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19 pages, 4273 KiB

Open AccessArticle

Statistical Models Supporting the High-Performance Self-Compacting Concrete (HPSCC) Design Process for High Strength

by Aleksandra Kostrzanowska-Siedlarz and Jacek Gołaszewski

Materials 2022, 15(2), 690; https://doi.org/10.3390/ma15020690 - 17 Jan 2022

Cited by 7 | Viewed by 2600

Abstract

The type of test ingredients used for obtaining self-compacting high-performance concrete (HPSCC) has been carefully selected to be universal. For this purpose, an extensive statistical analysis of the obtained results of the literature research was carried out. Then, universal and adapted to the [...] Read more.

The type of test ingredients used for obtaining self-compacting high-performance concrete (HPSCC) has been carefully selected to be universal. For this purpose, an extensive statistical analysis of the obtained results of the literature research was carried out. Then, universal and adapted to the typical range, highly fit statistical models are presented that can support the HPSCC design process for achieving high strength. For this purpose, a broad plan of statistical research was used, namely multivariate selection of sidereal points, which allowed the use of as many as five variable factors at three levels of variability. The sidereal points were equal to the respective minimum and maximum input values. Additionally, based on the analysis of variance (ANOVA) for factorial systems with the interaction of the obtained test results, the significance of the impact of the tested material factors on the compressive strength of the HPSCC tested was determined. Full article

(This article belongs to the Special Issue Material Modifications of High Performance Concrete Properties)

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14 pages, 4392 KiB

Open AccessArticle

Influence of Polymer Modifiers on Selected Properties and Microstructure of Cement Waterproofing Mortars

by Wacław Brachaczek, Adam Chleboś and Zbigniew Giergiczny

Materials 2021, 14(24), 7558; https://doi.org/10.3390/ma14247558 - 9 Dec 2021

Cited by 7 | Viewed by 2521

Abstract

This paper presents the results of research on the influence of polymer modifiers: styrene-acrylic copolymer, vinyl acetate/ethylene (EVA), vinyl acetate/acrylic copolymer (VAAc), and VA/VeoVa/acrylic terpolymer on the water permeability and adhesion of cement-containing waterproofing mortars in concrete. The content of the polymers in [...] Read more.

This paper presents the results of research on the influence of polymer modifiers: styrene-acrylic copolymer, vinyl acetate/ethylene (EVA), vinyl acetate/acrylic copolymer (VAAc), and VA/VeoVa/acrylic terpolymer on the water permeability and adhesion of cement-containing waterproofing mortars in concrete. The content of the polymers in the composition of the mortars was 15, 20 and 26% (m/m) in relation to the weight of the dry ingredients. Using microscopic methods, an attempt was made to analyse the relationship between the microstructure of the mortars and the properties of these polymers. The EVA and the vinyl acetate/acrylic copolymer, which were used in the form of dry powders, had the most favourable effect on water permeability and adhesion to the concrete substrate. They may prove to be useful for the production of one-component cement-containing waterproofing mortars. On the other hand, the VA/VeoVa/acrylic terpolymer modifier had the least favourable effect on the tested properties. For mortars with this modifier, the desired water-permeability parameters were not achieved. Depending on the amount of polymer modifier, the mortars were characterized by differences in watertightness, as established on the basis of changes in porosity and differences in the adhesion of the cement-polymer paste to the surface of aggregate grains. It was determined that the type of polymer and its dispergation properties influence the water permeability of mortars, as well as their adhesion to concrete substrates. Full article

(This article belongs to the Special Issue Material Modifications of High Performance Concrete Properties)

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24 pages, 25191 KiB

Open AccessArticle

Microstructure of CEM II/B-S Pastes Modified with Set Accelerating Admixtures

by Jan Pizoń and Beata Łaźniewska-Piekarczyk

Materials 2021, 14(21), 6300; https://doi.org/10.3390/ma14216300 - 22 Oct 2021

Cited by 6 | Viewed by 2264

Abstract

The presented paper aims to describe the influence of accelerating admixtures on the properties and microstructure of cement pastes and mortars. Blended slag cement CEM II/B-S containing two different clinkers (differing amounts of siliceous and aluminous phases) and four types of accelerators (calcium [...] Read more.

The presented paper aims to describe the influence of accelerating admixtures on the properties and microstructure of cement pastes and mortars. Blended slag cement CEM II/B-S containing two different clinkers (differing amounts of siliceous and aluminous phases) and four types of accelerators (calcium nitrate, sodium hydroxide, cement kiln dust, and crystal seeds) were used in research. Compressive strength tests (after 12, 24, 48 h of curing), Scanning Electron Microscope (SEM) observations together with an Energy Dispersive Spectroscopy (EDS) analysis, Mercury Intrusion Porosimetry (MIP) tests, and X-ray diffraction (XRD) analysis were conducted. Results have shown that SEM and EDS examination of the microstructure of cement pastes modified with accelerating admixtures at the observed points did not reveal differences that would be sufficient to explain the changes in compressive strength. Still, the increase in amorphous phase content indicates a faster hydration reaction rate for all pastes modified with accelerating admixture. It is backed up also by lower non-hydrated compounds content. All admixtures accelerate the hydration reaction of calcium silicate phases of cement, but only NaOH and cement kiln dust (CKD) influence the aluminate phase reaction rate. The pore volume is independent of the clinker type, while the pore size distribution is not. Full article

(This article belongs to the Special Issue Material Modifications of High Performance Concrete Properties)

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20 pages, 4049 KiB

Open AccessArticle

Variation of Durability and Strength Parameters of Pumice Based Mixtures

by Petr Lehner, Petr Konečný and Pratanu Ghosh

Materials 2021, 14(13), 3674; https://doi.org/10.3390/ma14133674 - 1 Jul 2021

Cited by 8 | Viewed by 2028

Abstract

The numerical modelling of chloride penetration into concrete is very sensitive to the correct description of the input data. In the recent era, high-performance concrete (HPC), which combines Portland cement and other supplementary cementitious materials, has been gaining attraction due to their desirable [...] Read more.

The numerical modelling of chloride penetration into concrete is very sensitive to the correct description of the input data. In the recent era, high-performance concrete (HPC), which combines Portland cement and other supplementary cementitious materials, has been gaining attraction due to their desirable material properties and durability. The presented results show the application of the modified approach for the evaluation of the suitability of the time-dependent model for the variation of the diffusion coefficient. The 26 various binary and ternary-based concrete mixtures blended with volcanic pumice pozzolan (VPP) as a major supplementary cementitious material (SCM) are compared with the reference Ordinary Portland Cement mixture. Other SCMs namely fly ash, slag, silica fume, and metakaolin were also utilized in ternary-based concrete mixtures. In-depth statistical analysis was carried out to show the variability and effects of the amount of the volcanic pumice as an SCM on the diffusion coefficient. The mean value and regression via linear approximation of the time-dependent coefficient of variation of the diffusion coefficients were used as well as the Root of Mean Squared Error approach. The presented results are suitable as the component of the input parameters for the durability-related probabilistic assessment of the reinforced concrete structures exposed to chlorides. In addition, the time-dependent ultimate limit state-related data was presented. Full article

(This article belongs to the Special Issue Material Modifications of High Performance Concrete Properties)

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13 pages, 17287 KiB

Open AccessArticle

Chemical Shrinkage of Low Water to Cement (w/c) Ratio CEM I and CEM III Cement Pastes Incorporating Silica Fume and Filler

by Judy Kheir, Benoît Hilloulin, Ahmed Loukili and Nele De Belie

Materials 2021, 14(5), 1164; https://doi.org/10.3390/ma14051164 - 2 Mar 2021

Cited by 9 | Viewed by 3730

Abstract

Chemical shrinkage (CS) is the reason behind early age cracking, a common problem for concrete with low water to cement ratios (w/c < 0.35) known as Ultra-High- and High-Performance Concrete (U-HPC). However, to avoid the crack development initiated by autogenous shrinkage, a precise [...] Read more.

Chemical shrinkage (CS) is the reason behind early age cracking, a common problem for concrete with low water to cement ratios (w/c < 0.35) known as Ultra-High- and High-Performance Concrete (U-HPC). However, to avoid the crack development initiated by autogenous shrinkage, a precise measurement of CS is required, as the values obtained can determine the correct amount of internal curing agent to be added in the mixture to avoid crack formation. ASTM C1608 is the standardized method for performing CS tests. In this study, recommendations are provided to improve the reliability of results obtained with this standard method, such as good compaction of samples and the use of superplasticizer (SP) for low w/c ratios (≤0.2). Cement pastes with CEM I and CEM III have been tested at different w/c ratios equal to 0.2, 0.3 and 0.4 with and without the addition of superplasticizer. CS results following ASTM-C1608 dilatometry showed that the presence of mineral additions such as silica fume and filler reduced the chemical shrinkage, while CS increased with increasing w/c. Low w/c ratio pastes of CEM III had slightly higher CS rates than CEM I, while the opposite was noticed at higher w/c. SEM images illustrated the importance of a careful compaction and SP use. Full article

(This article belongs to the Special Issue Material Modifications of High Performance Concrete Properties)

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12 pages, 6514 KiB

Open AccessArticle

Effect of 3D Printed Spatial Reinforcement on Flexural Characteristics of Conventional Mortar

by Jacek Katzer and Tomasz Szatkiewicz

Materials 2020, 13(14), 3133; https://doi.org/10.3390/ma13143133 - 14 Jul 2020

Cited by 26 | Viewed by 3175

Abstract

In their fourth decade of development, additive manufacturing technologies are slowly entering research programs dedicated to building materials. While the majority of research effort is focused on using 3D printing of concrete, the authors propose using the technology for creation of spatial plastic [...] Read more.

In their fourth decade of development, additive manufacturing technologies are slowly entering research programs dedicated to building materials. While the majority of research effort is focused on using 3D printing of concrete, the authors propose using the technology for creation of spatial plastic reinforcement. Obviously, the strength properties of a 3D printed polymer are much lower than those of steel. Nevertheless, the unconventional spatial shape of a 3D printed reinforcement can substitute for much of the lower mechanical performance of polymer. Flexural characteristics of a cement mortar prism specimen reinforced by hexagon spatial elements were tested and analyzed in this paper. The hexagonal geometric shape was chosen due to its high rigidness. It was proven that it is possible to efficiently reinforce concrete beams by spatial 3D printed polymer elements. Directions of needed research were pointed and discussed. Full article

(This article belongs to the Special Issue Material Modifications of High Performance Concrete Properties)

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12 pages, 4556 KiB

Open AccessArticle

Effects of Modified Nano-SiO₂ Particles on Properties of High-Performance Cement-Based Composites

by Zhidan Rong, Mingyu Zhao and Yali Wang

Materials 2020, 13(3), 646; https://doi.org/10.3390/ma13030646 - 1 Feb 2020

Cited by 41 | Viewed by 3834

Abstract

In this research, silane coupling agent was used to modify the surface of nano-SiO₂, particles and the effects of modified nano-SiO₂ particles on the mechanical properties of high-performance cement-based composites and its mechanism were systematically studied. The results indicated that [...] Read more.

In this research, silane coupling agent was used to modify the surface of nano-SiO₂, particles and the effects of modified nano-SiO₂ particles on the mechanical properties of high-performance cement-based composites and its mechanism were systematically studied. The results indicated that the optimum modification parameters were a coupling agent content of 10%, reaction temperature of 65 °C, and reaction time of 8 h. Compared with the unmodified nano-SiO₂, the modified nano-SiO₂ promoted and accelerated the hydration process of cement. The pozzolanic effect, filling effect, and nucleation effect of modified nano-SiO₂ made the microstructure of the composite more compact, and thus improved static mechanical properties of cement-based composites. Full article

(This article belongs to the Special Issue Material Modifications of High Performance Concrete Properties)

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12 pages, 2689 KiB

Open AccessConcept Paper

A Proposition of an In Situ Production of a Blended Cement

by Jacek Halbiniak, Jacek Katzer, Maciej Major and Izabela Major

Materials 2020, 13(10), 2289; https://doi.org/10.3390/ma13102289 - 15 May 2020

Cited by 10 | Viewed by 3597

Abstract

Many byproducts and waste materials with pozzolanic properties can substitute natural raw materials in cement production. Some of these waste materials like fly ash and blast furnace slag are commonly harnessed by cement industry. Others are of seldom use due to limitations of [...] Read more.

Many byproducts and waste materials with pozzolanic properties can substitute natural raw materials in cement production. Some of these waste materials like fly ash and blast furnace slag are commonly harnessed by cement industry. Others are of seldom use due to limitations of the very centralized cement production systems currently in use. In the authors opinion, it is necessary to change this system to enable efficient utilization of various waste materials that are available locally (e.g., white and red ceramics). In this study, a new partially centralized system of cement production is proposed. The adoption of a new system would significantly reduce the volume of long-distance transportation and enable utilization of numerous locally available waste materials that are currently dismissed. The last stage of production of the ready-to-use cement would take place in situ. The cement would be produced on demand and be immediately used for concrete production on-site. The research program was conducted considering the importance of the quality of cements obtained in the new way, substituting up to 12% of its mass by white ceramics. The research program was proof of concept of the proposed cement production system. It was shown that the quality of “in situ cement” does not differ from standard cements. Full article

(This article belongs to the Special Issue Material Modifications of High Performance Concrete Properties)

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