scholarly journals Estimating the Impact of Nanophases on the Production of Green Cement with High Performance Properties

Materials ◽  
2020 ◽  
Vol 13 (18) ◽  
pp. 4197
Author(s):  
Inas A. Ahmed ◽  
Najlaa S. Al-Radadi
Keyword(s):  
Compressive Strength ◽  
High Performance ◽  
Calcium Nitrate ◽  
Cement Pastes ◽  
Free Lime ◽  
Calcium Sulfoaluminate ◽  
Setting Times ◽  
Concrete Production ◽  
Hydrate Products ◽  
The Impact

Ordinary Portland cement (OPC) production is energy-intensive and significantly contributes to greenhouse gas emissions. One method to reduce the environmental impact of concrete production is the use of an alternative binder, calcium sulfoaluminate cement, which offers lower CO2 emissions and reduces energy consumption for cement production. This article describes the effect of adding nanophases, namely belite, calcium sulfoaluminate, calcium aluminum monosulfate (β-C2S, C4A3S, and C4AS, respectively) on OPC’s properties. These phases are made from nanosubstances such as nano-SiO2, calcium nitrate (Ca(NO3)2), and nano-aluminum hydroxide Al(OH)3 with gypsum (CaSO4·2H2O). The impact of β-C2S, C4A3S, and C4AS nanophases on the capabilities of cements was assessed by batch experimentations and IR, XRD, and DSC techniques. The results showed that the substituting of OPC by nano phases (either 10% C4A3S or 10% C4A3S and 10% β-C2S) reduced setting times, reduced the water/cement ratio and the free-lime contents, and increased the combined water contents as well as compressive strength of the cement pastes. The blends had high early and late compressive strength. The IR, XRD, and DSC analyses of the blends of 10% C4A3S or 10% C4A3S and 10% β-C2S cement displayed an increase in the hydrate products and the presence of monosulfate hydrate. The addition of 10% C4AS or 10% C4AS and 10% β-C2S to OPC reduced the setting times, decreased the W/C ratio, free lime, the bulk density, and increased the chemically-combined water and compressive strength. Overall, the results confirmed that the inclusion of the nanophases greatly enhanced the mechanical and durability properties of the OPCs.

Effect of Anhydrite on the Early Hydration Performance of Rapid Setting and Hardening Belite Sulfoaluminate Cement

2017 ◽  
Vol 898 ◽  
pp. 1990-1995 ◽  
Author(s):  
Ming Zhang Lan ◽  
Bin Feng Xiang ◽  
Jian Feng Wang ◽  
Xu Dong Zhao ◽  
Xiao Ying Wang
Keyword(s):  
Compressive Strength ◽  
Setting Time ◽  
High Strength ◽  
Cement Clinker ◽  
Hydration Kinetics ◽  
Early Hydration ◽  
Free Lime ◽  
Calcium Sulfoaluminate ◽  
Setting Times ◽  
Rapid Setting

In order to investigate the early hydration behavior of rapid setting and hardening belite sulfoaluminate cements, the methods of X-ray Diffraction, Scanning Electron Microscope, Compressive Strength test and Setting Times test were used to identify and quantify the hydration kinetics and microstructure of this new-found cements in China. The results showed that the main mineral compositions of high belite sulfoaluminate cement clinker included calcium sulfoaluminate (4CaO·3Al2O3·CaSO4), belite (2CaO·SiO2), ferrite phase, free gypsum and free lime. It was found that not only the setting time and compressive strength but also the composition of hydration products were influenced by anhydrite to some extent. Meanwhile, a mass of AFt and AFm generated along with the hydration process at different ages, overlapped, crossed and penetrated through calcium silicate hydrate gel and aluminum oxide to form a relatively dense structure which could contribute to the high strength of cement.

Microcrystalline cellulose as a reinforcement agent to cement pastes

2014 ◽  
Vol 43 (2) ◽  
pp. 104-110 ◽  
Author(s):  
M.S. Mohammed ◽  
A.E.-S.I. Ahmed ◽  
R.M. Osman
Keyword(s):  
Compressive Strength ◽  
Agricultural Waste ◽  
Agricultural Wastes ◽  
Uniform Size ◽  
Cement Pastes ◽  
Free Lime ◽  
Content Type ◽  
Setting Times ◽  
Wide Range ◽  
Mixing Water

Purpose – A try to find some useful applications for some products prepared from agricultural waste by mixing them with cement to act as reinforcement agents. The paper aims to discuss these issues. Design/methodology/approach – Cement was mixed with microcrystalline cellulosic (MCC) fibres prepared from baggase, soaked in mixing water, followed by cubic pastes formation. The mixing was performed using different ratios of MCC; 0.5, 0.75, 1 and 3 per cent. The cement properties were followed at timed intervals, up to 90 days. The initial and final setting times of the pastes were determined. Bulk density, apparent porosity and compressive strength of the harden cement pastes were also identified. The hydration kinetic was followed by identifying free lime ratio and chemically combined water content. The structure of the hard cement pastes was followed by SEM, FTIR, DSC and XRD. Findings – It was noticed that the weight of the prepared cement pastes using MCC was reduced, while the compressive strength was increased. In addition, lower ratios of MCC have shown better results at early ages of hydration and reported higher compressive strength than control. No interaction was reported between the fibres and cement constituents based on the performed analysis. Research limitations/implications – Different types of agricultural wastes can be compared in producing the best type of MCC for the same purpose of this research. Practical implications – This piece of work has suggested a simple way to convert a product prepared from agricultural wastes in a small uniform size to a reinforcement agent to cement. Consuming this type of waste reduces the risks resulting from its burning at some countries such as Egypt. Originality/value – MCC fibres have well-known binding properties and used successfully on wide range in medical applications for tablets production with low costs. These fibres have reduced the pastes weight and increased the compressive strength using low ratios of them. Moreover, there is no indication of a reaction between these fibres and cement constituents.

scholarly journals Extraction of lignin from wastes of sugarcane bagasse and its utilization as an admixture for Portland cement

NanoNEXT ◽  
2021 ◽  
pp. 13-27
Author(s):  
Darweesh H.H.M
Keyword(s):  
Compressive Strength ◽  
Image Analysis ◽  
Sugarcane Bagasse ◽  
Lignin Content ◽  
Total Porosity ◽  
Heat Of Hydration ◽  
Gradual Reduction ◽  
Cement Pastes ◽  
Free Lime ◽  
Setting Times

The influence of the prepared carboxy-methylated lignin extracted from sugarcane bagasse was investigated. Results showed that the w/c ratio and also setting times of the blank (L0) were reduced with the lignin content. The heat of hydration, combined water content, bulk density and compressive strength of the blank (L0) slightly increased with increasing of lignin content, but only up to 0.3 % lignin (L5) and then decreased. The free lime content decreased with the lignin content nearly at all hydration times up to 90 days due to the gradual reduction of the cement portion. The total porosity of the blank (L0) reduced gradually with lignin content up to 0.3 % lignin, and then increased with further increase of lignin. The FTIR spectra illustrated that the rate of hydration increased with lignin content. The SEM-EDAX image analysis showed the improved microstructure of cement pastes in presence of carboxy-methylated lignin when compared with that of the blank.

scholarly journals Effect of Calcium Nitrate on the Properties of Portland–Limestone Cement-Based Concrete Cured at Low Temperature

Materials ◽  
2021 ◽  
Vol 14 (7) ◽  
pp. 1611
Author(s):  
Gintautas Skripkiūnas ◽  
Asta Kičaitė ◽  
Harald Justnes ◽  
Ina Pundienė
Keyword(s):  
Compressive Strength ◽  
Cement Paste ◽  
Setting Time ◽  
Calcium Nitrate ◽  
Curing Temperature ◽  
Hardened Concrete ◽  
Cement Pastes ◽  
Initial Setting Time ◽  
Initial Setting ◽  
Early Strength

The effect of calcium nitrate (CN) dosages from 0 to 3% (of cement mass) on the properties of fresh cement paste rheology and hardening processes and on the strength of hardened concrete with two types of limestone-blended composite cements (CEM II A-LL 42.5 R and 42.5 N) at different initial (two-day) curing temperatures (−10 °C to +20 °C) is presented. The rheology results showed that a CN dosage up to 1.5% works as a plasticizing admixture, while higher amounts demonstrate the effect of increasing viscosity. At higher CN content, the viscosity growth in normal early strength (N type) cement pastes is much slower than in high early strength (R type) cement pastes. For both cement-type pastes, shortening the initial and final setting times is more effective when using 3% at +5 °C and 0 °C. At these temperatures, the use of 3% CN reduces the initial setting time for high early strength paste by 7.4 and 5.4 times and for normal early strength cement paste by 3.5 and 3.4 times when compared to a CN-free cement paste. The most efficient use of CN is achieved at −5 °C for compressive strength enlargement; a 1% CN dosage ensures the compressive strength of samples at a −5 °C initial curing temperature, with high early strength cement exceeding 3.5 MPa but being less than the required 3.5 MPa in samples with normal early strength cement.

scholarly journals The Impact of Traffic-Induced Bridge Vibration on Rapid Repairing High-Performance Concrete for Bridge Deck Pavement Repairs

2014 ◽  
Vol 2014 ◽  
pp. 1-9 ◽  
Author(s):  
Wei Wang ◽  
Shuo Liu ◽  
Qizhi Wang ◽  
Wei Yuan ◽  
Mingzhang Chen ◽  
...  
Keyword(s):  
Compressive Strength ◽  
High Performance ◽  
Bridge Deck ◽  
High Performance Concrete ◽  
Reduction Rate ◽  
Harmonic Vibration ◽  
Hydration Reaction ◽  
Self Healing ◽  
The Impact ◽  
Bridge Deck Pavement

Based on forced vibration tests for high-performance concrete (HPC), the influence of bridge vibration induced by traveling vehicle on compressive strength and durability of HPC has been studied. It is concluded that 1 d and 2 d compressive strength of HPC decreased significantly, and the maximum reduction rate is 9.1%, while 28 d compressive strength of HPC had a slight lower with a 3% maximal drop under the action of two simple harmonic vibrations with 2 Hz, 3 mm amplitude, and 4 Hz, 3 mm amplitude. Moreover, the vibration had a slight effect on the compressive strength of HPC when the simple harmonic vibration had 4 Hz and 1 mm amplitude; it is indicated that the amplitude exerts a more prominent influence on the earlier compressive strength with the comparison of the frequency. In addition, the impact of simple harmonic vibration on durability of HPC can be ignored; this shows the self-healing function of concrete resulting from later hydration reaction. Thus, the research achievements mentioned above can contribute to learning the laws by which bridge vibration affects the properties of concrete and provide technical support for the design and construction of the bridge deck pavement maintenance.

scholarly journals The Influence of Discharge Time, Kind of Additive, and Kind of Aggregate on the Properties of Three-Stage Mixed Concrete

2018 ◽  
Vol 10 (11) ◽  
pp. 3862 ◽  
Author(s):  
Alena Sicakova ◽  
Karol Urban
Keyword(s):  
Compressive Strength ◽  
Water Absorption ◽  
Recycled Concrete ◽  
Recycled Aggregates ◽  
Concrete Aggregate ◽  
Discharge Time ◽  
Concrete Mixtures ◽  
Concrete Properties ◽  
Concrete Production ◽  
The Impact

Application of recycled aggregates (RA) for concrete production is limited due to their poor quality. While the environmental benefits of using the RA are well accepted, some unsolved problems prevent this type of material from wide application in structural concrete. The research and development of techniques which can minimize the adverse effect of RA on the concrete properties are highly requested. A specific mixing approach can also be helpful; here, mineral additives play a significant role for improvement of RA performance within the mixing process. However, delivery process can influence the homogeneity and uniformity of the concrete mixtures, resulting in negative effect on technical parameters. In this study, the impact of delivery time (0 min, 45 min, and 90 min) on the set of hardened concrete properties is presented while the three-stage mixing is used. Two kinds of additives—fly ash (FA) and recycled concrete powder (RCP)—were tested to coat the coarse fraction of recycled concrete aggregate (RCA) in the first step of mixing. For comparison, cement as coating material and natural aggregate instead the RCA were also used. The following parameters were tested after 28 days of setting and hardening: density, compressive strength, splitting tensile strength, water absorption capacity, and depth of penetration of water under pressure. Generally, 90 min of working with concrete mixtures left no significantly negative influence on tested characteristics. Based on ANOVA results, with prolonged discharge time, the changes in composition of the mixtures become less important for compressive strength, density, and water absorption.

Development of Mix Proportion for High-Performance Concrete Using Locally Available Ingredients Based on Compressive Strength and Durability

2012 ◽  
Vol 174-177 ◽  
pp. 1067-1071 ◽  
Author(s):  
Jon Bi ◽  
Binsar Hariandja ◽  
Iswandi Imran ◽  
Ivindra Pane
Keyword(s):  
Compressive Strength ◽  
High Performance ◽  
High Performance Concrete ◽  
Research Result ◽  
Environmental Damage ◽  
Mix Proportion ◽  
Concrete Mix ◽  
Strength And Durability ◽  
The Impact ◽  
Local Materials

Keywords: High Performance Concrete, mix proportions, compressive strength , and durability Abstract. The use of concrete materials to date, remain a key ingredient in such construction work on the construction of building, bridges and infrastructure. One indicator is the increased production of readymix concrete which is nearly 16 billion tons in 2010. But the increased used of concrete, apparently bring the impact of environmental damage. This is due to the fact that production of raw materials contributes greatly to CO2 in the air. One effort to reduce such impact is to use of high performance concretes. Mix proportion of High Performance Concrete are strongly determined by the quality and availablity of local materials. The implications of research result from other countries can‘t be directly used. Therefore is need to the research on development of High Performance Concrete mix using locally available materials. In this research the mix proportions for f’c : 60 and 80 MPa are developed using local materials that are commonly used by readymix producers. The high Performance Concrete is developed based on compressive strength and durability. The result is expected to be applied to readymix industry particularly for construction use in Indonesia.

scholarly journals Mechanical Performance and Microstructure of Ultra-High-Performance Concrete Modified by Calcium Sulfoaluminate Cement

2021 ◽  
Vol 2021 ◽  
pp. 1-9
Author(s):  
Meimei Song ◽  
Chuanlin Wang ◽  
Ying Cui ◽  
Qiu Li ◽  
Zhiyang Gao
Keyword(s):  
Compressive Strength ◽  
High Performance ◽  
Mechanical Performance ◽  
High Performance Concrete ◽  
Autogenous Shrinkage ◽  
Ultra High Performance Concrete ◽  
Maximum Heat ◽  
Degree Of Hydration ◽  
Calcium Sulfoaluminate ◽  
Shrinkage Property

High autogenous shrinkage property is one of the disadvantages of ultra-high-performance concrete (UHPC), which may induce early age cracking and threaten the safety of concrete structure. In the present study, different dosages of calcium sulfoaluminate (CSA) cement were added in UHPC as an effective expansive binder. Hydration mechanism, autogenous shrinkage property, and compressive strength of UHPC were carried out to investigate the effect of CSA addition on the mechanical properties of UHPC. Scanning electron microscopy was also employed to characterize the intrinsic microstructural reasons relating to the changes in macroproperties. Based on the XRD diagram, increasing formation of ettringite and Ca(OH)2 can be found with increasing CSA content up to 15%. In the heat flow results of UHPC with 10% CSA addition, the maximum heat release increases to 2.6 mW/g, which is 8.3% higher than the reference UHPC, suggesting a higher degree of hydration with CSA addition. The results in autogenous shrinkage show that CSA expansion agent plays a significantly beneficial role in improving the autogenous shrinkage of UHPC. The corresponding autogenous shrinkage of UHPC is −59.66 μ ε , −131.11 μ ε , and −182.31 μ ε , respectively, at 7 d with 5%, 10%, and 15% addition, which is 108%, 117%, and 123% reduction compared to the reference specimen without CSA. In terms of compressive strength, UHPC with 5%, 10%, 15%, and 20% CSA addition has 10.5%, 17.4%, 30.2%, and 22.1% higher compressive strength than that for the reference UHPC at 28 d. Microstructural study shows that there is an extremely dense microstructure in both the bulk matrix and interfacial transition zone of UHPC with 10% CSA addition, which can be attributed to the higher autogenous shrinkage property and can therefore result in higher mechanical performance.

scholarly journals Analysis of the Effect of Various Types of Limestone as a Main Constituent of Cement on the Chosen Properties of Cement Pastes and Mortars

2019 ◽  
Vol 65 (3) ◽  
pp. 75-86
Author(s):  
J. Gołaszewski ◽  
G. Cygan ◽  
M. Gołaszewska
Keyword(s):  
Compressive Strength ◽  
Rheological Properties ◽  
Yield Stress ◽  
Drying Shrinkage ◽  
Plastic Viscosity ◽  
Main Constituent ◽  
Cement Pastes ◽  
Mortar Strength ◽  
The Impact

AbstractThe article is an attempt to compare the impact of the use of various types of limestone as the main constituent of cement on selected mortar properties. Four different limestones were added in amount of 15, 30, 40% to CEM I 42.5 R to obtain limestone cemens. Rheological properties (yield stress, plastic viscosity) of fresh mortar, tensile and compressive mortar strength, early shrinkage, and drying shrinkage were tested. Obtained results indicate that both tensile and compressive strength decreases with the increase of the limestone content in cement. Limestone can worsen or improve workability, depending on distribution of limestone grains. The addition of limestone increases the early shrinkage, but reduces the shrinkage after 28 days. Studies show that the granulation of limestone plays an important role in determining the influence of limestone on mortar properties.

scholarly journals Influence of a Chromium-rich Industrial Waste on the Hydration and Hardening Processes of Portland Cements with Slag and Limestone Additions

2020 ◽  
Vol 71 (2) ◽  
pp. 252-261
Author(s):  
Carmen-Lidia Oproiu ◽  
Marius-George Parvan ◽  
Georgeta Voicu ◽  
Alina-Ioana Badanoiu ◽  
Roxana Trusca
Keyword(s):  
Compressive Strength ◽  
Industrial Waste ◽  
Chromium Content ◽  
Potassium Dichromate ◽  
Research Work ◽  
Limestone Filler ◽  
Portland Cements ◽  
Cement Pastes ◽  
Setting Times ◽  
Lower Limits

This research work assesses the influence of a chromium-rich waste (from potassium dichromate manufacture) on the hydration and hardening processes of two types of Portland cements with limestone filler and slag additions. Therefore, mixtures of Portland cement and chromium-rich waste, corresponding to 0.5% wt. and 1% wt. Cr, were prepared and tested. The analyses performed on cement pastes with chromium waste content, showed that chromium immobilization is mainly due to the formation of Ca6Al2Cr3O18�32H2O (CrEt); this compound results by the substitution of [SO4]2- groups from ettringite lattice of with [CrO4]2-. CrEt crystals growth on the surface of clinker particles forms a diffusion barrier which explains longer setting times for cements with chromium content. The increase of chromium content in the studied systems decreases the compressive strength values but these remain above the lower limits imposed for this type of materials. The chromium content in leachates prepared according to the method described in SR EN 12457-2, was well below the legal limit of 70 mg/Kg established by Romanian legislation. A better chromium immobilisation was achieved in the cement with slag content, in good correlation with the nature and amount of formed hydrates.

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