scholarly journals Frost durability of steel fiber self-compacting concrete for pavements

2016 ◽  
Vol 11 (1) ◽  
pp. 35-42 ◽  
Author(s):  
Jerzy Wawrzeńczyk ◽  
Agnieszka Molendowska ◽  
Adam Kłak
Keyword(s):  
Steel Fibre ◽  
Air Entrainment ◽  
Hardened Concrete ◽  
Polymer Microspheres ◽  
Self Compacting Concrete ◽  
Freeze Thaw ◽  
Concrete Mix ◽  
Finished Surface ◽  
Frost Durability ◽  
Scaling Resistance

The paper presents the results from the research on self-compacting concrete with different steel fibre type addition. The reference self-compacting concrete mix with water/binder = 0.33 was prepared, then modified with steel fibres in the amounts of 0–60 kg/m3 and air entrained with polymer microspheres (40 μm diameter). The major objective of the research was to determine the effect of steel fibre and air content on the self-compacting concrete mix properties and hardened concrete frost durability. The tests also included internal cracking and scaling resistance evaluation for concrete specimens subjected to cyclic freeze-thaw process − two beams were frozen in air and two beams were partially submerged in water and then frozen. The scaling resistance was tested using the slab method on the specimens with sawn surface and on the specimens with natural finished surface. Non-air entrained steel fibrereinforced concretes, despite their high strength class (C55/67–C60/75) and medium absorption (4.34–5.11%), showed unsatisfactory resistance to internal cracking and scaling tests. The beams partially submerged in water failed after 100 freeze-thaw cycles, which confirms a significant influence of water uptake from moist environment during freeze-thaw cycles and the acceleration of the damage process. Test results indicate that air entrainment with polymer microspheres is a very effective method and allows obtaining very good air pore structure parameters and frost resistance results. The specimens with top − finished surface exhibited less damage in the scaling resistance tests in relation to the specimens with sawn surface.

The Influence of W/C Ratio and Superplasticizer Type on Porosity of Concrete with Air-Entraining Cement with Fly Ash

2018 ◽  
Vol 279 ◽  
pp. 266-270
Author(s):  
Beata Łaźniewska-Piekarczyk
Keyword(s):  
Fly Ash ◽  
Fresh Concrete ◽  
Air Entrainment ◽  
Hardened Concrete ◽  
Research Results ◽  
Concrete Mix ◽  
European Standards ◽  
New Generation ◽  
Air Entrained Concrete

The research results of stability of air-entrainment of concrete acc. PN-EN 480-1 in case of innovate air-entraining multi-component cement CEM II/B-V is presented in the paper. The influence of PCE, naphthalene and phosphonamidite based superplasticizers and w/c ratio: 0.45, 0.50 and 0.55 on air-entrainment and consistency of fresh concrete mix was investigated. The research results indicated that with increasing w/c ratio the air-entrainment of concrete increases. Moreover, in case of an increase in the degree of liquidity of the air-entrained concrete made of participation of the innovative, air-entraining multi-component cement CEM II/B-V, first and new generation superplasticizers based on modified naphthalene, and then modified phosphonamidite should be used. PCE based superplasticizer cause the too high air-entrainment of concrete. The research results proved, that the porosity of hardened concrete meets the European standards for frost-resistant concrete.

Surface Layer Parameter of Concrete in Relation to Deicing Salt Scaling Resistance

2014 ◽  
Vol 1000 ◽  
pp. 298-301 ◽  
Author(s):  
Jaroslav Urban ◽  
Michaela Kostelecká ◽  
Tomas Klecka
Keyword(s):  
Surface Layer ◽  
Porous Structure ◽  
Concrete Structure ◽  
Hardened Concrete ◽  
Deicing Salt ◽  
Salt Scaling ◽  
Layer Parameter ◽  
Concrete Mix ◽  
Gaseous Media ◽  
Scaling Resistance

The porous structure together with surface layer, made by the compaction of concrete mix designed and by the following treatment of concrete placed, has a decisive influence on the penetration of aggressive media into the inside of concrete structure. In principle, it influences the parameters of hardened concrete and the transport of liquid and gaseous media. The surface layer of concrete is contacted as the first with aggressive substances and is an entrance gate for unwanted ones.

scholarly journals Study of the Influence of an Air-Entraining Agent on the Rheology of Motars

2018 ◽  
Vol 149 ◽  
pp. 01054
Author(s):  
Nadia Tebbal ◽  
Zine El Abidine Rahmouni ◽  
Lamis Rabiaa Chadi
Keyword(s):  
Compressive Strength ◽  
Rheological Properties ◽  
Fresh Concrete ◽  
Experimental Studies ◽  
Air Entrainment ◽  
Mix Design ◽  
Hardened Concrete ◽  
Concrete Mix Design ◽  
Concrete Mix ◽  
Mixing Water

The objective of this study is to analyze the effect of the air entrainment on the fresh rheological properties as well as on the compressive mechanical resistances of the mortars. The hardened concrete contains a certain amount of randomly spread air, coming either from a drive during kneading or from the evaporation of the mixing water. The air quantity is in the order of 20 l / m3, ie 2% of the volume. However, the presence of a large volume of air bubbles causes the mechanical resistances to fall in compression. On the other hand, the use of air entrainment could improve the rheological properties of fresh concrete. Experimental studies have been carried out to study the effect of air entrainment on compressive strength, density and ingredients of fresh concrete mix. During all the study, water cement ratio (w/c) was maintained constant at 0.5. The results have shown substantial decreasing in water and mortar density followed with decreasing in compressive strength of mortar. The results of this study has given more promising to use it as a guide for mortar mix design to choose the most appropriate concrete mix design economically.

scholarly journals Assessment of sulfur concrete properties for use in civil engineering

2018 ◽  
Vol 219 ◽  
pp. 03006 ◽  
Author(s):  
Michał Lewandowski ◽  
Renata Kotynia
Keyword(s):  
Structural Damage ◽  
Civil Engineering ◽  
Combustion Products ◽  
Engineering Industry ◽  
Hardened Concrete ◽  
Test Results ◽  
Freeze Thaw ◽  
Resistance Surface ◽  
Concrete Properties ◽  
Scaling Resistance

Sulfur concrete is a material that was introduced to the civil engineering industry as a substitute of a typical concrete in which cement is a binder. Sulfur concrete properties are provided by a sulfur polymer produced in the process of synthesis of the ordinary sulfur with modifiers that prevent a process of crystallization of sulfur what results in stabilizing sulfur polymer structure. The purpose of this investigation was to evaluate characteristics of sulfur concrete, which was designed with combustion products. It was established that mechanical parameters of sulfur concrete should correspond with properties of a cement concrete used in production processes of prefabricated elements of road and construction industry. Accurateness of parameters of a designed mixture was confirmed and rated by a series of tests of hardened concrete – physical, mechanical (compression strength), durability in harsh environment. The test results confirmed low water absorption, high resistance to wear abrasion, high freeze-thaw scaling resistance (surface weathering) in a salty environment and high compressive and tensile strength of individual compositions. However, due to the internal structural damage, the freeze-thaw-attack cube tests did not prove the freeze-thaw resistance of the sulfur concrete specimens. The reason was low freeze-thaw-attack resistance of sulfur binders.

scholarly journals INFLUENCE OF VISCOSITY MODIFYING AGENT ON SOME RHEOLOGICAL PROPERTIES, SEGREGATION RESISTANCE AND COMPRESSIVE STRENGTH OF SELF-COMPACTING CONCRETE

2013 ◽  
Vol 19 (1) ◽  
pp. 1-8 ◽  
Author(s):  
Anna M. Grabiec
Keyword(s):  
Compressive Strength ◽  
Rheological Properties ◽  
Concrete Strength ◽  
Vertical Direction ◽  
Reference Level ◽  
Hardened Concrete ◽  
Self Compacting Concrete ◽  
Modifying Agent ◽  
Air Content ◽  
Concrete Mix

Rheological properties of self-compacting concrete mixes containing a viscosity modifying agent (VMA) in their composition were studied. After preliminary studies self-compacting concrete mixes and, particularly, a fluid concrete mix prone to segregation of its ingredients were chosen. VMA was added in various amounts to that concrete mix to check how it performed in fresh and hardened concrete. Main studies focused on the influence of VMA on the following properties of concrete mixes: the slump flow, the flow time into the diameter of 500 mm and the resistance to segregation in the vertical direction. Moreover, the air content of concrete mixes and the 28-day compressive strength of concrete were measured. Test results showed that VMA significantly influenced the rheological properties of concrete mix, stabilised it and reduced the segregation. It was proved, that the concrete mix modified by VMA used in the optimal amount, featured the smallest scatter of concrete strength results. Besides, the Tukey's test showed that a reduction of the concrete compressive strength is possible to be statistically insignificant when compared to the reference level.

Preliminary Investigation on the Flexural Behaviour of Steel Fibre Reinforced Self-Compacting Concrete Ribbed Slab

2018 ◽  
Vol 15 (1) ◽  
pp. 31
Author(s):  
Nur Aiman Suparlan ◽  
Muhammad Azrul Ku Ayob ◽  
Hazrina Ahmad ◽  
Siti Hawa Hamzah ◽  
Mohd Hisbany Mohd Hashim
Keyword(s):  
Ultimate Load ◽  
Steel Fibre ◽  
Preliminary Investigation ◽  
Bending Test ◽  
Flexural Behaviour ◽  
Self Compacting Concrete ◽  
Two Samples ◽  
Simple Support ◽  
Set Up ◽  
Ultimate Load Carrying Capacity

A ribbed slab structure has the advantage in the reduction of concrete volume in between the ribs resulting in a lower structural self-weight. In order to overcome the drawbacks in the construction process, the application of steel fibre self-compacting concrete (SCFRC) is seen as an alternative material to be used in the slab. This preliminary investigation was carried out to investigate the flexural behaviour of steel fibre self-compacting concrete (SCFRC) as the main material in ribbed slab omitting the conventional reinforcements. Two samples of ribbed slab were prepared for this preliminary study; 2-ribbed and 3-ribbed in 1 m width to identify the effect of the geometry to the slab’s flexural behaviour. The dimension of both samples is 2.5 m x 1 m with 150 mm thickness. The compressive strength of the mix is 48.6 MPa based on the cubes tested at 28 days. Load was applied to failure by using the four point bending test set-up with simple support condition. The result of the experiment recorded ultimate load carrying capacity at 30.68 kN for the 2-ribbed slab and 25.52 kN for 3-ribbed slab. From the results, the ultimate load of the 2-ribbed sample exceeds 3-ribbed by approximately 20%. This proved that even with lower concrete volume, the sample can still withstand an almost similar ultimate load. Cracks was also observed and recorded with the maximum crack width of 2 mm. It can be concluded that the steel fibres do have the potential to withstand flexural loadings. Steel fibre reduces macro-crack forming into micro-cracks and improves concrete ductility, as well as improvement in deflection. This shows that steel fibre reinforced self-compacting concrete is practical as it offers good concrete properties as well as it can be mixed, placed easier without compaction. 

scholarly journals Functional Method of Designing Self-Compacting Concrete

Materials ◽  
2021 ◽  
Vol 14 (2) ◽  
pp. 267
Author(s):  
Tomasz Rudnicki
Keyword(s):  
Coarse Aggregate ◽  
Cement Mortar ◽  
Experimental Studies ◽  
Functional Method ◽  
Structural Viscosity ◽  
Self Compacting Concrete ◽  
Theoretical Assumptions ◽  
Concrete Mix ◽  
Selection Of ◽  
Double Coating

The article presents a new functional method of designing self-compacting concrete (SCC). The assumptions of the functional method of designing self-compacting concrete were based on the double coating assumption (i.e., it was assumed that the grains of coarse aggregate were coated with a layer of cement mortar, whereas the grains of sand with cement paste). The proposed method is composed of four stages, each of which is responsible for the selection of a different component of the concrete mix. The proposed designing procedure takes into consideration such a selection of the mineral skeleton in terms of the volumetric saturation of the mineral skeleton, which prevents the blocking of aggregate grains, and the designed liquid phase demonstrated high structural viscosity and low yield stress. The performed experimental studies, the simulation of the elaborated mathematical model fully allowed for the verification of the theoretical assumptions that are the basis for the development of the method of designing self-compacting concrete.

scholarly journals Consistency and mechanical properties of sustainable concrete blended with brick dust waste cementitious materials

2021 ◽  
Vol 3 (4) ◽  
Author(s):  
S. Y. Amakye ◽  
S. J. Abbey ◽  
A. O. Olubanwo
Keyword(s):  
Tensile Strength ◽  
Fresh Concrete ◽  
Environmental Benefits ◽  
Partial Replacement ◽  
Target Range ◽  
Hardened Concrete ◽  
Index Test ◽  
Demolition Waste ◽  
Concrete Mix ◽  
Brick Dust

AbstractThe reuse of waste materials in civil engineering projects has become the topic for many researchers due to their economic and environmental benefits. In this study, brick dust waste (BDW) derived from cutting of masonry bricks and demolition waste which are normally dumped as land fill is used as partial replacement of cement in a concrete mix at 10%, 20% and 30% respectively, with the aim of achieving high strength in concrete using less cement due to the environmental problems associated with the cement production. To ascertain the effects of BDW on the consistency and mechanical performance of concrete mix, laboratory investigations on the workability of fresh concrete and the strength of hardened concrete were carried out. Slump and compaction index test were carried out on fresh concrete mix and unconfined compressive strength (UCS) test and tensile strength test were conducted on hardened concrete specimen after 7, 14 and 28 days of curing. The results showed high UCS and tensile strength with the addition of 10% BDW to the concrete mix, hence achieving the set target in accordance with the relevant British standards. A gradual reduction in strength was observed as BDW content increases, however, recording good workability as slump and compaction index results fell within the set target range in accordance with relevant British standards. Findings from this study concluded that BDW can partially replace cement in a concrete mix to up to 30% igniting the path to a cleaner production of novel concrete using BDW in construction work.

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