Properties Of Blended Cements Research Articles

Effect of partially replacement of ordinary Portland clinker by basaltic rocks on the properties of blended cement

ABSTRACT The cement industry ranks as one of the most significant contributors to carbon emissions among industrial sectors globally. Carbon dioxide (CO2) emissions have the potential to lead to considerable health and economic concerns. CO2 is the second-leading gas after steam, in creating the greenhouse effect. A significant percentage of CO2 emissions in cement plants come from the calcination of limestone to produce clinker. This study examines the impact of partially substituting ordinary Portland clinker with basaltic rocks on the characteristics of the resulting cement. These are employed to mitigate the impact of environmental contamination (CO2 emissions). The studied basaltic rocks were tested to determine the optimal weight percentage replacement. Five mixtures were produced through the partial substitution of clinker with varying proportions of basaltic rocks (10%, 15%, 20%, 25%, and 30%). An investigation was carried out to examine the impact of basaltic rocks on various properties of the produced cement, including workability, setting time, and strength. The parameters were investigated and evaluated by carrying out tests on fresh and hardened mortar specimens at specific time intervals. The results of the investigation lead to the conclusion that the ideal suggested proportion of the studied basaltic rocks as a partial substitute for ordinary Portland clinker is 15%.

Effect of ultrafine recycled brick powder on the properties of blended cement: Hydration kinetics, microstructure evolution and properties development

Ultrafine grinding is expected to be an effective method to increase the pozzolanic activity of RBP, since RBP has superior grindability. The aim of this paper was to investigate the effects of 30 % ultrafine RBP with particle size of 8.6 μm, 4.5 μm, 3.6 μm and 2.7 μm on the fundamental properties, hydration kinetics and microstructure evolution of blended cement. The setting times, water requirement for normal consistency, rheological properties, hydration heat, hydration degree, mechanical strength and pore structure of cementitious material were evaluated. Results show that when 30 % RBP was added, the water requirement and viscosity of blended cement increased significantly with the decrease of RBP particle size, while the setting time was shortened due to the acceleration of early-age cement hydration. The parameters for the Boundary Nucleation and Growth (BNG) model indicate that the nucleation and growth rates of hydration products increased by 1.43 times and 1.27 times when RBP with D50 = 2.7 μm was added, thus the cement hydration degree reached more than 50 % in the first 72 h. Based on the thermogravimetric analysis (TGA), the pozzolanic reaction degree of ultrafine RBPs was more than 15 %–25 % depending on its size, and the hydration degree of cement in RBP-PC pastes was more than 80 %. As a result, blended cement mortars with up to 30 % ultrafine RBPs has slight or even no strength loss after curing for 90 days, as RBP-PC paste has a denser microstructure.

A Properties of Municipal Solid Waste Incineration Fly Ash (IFA) And Cement Used in The Manufacturing of New Inventive Blended Cement

Municipal solid waste incinerator fly (IFA) ash is prone to accumulate high concentration heavy metals. Due to the increasing costs to treat remaining fly ash at the landfill, a lot of research has been done to recycle IFA. This studywas focusing on the properties of IFA and cement as main raw materials in new inventive blended cement. The properties of blended cement were also being investigated. Properties of IFA and cement were examined through several test which includes density, specific gravity, X-Ray Fluorescence (XRF), Loss of Ignition (LOI) and through Toxicity Characteristic Leaching Procedure (TCLP) test. The density test and LOI test were also being done for the blended cement. From the tests for IFA and cement, it can be found that density the density of fly ash and cementthat has been used for this study were found to be 0.76 g/cm3and 3.67 g/cm3respectively. Then, the specific gravity of fly ash and cementwere 1.69 and 2.98, accordingly. XRF results shows that both materialshave highest content of aluminium, silicaand iron, as expected. LOI of fly ash and cementwere found to be 17.33 % and 12.33 %, respectively.In terms of the leaching rates of heavy metals (Mn, Ni, Cd, Cr, Cu), only Cd leached at rate 2.39 mg/L, which is above the USEPA's regulatorylevel, 1.0 mg/L. 5 %, 10 % and 15 % of IFA was mixed with cement to produced blended cement. As the density of blended cement, it was found to be 1.12 g/cm3, 1.08 g/cm3and 1.09 g/cm3for each of 5 %, 10 % and 15 % of fly ash in blendedcement.

Properties of Blended Cement Containing Iron Tailing Powder at Different Curing Temperatures.

The properties of blended cement containing 0%, 20%, and 50% iron tailing powder (ITP) at 20 °C and 60 °C were investigated by determining the hydration heat, microstructure, and compressive strength. The addition of ITP decreases the exothermic rate and cumulative hydration heat of blended cement at 20 °C. The high temperature increases the hydration rate and leads to the hydration heat of blended cement containing 20% ITP higher than that of Portland cement. Increasing the amount of ITP decreases the non-evaporable water content and Ca(OH)2 content as well as compressive strength at both of the two studied temperatures. The addition of ITP coarsens the early-age pore structure but improves the later-age pore structure at 20 °C. The high temperature significantly improves the early-age properties of blended cement containing ITP, but it is detrimental to the later-age properties development. The reaction of ITP is limited even at high temperature. The large ITP particles bond poorly with surrounding hydration products under early high-temperature curing condition. The properties of blended cement containing a large amount of ITP are much poorer at high temperature.

The influence of alkali activators on the properties of ternary blended cement incorporated with ferronickel slag

In this study, the influence of alkali activators on the properties of blended cement containing pulverized fly ash (PFA) or/and ferronickel slag (FNS) powder was investigated. As a binder, ordinary Portland cement (OPC), PFA, and FNS were used to produce alkali-activated blended mixes; OPC and ternary mix, including two different types of admixtures, respectively. Setting time, adiabatic temperature rise, and development of compressive strength was evaluated for physical performance. Hydration characteristics of the blended pastes with hydroxide activators were analyzed by x-ray diffraction, thermogravimetric analysis, and scanning electron microscope. It was found that blended cement containing FNS as the binder can prolong the setting time and hydration heat which was substantially mitigated due to a latent hydration characteristic. In terms of geopolymerization, the formation of hydration products was enhanced in ternary blended cement, which showed the highest compressive strength in the long-term curing.

Investigation on the Role of Steel Slag Powder in Blended Cement Based on Quartz Powder as Reference

To clarify the role of steel slag powder in blended cement, steel slag powders with different amounts and particle sizes were mixed into blended cement and the inert quartz powder was selected as the reference. The influences of steel slag powder with different amounts and particle sizes on the hydration and hardening properties of blended cement were studied from hydration heat, nonevaporable water content, porosity, hydration products, and strength. The results show that the influence coefficient of nonevaporable water content (ՓWn) of blended cement paste is in an exponential relationship with the amount of steel slag powder. Moreover, at a dosage of 30%, ՓWn of blended cement gradually decreases with the increase of steel slag particle size. Both the early and late compressive strengths of blended cement are in a binomial relationship with the amount of steel slag powder. The influence coefficient of steel slag powder on the compressive strength of blended cement is negative at the age of 3 days, whereas it is positive at the age of 28 days. The chemical filling effect of 30% steel slag powder with different particle sizes in the blended cement paste is very small, only 1.13%–5.06%. The hydration products of blended cement containing steel slag are mainly amorphous C‐S‐H gels and platy Ca(OH)2, and their density are consistent with the law of their porosity.

- Behavior of Concrete Containing Alternative Pozzolan Calcined Marl Blended Cement

Natural marl which is calcined at appropriate temperature has potential being alternative pozzolan. Therefore, the calcined marl is wanted to be used as replacement material in blended cements with less clinker. This situation leads to improved performance of cement/concrete, reduced CO2 emissions, saving of energy. The properties of used pozzolan positively effect to some behavior of concrete. Shrinkage is one of these properties. The shrinkage of concrete is inherent property that needs to be control. Moreover, the shrinkage of concrete becomes even more important in some applications such as mass concrete, prestressed concrete. The aim of study is to determinate how will affected shrinkage of concrete containing alternative pozzolan calcined marl blended cements. Accordingly, the natural marl was calcined at 800 °C for pozzolanic activation. The calcined marl was replaced with Portland cement at ratios of 0, 10, 30, 50 wt.%. The setting times, volume expansion, water demand, density, performance energy evaluation of blended cements were determined. The autogenous-drying shrinkage, mass loss and compressive strength tests were performed on concretes containing calcined marl blended cements. According to the results, pozzolanic activity of calcined marl and properties of blended cements containing calcined marl are comply with limit values of TS 25 and EN197-1. It was observed that autogenous-drying shrinkage and mass loss of concretes containing calcined marl blended cement were lower than that of concretes containing Portland cement. On the other hand, it was seen that compressive strength of concretes was increased up to 50 % replacement ratio.

Effect of the fineness of over-burnt magnesia on the hydration and expansion properties of blended cement

Previous research has indicated that the poor stability of steel slag is caused by the hydration of free calcium oxide and magnesia in the slag, and a great deal of research has been done on the hydration expansion properties of free calcium oxide. However, there is little reported research on the hydration expansion properties of magnesia in steel slag. In this work, the effects of the fineness of over-burnt magnesia on the expansion properties and hydration characteristics of blended cement paste (BCP) were investigated and their correlations were studied. The results indicated that the fineness of the over-burnt magnesia was the intrinsic factor controlling the expansion properties and hydration characteristics of the BCPs. At 20°C, the expansion rate of the BCPs gradually increased with an increase in magnesia fineness increase; however, at 60°C, the expansion rate of the BCPs gradually decreased with increased magnesia fineness. The incorporation of magnesia reduced the cement hydration heat, with a lesser reduction for a greater fineness of magnesia. Furthermore, no great difference in the hydration degree of cement was observed with the use of magnesia of different fineness.

Glass powder as a partial precursor in Portland cement and alkali-activated slag mortar: A comprehensive comparative study

Prior studies were conducted in an isolated manner for the use of glass powder (GP) either as ordinary Portland cement (OPC) replacement material in blended cement or as a precursor in AAM material. There was no reported literature that made a direct comparison on the properties of blended cement and AAM containing GP with an equivalent mix composition. The present study was aimed to evaluate and compare the effects of GP as a partial precursor on properties of both OPC and alkali-activated slag (AAS) mortars. For this purpose, cement and ground granulated blast furnace slag (GGBFS) was partially replaced with 10%, 20%, 30%, and 40% (by weight) GP in OPC and AAS mortars, respectively. The mortar mixes were prepared for a fixed water-to-solid (W/S) ratio to make them equivalent. The evaluation was carried out on the workability, mechanical strength, water absorption, alkali-silica reaction (ASR) response and ecological analysis of the mortar. According to the test results, the flow of the fresh mortar increased monotonically with GP content, and AAS mortars showed a higher flow value than OPC mortars. Based on the mechanical properties, the optimum GP content in OPC and AAS mortars was found to be 20% and 30% by the total weight of the binder, respectively. In general, the inclusion of GP was more effective in enhancing the strength properties of AAS mortars as compared to OPC counterparts. Furthermore, the use of GP led to a systematic increase in the water absorption of mixes due to moisture instability of the sodium silicate gel produced by GP activation. According to the results of SEM analysis, AAS mortars showed a higher degree of micro-cracking, which resulted in higher water absorption and a lower flexural strength as compared to OPC mortars. Also, the incorporation of GP densified the pore system of the paste. The potential of ASR was evaluated via the accelerated mortar bar test. The OPC mortars showed up to a 55% reduction in the ASR expansion at 40% GP content. The AAS mortars, on the other hand, showed shrinkage during the first days and then started to show expansion with increasing GP content, which was beneficial as it compensated the shrinkage. The ecological analysis of mixes revealed that the carbon footprint of AAS mortars was about 60% lower than that of OPC counterpart mixes, and the use of GP reduced the CO2 emissions and energy demand of mixes.

The particle-size effect of waste clay brick powder on its pozzolanic activity and properties of blended cement

Abstract The manufacture of cement is considered as a high energy consumption and environmental pollution process, and it is necessary to figure out a way to reduce the consumption of cement in construction industry. The waste clay brick is a kind of construction waste with pozzolanic activity, which could be used to prepare blended cement after grinding. However, the particle size of clay brick powder (CBP) will influence its pozzolanic activity and properties of blended cement, which needs to be clarified. Therefore, in this study, the pozzolanic activity of CBP and properties of blended cement containing CBP were investigated. The results show that with the increase of grinding time, the CBP particles tend to be refined and spherical, which will increase the specific surface area and pozzolanic activity of CBP. The decrease of CBP particle size in blended cement paste can accelerate the early-age hydration and decrease the setting time since the ultrafine CBP could become the crystallization nucleus. The compressive strength of mortars with 30% CBP is 10%–35% lower than that without CBP, and the smaller the CBP particle size, the faster the compressive strength grows. Moreover, the hydration products and pore structure results also prove that the CBP with smaller particle size will consume more calcium hydroxide to react, which could make the microstructure denser and obtain stronger compressive strength growth at later ages. Meanwhile, the environmental impact and cost calculations indicate that the energy intensity and CO2 emissions of blended cement are obviously lower than Portland cement. It could be concluded that the pozzolanic activity of CBP will be enhanced with the decrease of particle size, and this research provided the reference for application of waste clay brick to produce green construction materials.

Effect of the polynaphtalene sulfonate based superplasticizer on mechanichal and physical properties of blended cement repaced by Bayburt Stone with different fineness

Effect of the polynaphtalene sulfonate based superplasticizer on mechanichal and physical properties of blended cement repaced by Bayburt Stone with different fineness

High-gravity carbonation of basic oxygen furnace slag for CO2 fixation and utilization in blended cement

This study explores the feasibility of developing carbon dioxide (CO2) fixation and utilization as supplementary cementitious materials (SCMs) using basic oxygen furnace slag (BOFS) through a high-gravity carbonation process. The developed process is considered as a cleaner approach, compared to convention treatment processes in steelmaking industry, to simultaneous reduction of CO2 emission and stabilization of BOFS. The carbonated BOFS can be used as SCMs in blended cement. First, the CO2 fixation capacity of BOFS was quantified by thermo-gravimetric analysis in this study. The kinetics of the high-gravity carbonation process were also determined using a surface coverage model. The results indicated that up to 215 g of CO2 was fixed per kg of BOFS through high-gravity carbonation for 3 h at 60 °C. In addition, engineering properties and hydration characteristics of blended cement with 10% fresh or 10% carbonated BOFS as SCMs were investigated. Cement blended with 10 wt% of carbonated BOFS resulted in reduced setting times and accelerated early strength development, which was consistent with the hydration heat releases and X-ray diffraction analyses. The observations of scanning electron microscope suggest that the carbonated BOFS serve as nuclei for the precipitation of hydration products, thereby accelerating the hydration. It is also noted that the properties of blended cement using carbonated BOFS met ASTM requirements for setting time, compressive strength, autoclave expansion, and sulfate resistance. Furthermore, costs and benefits of the high-gravity carbonation for CO2 fixation and BOFS utilization were estimated.

Properties of blended cement using metakaolin and hydrated lime

Thermal activation of Ga'ara kaolin is used to produce a good quality metakaolin. Portland cement clinker is ground and blended with 3% gypsum. In this study, two types of mixes are made: the first using 10% hydrated lime and different percentages of metakaolin as replacement by weight of the blended cement; in the second type, only metakaolin is used, without hydrated lime, in mixes as a replacement by weight of the blended cement. The aim of this study is to make a new type of environmentally friendly, blended cement with good fresh and hardened properties. Energy savings can be achieved by using materials produced as industrial by-products (metakaolin, hydrated lime). The compressive strength is 42·1 MPa for the mix with 12% metakaolin and 0% hydrated lime, and 38·8 MPa for 12% metakaolin with 10% hydrated lime, as compared to the reference mix value of 37·9 MPa at age 90 d. Blended cement can be made with 86% Portland cement fineness, adding 22% metakaolin + hydrated lime as a replacement by weight of the blend, to give almost the same compressive strength as the reference mix, with excellent soundness properties. This could reduce the annual production of cement, as well as the associated emission of gaseous pollutants from factories during the cement production process.

Ultrafine grinding of fly ash with grinding aids: Impact on particle characteristics of ultrafine fly ash and properties of blended cement containing ultrafine fly ash

This paper presents the ultrafine grinding performance of fly ash with grinding aids (GA) and effect of GA on the particle characteristics, pozzolanic reaction degree of ultrafine fly ash (UFFA) and properties of blended cement containing UFFA. The experimental results indicate that GA can improve the particle characteristics of ground fly ash. The specific surface area of UFFA with 0.05wt% GA is higher by 104m2/kg than control sample. The particle size distribution of UFFA with GA becomes narrow and particle content of less than 16μm is obviously increased. Additionally, the fluidity and loose bulk density of UFFA have also been improved. For pozzolanic reaction degree, 3-day, 7-day and 28-day hydration degree of UFFA with GA is increased by 1.2%, 2.3% and 4.6%, respectively; and 3-day, 7-day and 28-day activity index of UFFA with GA is also increased by 6%, 8% and 9%, respectively. For properties of blended cement containing UFFA, enhancement effect of UFFA with GA on the strength of blended cement containing 20wt%, 30wt% and 40wt% fly ash are significant, and 3-day strength is increased by 12.6%, 6.6% and 6.6%, respectively, 28-day strength is increased by 6.5%, 9.3% and 10.5%, respectively. In this study, the hydration degree and microstructure of blended cement containing UFFA paste are also analyzed by SEM, XRD, IR and TG-DTA. The studies show that improvements such as hydration degree, products quantity, uniformity and compactness of products structure of blended cement containing UFFA are attributed to finer particle size and better particle size distribution caused by the addition of GA.

Setting behavior of blended cement with limestone: influence of particle size and content

The combined effects of particle size, surface area, and limestone content on the properties of blended cement with limestone were studied. Limestone powders with six different particle diameters and surface areas relative to the cement particles were tested: two sizes smaller with greater surface area, two sizes larger with less surface area, and two sizes similar to the original cement particle. Two systems were studied: blended cement with limestone consisting of one particle size distribution and limestone consisting of a combination of three particle sizes. The setting history and hydration degree were examined using a Vicat needle apparatus and performing Rietveld quantitative phase analysis of X-ray diffraction. The packing density of the different pastes was calculated based on the amount of water required for normal consistency. It was shown that the properties of blended cements with different particle sizes were affected significantly by two mechanisms: nucleation and packing density. These two mechanisms affected the chemical and physical properties of the blended cement by altering its setting rates.

Effect of activated coal mining wastes on the properties of blended cement

Abstract The large volumes of coal waste generated world-wide in mining operations are mostly deposited in refuse dumps, to the severe detriment of the surrounding groundwater and soil. After calcination under controlled conditions, this waste has been shown to exhibit high pozzolanicity, making it apt for use as an addition in the manufacture of blended cements. The present paper describes the first detailed study designed to evaluate the behavior of coal tailings from different sources. After activation at 650 °C for 2 h, this waste was used to manufacture blended cements containing 10 and 20 wt.% of the addition. Inclusion of this pozzolan did not affect the initial setting time, although the compressive strength of the blended mortars declined, by 4.7–8.3% in the 10% and by 9.76–14.9% in the 20% material. Nonetheless, the activated carbon waste (ACW) blends complied with all the requirements for Type II/A cement in the existing European legislation.

Properties of blended cements with thermally activated kaolin

Kaolin, one of the materials of major importance for the ceramic and paper industry, is also used in the construction industry as a raw material for the production of white cement clinker and, in the form of metakaolin, as an artificial pozzolanic additive for concrete. Metakaolin is a vital component of high-performance and architectural concrete; however, its application in regular concrete is very limited due to relatively high production costs. This report evaluates the performance of a low-cost metakaolin-based additive called thermally activated kaolin (TAK), in cement. Due to its pozzolanic properties and the densification of cement matrix, the application of TAK provides a 15% improvement of the compressive strength. It was shown that TAK of optimal quality can be manufactured by the thermal treatment of raw kaolin with 74% of kaolinite at 750 °C without the intermediate beneficiation stage. The application of a developed approach can significantly reduce production expenditures and make the application of such an additive feasible even in regular-grade cement and concrete.

Effect of material characteristics on the properties of blended cements containing high volumes of natural pozzolans

The effect of three different natural pozzolans from Turkish deposits on the properties of blended cements produced by intergrinding cement clinker with a high volume of natural pozzolan (55 wt.% of the cementitious material) was investigated. The particle size distribution of blended cements, setting time, heat of hydration, and compressive strength of blended cement mortars were determined. Experimental results showed that the hardness of the pozzolanic material strongly influenced the particle size distribution and the related properties of the blended cements by affecting the fineness of the components of the blended product. The early strength of the mortars was strongly affected by the particle size distribution of blended cements, whereas the strength development performance of the mortars was more related to the pozzolanic activity of the natural pozzolan present in the blended cement.

Effect of material characteristics on the properties of blended cements containing high volumes of natural pozzolans

Effect of material characteristics on the properties of blended cements containing high volumes of natural pozzolans

The influence of natural pozzolana mineralogical composition in the properties of blended cement

The pozzolana activity is the main property of the active additions but, in order to select them, we have to consider - between other factors- its mineralogical composition with a great influence, not only in the active component, but also in other cement properties. In the present work we have studied 4 different Cuban natural pozzolanes, characterized with the help of X ray diffraction and with thermic and chemical analysis. The pozzolanic activity was also evaluated through a chemical and physicomechanic method. Some cements were prepared with different contents of each one of the pozzolanics, and analysed their physicomechanic and chemical properties. Finally, we found that the pozzolanics mineralogical composition has a great influence in the pozzolanic activity and in the properties of mixed cements. Also we found that it 5 possible to obtain the best resistances in the time and the smaller needs of water when the vitreous phase prevail in the additions.