artificial) pozzolan or pumice as a natural pozzolan. Samples were cured for 7, 14, and 28 days to investigate uniaxial compressive strength development. Backfill samples containing 10 wt.% pumice had almost a similar compressive strength as reference samples. There is strong potential for pumice to be used in cemented backfill to minimize costs, improve backfill properties, and promote the sustainability of the mining industry.

A Modified Chemical Index to Predict Fly Ash Dosage for Mitigating Alkali-Silica Reaction

Abstract It is well chronicled that coal fly ash can mitigate the risk of alkali-silica reaction (ASR) in concrete structures. However, the efficacy of individual fly ashes is highly dependent on their chemical composition. Prescriptive requirements for ASR mitigation have largely focused on whether the fly ash is classified as Class F or Class C per ASTM C618, Standard Specification for Coal Fly Ash and Raw or Calcined Natural Pozzolan for Use in Concrete, whereas performance requirements may require extensive testing to satisfactorily demonstrate mitigation potential of a fly ash. Previous research established the need for an accurate model to predict required fly ash replacement rates for ASR mitigation based on the chemical constituents of cement and fly ash. Therefore, a new model is proposed to account for the availability of each chemical constituent from cement and fly ash separately, utilizing ASTM C1260, Standard Test Method for Potential Alkali Reactivity of Aggregates (Mortar-Bar Method), and ASTM C1567, Standard Test Method for Determining the Potential Alkali-Silica Reactivity of Combinations of Cementitious Materials and Aggregate (Accelerated Mortar Bar Method), test data. The successful development of models based on 14-day and 28-day expansion data from these tests is presented in this article.

Characterization of scoria rock from Arabian lava fields as natural pozzolan for use in concrete

The feasibility studies of using alternative cementitious materials (ACMs) in concrete construction are conducted using various characterization tests. Different samples of scoria rocks (SR) were procured from different regions of the Arabian Shield and investigated for use as ACMs. Various methods and characterization techniques were conducted. Characterization results revealed that the pozzolanic activity of SR in mortar does not correlate well with the sum of the main elemental oxides (SiO2+Al2O3+Fe2O3), as per the requirement of ASTM C618. Concrete mixtures containing 30% SR per cement weight were prepared and tested at 28 and 90 days to evaluate the performance of SR for construction applications. Furthermore, the mortar and concrete mixtures containing SR have shown a slow rate of pozzolanic activity at early ages. However, the development in compressive strength was enhanced at later ages dependent on the mineralogical compositions of SR. It is concluded that the improvement in strength could be corroborated based on the formation of tobermorite-like structures, as confirmed using XRD and thermal analyses. These structures result from the reaction of minerals of amorphous sodium aluminosilicate phase (albite minerals) in SR with portlandite liberated during cement hydration. Conclusively, SR reacts as a pozzolan not as a filler.

The effect of using natural pozzolan-based cement concretes on zinc phosphated rebars corrosion

Studies on using zinc phosphating in reinforced concrete (RC) field are still in the early stages. Use of natural pozzolan (NP) as cement replacement is growing rapidly in the construction industry due to its economical, ecological and technical benefits. Four phosphating baths were prepared; Zn phosphate (P-Zn), Zn-Ni phosphate (P-Zn-Ni), Zn-Cu phosphate (P-Zn-Cu) and Zn-Mn phosphate (P-Zn-Mn) respectively. Ø14 mm reinforcing steel bars were treated at 55-60 °C for 15 min in the phosphating baths. Concrete specimens were produced with different levels of NP; 0% (control specimen), 10 %, 20% and 30%, respectively. The effectiveness of using both NP and P-Zn coatings in retarding rebar corrosion has been investigated using an accelerated test after 28 and 90 days concrete curing. In addition, the bond strength between the concrete and the rebar was investigated by the pull-out test. Test results revealed that the concretes containing higher replacement levels of NP and rebars treated in bi-cationic baths exhibited corrosion initiation periods several times longer than the control specimens with uncoated steel and a zero NP content. Moreover, the results showed that the bond strength was not affected by adding NP and P-Zn coatings. SEM analysis was employed, as well.

Inhibition Effect of Natural Pozzolan and Zinc Phosphate Baths on Reinforcing Steel Corrosion

Zinc phosphate (ZnP) baths are widely used for increasing corrosion resistance and surface preparation for painting. Studies on exploiting these baths in the reinforced concrete (RC) are still in the early stages. This is probably due to the shortcomings, such as the alkaline instability and high porosity of the obtained coatings. Use of natural pozzolan (NP) as cement replacement is growing rapidly due to its economic, ecological, and technical benefits. The combined effect of using ZnP baths and NP-based cement on the resistance of concrete against damage caused by corrosion has been investigated. Four phosphating baths were prepared: ZnP, ZnP-Ni, ZnP-Cu, and ZnP-Mn. Steel specimens were phosphated at 55-60°C for 15 min. Concrete specimens were produced with four different levels of NP: 0% (control), 10 %, 20%, and 30%. The investigation was carried out using RC specimens where a constant anodic potential was impressed after 28 and 90 days of concrete curing. The electrochemical behavior of the coated steel has further been evaluated in chloride contaminated Ca(OH)2 saturated solution (CH-Cl) using the open circuit potential (OCP), the potentiodynamic polarization, and the polarization resistance with time. The bond strength between the coated steel and concrete has been evaluated by the pull-out test. Test results showed that concrete containing NP at higher replacement levels and steel specimens treated in bication baths exhibited corrosion initiation times several times longer than the control concrete with uncoated steel. In addition, the best corrosion performance was noted in the steel specimen treated in the ZnP-Cu bath. Its corrosion density was about twentyfold lower with respect to the bare steel, and its inhibition efficiency exceeded 95% in (CH-Cl) solution. In addition, its polarization resistance was about fifteenfold lower with respect to the bare steel. SEM, EDX, and XRD techniques have been employed, as well.

Applicability of Artificial Neural Networks to Predict Mechanical and Permeability Properties of Volcanic Scoria‐Based Concrete

Numerous volcanic scoria (VS) cones are found in many places worldwide. Many of them have not yet been investigated, although few of which have been used as a supplementary cementitious material (SCM) for a long time. The use of natural pozzolans as cement replacement could be considered as a common practice in the construction industry due to the related economic, ecologic, and performance benefits. In the current paper, the effect of VS on the properties of concrete was investigated. Twenty‐one concrete mixes with three w/b ratios (0.5, 0.6, and 0.7) and seven replacement levels of VS (0%, 10%, 15%, 20%, 25%, 30%, and 35%) were produced. The investigated concrete properties were the compressive strength, the water permeability, and the concrete porosity. Artificial neural networks (ANNs) were used for prediction of the investigated properties. Feed‐forward backpropagation neural networks have been used. The ANN models have been established by incorporation of the laboratory experimental data and by properly choosing the network architecture and training processes. This study shows that the use of ANN models provided a more accurate tool to capture the effects of five parameters (cement content, volcanic scoria content, water content, superplasticizer content, and curing time) on the investigated properties. This prediction makes it possible to design VS‐based concretes for a desired strength, water impermeability, and porosity at any given age and replacement level. Some correlations between the investigated properties were derived from the analysed data. Furthermore, the sensitivity analysis showed that all studied parameters have a strong effect on the investigated properties. The modification of the microstructure of VS‐based cement paste has been observed, as well.

Use of natural pozzolans with lime for producing repair mortars

Natural pozzolans were used selectively in combination with lime for the production of mortars used in structures where water tightness was required such as aqueducts, baths, and pipes many centuries ago. Their use in building materials was diachronic. The appreciated properties of mortars containing pozzolans were the increased durability and strength and the dense structure in relation to pure lime mortars. In the present paper, two natural pozzolans from Greece were analyzed systematically in order to record their mineralogical, chemical, morphological and physical properties. These pozzolans were used for the production of repair mortar, and the mechanical and physical properties of the mortars were also recorded. From the results, it is derived that the pozzolans tested were materials of high quality and reactivity and could be used for the production of compatible repair mortars for the restoration of monuments and historic buildings. The elaboration of natural pozzolans by grinding could lead to further increase of their reactivity. From the analysis, valuable criteria could be instituted for the qualitative evaluation of natural pozzolans.

Production of More Sustainable Mortar Using Finer Volcanic Scoria-based Blended Cements

Use of natural pozzolan is growing rapidly in the construction industry due to its economical, ecological and technical benefits. However, they are often associated with shortcomings such as the need to moist-curing for longer time and a reduction of strength at early ages. Syria is relatively rich in volcanic scoria. The objective of the study is to investigate the effect of Blain fineness of cement on the strength development of scoria-based cement mortars. In the study, mortar specimens have been produced with four types of cement: one plain Portland cement (control) and three scoria-based blended cements with three replacement levels: 25, 30% and 35%, respectively. All blended cement types have been interground into four different Blaine fineness: 2400, 3200, 4200 and 5100 cm 2 /g. The development of the compressive and flexural tensile strength of all mortar specimens with curing time has been investigated. The effects of the Blaine fineness of the scoria-based blended cement on the compressive and flexural strengths of mortar have been evaluated at curing ages of 2, 7, 28 and 90 days, respectively. Test results revealed that there is a decrease in strength with increasing amounts of scoria. In addition, there was found an increase in strength with increasing the Blaine fineness values. Good correlations between mechanical strengths and Blaine fineness have also been observed at different curing times. Further, based on the results obtained, an empirical equation was derived to predict the mechanical strengths of scoria-based cement mortars with curing times based on Blaine fineness. Effects of Blaine fineness on some physical properties of blended cements have been reported, as well. DOI: http://dx.doi.org/10.5755/j01.sace.13.4.13245

A Study of Natural Pozzolan Mortars Exposed to Chlorides as a Sustainable Building Material

Reinforcement corrosion is caused either by chloride ions or carbonation, although chloride-induced reinforcement corrosion is the most widespread and serious problem. Moreover, the use of supplementary cementitious materials has been proposed in order to mitigate the durability problem, reduce the production costs and control the emission of greenhouse gases (GHGs). This paper reports the results of a study conducted to investigate the influence of Algerian natural pozzolan on reinforcement corrosion in blended cement mortars exposed to chlorides. Compositions, with replacement levels of 0, 10, 20 and 30% of normal Portland cement by mass of cement by natural pozzolan, were investigated. The exposure solution contained a fixed concentration of 5% sodium chloride. The compressive strength, corrosion potential, corrosion current density, sorptivity, rapid chloride ion penetration, in accordance with the standard ASTM C1202-12, were determined in order to characterize the mechanical and electrochemical behavior of the mortars. It was found that the use of natural pozzolan had resulted in a significant decrease in the corrosion rate of rebars, better mechanical performances and also a resistance to penetration of chlorides ions.