scholarly journals CEMENT MATRIX CONTAINING MICRONIZED RECYCLED CONCRETE AND THE INFLUENCE OF ADDITIVES

2018 ◽  
Vol 15 ◽  
pp. 20-24
Author(s):  
Jakub Ďureje ◽  
Zdeněk Prošek ◽  
Jaromír Hrůza ◽  
Pavel Tesárek
Keyword(s):  
Dynamic Modulus ◽  
Resonance Method ◽  
Cement Composite ◽  
Recycled Concrete ◽  
The Other ◽  
Cement Matrix ◽  
Dynamic Shear Modulus ◽  
Dynamic Shear ◽  
Reference Samples ◽  
Selection Of

The article deals with the selection of a suitable additives in cement composite material for the production of a masonry block. The blocks contains recycled concrete which replacing 40% cement. The recyclate comes from concrete drainage gutters. Based on previous measurements, two hardening accelerators and one superplasticizer were selected. To determine the effect of these additives on the recycled cement composite, pairs of samples sets were produced, of which one set contains concrete recyclate and the other one does not contain it. The dynamic modulus of elasticity and the dynamic shear modulus were measured by the resonance method at the age of samples 1, 7, 14, 21 and 28 days, and by an ultrasound method at 28 days of age. Then was measured compressive strength. All values were compared with the values measured on the reference samples.

scholarly journals CEMENT PASTE CONTAINING MICRONIZED RECYCLED CONCRETE - INFLUENCE OF HARDENING ACCELERATORS ON THE MODULUS OF ELASTICITY

2020 ◽  
Vol 26 ◽  
pp. 19-23
Author(s):  
Jakub Ďureje ◽  
Zdeněk Prošek
Keyword(s):  
Modulus Of Elasticity ◽  
Mass Production ◽  
Resonance Method ◽  
Cement Composite ◽  
Recycled Concrete ◽  
Initial Strength ◽  
Non Destructive ◽  
Reference Samples ◽  
Moduli Of Elasticity ◽  
Selection Of

The article deals with the selection of a suitable hardening accelerator for cement composite material for mass production of masonry blocks. The blocks contain cement and finely ground recycled concrete in ratio 1:1. Three different hardening accelerators in different quantity were tested for possibility of fast removing formwork. The dynamic modulus of elasticity was measured by non-destructive resonance method to determine the initial strengths. The modulus of elasticity was measured 7 and 12 hours after sample production to determine the increase in initial strength. Subsequently, the modulus of elasticity was measured at 1, 7, 14, 21 and 28 days after production of the test specimens. The resulting moduli of elasticity were compared with reference samples.

scholarly journals LONG-TIME INVESTIGATION OF CEMENT COMPOSITE MATERIAL WITH MICRONIZED WASTE MARBLE POWDER: DYNAMIC MODULES

2017 ◽  
Vol 13 ◽  
pp. 93
Author(s):  
Zdeněk Prošek ◽  
Jaroslav Topič
Keyword(s):  
Shear Modulus ◽  
Modulus Of Elasticity ◽  
Dynamic Modulus ◽  
Blended Cement ◽  
Resonance Method ◽  
Partial Replacement ◽  
Dynamic Shear Modulus ◽  
Dynamic Shear ◽  
Dynamic Modulus Of Elasticity ◽  
Marble Powder

This article focus on “blended cement”. The blended cement was created by using waste marble powder (WMP) as a partial replacement for cement. We investigated the influence of WMP on the developing of the dynamic modulus of elasticity and the dynamic shear modulus in time. Four different cement composites with WMP as a partial replacement for cement were studied (5, 10, 15 and 50 wt. %) together with reference samples. Dynamic modulus of elasticity was monitored during the first 377 days since manufacture by use of non-destructive testing (resonance method). The results showed that WMP in a small amount had a no effect on the dynamic modulus of elasticity and the dynamic shear modulus.

Influence of Waste Crushed Limestone and Waste Micronized Marble Powder on Mechanical Properties of Cement Composite

2016 ◽  
Vol 722 ◽  
pp. 222-227 ◽  
Author(s):  
Zdeněk Prošek ◽  
Jaroslav Topič ◽  
Karel Šeps ◽  
Pavel Tesárek
Keyword(s):  
Mechanical Properties ◽  
Dynamic Modulus ◽  
High Speed ◽  
Cement Composite ◽  
Dynamic Shear Modulus ◽  
Dynamic Shear ◽  
Binding Properties ◽  
Marble Powder ◽  
Crushed Limestone ◽  
Marble Sludge

For production of the samples were used several types of aggregate: the standard sand from Zalezlice, the standard sand from Gaza, waste crushed limestone, waste marble sludge and waste micronized marble powder. The Portland cement CEM I 42.5 R produced in Radotín was used as binder. Testing was carried at prismatic samples of dimension 40 × 40 × 160 mm. Another approach than previously used solutions consists primarily in micronization marble sludge with a high-speed mill, this modified micronized filler may also an impact on the final properties of composite materials based on cement. The micronized powder may have binding properties that are activated in this way. Dynamic modulus of elasticity, dynamic shear modulus, flexural strength and compressive strength were determined for the 28 days old samples.

scholarly journals PLASMA MODIFICATION OF MICROFIBERS - APPLICATION TO LIGHTWEIGHT CEMENT COMPOSITE CONTAINING RECYCLED CONCRETE

2021 ◽  
Vol 30 ◽  
pp. 7-11
Author(s):  
Jakub Ďureje ◽  
Zdeněk Prošek ◽  
Jan Trejbal ◽  
Pavel Tesárek ◽  
Štěpán Potocký
Keyword(s):  
Mechanical Properties ◽  
Composite Material ◽  
Oxygen Plasma ◽  
Cement Composite ◽  
Recycled Concrete ◽  
Plasma Modification ◽  
Cement Matrix ◽  
Foaming Agent ◽  
Cementitious Matrix

The article deals with the optimalization of composition for reinforced lightweight cement composite containing micronized recycled concrete, which will be used to produce masonry blocks. The composite material is reinforced with polypropylene microfibers. To increase the cohesion between the fibers and the cementitious matrix, the optimal modification using oxygen plasma was chosen. Furthermore, a suitable foaming agent was chosen to lighten the cement matrix. A suitable ratio of cement and micronized recycled concrete was determined. Finally, a cement composite was made from the optimized components. The mechanical properties of this composite were tested. The resulting mechanical properties of the lightweight samples were compared with the non-light samples.

The Effect of Micronized Waste Marble Powder as Partial Replacement for Cement on Resulting Mechanical Properties of Cement Pastes

2017 ◽  
Vol 1144 ◽  
pp. 54-58
Author(s):  
Zdeněk Prošek ◽  
Karel Šeps ◽  
Jaroslav Topič
Keyword(s):  
Mechanical Properties ◽  
Compressive Strength ◽  
Reference Material ◽  
Dynamic Modulus ◽  
Blended Cement ◽  
Partial Replacement ◽  
Dynamic Shear Modulus ◽  
Dynamic Shear ◽  
Cement Pastes ◽  
Marble Powder

This article was focused on the influence of the micronized waste marble powder on mechanical properties of cement pastes. Resulting blended cement was composed of Portland cement CEM I 42.5 R and micronized marble powder with different percentage amounts (0 wt. %, 5 wt. %, 10 wt. % and 15 wt. %). Testing was carried at prismatic samples of dimension 40 × 40 × 160 mm. The investigated mechanical properties were dynamic modulus of elasticity, dynamic shear modulus, flexural strength and compressive strength for the 28 days old samples. The results obtained from these materials were compared with reference material.

Development of Mechanical Properties of Cement Paste with Different Addition of Polyvinyl Alcohol

2015 ◽  
Vol 732 ◽  
pp. 81-84 ◽  
Author(s):  
Jaroslav Topič ◽  
Pavel Tesárek ◽  
Václav Nežerka ◽  
Zdeněk Prošek ◽  
Tomáš Plachy
Keyword(s):  
Mechanical Properties ◽  
Shear Modulus ◽  
Polyvinyl Alcohol ◽  
Cement Paste ◽  
Resonance Method ◽  
Dynamic Shear Modulus ◽  
Dynamic Shear ◽  
Alcohol Content ◽  
Dynamic Young’S Modulus ◽  
Dynamic Young's Modulus

This paper deals with using resonance method for determine the development of the mechanical properties of cement paste with different polyvinyl alcohol content. Main properties which were monitored are the dynamic Young’s modulus and dynamic shear modulus. Those properties were measured during 161 days for better understanding of influence of Polyvinyl Alcohol (PVA) added in the cement paste. Difference between this paper and already published articles is in several parameters. Main difference is that samples in this paper were cured on air, not in water. Moreover was used higher amount of polyvinyl alcohol on modification of cement paste.

Mechanical Properties of Gypsum Matrix Reinforced with Recycled Fibers

2016 ◽  
Vol 825 ◽  
pp. 3-6 ◽  
Author(s):  
Lukáš Hlubocký ◽  
Jaromír Hrůza ◽  
Lukas Novák ◽  
Jaroslav Topič
Keyword(s):  
Mechanical Properties ◽  
Composite Materials ◽  
Shear Modulus ◽  
Glass Fibers ◽  
Resonance Method ◽  
Steel Fibers ◽  
Dynamic Shear Modulus ◽  
Dynamic Shear ◽  
Metallic Reinforcement ◽  
Recycled Fibers

This paper deals with using resonance method for determine a development of mechanical properties of gypsum matrix reinforced with steel fibers from recycled tires. Mechanical properties which were monitored are the dynamic Young's modulus and dynamic shear modulus. Both properties were measured by a resonance method on samples 28 days old. The aim was to check the possibilities of using the recycled tires in construction as reinforcement to the gypsum binder. Many published papers deals with composite materials based on gypsum, but mainly with standard non-metallic reinforcement such as glass fibers, PP and PE fibers etc.

Note on Selection of Coordinate Systems for Geodynamics

1975 ◽  
Vol 26 ◽  
pp. 395-407
Author(s):  
S. Henriksen
Keyword(s):  
Sea Level ◽  
The Other ◽  
Coordinate Systems ◽  
Mean Sea Level ◽  
The Earth ◽  
The One ◽  
Static Systems ◽  
Selection Of

The first question to be answered, in seeking coordinate systems for geodynamics, is: what is geodynamics? The answer is, of course, that geodynamics is that part of geophysics which is concerned with movements of the Earth, as opposed to geostatics which is the physics of the stationary Earth. But as far as we know, there is no stationary Earth – epur sic monere. So geodynamics is actually coextensive with geophysics, and coordinate systems suitable for the one should be suitable for the other. At the present time, there are not many coordinate systems, if any, that can be identified with a static Earth. Certainly the only coordinate of aeronomic (atmospheric) interest is the height, and this is usually either as geodynamic height or as pressure. In oceanology, the most important coordinate is depth, and this, like heights in the atmosphere, is expressed as metric depth from mean sea level, as geodynamic depth, or as pressure. Only for the earth do we find “static” systems in use, ana even here there is real question as to whether the systems are dynamic or static. So it would seem that our answer to the question, of what kind, of coordinate systems are we seeking, must be that we are looking for the same systems as are used in geophysics, and these systems are dynamic in nature already – that is, their definition involvestime.

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