Pozzolanic Activity Tests Research Articles

Enhanced mortar strength and resistance to seawater degradation in the presence of calcined coal-series kaolin

The hydration process of blended mortars and its resistance to seawater degradation in the presence of calcined coal-series kaolin (CCK) was investigated in this study. The TG tests were used to quantify the effect of calcination temperature on the chemical-bound water content of the blended pastes while the XRD tests were applied to analyze the main crystalline hydration phases of the blended pastes, which were further quantified using the Rietveld-XRD refinement. In addition, microcalorimetric tests were used to characterize the degree of hydration. The hydration process of the blended mortars was further investigated in detail via combining SEM and pozzolanic activity tests. Based on this, the resistance to seawater degradation of the blended mortars with added CCK were verified via the expansion and strength loss tests, and the mechanism was analyzed via the electric flux and the total Cl− content tests. The optimal percentage of CCK (12%) was determined via a linear weighted sum method. The CCK obtained at 800 °C had the highest pozzolanic activity, promoting hydration reactions to form new gels (C-S-H, C-A-H and C-A-S-H) at active nucleation sites in mortars. These further enhanced both the flexural and compressive strengths (the compressive strength reached ∼53.7 MPa) of the blended mortars. However, CCK reduced the generation of Mg(OH)2, AFt and Friedel’s salt, decreasing seawater degradation to the mortars. Therefore, this study provides a new strategy to prepare high-strength mortar with high resistance to seawater degradation.

Utilization of extracted carbonaceous shale waste in eco-friendly cementitious blends

This research concerns the analysis and application of extracted shale from mining waste at the Lubelski Węgiel „Bogdanka“ S.A. coal mine in Poland. Various analyses were performed on both raw and thermally activated forms of extracted shale, and then the thermally activated one was used as a partial cement substitute in a PC-based paste. In order to reduce the required additional energy, the activation temperature for the extracted shale was chosen to be 600 °C according to the simultaneous thermal analysis measurement. Chemical, mineralogical, physical, and morphological analyses, thermogravimetry, and pozzolanic activity tests of raw and thermally activated extracted shale were conducted. The Portland cement pastes containing either 10 wt%, 15 wt%, or 20 wt% of thermally activated extracted shale were compared to a reference plain cement paste. Cement pastes with the thermally activated extracted shale were studied in the fresh and also hardened state after 7, 28, and 90 days of setting. Furthermore, mechanical, structural, and microstructural properties were measured and compared with the reference. Simultaneous thermal analysis with a mass spectrometer (STA-MS), isothermal calorimetry, X-ray powder diffraction (XRD), and strength activity index (SAI) evaluation were used to assess the evolution and rate of the pozzolanic reaction. All the performed analyses confirmed the pozzolanic activity of the thermally treated extracted shale and its potential in cement industry applications. The extracted shale also acted partially as a microfiller. The use of calcined extracted shale reduced the porosity of the cement matrix and increased its flexural and compressive strength. For 90-day samples, a slight hindrance in the precipitation of final substances was observed as a result of different kinetics of hydration and pozzolanic reactions. Taking all of the results into consideration, the coal mining waste – calcined extracted shale – can find use as a partial cementitious substitute for up to 20 wt%.

Study on phase evolution and promoting the pozzolanic activity of electrolytic manganese residue during calcination

Electrolytic manganese residue (EMR) is a harmful by-product in the electrolytic manganese industry. Calcination is an efficient method for disposing EMR. In this study, thermogravimetric-mass spectrometry (TG-MS) combined with X-ray diffraction (XRD) was used for analysing the thermal reactions and phase transitions during calcination. The pozzolanic activity of calcined EMR was determined by the potential hydraulicity test and strength activity index (SAI) test. The leaching characteristics of Mn were determined by TCLP test and BCR SE method. The results showed that MnSO4 was converted into stable MnO2 during calcination. Meanwhile, Mn-rich bustamite (Ca0.228Mn0.772SiO3) was converted into Ca(Mn, Ca)Si2O6. The gypsum was transformed into anhydrite and then decomposed into CaO and SO2. Additionally, the organic pollutants and ammonia were completely removed following calcination at 700 °C. The leaching concentration of Mn decreased from 819.9 mg L−1 to 339.6 mg L−1 following calcination at 1100 °C. The chemical forms of Mn were transformed from acid-soluble fraction to residual fraction. The pozzolanic activity tests indicated that EMR1100-Gy maintained a complete shape. The compressive strength of EMR1100-PO reached 33.83 MPa. Finally, the leaching concentrations of heavy metals met the standard limits. This study provides a better understanding for the treatment and utilization of EMR.

Thermally treated coal mining waste as a supplementary cementitious material – Case study from Bogdanka mine, Poland

The presented study deals with the comprehensive analysis of coal gangue from the Bogdanka mine (Lubelski Węgiel „Bogdanka" S.A.) in terms of its properties in both raw and activated states, and with the evaluation of the functional parameters of blended cement pastes containing 10 wt%, 15 wt%, and 20 wt% of thermally treated mining waste. The assessment of the raw material included chemical, physical, mineralogical, and morphological characterization, thermogravimetry, and pozzolanic activity tests. The motivation for the research was the intention to utilize a significant amount of waste from the Bogdanka mine with low additional energy consumption for processing. For this purpose, the temperature of 600 °C was chosen for its thermal activation based on the simultaneous thermal analysis (STA) measurement. The activated coal gangue was tested in the same way as the raw materials and then applied in the blended cement pastes as a partial cement substitute. The cement pastes were evaluated in the fresh state (flow table test), and also at the age of 7, 28, and 90 days. The structural, microstructural, mechanical, and hygric parameters were investigated and compared with the plain cement paste. Furthermore, the development and rate of the pozzolanic reaction were studied using simultaneous thermal analysis with mass spectrometry (STA-MS), X-Ray diffraction (XRD), isothermal calorimetry, and assessment of strength activity index (SAI). The performed analyses gave evidence of the pozzolanic activity of thermally activated coal mining waste (ACMW) from the Bogdanka mine and its effectiveness in cement blends. The slightly dropped hydration degree was later compensated by prolonged curing time and progress in the pozzolanic reaction. The blending of Portland cement with the examined ACMW did not negatively affect the rheology and setting time of fresh blended pastes. Considering the hardened cement blends' structural, microstructural, and mechanical parameters, ACMW can be safely used as a part of a PC-based blended binder for up to 20% replacement of cement mass.

Calcined Palygorskites as Supplementary Cementitious Materials

AbstractReducing the environmental footprint of cement is an absolute necessity to meet the commitments of COP26 and to limit global warming to + 1.5°C compared to the pre-industrial level. In this context, particular interest has developed in recent years in the use of calcined clays as supplementary cementitious materials (SCMs). Due to their high reactivity, large reserves and homogeneous distribution on the earth's surface, calcined clays represent a viable alternative to conventional SCMs. Clay minerals are highly variable and numerous, each with their own characteristics. As a result, not all of them have potential for use as SCMs. The present paper investigated the use of palygorskite (a clay that has been relatively poorly studied) as an SCM. Two commercial palygorskites of different grades were selected and their calcination was studied by X-ray diffraction and pozzolanic activity tests. Blended cements incorporating 20% of each calcined palygorskite were prepared and the mechanical performance and resistivity of the mortars measured. The results show that the optimum calcination temperature is 800°C (allowing complete amorphization of the clay fraction and the highest pozzolanic reactivity) for both clays. Mortars made with 80% ordinary Portland cement (OPC) blended with 20% of 800°C calcined palygorskite allowed a significant increase in compressive strength and electrical resistivity compared to the reference (100% OPC). The clay sample with palygorskite as the dominant mineral exhibited the greatest pozzolanic reactivity and mechanical performance in cementitious systems, confirming that palygorskite is a clay mineral with a significant potential for a use as a SCM. The second sample with smaller palygorskite content also allowed a significant increase in mechanical performance. This demonstrated that it is not necessary to use high-purity samples and enhances the value of this type of material.

Asidik ve bazik karakterli tüflerin puzolanik özelliklerinin araştırılması: Elazığ ve Gümüşhane yörelerinden örnek bir çalışma

Pozzolans are used as additives in stabilizing clayey soils and as trass in cement production. Natural and unnatural pozzolans added to the ground in the stabilization process increase the bearing strength and strength of the soil, reduce the deformations that will occur as a result of stresses, settlements, swelling potential, liquefaction potential and permeability. It Pozzolans, which are used in cement and called trass, reduce the heat of hydration, increase the resistance of concrete against cracking, increase the waterproofing of the concrete and prevent the expansion caused by the alkali-aggregate reaction. For this reason, researching materials with natural pozzolanic properties and examining their pozzolanic properties are important for the country's economy. 
 In this study, chemical and mineralogical studies were carried out to determine the pozzolanic properties of acidic and basic tuffs, and pozzolanic activity tests were carried out on the tuffs. As a result of the studies, although the acidic character tuffs belonging to the Kızılkaya Formation meet the conditions for use as an additive in the stabilization and cement production recommended in the standards, they cannot provide sufficient compressive strength in the pozzolanic activity test. This is due to the low CaO ratio. For this reason, it is necessary to increase the CaO ratio with lime additives in the use of acidic tuffs. It has been concluded that the chemical properties of the basic character tuffs of the Karabakır Formation are not in accordance with the limit values given in the standards, they will not create sufficient pozzolanic reaction and cannot be used as an additive material.

Robustness of self-compacting concrete incorporating bone china ceramic waste powder along with granite cutting waste for sustainable development

Keeping sustainability at the centre of this work, two solid waste materials have been selected for this study. First is bone china ceramic waste powder (BCCWP) obtained from broken or distorted bone china ceramic waste products, and the second is granite cutting waste (GCW) from the granite cutting and shaping industry. The present study aims at assessing fresh state, mechanical and durability characteristics of the SCC mixes incorporating BCCWP and GCW as cement and fine aggregate replacement, respectively. In a preliminary state, the raw BCCWP was evaluated for various pozzolanic activity tests such as the Frattini test, strength activity index and lime saturation test. SCC mixes were tested for compressive strength, splitting tensile strength, corrosion and chloride resistance tests. SCC mixtures were also tested at elevated temperatures by conducting thermogravimetric analysis (TGA) and differential thermal analysis (DTA) tests. Outcomes of fresh properties were found in the satisfactory limit as per EFNARC standard, except the SCC mix prepared with 30% BCCWP and 40% GCW. SCC mix with 10% BCCWP and 30% GCW showed the maximum strength properties. Moreover, statistical analysis using ANOVA was carried out to find the effectiveness of BCCWP and GCW parameters on various hardened state characteristics. From ecological and economic analysis, lesser embodied energy and embodied carbon dioxide emission, as well as cost reduction, was observed for SCC mixes containing BCCWP and GCW.

Pasinler Obsidiyeni ve Çinko Cürufunun Puzolanik Aktivite İndekslerinin İncelenmesi

Pozzolanes are mineral additives that have been widely used in concrete production recently. The main purposes of pozzolana additives used in concrete are to provide economy and improve various properties of concrete. In this study, obsidian mineral which located in Pasinler District of Erzurum Province and has high amount of reserves in the world with high silica content, and zinc slag which occurring during the production of zinc metal, in the metal industry mainly in Turkey and high production capacity in the world, pozzolanic properties has been investigated. For the pozzolanic activity test, mortar samples were produced by using 5, 10, 15, 20 and 25% obsidian; 2.5, 5, 7.5 and 10% zinc slag instead of cement. Samples produced for the determination of pozzolanic activity index were kept at 7 and 28-days standard cure. At the end of the curing period, pozzolanic activity indexes were determined on the basis of compressive strength. As a result of the pozzolanic activity test, the highest pozzolanic activity value was obtained at the rate of 15% for obsidian and 5% for zinc slag. When the results are examined, it is determined that both materials can be used as pozzolan instead of cement.

Suitable pretreatment process for rice husk ash towards dosage optimization and its effect on properties of cementitious mortar

AbstractPretreatment processes on rice husk ash (RHA) influence its properties and in turn, the performance of concrete. However, most of the available literature captures only the influence of the RHA usage in concrete without focusing on the systematic pretreatment process and optimization of RHA dosage on physical and chemical perspective. Further, the replacements were done on weight basis, leading to higher binder volume and inaccuracies in the performance evaluation. The main objective of the present study is to adopt adequate pretreatment process and to systematically optimize the RHA dosage (vol. %) towards better strength and durability properties. Hence, the current study focuses on understanding the nature of RHA through characterization, followed by suitable pretreatment processes for enhancing the properties of RHA. The enhancement in the chemical activity of the treated RHA was assessed through pozzolanic activity tests (strength activity index, lime consumption test, and soluble silica). Based on the physical properties (particle size, surface area, and packing density), chemical characteristics (strength activity index) and the energy required, the grinding time (30 min) was optimized rationally. The optimized dosage of RHA (20% by vol.) was evaluated for its performance through fresh, mechanical, and durability properties. From the results, it is evident that adequate pretreatment, along with systematically optimized RHA dosage yields enhanced performance in concrete properties.

Evaluation of Industrial by-products as pozzolans: A road map for use in concrete production

The concrete industry is eagerly pursuing the economic advantages of concrete and the improvement of its long-term properties. One of the most effective approaches to improve concrete properties is associated with replacing part of the Portland cement with pozzolanic additives. Although commercial pozzolans like silica fume have proven to be effective, they come at a high cost. Therefore, the modern construction industry is researching pozzolan alternatives. These new pozzolans could come as by-products from different industries, usually accompanied by low-prices, but their efficiency is questionable in most cases. Therefore, fast and reliable evaluation of the materials’ efficiency is necessary. This study aims to summarize techniques adapted for evaluation of pozzolanic materials in a roadmap and do evaluation of waste stream pozzolanic materials. Four characterization directions were considered – chemical and physical analysis (i and ii) and direct and indirect pozzolanic activity test methods (iii and iv). Five commercial or waste stream pozzolanic materials were compared and results evaluated. Industrial by-products (glass E, glass K, metakaolin) are studied as alternative pozzolans and compared to silica fume and fly ash. Selected materials are evaluated using testing methods, such as XRF, FTIR, XRD, micro-granulometry, BET, Frattini test, saturated lime test, strength activity index and alkali–silica reaction tests. The evaluation roadmap for pozzolan quality assessment is proposed. Results indicate that commercial material silica fume can meet the requirements followed by the test procedures given in roadmap. Promising result was obtained for E glass which also passed the quality assessment and showed respectable performance results. Rest of materials failed such an important parameter as alkali content. Besides, it was concluded that only complex dissemination provides a trusted result, as the Frattini test and saturated lime test showed promising results, the results do not always match the results of the strength activity index and alkali–silica reaction.

Evaluation of the pozzolanic activity of red ceramic waste using mechanical and physicochemical methods

Abstract Alternative cementitious materials can potentially reduce the environmental impact of the extraction of lime and the hazardous production of Portland cement. Red ceramic waste can be comminuted to fine particles with both filler and pozzolanic activity and used in Portland and lime mortars. This study presents the evaluation of the pozzolanic activity of red ceramic waste by physicochemical and mechanical methods using Portland cement and lime mortars. The evaluated waste depicted high pozzolanic activity and absence of Na2O, and consumed 32% of CaO according to the adapted Chapelle test. The compressive strength recorded in the pozzolanic activity test with lime was 7.1 MPa at 7 days. Moreover, the compressive strength of mixes with 25% replacement of Portland cement by red ceramic waste was 11% higher than the reference waste-free composition. The red ceramic waste depicted adequate characteristics to be used in the production of large volumes of Portland and lime mixes commonly employed in the civil construction.

Suitability of Gini moraines as natural pozzolanic material for Diamer Basha dam project

Diamer Basha dam is to be located on the mighty Indus River about 315 km upstream of Tarbela dam. The dam will be 272 m high and constructed from roller-compacted concrete (RCC). Earlier studies for the RCC mixture and placement conditions regarding heat development showed that extensive use of cement substitutes is essential for the construction of the RCC dam. The total amount of cementitious substitutes will be up to 2·0 Mt, which need to be supplied over a period of 4·5–5 years. Potential substitutes (blast-furnace slag from Pakistan Steel Mills, Karachi and fly ash from Lakhra, Pakistan and Bathinda, India) were considered unfeasible due to low production capacities, long distances from the project site and political reasons. In this study, locally available potential pozzolanic materials from Gini Gah, about 54 km upstream of the dam site, were investigated through physical, chemical and pozzolanic activity tests to assess their suitability for use in mass concrete. The results revealed that glacial moraines obtained from Gini are acceptable for use in RCC.

Investigation of Mortars and Plasters of a Byzantine Church in Southwest Anatolia with Emphasis on Possible Pozzolan Use

Characterization of mortars and plasters used in historical structures is crucial before conservation interventions in order to propose proper repair materials and avoid any damage caused by material incompatibility. In the present study, mortars and plasters of a Byzantine Church in the ancient city of Stratonikeia dated back to 5th – 7th centuries were examined in terms of physical/physico-mechanical characteristics and raw materials used by various analytical techniques. Possible use of pozzolanic materials in mortar and plaster samples were investigated by pozzolanic activity tests performed on the aggregates (< 125 µm) and examining the reaction products formed after immersion of these aggregates in a saturated solution of Ca(OH)2. Investigated mortar and plaster samples were found to have relatively low bulk density and high effective porosity. Compressive strength values of mortar samples were found to be in the range of 3.92 – 4.47 MPa. Binder used in the mortar and plaster samples were assessed to be fat lime. Aggregates of the samples smaller than 125 µm were found to have good pozzolanicity. Formation of pozzolanic reaction products by the reaction of the finer aggregates with Ca(OH)2 were confirmed by the results of SEM-EDX and FTIR analyses.DOI: http://dx.doi.org/10.5755/j01.ms.24.3.18590

Effect of the Addition of Aluminum Recycling Waste on the Pozzolanic Activity of Sugarcane Bagasse Ash and Zeolite

The pozzolanic activity of aluminum recycling waste (AW) was evaluated along with sugarcane bagasse ash (BA) and zeolite (ZE) to give a more sustainable use. These materials were characterized and submitted to the pozzolanic activity test by a modified Chapelle test and the compressive strength of mortars prepared with limestone Portland cement (LPC). The final solids were characterized again to determine the hydrated products. The main reactive chemical components of AW are Al2O3 and MgO, which are in the form of hydroxides, such as nordstrandite (Al(OH)3), meixnerite ([Mg5Al3(OH)16][(OH)3·(H2O)4]), brucite (Mg(OH)2) and magnesium chloride hydroxide hydrate (Mg3(OH)5Cl·4H2O). All of the studied materials were classified as pozzolans by the modified Chapelle test, and the main hydrated products formed in the AW sample were katoite, ettringite, talc and amesite. When mixed with BA and ZE, C-A-S-H and C-S-H phases were also formed. The C-S-H phases and portlandite were detected only in the solids of the modified Chapelle test of BA and ZE. Calcite was present in all samples, indicating that part of the Ca(OH)2 was consumed by the carbonation process. The compressive strength test of mortars revealed that only ZE is a pozzolan. In mortars containing AW the production of ettringite and calcium carboaluminate increased due to the reactions of aluminum, respectively, with gypsum and calcite present in LPC. In addition to portlandite, C-S-H was formed only in the BA and ZE mortars. Although hydration reactions were not sufficient to form C-S-H in AW mortar, reactive aluminum favors the formation of primary ettringite.

The utilisation of feed and byproducts of mineral carbonation processes as pozzolanic cement replacements

Abstract Utilising the byproducts of mineral carbonation processes contributes to rendering the technology environmentally benign and enhances the economically viability of the process. In this work we synthesised, characterised and investigated the technical feasibility and environmental benefits of utilising feed and byproducts of mineral carbonation technology as Portland cement substitutes. These materials, with and without pre-treatment, were used to substitute 5, 10 and 20 wt% of Portland cement in mortars. Pozzolanic activity tests indicated that acid treated silica enriched residue (ATSER) displayed pozzolanic activity. At 5% cement replacement all materials showed compressive strengths comparable to the control. When 10 wt% of cement was replaced, only heat activated lizardite showed strength results similar to the control. The compressive strength of mortars containing other samples with 10 wt% or greater cement replacement showed that the extra water demand outweighed any pozzolanic contribution of mineral carbonation materials and resulted in a lowering of the compressive strength of these mortars compared to controls, in particular when in excess of 10 wt% of cement is replaced. An environmental analysis showed that in addition to significant CO2 emissions reduction, the economic and environmental costs of waste disposal were avoided when mineral carbonation byproducts substituted Portland cement.

Use of glass powder residue for the elaboration of eco-efficient cementitious materials

Abstract The glass powder is a waste resulting of the manufacturing process of flat glass (regular glass). This study evaluates the eco-efficiency of cement production using glass powder residue as partial replacement of cement. The glass powder residue (GPR) was used as partial replacement up to 50% by weight in cement pastes to evaluate the potential use of this matrix for application in fiber cement composites. For mortar specimens, the percentage of substitution of cement (up to 20% by weight) was used to evaluate the applicability of the glass powder in masonry construction. Primarily, several experiments such as thermogravimetric analysis, compressive strength tests, pozzolanic activity and durability tests were carried out to evaluate the potential use of GPR in cement industry. Secondly, to evaluate the eco-efficiency of the material elaborated, the energy demand of cement partially replaced by glass powder residue and the energy performance of mortars were calculated using mathematical equations. The results showed that GPR presents a pozzolanic activity and a free calcium hydroxide cement matrix is obtained when the ordinary Portland cement is partially replaced by 50% by weight of GPR in cement pastes. Moreover, the partial replacement of cement by 10% by weight of GPR leads to an increase of physico-mechanical properties of mortars. Finally, the energy consumption per MPa of mortars partially replaced by GPR (10 and 20% by weight) is lower than the one of original Portland cement suggesting the eco-efficiency of GPR for applications in cement production and the elaboration of cementitious materials. According to the results of the study, the residue from polishing process of flat glass can be used for the elaboration of green cement and eco-efficient cementitious materials.

Effect of Waste Brick as Mineral Admixture on the Mechanical Performance of Cemented Paste Backfill

This study presents the replacement and addition of granulated waste brick (WB) to ordinary Portland cement (OPC) in a cemented paste backfill (CPB) of sulphide tailings. The addition and OPC rate is about 15-45% and 7% in weight respectively. Pozzolanic activity tests indicated the fineness of WB samples being the major factor of pozzolanic activity instead of chemical composition. All CPB samples displayed the required strength and durability when WB was used as an additive to OPC. On the other hand, a binder dosage of >7wt % was needed to apply the required 28-day strength of ≥ 0.7 MPa when the OPC was replaced by 15-45 wt% WB samples. The durability of CPB samples is closely inter-related with the calcination temperatures and glass phase content of WB.

Pozzolanic Activity and Compressive Strength of Concrete Incorporated nano/micro Silica

This paper aims to give a recommendation about the suitable nano silica proportion and curing method for testing its strength pozzolonic activity, in addition to suggest a mixing or batching procedure of this material with other concrete ingredients. Theinfluence of nanoand micro silicaon concrete compressive strength is also studied. Three proportions of nano silica (0.5, 5, &10%) , two curing methods (accelerated in oven and normal in water) and two tested agesare used in pozzolonic activity test of nano silica. For compressive strength test, eleven mixes are considered:without-adding (two mixes), three micro silica (M) mixes with replacement ratios of 5, 10 & 15%, four nano silica (N) mixeswith replacement ratiosof 0.5,1.5, 3 & 5%, and three micro plus nano silica mixes (0.5N+9.5M,1.5N+8.5M and 3N+7M%) are adopted.Results of pozzolanic activity test denoted that nano silica has remarkable pozzolanic activity for all tested replacements.However, it is suggest using 5% nano silica for performing this testby usingeither accelerated or water curing. Additionally, it was found that nano silica had more impact on compressive strength of concrete than micro silica for all tested ages.Where, maximum enhancement ratios of compressive strength were about 33% and 27% for 3% nano silica mix at 7 and 90 days age respectively, and 22% for 5% nano silica mix at 28 days age. For micro silica mixes, higher improvement ratios were found in 15% micro silica mix: 2%,5%&7% at 7,28 &90 days age respectively.

Performance of steel slag and steel sludge in concrete

The impact of environmental cleansing through inclusion of hazardous wastes in cement related products cannot be overemphasized. This paper presents outcomes of laboratory experiments on the utilizations of electric arc furnace steel slag and steel sludge (by-products from steel making industries) as cement replacements in concrete. Pozzolanic properties of steel slag and steel sludge were evaluated using pozzolanic activity test specified by ASTM C618. In addition, the materials were subjected to X-ray Fluorescence and X-ray Diffraction tests in order to identify their chemical as well as mineral compositions respectively. In the process, conductivity of materials suspension in calcium hydroxide (Ca(OH)2) solution were monitored. Mechanical properties of the concrete containing the steel slag and steel sludge were also evaluated. The results of pozzolanic activity tests show that steel sludge has a higher reactivity due its higher loss of conductivity which is about 72.9% as against 43.3% for steel slag. However, both materials show good reactivity in Ca(OH)2 solution. In fact, the strength activity index of both materials were observed to reach a minimum of 75% based on ASTM C618 requirement. Eventually, compressive strength development in concrete due to inclusion of 15% and 20% steel sludge and steel slag respectively yielded higher strength gains over the control mix particularly at later curing ages.

Farklı Sınıf Çimento Harcı Üretiminde Metakaolin Katkısı Kullanımının Araştırılması

In this study, it was studied physical and mechanical properties of Portland cement mortars with different strength classes and metakaolin (MK) substituted. Two different Portland cement such as CEM II/B-M 32.5 R (A cement) and CEM I 42.5 R (B cement) is used in the production of mortar samples. Metakaolin which is substituted by cement was obtained as a result with sintering of kaolin clay in five different temperatures (600, 700, 800, 900 ve 1000 o C) in the laboratory conditions. 7-day sintered metakaolin samples were conducted pozzolanic activity test and the highest pozzolanic activity index was obtained in the samples sintered at 900 o C. Then, it was substituted at a rate of 10 % and 20 % metakaolin material sintered 900 o C and it was compared with the reference cement mortar. Standard sand was used in the production and the samples were placed with vibration method in 40 x 40 x 160 mm metal mould according to TS EN 196-1. Later, 7 and 28 days water cure is applied to samples. Finally, the physical tests such as water absorption, porosity, bulk density and apparent density with the mechanical properties such as flexural strength and compressive strength were determinated. However, the ultrasound values were determinated from the samples. As a result, the highest compressive strength values were obtained from the samples with 20 % MK together A cement and 10 % MK together B cement.