scholarly journals Photocatalytic Activity and Mechanical Properties of Cements Modified with TiO2/N

Materials ◽  
2019 ◽  
Vol 12 (22) ◽  
pp. 3756 ◽  
Author(s):  
Magdalena Janus ◽  
Szymon Mądraszewski ◽  
Kamila Zając ◽  
Ewelina Kusiak-Nejman ◽  
Antoni W. Morawski ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Photocatalytic Activity ◽  
Building Materials ◽  
Cement Content ◽  
Setting Time ◽  
Cement Matrix ◽  
Final Setting Time ◽  
Cement Mortars ◽  
Fresh State ◽  
Positive Effect

In this paper, studies of the mechanical properties and photocatalytic activity of new photoactive cement mortars are presented. The new building materials were obtained by the addition of 1, 3, and 5 wt % (based on the cement content) of nitrogen-modified titanium dioxide (TiO2/N) to the cement matrix. Photocatalytic active cement mortars were characterized by measuring the flexural and the compressive strength, the hydration heat, the zeta potential of the fresh state, and the initial and final setting time. Their photocatalytic activity was tested during NOx decomposition. The studies showed that TiO2/N gives the photoactivity of cement mortars during air purification with an additional positive effect on the mechanical properties of the hardened mortars. The addition of TiO2/N into the cement shortened the initial and final setting time, which was distinctly observed using 5 wt % of the photocatalyst in the cement matrix.

scholarly journals A New Preparation Method of Cement with Photocatalytic Activity

Materials ◽  
2020 ◽  
Vol 13 (23) ◽  
pp. 5540
Author(s):  
Magdalena Janus ◽  
Szymon Mądraszewski ◽  
Kamila Zając ◽  
Ewelina Kusiak-Nejman
Keyword(s):  
Compressive Strength ◽  
Photocatalytic Activity ◽  
Building Materials ◽  
Water Adsorption ◽  
Crystal Size ◽  
Preparation Method ◽  
Setting Time ◽  
Cement Matrix ◽  
Final Setting Time ◽  
Titanium White

The studies of some mechanical properties and photocatalytic activity of new cements with photocatalytic activity are presented. The new building materials were obtained by addition of semi-product from titanium white production. Semi-product was calcined at 300 and 600 °C for one, three, and five hours and then this material was added to cement matrix in an amount of 1 and 3 wt.%. New materials were characterized by measuring the flexural and compressive strength and the initial and the final setting time. The photocatalytic activity was tested during NOx photooxidation. The cement with photocatalytic activity was also characterized by sulphur content measurements. The measurement of reflectance percentage of TiO2-loaded cements in comparison with pristine cement and TiO2 photocatalyst calcined at 600 °C were also performed. It should be emphasized that although in some cases, the addition of photocatalyst reduced the flexural and the compressive strength of the modified cements, these values were still within the norm PN-EN 197-1:2012. It was also found that the initial and the final setting time is connected with the crystal size of anatase, and the presence of larger crystals significantly delays of the setting time. This was probably caused by a water adsorption on the surface of anatase crystals.

scholarly journals Modification of early strength parameters of concrete by the addition of fly ash and admixture of nano C-S-H for application in 3D printing

2020 ◽  
Vol 323 ◽  
pp. 01016
Author(s):  
Bartosz Szostak ◽  
Grzegorz L. Golewski
Keyword(s):  
Fly Ash ◽  
Setting Time ◽  
Hydraulic Press ◽  
Cement Matrix ◽  
Strength Parameters ◽  
Early Maturation ◽  
Cement Mortars ◽  
Compressive Strength Test ◽  
The Impact ◽  
Positive Effect

In the paper, the authors present the results of tests concerning traditional cement mortars with the addition of silica fly ash and the C-S-H nano-admixture. The use of fly ash results in improved plasticity of the mixture. The use of the C-S-H nano-admixture has a positive effect on shortening the setting time and a rapid increase in the strength of mixtures without losing their subsequent properties, which is presented in the research described in the paper. On this basis, the impact of fly ash and the nano-admixture on the selected parameters of the cement paste in the early maturation periods was determined – after 4, 8, 12, 24, 72h and also 7 and 28 days. The following tests were carried out on previously prepared samples: the compressive strength test on a hydraulic press, the test of setting time and the test of cement matrix shrinkage.

scholarly journals Comparative Overview of the Performance of Cementitious and Non-Cementitious Nanomaterials in Mortar at Normal and Elevated Temperatures

Nanomaterials ◽  
2021 ◽  
Vol 11 (4) ◽  
pp. 911
Author(s):  
M. Arsalan Khan ◽  
M. Khalid Imam ◽  
Kashif Irshad ◽  
Hafiz Muhammad Ali ◽  
Mohd Abul Hasan ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Building Materials ◽  
Elevated Temperatures ◽  
Cement Mortar ◽  
Setting Time ◽  
Microstructural Characterization ◽  
Shrinkage Strain ◽  
Durability Properties ◽  
Fresh State ◽  
Hard State

Nanotechnology has emerged as a field with promising applications in building materials. Nanotechnology-based mortars are examples of such building materials that have widespread applications in the construction industry. The main nanomaterials used in mortars include nano-silica, nano-magnesium oxide, nano-alumina, nano-titanium oxide, nano-zinc oxide, nano-clay, and nano-carbon. This review paper presents a summary of the properties and effects of these nanomaterials on cement mortar in terms of its fresh-state and hard-state properties. The fresh-state properties include the setting time, consistency, and workability, while the hard-state properties include mechanical properties such as compressive, flexural, tensile strengths, as well as the elasticity modulus, in addition to durability properties such as water absorption, shrinkage strain, strength loss due to freeze–thaw cycles, and chloride penetration, among others. Different nanomaterials cause different physical and chemical alterations within the microstructures of cement mortar. Therefore, the microstructural characterization and densification of mortar are discussed in detail at varying temperatures. In general, the involvement of nanomaterials in cement mortar influences the fresh-state properties, enhances the mechanical properties, and impacts the durability properties, while reducing the porosity present in the mortar matrix. Cementitious nanomaterials can create a pathway for the easy injection of binding materials into the internal microstructures of a hydration gel to impact the hydration process at different rates, whereas their non-cementitious counterparts can act as fillers. Furthermore, the research gaps and future outlook regarding the application of nanomaterials in mortar are discussed.

Nanocomposite Photocatalyst Based on Layered Double Hydroxides (LDHs) Associated with TiO2

2014 ◽  
Vol 92 ◽  
pp. 100-109 ◽  
Author(s):  
Jonjaua Ranogajec ◽  
Andrijana Sever-Skapin ◽  
Ognjen Rudic ◽  
Snezana Vucetic
Keyword(s):  
Photocatalytic Activity ◽  
Layered Double Hydroxides ◽  
Direct Contact ◽  
Building Materials ◽  
Specific Problem ◽  
The Self ◽  
Different Types ◽  
Double Hydroxides ◽  
Positive Effect ◽  
Material Porosity

The surfaces of building materials are constantly exposed to the actions of environmental factors, pollutants of inorganic and organic origin as well as to microorganisms, which significantly contribute to corrosion phenomena.The application of coatings decreases the negative action of the pollutants minimizing their direct contact with the substrate. Different types of coatings with additional functions have been developed. A specific problem of these applications is the lack of compatibility of the photocatalysts with the surface of the building materials and the detachment of potentially toxic TiO2nanoparticles. In the present study, this problem was solved by the proper immobilization of TiO2nanoparticles onto the photocatalyst support, layered double hydroxides (LDHs). The newly formed coating possesses acceptable porosity for a porous building material (porosity within the range of 30-46 %) and satisfied photocatalytic activity, as well as mineralogical compatibility with the substrates (mortars, renders, bricks). Additionally, a positive effect considering the self-cleaning phenomenon was attained.

The Influence of Purification of Ethyl Acrylate on the Properties of Cement Matrix

2010 ◽  
Vol 150-151 ◽  
pp. 1143-1151
Author(s):  
Chau Lee ◽  
Nian Fu Wang ◽  
Meng Xun Xiem
Keyword(s):  
Hydrogen Peroxide ◽  
Early Stage ◽  
Setting Time ◽  
Ethyl Acrylate ◽  
Cement Matrix ◽  
Strength Development ◽  
Final Setting Time ◽  
Before And After ◽  
Analysis Of Performance ◽  
Acrylate Polymer

This research mainly probes into the analysis of performance and assessment that ethyl acrylate polymer is applied to the cement matrix. The result shows that, before and after the purification, ethyl acrylate can increase the flowability of modified mortar, and with the increasing the dosage of polymer, the flowability is getting better. But if the dosage of hydrogen peroxide used to remove the residua alcohol is excessive, it is easy to cause high mortar viscosity, and that is unfavorable to the flowability. According to the setting time of the mortar under normal consistency, the result shows that the ethyl acrylate before the purification, has retarding effects on both initial and final setting time. With the increasing the dosage of polymer, it takes longer for both setting time. Besides, because hydrogen peroxide has accelerative effect, the purified ethyl acrylate can shorten the setting time of initial and final setting time. However, over dosage of hydrogen peroxide can easily lead to poor strength development in later stage. Using purified ethyl acrylate can overcome the shortcoming of lower strength of 3、7- day early stage. when hydrogen peroxide consumption is 0.5% of the total amount of acid and alcohol, the ethyl acrylate has the positive effect on improving the compressive strength. Finally, among the comprehensive assessments of the mortar testing results, EH0.5-0.1 has the significant effect of modification.

scholarly journals Influence of calcined mud on the mechanical properties and shrinkage of self-compacting concrete

2018 ◽  
Vol 149 ◽  
pp. 01026
Author(s):  
Taieb Fatima ◽  
Belas Nadia ◽  
Belaribi Omar ◽  
Belguesmia Khalil ◽  
Hadj Sadok Rachid
Keyword(s):  
Mechanical Properties ◽  
Cement Content ◽  
Partial Replacement ◽  
Self Compacting Concrete ◽  
Fresh State ◽  
Beneficial Impact ◽  
Mineral Additions ◽  
Mechanical Strengths ◽  
Specific Formulation ◽  
Dredging Sediments

The use of SCC has a particular interest in terms of sustainable development. Indeed, their specific formulation leads to a greater volume of dough than for common concretes, thus, a larger quantity of cement. However, for economical, ecological and technical reasons, it is sought to limit their cement content [1]. It is therefore necessary to almost always use mineral additions as a partial replacement for cement because the technology of self-compacting concretes can consume large quantities of fines, in this case calcinated mud issued from dams dredging sediments that can give and/or ameliorate characteristics and performances of this type of concretes. Four SCCs had been formulated from the same composition where the only percentage of calcinated mud of Chorfa (west of Algeria) dam changed (0%, 10%, 20% and 30%). The effect of calcinated mud on characteristics at fresh state of SCC according to AFGC was quantified. Mechanical strengths and shrinkage deformation (total, autogenous, drying) were evaluated. The results show the possibility to make SCCs with different dosages of calcinated mud having strengths that can defy those of the control SCC. The analysis of free deformations indicates the beneficial impact of the mud by contributing to decrease the amplitudes of the shrinkage compared to those of the control SCC.

scholarly journals Impact of fibre incorporation and compaction method on properties of pervious concrete

2021 ◽  
Vol 71 (342) ◽  
pp. e245
Author(s):  
S. Juradin ◽  
I. Netinger-Grubeša ◽  
S. Mrakovčić ◽  
D. Jozić
Keyword(s):  
Mechanical Properties ◽  
Short Duration ◽  
Pervious Concrete ◽  
Cement Matrix ◽  
Viscous Layer ◽  
Concrete Properties ◽  
Different Types ◽  
Porosity And Permeability ◽  
Positive Effect ◽  
Compaction Method

This paper deals with the possibility of the improvement of pervious concrete properties by incorporation of different types of fibres and studies the effect of short duration vibration of pervious concrete properties in comparison with compaction with wooden lath and hammer. Ten mixtures of pervious concrete were prepared, five of which were compacted with wooden lath and hammer and five by short duration vibration. Density, porosity, permeability and mechanical properties were tested for in hardened pervious concrete specimens. It was concluded that mixtures compacted by short duration vibration had better mechanical properties due to the formation of a viscous layer at the contact surface between the aggregate grain and the cement matrix during the compaction, as well as pore-related properties. The addition of fibres negatively affected porosity and permeability but generally improved mechanical properties of concrete. The positive effect of fibre addition was more emphasised in cases of vibrated mixtures.

scholarly journals Mechanical properties and carbon footprint of 3D-printable cement mortars with biochar additions

2020 ◽  
Vol 323 ◽  
pp. 01017
Author(s):  
Devid Falliano ◽  
Dario De Domenico ◽  
Salvatore Quattrocchi ◽  
Paolo Cosenza ◽  
Giuseppe Ricciardi ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Compressive Strength ◽  
Research Work ◽  
Point Of View ◽  
Maximum Diameter ◽  
Future Research ◽  
Cement Mortars ◽  
Fresh State ◽  
High Consistency

This contribution focuses on the design and the characterization of innovative mix designs of high consistency mortars with biochar additions in different percentage with respect to the cement weight. Biochar is a by-product material that gives the cementitious mix a sustainable connotation from an environmental point of view. The mix designs presented here are characterized by a good dimensional stability in the fresh state, peculiarity that gives them the possibility to be extruded and so, to be used in automated construction processes. In addition to the mechanical properties (flexural and compressive strength), the assessment of the CO2 emission of representative mixes is presented. Different biochar content and maximum diameter of the aggregate are studied, obtaining interesting indications on these parameters to optimize mechanical properties. Finally, on the basis of the CO2 emission assessment, certain venues for future research work to minimize CO2 emissions are reported.

scholarly journals Physicomechanical and Antimicrobial Characteristics of Cement Composites with Selected Nano-Sized Oxides and Binary Oxide Systems

Materials ◽  
2022 ◽  
Vol 15 (2) ◽  
pp. 661
Author(s):  
Patryk Jędrzejczak ◽  
Łukasz Ławniczak ◽  
Agnieszka Ślosarczyk ◽  
Łukasz Klapiszewski
Keyword(s):  
Binary Systems ◽  
Building Materials ◽  
Inhibitory Effect ◽  
Physicochemical Analysis ◽  
Cement Matrix ◽  
Oxide Systems ◽  
Potential Measurement ◽  
Cement Mortars ◽  
Single And Binary Systems ◽  
Bacteria And Fungi

In recent years, increasing attention has been paid to the durability of building materials, including those based on cementitious binders. Important aspects of durability include the increase of the strength of the cement matrix and enhancement of material resistance to external factors. The use of nanoadditives may be a way to meet these expectations. In the present study, zinc, titanium and copper oxides, used in single and binary systems (to better the effect of their performance), were applied as additives in cement mortars. In the first part of this work, an extensive physicochemical analysis of oxides was carried out, and in the second, their application ranges in cement mortars were determined. The subsequent analyses were employed in determining the physicochemical properties of pristine oxides: Fourier transform infrared spectroscopy (FTIR), energy dispersive X-ray fluorescence (EDXRF), scanning electron microscopy (SEM), measurement of the particle size distribution, as well as zeta potential measurement depending on the pH values. Influence on selected physicomechanical parameters of the cement matrix and resistance to the action of selected Gram-positive and Gram-negative bacteria and fungi were also examined. Our work indicated that all nanoadditives worsened the mechanical parameters of mortars during the first 3 days of hardening, while after 28 days, an improvement was achieved for zinc and titanium(IV) oxides. Binary systems and copper(II) oxide deteriorated in strength parameters throughout the test period. In contrast, copper(II) oxide showed the best antibacterial activity among all the tested oxide systems. Based on the inhibitory effect of the studied compounds, the following order of microbial susceptibility to inhibition of growth on cement mortars was established (from the most susceptible, to the most resistant): E. coli < S. aureus < C. albicans < B. cereus = P. aeruginosa < P. putida.

scholarly journals Effect of nano-silica as cementitious materials-reducing admixtures on the workability, mechanical properties and durability of concrete

2021 ◽  
Vol 10 (1) ◽  
pp. 1395-1409
Author(s):  
Changjiang Liu ◽  
Xin Su ◽  
Yuyou Wu ◽  
Zhoulian Zheng ◽  
Bo Yang ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Building Materials ◽  
Setting Time ◽  
Microscopic Analysis ◽  
Chloride Ion ◽  
Cementitious Materials ◽  
Hydration Reaction ◽  
Ion Permeability ◽  
Nano Silica ◽  
Durability Of Concrete

Abstract Nano-silica (NS) is one of the most important nanomaterials in recent years. It is used as a new cement-based composite reinforcement in building materials because of its high volcanic ash activity. In order to achieve the goal of carbon peaking and carbon neutralization, combined with the research idea of cementitious materials-reducing admixture for concrete, under the condition of reducing the amount of cement in concrete by 20%, the influence of different dosages of NS on the setting time and mechanical properties of concrete was analyzed. In addition, the shrinkage performance, impermeability, and resistance to chloride-ion permeability of concrete were also studied. The results show that under the same curing conditions and ages, when the NS dosage is 2.5%, the compressive strength and splitting tensile strength of the specimen after 28 days of curing are the highest, reaching 40.87 and 3.8 MPa, which show an increase by 6.6 and 15.15%. The shrinkage performance of concrete increases with the increase in NS dosage. In addition, when the NS dosage is 2.0%, the durability of concrete has also been greatly improved. The impermeability of concrete increased by 18.7% and the resistance to chloride-ion permeability increased by 14.7%. Through microscopic analysis it was found that NS can promote the hydration reaction, generate more hydration products such as calcium silicate hydrate (C–S–H), enhance the interfacial adhesion between the matrix and the aggregate, and form a closer interfacial transition zone. Moreover, the addition of NS also reduces the cumulative pore volume in concrete, refines the pore size, and makes the internal structure of concrete denser.

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