High Calcium Oxide Research Articles

Strength, durability, and heat development characteristics of high-performance concrete containing ground coal bottom ash with low and high calcium

Currently, the availability of fly ash has reduced continuously due to the shutdowns of coal-fired power generating plant as climate change concerns have increased. Therefore, the aim of this paper is to find an alternative pozzolan by examining the employment of low- and high-calcium oxide (CaO) ground bottom ash which has been abandoned rather using in concrete production. The bottom ashes were blended with fly ash as a partial substitution of cement (OPC) by observing their generic effects on the compressive strength, cumulative heat generation, chloride ion penetration, and water sorptivity of high-performance concrete. The samples of bottom ash were prepared by oven drying, particle size cutting, and grinding to enhance the reactivity and consistency. High-performance concretes were made at a water-to-binder (W/B) ratio of 0.27 and partial replacement of OPC up to 50 % by weight of the binder. The results indicated that the concretes with 28-day compressive strengths of 101.0 and 109.0 MPa (21.6 % and 28.2 % stronger than OPC concrete) were produced with 50 wt% OPC replacement with high- and low-calcium ground coal bottom ashes (HCBA and LCBA), respectively. These findings suggest that HCBA and LCBA have high pozzolanic reactivity and high possibility for utilization as pozzolan or supplementary cementitious materials in concrete. In addition, the binary blended binders (OPC-HCBA and OPC-LCBA) and ternary blended binders (OPC-HCBA-FA and OPC-LCBA-FA) produced had better chloride ion penetration resistance, less cumulative heat evolution, and lower water sorptivity than 100 % OPC as a cementitious material. Partial OPC replacement by HCBA and LCBA improved the chloride ion penetrability class of OPC concrete from “very low” to “negligible.” The cumulative heat generation due to the pozzolanic reaction of HCBA and LCBA from the partial replacement of OPC up to 50 % reduced 30–44 % relative to the OPC-based mixture throughout during 72 hours after mixing. The CaO content strongly influenced early compressive strength development and cumulative heat evolution but had less impact on chloride ion penetration resistance and water sorptivity.

Long-Term Performance of Mortars with Combined Incorporation of Ladle Furnace Slag and Metakaolin

Ladle furnace slag (LFS) is used as a supplementary cementitious material (SCM) due to its high calcium oxide (CaO) content. Its binding properties are enhanced in the presence of siliceous materials, such as metakaolin (MK), forming a ternary mixture that can directly replace ordinary Portland cement (OPC). However, despite this blend having already been evaluated in alkali-activated mixtures, knowledge about this mixture in situations of direct replacement of OPC by slag is still lacking. This study evaluates the synergistic effects of combining LFS and MK in cementitious mortars. Due to an insufficient hydration reaction observed in the short term, this study focuses on assessing the long-term performance of these mortars. Both the fresh and hardened states at 28 and 180 days are evaluated, and the resulting microstructural characteristics and constituent phases are also examined. After 180 days of curing, the mortar with MK exhibits superior binding activity compared to the results at 28 days. Although the nominal resistance does not show a clear advantage with the application of MK, a significant reduction in the porosity of the mortar is observed. Microstructural analysis indicates that the addition of MK increases the hydration compounds when mixed with LFS. Importantly, the sample containing MK and LFS showed a 42% reduction in cement consumption, highlighting the potential for resource efficiency. Thus, this study contributes to promoting a circular economy between the steelmaking and civil construction sectors.

Utilization of waste high calcium oxide fly ash as hybrid activator for vulcanization of natural rubber/carbon black composites: Reducing zinc oxide requirement

A high calcium oxide fly ash (FA), a by-product waste of electric power generation has been used as hybrid activator in natural rubber (NR) composites filled with carbon black (CB). The aim of using FA is to reduce the environmental contamination by zinc oxide (ZnO) needed as activator for sulfur-vulcanization/crosslinking in final NR products. The FA was varied by adding in the composites with and without ZnO, and it was observed that chemical crosslinking could be generated although no ZnO was used anymore. The synergistic FA/ZnO-blend with FA 9 phr and ZnO 3 phr presented the best fit for the NR/CB composites, where it showed a proper crosslink density, reinforcement efficiency, cure characteristics, and mechanical properties in terms of modulus, tensile strength, elongation at break and tear resistance. This relates to the inorganic composition of the FA, in particular calcium oxide (CaO), which induces the thermal conductivity throughout the NR matrix and activates crosslinking between the NR molecules. The results showed effective use of FA in the composites, which can be applied to the CB-based formulations used in commercial NR applications like tires, barriers, and elastic stopper.

DIAGNOSIS OF THE DETERIORATION AND CONSERVATION OF BES POTTERY JAR FROM THE TOMB OF PETAH UMM UYA IN SAQQARA

The purpose of this study was the chemical characterization and conservation of the Bes pottery jar. Pottery jars were important in Egypt from prehistoric times until the end of late history; they had their ideological symbolism and important role in daily life. "Bes" jar is a kind of healing jar, which was known and spread during the end of the New Kingdom and Late Period of ancient Egypt. AutoCAD, digital microscope, and polarized microscope (PLM) were used to clarify the deterioration state of the pottery jar. The XRD method was used to investigate the mineralogical composition of the pottery jar. Besides, the pottery's internal morphology and chemical composition were studied using scanning electron microscopy with energy dispersive X-ray spectroscopy (SEM-EDX). The examination revealed that the selected pottery jar exhibited numerous cracks, dust accumulation, salt crystallization, and black spots. PLM showed the presence of several minerals, such as calcite, quartz, biotite, and plagioclase. SEM-EDX analysis revealed high calcium oxide concentrations due to the use of calcium carbonate in the slip layer, besides chloride salts. XRD analysis indicated that quartz was the predominant mineral in all the samples. Additionally, calcite, diopside, anorthite, halite, and dolomite were also detected in varying proportions. The pottery jar underwent various treatments, including mechanical and chemical cleaning. In addition, dental gypsum and grog were used in the completion process. Furthermore, the paraloid B-72 was used to achieve the consolidation process.

Turning fly ash and waste gypsum into a resource for backfilling applications

Flue Gas Desulfurization Gypsum (FGDG), an industrial by-product generated by power plants, was thermally treated and incorporated in cement-free fly ash bricks. This study aimed to determine the effects of using a thermally treated FGDG as an additive to improve the mechanical and structural properties of cement-free fly ash bricks. FGDG was thermally treated for 2 h at different temperatures. The influence of varying amounts (10–50%) of thermally treated FGDG on the performance of cement-free bricks was analyzed through mechanical properties, micrography, durability, the evolution of particle size distribution and environmental characteristics experiments. The effect of curing temperatures and curing age on the strength development and microstructural properties was also investigated. A Toxicity Characteristic Leaching Procedure (TCLP) was carried out to determine the leachability of metals from the synthesized FA cement-free brick. The results showed that the FGDG had a high calcium oxide content. In contrast, FA is mainly composed of silica, and both materials carry cementitious properties making both good raw materials for this study. The FA cement-free bricks containing 30% of thermally treated FGDG, oven-cured at 60 ℃, yielded the highest unconfined compressive strength (UCS) of 7.14 MPa. However, curing at ambient temperature for 28 days yielded a better UCS of 7.37 MPa. The particle size distribution showed that particles transformed from fine particles at 7 days to larger particles at 28 days due to particle growth. Durability tests showed that the developed bricks could withstand 7 wet/dry cycles. The TCLP showed that the leachability concentrations of all metals are within the limit and, therefore, can be potentially used as a building material in backfilling. The synthesis of FA/FGDG composite will aid in reducing the generated waste gypsum in landfills consequently eradicating human health challenges and loss of biodiversity. This paper showed that developing FA/FGDG composites will reduce their environmental impact and make them a resource for other valuable products such as backfilling applications and green building bricks.

A novel approach to accelerate carbon dioxide sequestration of ladle furnace slag using sodium bicarbonate solution

The annual output of ladle furnace (LF) slag exceeds 20 million tons. The slag pulverises easily and contains heavy metals, leading to severe environmental pollution during stacking. However, slag issuitableas a material for carbon dioxide sequestration owing to its high calcium oxide content. This study focuses on exploring a new scheme because the direct carbonation method requires strict operating conditions and the indirect carbonation method hinders the materialisation of ladle furnace slag. In this new scheme, a sodium bicarbonate solution acts as the treatment solution for the carbonate LF slag, and the treated solution regenerates by injecting carbon dioxide. The experimental results show that the sodium bicarbonate concentration, stirring speed, and liquid-to-solid ratio have minor effects on the CO2 uptake percentage. With increasing reaction time, the CO2 uptake percentage increases during the first 120 min and then remains constant. The rise in temperature has a negative impact on the CO2 uptake percentage. However, decreasing the particle size of the LF slag greatly improves the CO2 uptake. CO2 injection at a flow rate of 1 L/min for 100 min decreased the pH of the treated solution to 8.9, achieving regeneration of the treated solution. Thermodynamic analysis indicates that for the reactions between sodium bicarbonate solution and minerals, calcium oxide and calcium aluminate have a significant thermodynamic driving force, indicating that slag with high basicity and CaO-Al2O3 base slag is moresuitedfor sequestering CO2. The study provides a novel method for CO2 sequestration and ladle furnace slag stabilization.

Comparative environmental assessment of low and high CaO fly ash in mass concrete mixtures for enhanced sustainability: Impact of fly ash type and transportation

The effect of fly ash type on the sustainability of concrete mixtures has yet to be quantified. This study aims to assess the environmental impacts of low calcium oxide (CaO) and high CaO fly ash in mass concrete mixtures from Thailand. The study analyzed 27 concrete mixtures with varying percentages of fly ash as a cement replacement (0%, 25%, and 50%) for 30 MPa, 35 MPa, and 40 MPa compressive strengths at specified design ages of 28 and 56 days. Sources of fly ash have been located between 190 km and 600 km away from batching plants. The environmental impacts were assessed using SimaPro 9.3 software. The global warming potential of concrete is reduced by 22–30.6% and 44–51.4% when fly ash, regardless of type, is used at 25% and 50%, respectively, in comparison with pure cement concrete. High CaO fly ash has more environmental benefits than low CaO fly ash when utilized as a cement substitute. The reduction in environmental burden was most significant for the midpoint categories of mineral resource scarcity (10.2%), global warming potential (8.8%), and water consumption (8.2%) for the 40 MPa, 56-day design with 50% fly ash replacement. The longer design age (56 days) for fly ash concrete showed better environmental performance. However, long-distance transport significantly affects ionizing radiation and ecotoxicity indicators for terrestrial, marine, and freshwater environments. Furthermore, the results show that a high cement replacement level (50%) may not always have a reduced environmental impact on mass concrete when considering long-distance transportation. The critical distance calculated based on ecotoxicity indicators was shorter than those calculated using global warming potential. The results of this study can provide insights for developing policies to increase concrete sustainability using different types of fly ash.

Synthesis of precipitated calcium carbonate from LD-slag using CO2

The waste Linz-Donawitz (LD) slag produced in the steel industries is known to have high calcium oxide (CaO) content along with other inorganic salts. There is an untapped potential for the valorization of the waste LD-slag, where the constituent calcium oxide can be converted to valuable calcium carbonate and subsequently contributes to the sequestration of carbon dioxide. In this study, table sugar was introduced as a promoter to enhance the conversion of CaO to CaCO3. The valorization of the LD-slag process was conducted in a CO2 atmosphere by varying the temperature over 25–55 °C. The highest calcium oxide conversion was found at 55 °C. Various techniques were employed in order to assess the crystal growth, textural properties, and thermal behavior of the synthetic CaCO3 formed. The calcite phase is dominated in a temperature range of 25–55 °C, whereas unstable vaterite was identified at 45 °C. Further, at higher temperature ∼55 °C, the needle-like aragonite phase was found to dominate. The reaction kinetic data are well-fitted with the pseudo-second-order model (R2 = 0.99) as compared to other models. The whiteness of the obtained samples was measured via UV-spectrometer and the PCC sample achieved at 55 °C showed significant whiteness characteristics among others. The CO2 sequestration efficiency in this study was found to be ∼17%. It was estimated that 500 g of CO2 could sequestrate by 1 kg of LD-slag. Moreover, the “t” value obtained from the hypothesis test is 49.92, which reveals that the presence of table sugar in the reaction, leads to a higher Ca(OH)2 concentration.

Comprehensive Evaluation of the Performance and Benefits of SSA-GGBS Geopolymer Mortar.

The activity of sewage sludge ash (SSA) is not high; ground granulated blast slag (GGBS) has a high calcium oxide content that can accelerate polymerization rates and exhibit better mechanical performance. In order to improve the engineering application of SSA-GGBS geopolymer, it is necessary to conduct a comprehensive evaluation of its performance and benefits. In this study, the fresh properties, mechanical performance and benefits of geopolymer mortar with different SSA/GGBS, modulus and Na2O contents were studied. Taking the economic and environmental benefits, working performance and mechanical performance of mortar as evaluation indexes, the entropy weight TOPSIS (Technique for Order Performance by Similarity to Ideal Solution) comprehensive evaluation method is used to evaluate the geopolymer mortar with different proportions. The results show that as SSA/GGBS increases, the workability of mortar decreases, the setting time first increases and then decreases, and the compressive strength and flexural strength decrease. By appropriately increasing the modulus, the workability of the mortar decreases and more silicates are introduced, resulting in increased strength in the later stage. By appropriately increasing the Na2O content, the volcanic ash activity of SSA and GGBS is better stimulated, the polymerization reaction is accelerated, and the early strength increases. The highest Ic (integrated cost index, Ctfc28) of geopolymer mortar is 33.95 CNY/m3/MPa, and the lowest is 16.21 CNY/m3/MPa, which is at least 41.57% higher than that of ordinary Portland cement (OPC). The minimum Ie (embodied CO2 index, Ecfc28) is 6.24 kg/m3/MPa, rising up to 14.15 kg/m3/MPa, which is at least 21.39% lower than that of OPC. The optimal mix ratio is a water-cement ratio of 0.4, a cement-sand ratio of 1.0, SSA/GGBS of 2/8, a modulus content of 1.4, and an Na2O content of 10%.

Evaluation of Adhesive Properties of Different Mineral Compositions in Asphalt Mixtures with Experimental and Molecular Dynamics Analyses

The adhesion between bitumen and mineral composition plays a vital role for the performance of asphalt mixtures. This study compares the adhesion of limestone, dolomite, and granodiorite to bitumen and evaluates the effects of different mineral components on adhesion. Three kinds of aggregates were tested through rolling-bottle tests. Afterwards, the respective fillers were integrated into asphalt mastic in a 1.6:1 mass ratio with bitumen and were subjected to frequency scan tests separately. A modified Luis Ibrarra-A model, K. Ziegel-B model, and K-B-G model were used to evaluate the bitumen–filler interactions based on the rheology of the asphalt mastic. In addition, the interface behavior between eight mineral components from these fillers/aggregates and bitumen were investigated by molecular dynamics (MD) simulations. The work of the adhesion and molecule concentration profiles were obtained from MD simulations. The results showed that the limestone and dolomite had better interfacial adhesion to the bitumen than the granodiorite. The calcium oxide and titanium oxide had the highest potential adsorption effect on the bitumen. Moreover, the high calcium oxide content contributed to better bitumen adhesion with the limestone and dolomite than with the granodiorite, which was further confirmed by additional molecule concentration profile analysis. This research contributes to the in-depth understanding of the effect of different chemical properties on the performance of asphalt mastic and the selection of suitable mineral components to improve the bitumen–filler/aggregate interface and asphalt mixture performance in general.

Preparation of low-cost and non-conventional macroalgae-based biosorbent for fast and effectively selective dye adsorption

In the present work, a low-cost, non-conventional, and novel biosorbent was developed by an easy and eco-friendly pathway using Ulva Lactuca (U. Lactuca) marine algae and calcined eggshell. The dead U. Lactuca biomass was alkali treated with a calcined eggshell which has high calcium carbonate and calcium oxide content. The new biosorbent was characterized using XRD, FTIR, SEM-EDS, XPS, TGA, and Zeta-potential and then employed for selective and individual dye adsorption. Interestingly, it was found that the biosorbent rapidly separated both cationic methylene blue (MB) and anionic Congo red (CR) from various binary dye solutions. A number of individual MB and CR adsorption studies on the biosorbent were conducted under different conditions. The results showed that the adsorption capacity of the algae was enhanced after being treated with a calcined eggshell, and it exhibited excellent adsorption performance for MB removal with a maximum adsorption capacity of 2000 mg g−1. In addition, the adsorption process was so fast that it reached equilibrium within 15 min. Over the four cycles, the biosorbent exhibited no significant loss in adsorption capacity. The MB dye adsorption data onto the biosorbent were well fitted by the second-order kinetic model and the Langmuir isotherm. Based on the possible adsorption mechanisms of the biosorbent for two dyes, the adsorption process of MB can be attributed to the unconverted calcium carbonate mineral phase in the biosorbent structure, electrostatic interactions, and hydrogen bonding, while the removal of CR can be attributed to the mineral phase and hydrogen bonding. This study shall provide a new perspective on the development of an inexpensive, easily prepared, and excellent adsorption performance biosorbent for the rapid removal of organic dyes from wastewater.

Effects of Filler Properties on Fatigue Performance and Bond Strength of Asphalt Mastics

Mineral fillers are a vital part of asphalt mastic and mixtures that are known to have a major role in the mixtures’ performance. A better understanding of the effects of the filler properties on asphalt mastic is important to control the distresses of the asphalt mixtures. This study evaluates the effects of physical and chemical properties of filler on fatigue and bond strength of asphalt mastic. Twelve asphalt mastics are prepared in the laboratory using three types of asphalt and four types of fillers. A filler to binder ratio of 1 (by mass) is used for all mastic sample preparation in the laboratory. Rigden voids (RV), fineness modulus (FM), calcium oxide (CaO), and methylene blue value (MBV) are used as properties of the filler for characterizing the fillers. The fatigue cracking behavior of asphalt mastic is evaluated using linear amplitude sweep (LAS) test, and asphalt bond strength (ABS) test is used to evaluate the interfacial bond strength between aggregate samples and mastics. The results from LAS test showed that the rolling thin-film oven (RTFO) aged mastic with a high percentage of FM containing filler has a better fatigue life than RV, CaO, and MBV containing filler. For pressure aging vessel (PAV)-aged mastic, the overall test result indicated that the fatigue cracking resistance of mastic is dependent on the interaction between base asphalt binder and filler type. The failure criteria of the LAS test method is an important parameter to characterize the mastic properties. The LAS and ABS test methods reveal that mastics prepared with high MBV and low CaO containing filler have better bond strength and worst fatigue performance. The bond strength performance of the mastic prepared with high FM filler is worse than base asphalt. FM, MBV, and CaO are major filler properties that could influence the asphalt mastic’s fatigue and bond strength performance.

Development of Density Control Technology for Improving Medical Radiation Shielding Performance of Waste Marble Powder Mixture

The marble used at construction sites creates a large amount of sludge after processing. Because waste marble has a high calcium oxide content, it is often used as a concrete mix building material. In this study, the use of waste sludge in the fabrication of radiation shields was investigated for medical shielding applications. A shielding sheet was produced by mixing a polymer and waste marble powder. A method for improving the density of the shielding sheet was developed to improve the shielding performance. To improve the density of the shielding sheet using the WMP mixture, the gap between particles was narrowed by making the WMP particles small and by mixing in a material with a proven shielding effect, such as bismuth oxide. In addition, a stirring defoaming process was used to reduce the voids between particles, and we presented a method to control the density by processing the WMP at a high temperature of 1200 °C. The experimental results revealed that the waste marble powder exhibited the highest shielding effect when mixed with radiation shielding materials such as bismuth oxide. The reduction of voids and the size of the particles used in preparing the shielding sheet proved to be effective in reducing the gap between the particles, resulting in an improvement of shielding of approximately 15% to 20%. The investigated shielding material based on waste marble powder was shown to be effective in shielding low-dose radiation.

Flexible canvas produced from uncured-natural rubber composites filled with high calcium oxide fly ash/cement hybrid filler

Concrete canvas (CC) is an attractive composite based on a combination of textile and cement, applying for the slope protection and ditch lining. However, there is no binder between both the materials and its high thickness causes a strong detachment of cement particles, and the complex designing of CC shapes is limited. Therefore, the possibility of incorporating natural rubber (NR) as a binder for extending the applications of cement-based composites has been considered. In the present work, NR composites with fly ash (FA) and cement (CM) are prepared through an internal mixer and a two-roll mill with a total filler concentration of 1000 phr. It can be found that, FA/CM hybrid filler is successfully adhered together through the NR matrix, and it promotes the flexible canvas composites with controlled thickness and provides complex shapes. The existing calcium oxide (CaO) present in the filler reacts with water molecules, and the NR composites become hardened and restrict the deformation and decomposition. The optimum ratio of FA/CM hybrid filler has been fixed at 300/700 phr, which has recognized as the product-like concrete canvas. Tensile properties, dynamic properties and thermal stability are improved upon the incorporation of hybrid fillers and its flexibility is found to be sustained on soaking with water. The structural changes are confirmed from the infrared spectrum which clearly explains the transformation of CaO to the CSH network structure in the NR composites. Un-crosslinked composites exhibited similar mechanical properties compared to the chemically crosslinked NR with sulfur curing system. Thus the composites can be used as the flexible canvas, although it has not been vulcanized. To clarify this statement, tensile properties, abrasion resistance and bending propagation of NR composites, NR vulcanizates and commercial concrete canvas are compared. The composites exhibited comparable properties with superior flexibility performance. Along with the waste utilization, the uses of FA, provides an opportunity of using FA/CM as the flexible canvas.

Ground palm oil fuel ash and calcined eggshell powder as SiO2–CaO based accelerator in green concrete

Some applications in the construction industry such as precast concrete demand for early strength development. This is normally achieved using accelerator, but most accelerators in the market contain chemicals that adversely affect the environment. This study proposes the incorporation of ground palm oil fuel ash (GPOFA) and eggshell powder (ESP) derived from agriculture and aviculture wastes as bio-accelerator. GPOFA contains high level of silicon dioxide (SiO2) while ESP has high calcium oxide (CaO) content that are responsible for early and later strength development in concrete, respectively. The engineering, chemical and mineral properties of the resultant green concrete were evaluated and discussed. The GPOFA-ESP accelerator had enhanced the mechanical and durability of the concrete when compared to a normal concrete mix. Three types of ESP had been prepared and blended with GPOFA, namely the uncarbonized eggshell powder (UC-ESP), carbonized eggshell powder (C-ESP) and decarbonized eggshell powder (DC-ESP). The combination of 15% GPOFA and 5% DC-ESP resulted in a concrete with the highest average compressive strength, flexural strength and splitting tensile strength consistently over a 90-day curing period. The concrete also had the smoothest surface, highest resistance to chloride and sulphate attack. Thus, this study strongly proposes further research into this GPOFA-ESP combination as concrete accelerator to contribute towards a more sustainable future.

Reactivity of Unconventional Fly Ashes, SCMs, and Fillers: Effects of Sulfates, Carbonates, and Temperature

Abstract Reactivity information for a range of unconventional fly ashes is unavailable in literature. The objective of this study is to quantify the reactivity of numerous unconventional fly ashes using the R3 test (ASTM C1897-20, Standard Test Methods for Measuring the Reactivity of Supplementary Cementitious Materials by Isothermal Calorimetry and Bound Water Measurements) and the modified R3 test and to determine how sulfates, carbonates, and temperature affect the measured reactivity. A small set of other supplementary cementitious materials and fillers was used to benchmark the fly ash results. Heat release, calcium hydroxide consumption, and bound water were measured for the different materials. For siliceous materials with relatively low calcium oxide (CaO) + aluminum oxide (Al2O3) contents, temperature had a dominant effect on the heat release. On the other hand, for materials with higher CaO + Al2O3 contents, the effects of sulfates and carbonates dominated the effect of temperature. The slow but sustained reactivity of Class F fly ashes highlighted the importance of kinetic corrections or extrapolations to the reactivity measured in the R3 test. However, when testing at 50°C, the heat release curves of all tested materials plateaued at the end of 10 days, indicating that kinetic corrections were not required. Correlations between reactivity and early- and later-age paste properties are discussed.

Utilization of high and low calcium oxide fly ashes as the alternative fillers for natural rubber composites: A waste to wealth approach

Recently, fillers from renewable resources or agricultural wastes have been considered as the alternative fillers to reduce the environmental problems. Therefore, utilization of the fly ashes (FA) collected from the electric power plants as the reinforcing filler in natural rubber (NR) composites was carried out and compared these high (HCaO) and low (LCaO) calcium oxides with carbon black (CB). The FA concentration was varied up to an optimum loading of 1000 parts per hundred rubber (phr) by using melt mixing technique. Particle size and chemical composition of HCaO and LCaO were reported and the properties of NR composites in terms of cure characteristics, Payne effect, mechanical and dynamical properties together with morphologies were examined. It was found that the addition of HCaO significantly reduced the vulcanization time of the NR composites, while the one with LCaO provided higher degree of reinforcement efficiency to the NR matrix. It clearly supports the relation of storage modulus as a function of strain sweep and their morphologies, which are the major requirements in case of composites. Upon increasing of FA loading, NR has changed its role from rubber matrix to an adhesive binder and therefore the Young’s modulus was found to be strongly changed. FA can be used to replace CB in NR composites with the composition ratios starting from 1:2–1:6 phr. Although, CB exhibited a slightly better reinforcing effect than FA, based on the lowered glass transition temperature (Tg), Tan delta (Tan δ) exhibited the same elasticity and CB can be replaced in case of several CB-based composites, particularly, the artificial wood, car stopper and tire industries to produce rubber belt and bead.

Flexural Behaviour, Microstructure and Cost-Benefit Analysis of Ternary Binder Foamed Concrete

Foamed concrete is a controlled low-density concrete, and due to its excellent thermal insulating and acoustic absorption properties, its application has been on a steady rise. Palm Oil Fuel Ash (POFA), an agricultural waste generated by the Palm Oil industry and Eggshells, causes many environmental problems. The pozzolanic nature of POFA and the high calcium oxide content in Eggshell Powder (ESP) are the components that contribute to their suitability as a partial cement replacement in concrete. This experimental work studied the flexural behavior, as well as the compressive strength of lightweight ternary binder foamed concrete incorporating 20% - 25% POFA and 5% - 10% ESP by weight of the total binder, as partial cement replacement. The test results were analyzed and compared with conventional foamed concrete without POFA and ESP. It was observed that POFA is a class C pozzolanic material. The combined utilization of POFA and ESP increased the compressive and flexural compared with control concrete. Furthermore, most of the cracks of the prisms were nearer to the middle of the samples and between two locations of loads applied due to the same load value applied at both locations. It was also observed the air voids were blocked due to increased pozzolanic activity and development of C-S-H gels and thus increase in strength. The utilization of POFA and ESP in concrete can be beneficial in reducing the overall cost. The cost to produce 1 m3 of concrete incorporating POFA and ESP was reduced ranging from was reduced by 12.59% (with 20% POFA and 5% ESP) to 17.53% (with 25% POFA and 10% ESP). It can be concluded that the M4 concrete mix is the optimum and cost-effective, as the maximum cement content is replaced (35%), as well as the compressive and flexural strengths are significantly higher than the control concrete M0.

Influence of Ground Calcium Carbonate Waste on the Properties of Green Self-Consolidating Concrete Prepared by Low-Quality Bagasse Ash and Rice Husk Ash.

Bagasse ash (BA) and rice husk ash (RHA) are by-products from electricity power plants. Ground calcium carbonate waste (GCW) is the by-product of the mining of calcium carbonate (CaCO3) in the color pigment manufacturing industry. Both BA and RHA are classified as low-quality pozzolanic materials, differing from GCW, which contains a high calcium oxide (CaO) content that leads to products equivalent to the hydration reaction. Therefore, GCW is likely able to improve the properties of self-consolidating concrete (SCC) incorporating BA and RHA. This paper discusses the production of green self-consolidating concrete (gSCC) and identifies the benefit of using GCW in gSCC prepared by triple combined GCW (10 and 20 wt%), BA (10, 20, and 30 wt%), and RHA (20 wt%). The results indicate that the majority of the gSCC retain acceptable flowability. The differences in the levels of gSCC substitution and the V-funnel flow results show general correlations with the increase in GCW. The gSCC prepared by 10 wt% GCW associated with 10 wt% BA and 20 wt% RHA was improved significantly. The filling and passing abilities of the gSCC were improved by using GCW. In addition, gSCC achieved mechanical property development and was able to minimize the consumption of OPC by up to 40%.

Added Value of Limestone Batumilmil and Its Application in Industry

This study explains the added value of the North Sumatra Langkat limestone and its derivative products. Limestone is classified as high calcium, characterized by its high calcium oxide (CaO) content of 38.39% -55.84%, its physical characteristics show dark gray color, dominant calcite, smooth, hard and fossilized texture. So far, the use is in the form of chunks, especially as a raw material for building which gives a low value to the limestone. The 3 limestone samples SK5, SK7 and SK8 were calcined to obtain quicklime and hydrated lime products with different temperatures of 900°C-1100°C. Limestone SK7 and SK8 CaO content increased 59.7% and 66.08% respectively and were light white compared to SK5 55.8% and colored brownish gray. To produce hydrated lime, it is done by adding / soaking with water (H2O) to the quicklime to produce a heat rate of hydration (slaked). SK8 limestone shows an optimum temperature increase of 74.6°C for 75 seconds compared to SK7 and SK5 limestone 50.2°C and 48°C respectively at 900°C combustion temperature. The heat transper occurs on the outer side of the limestone, then spreads to the limestone body. The difference in hydrated heat in the limestone is due to the presence of mineral impurities and non-uniform grain size so that the heat obtained is not perfectly distributed. The impurities such as SiO2, Fe2O3, Al2O3 and MgO contribute to the product quicklime and reactivity of these samples. Besides the quicklime and hydrated lime products, the added value of Batumilmil limestone is derived by making ground calcium carbonate (GCC). The GCC product is fine mesh size of 60 mesh - 400 mesh ultrafine, with high calcium quality and bright / bright color. The increase in added value added from limestone products contributes to the selling value and various applications in the industrial sector.