scholarly journals Effect of temperature on early-age properties of self-consolidating concrete equivalent mortar

2020 ◽  
Vol 5 ◽  
pp. 114-122
Author(s):  
Nima Farzadnia ◽  
Jing Pan ◽  
Kamal Khayat ◽  
Eric Wirquin
Keyword(s):  
Heat Flux ◽  
Compressive Strength ◽  
Effect Of Temperature ◽  
Early Age ◽  
Test Results ◽  
Hydration Kinetics ◽  
Self Consolidating Concrete ◽  
Air Content ◽  
Cementing Material ◽  
Material Temperature

In this study, the effect of material temperature during casting on fresh properties, hydration kinetics, and early-age compressive strength of self-consolidating concrete (SCC) was evaluated. Concrete equivalent mortars (CEMs) based on SCC mixture designs with water-to-binder ratios of 0.41 and 0.45 were investigated. The SCC mixtures are targeted for infrastructure and building construction and precast applications. The CEMs were prepared at temperatures ranging from 8 to 36°C.  Superplasticizer (SP) and air-entraining agent (AEA) demand were evaluated for the CEM mixtures made with different supplementary cementing material (SCM) and limestone filler types. Test results showed that the ambient temperature can significantly affect the SP and AEA demand, hydration kinetics, and compressive strength after 1 d of age. According to the ultraviolet–visible spectrophotometry (UV/Vis) test, the absorption rate of polycarboxylate-based SP decreased with temperature. In contrast, the sensitivity of polynaphthalene sulfonate-based SP to temperature was minimal. Relationships between the variations of different admixture contents, heat flux, and compressive strength with temperature were developed. For a constant slump flow and air content, the demand of the SP and AEA, heat flux, and 1-d compressive strength of CEMs increased linearly with material temperature.

scholarly journals AIR CONTENT OF SELF-CONSOLIDATING CONCRETE AND ITS MORTAR PHASE INCLUDING RICE HUSK ASH / ORO KIEKIS SAVITANKIAME BETONE IR JO SKIEDINIO DALYJE SU RYŽIŲ LUKŠTŲ PELENAIS

2011 ◽  
Vol 17 (3) ◽  
pp. 319-329 ◽  
Author(s):  
Md. Safiuddin ◽  
Jeffrey S. West ◽  
Khaled A. Soudki
Keyword(s):  
Rice Husk ◽  
Strong Correlation ◽  
Simple Technique ◽  
Rice Husk Ash ◽  
Test Results ◽  
Excellent Correlation ◽  
Self Consolidating Concrete ◽  
Air Content ◽  
Cementing Material

This paper presents the air content results of self-consolidating concrete (SCC) and its mortar phase including rice husk ash (RHA) as a supplementary cementing material. Moreover, this paper demonstrates a simple technique to determine the dosage of air-entraining admixture (AEA) required for the target air content in SCC. Different SCC mixtures were designed based on the water/binder (W/B) ratios of 0.30–0.50 and design air content of 4–8%. RHA was incorporated in the concretes substituting 0–30% of cement by weight. The mortars were formulated from the mixture proportions of the corresponding parent concretes and tested to determine the air content at various AEA dosages. The effects of W/B ratio and RHA content on the air content of both mortar and concrete were observed. The effect of mortar volume on the air content of concrete was also noticed. Besides, the AEA dosages required for the target air contents of concrete were estimated based on the equivalent mortar air contents. Later the air-entrained SCC mixtures were produced using AEA and tested for the air content. Test results exhibit that the air contents of both mortar and concrete were significantly influenced by the W/B ratio and RHA content. The concrete air content was also greatly influenced by its mortar volume. The AEA dosage increased with lower W/B ratio, higher RHA content, and greater mortar volume for the target air contents. In addition, the actual AEA dosages were consistent with the estimated AEA dosages of the concretes. An excellent correlation was observed between the actual and estimated AEA dosages. The strong correlation suggests that the AEA dosage needed for a target air content in concrete can be determined based on the equivalent air content of its mortar phase. Santrauka Straipsnyje pateikiami oro kiekio nustatymo savitankiame betone (SCC) ir jo skiedinio dalyje su ryžių lukštų pelenais (RHA), naudojamais kaip papildoma cementavimo medžiaga, rezultatai. Be to, pateikiamas paprastas būdas parinkti orą įsiurbiančio priedo (AEA) dozę, siekiant gauti reikalingą oro kiekį SCC. Suprojektuoti skirtingi SCC mišiniai su skirtingu vandens ir rišiklio (W/B) 0,30–0,50 santykiu ir numatytu 4–8 proc. oro kiekiu, RHA buvo dedamas į betoną pakeičiant 0–30 proc. cemento pagal masę. Skiediniai buvo formuojami pagal jiems artimo betono sudėtis ir oro kiekis juose bandomas su skirtingomis AEA dozėmis. Nustatyta W/B santykio ir RHA kiekio įtaka oro kiekiui tiek skiedinyje, tiek betone bei skiedinio tūrio įtaka oro kiekiui betone. Be to, AEA dozės, reikalingos numatytam oro kiekiui betone pasiekti, nustatytos pagal ekvivalentinį oro kiekį skiedinyje. Vėliau SCC mišiniai su orą įsiurbiančiu priedu buvo pagaminti naudojant AEA ir išbandytas juose esantis oro kiekis. Tyrimų rezultatai rodo, kad tiek skiedinį, tiek betono oro kiekį labai veikia W/B santykis ir RHA kiekis. Oro kiekį betone taip pat smarkiai veikia skiedinio tūris. Mažėjant W/B santykiui, didėjant RHA kiekiui ir skiedinio tūriui AEA dozė turi būti didinama norimam oro kiekiui pasiekti. Taip pat faktinės AEA dozės atitiko suskaičiuotas betonų AEA dozes. Tarp faktinių ir suskaičiuotų AEA dozių gauta labai gera koreliacija. Ji rodo, kad AEA dozę, reikalingą numatytam oro kiekiui betone pasiekti, galima skaičiuoti pagal ekvivalentinį oro kiekį šio betono skiedinio dalyje.

scholarly journals Improvement of the Early-Age Compressive Strength, Water Permeability, and Sulfuric Acid Resistance of Scoria-Based Mortars/Concrete Using Limestone Filler

2017 ◽  
Vol 2017 ◽  
pp. 1-17 ◽  
Author(s):  
Aref Al-Swaidani ◽  
Andraos Soud ◽  
Amina Hammami
Keyword(s):  
Compressive Strength ◽  
Acid Resistance ◽  
Early Age ◽  
Test Results ◽  
Natural Pozzolan ◽  
Water Penetration ◽  
Limestone Filler ◽  
Concrete Permeability ◽  
Strength And Durability ◽  
Penetration Depths

Natural pozzolan is being widely used as cement replacement. Despite the economic, ecological, and technical benefits of its adding, it is often associated with shortcomings such as the need of moist-curing for longer time and a lower early strength. This study is an attempt to investigate the effect of adding limestone filler on the compressive strength and durability of mortars/concrete containing scoria. Sixteen types of binders with different replacement levels of scoria (0, 10, 20, and 30%) and limestone (0, 5, 10, and 15%) were prepared. The development of the compressive strength of mortar/concrete specimens was investigated after 2, 7, 28, and 90 days’ curing. In addition, the acid resistance of the 28 days’ cured mortars was evaluated after 90 days’ exposure to 5% H2SO4. Concrete permeability was also evaluated after 2, 7, 28, and 90 days’ curing. Test results revealed that there was an increase in the early-age compressive strength and a decrease in water penetration depths with adding limestone filler. Contrary to expectation, the best acid resistance to 5% H2SO4 solution was noted in the mortars containing 15% limestone. Based on the results obtained, an empirical equation was derived to predict the compressive strength of mortars.

scholarly journals An Experiment to scrutinize the impact of Lightweight Expanded Clay Aggregates (LECA) And Metakaolin on Structural Lightweight Concrete

2020 ◽  
Vol 9 (3) ◽  
pp. 323-328
Keyword(s):  
Compressive Strength ◽  
Lightweight Concrete ◽  
Relative Increase ◽  
Partial Substitution ◽  
Early Age ◽  
Test Results ◽  
Conventional Concrete ◽  
Selective Substitution ◽  
Clay Aggregates ◽  
The Impact

Lightweight concrete is to be treated as structural concrete (using LECA as CA), it must satisfy the density in range of 1120-1920 kg/m3 and strength not less than 20 N/mm². In order to accomplish required strength, LECA with metakaolin was used at different concentrations of (20% to 26%) by weight of cement at equal increments of 2%. Test results clearly indicates that, using LECA and metakaolin as selective substitution increases the compressive strength and durable properties. The prerequisite of using additional cementious material as metakaolin was to enhance the compressive strength, durability of LWC. Metakaolin content seems to lead high early age strength with relative increase in strength of 28 days. The effective content of metakaolin was 24% along with 60% LECA as partial substitution gave very much appreciable results. The percentage reduction in density recorded was 33%. The durable aspects such as resistance offered to acidic environment was also affirming when as compared to conventional concrete.

scholarly journals Towards Innovative and Sustainable Construction of Architectural Structures by Employing Self-Consolidating Concrete Reinforced with Polypropylene Fibers

2020 ◽  
Author(s):  
Wael Zatar ◽  
Hai Nguyen
Keyword(s):  
Compressive Strength ◽  
Reinforced Concrete ◽  
Fiber Reinforced Concrete ◽  
Sustainable Construction ◽  
Fiber Reinforced ◽  
Compression Tests ◽  
Self Consolidating Concrete ◽  
Air Content ◽  
Slump Flow ◽  
Architectural Structures

Self-consolidating concrete (SCC) has been successfully employed to reduce construction time and enhance the quality, performance, and esthetic appearance of concrete structures. This research aimed at developing environmentally friendly fiber-reinforced concrete (FRC) consisting of SCC and recycled polypropylene (PP) fibers for sustainable construction of city buildings and transportation infrastructure. The addition of the PP fibers to SCC helps reducing shrinkage cracks and providing enhanced mechanical properties, durability, and ductility of the concrete materials. Several mix designs of self-consolidating fiber-reinforced concrete (SCFRC) were experimentally examined. Material and esthetic properties of the SCFRC mixtures that include micro silica, fly ash, and PP fibers were evaluated. Trial-and-adjustment method was employed to obtain practically optimum SCFRC mixtures, mixtures that are affordable and easy to make possessing enhanced compressive strength and esthetic properties. Slump flow and air content testing methods were used to determine the fresh properties of the SCFRC mixtures, and the esthetic properties of the mixtures were also evaluated. The hardened properties of the SCFRC mixtures were examined using three- and seven-day compression tests. The amount of fine/coarse aggregate, water, and other admixtures were varied while the Portland cement content in all mixtures was maintained unchanged. The maximum three-day compressive strength was 43.17 MPa and the largest slump flow was 736.6 mm. Test results showed enhanced material properties such as slump flow, air content and compressive strength values of the SCFRC mixtures and their excellent esthetic appearance. The favorable seven-day compressive strength of the SCFRC mixture, with 4.8 percent air content and 660.4 mm slump flow, is 39.26 MPa. The mixtures’ in this study are proven to be advantageous for potential SCFRC applications in architectural structures including building façades and esthetically-pleasing bridges.

Influence of Metakaolin on Strength and Microstructure of Steam-Cured High-Strength Concrete

2013 ◽  
Vol 838-841 ◽  
pp. 42-46 ◽  
Author(s):  
Jun Jie Zeng ◽  
Zhi Hong Fan ◽  
Long Chen
Keyword(s):  
Compressive Strength ◽  
High Strength Concrete ◽  
High Strength ◽  
Pozzolanic Reaction ◽  
Early Age ◽  
Test Results ◽  
Replacement Level ◽  
Strength Concrete ◽  
Pozzolanic Reactivity ◽  
Compressive Strength Test

The influence of metakaolin (MK) on strength and microstructure of steam-cured high-strength concrete has been investigated using compressive strength test, XRD, MIP and SEM. Three MK replacement levels were considered in the study: 5%, 10% and 15% by weight of cement. A mix double blended with 10% MK and 10% slag was prepared too. Test results have indicated that MK can increase the compressive strength of steam-cured concrete, especially at early age. Compressive strength up to 90MPa at 1 and 28 days is obtained with the incorporation of 10% MK and 10% slag. When the replacement level of MK is higher than 10%, the enhancement of strength becomes less significant. Content of Ca (OH)2 crystals is decreased while content of hydrates with Al is increased due to the pozzolanic reactivity of MK. Concrete pore structure is significantly refined and a denser hydrates structure is obtained due to the pozzolanic reaction and filler effect of MK. Meanwhile, combination of aggregate and paste is enhanced too. The improvements of strength and microstructure become more obvious when MK and slag are double incorporated.

scholarly journals Effects of Shrinkage Reducing Agent and Expansive Additive on Mortar Properties

2017 ◽  
Vol 2017 ◽  
pp. 1-11 ◽  
Author(s):  
Sarapon Treesuwan ◽  
Komsan Maleesee
Keyword(s):  
Compressive Strength ◽  
Reducing Agent ◽  
Early Age ◽  
Alkyl Ether ◽  
Test Results ◽  
Steam Curing ◽  
Plastic Shrinkage ◽  
Compressive Strength Test ◽  
Expansive Additive ◽  
Shrinkage Reducing Agent

This research is to study the effect of mortar mixed with shrinkage reducing agent (polyoxyalkylene alkyl ether type), expansive additive (CaO type), and fly ash (hereinafter “SRA,” “EX,” and “FA,” resp.). Moreover, steam curing was studied to improve the properties of mortar. The plastic shrinkage test was conducted by using the strain gauge embedded at 0.5 cm from the surface according to the ASTM C1579-06 standard within early age followed by the total shrinkage test and compressive strength test. The test results showed that mixing both the EX and SRA increases the plastic enlargement of the mortar during the early age more than using either the EX or SRA solely. The steam curing helps to reduce the plastic shrinkage when the mortar is added with the FA and SRA while adding the EX increases the enlargement compared to the normal curing. When the EX, SRA, and FA are all added to the mortar mixing, great attention should be paid due to the increase of greater enlargement. For the compressive strength view, the steam curing increases the compressive strength in all types of mixture. The steam curing significantly helps increasing the compressive strength of mortar with combination of EX, SRA, and FA. Nevertheless, the XRD and SEM tests explain such enlargement accordingly.

Research on Hydration Reaction of Slag-Cement Material System

2014 ◽  
Vol 629-630 ◽  
pp. 376-381
Author(s):  
Qing Wang ◽  
Zhao Yang Ding ◽  
Ning Wang ◽  
Wei Jiang ◽  
Tao Jun Wu
Keyword(s):  
Compressive Strength ◽  
Cement Composite ◽  
Hydration Reaction ◽  
Material System ◽  
Slag Cement ◽  
Hydration Kinetics ◽  
Cement Material ◽  
Cementing Material ◽  
Kinetics Of ◽  
Scanning Electron

The influence of slag dosage on the hydration kinetics of slag-cement composite cementing material system is studied. The results show that the exothermic rate of hydration decreases as the slag dosage increases or the temperature of hydration decreases. The non-evaporable water content increases at first and then decreases with the increasing of slag dosage, and reaches the maximum as slag dosage is 30%. The compressive strength decreases as slag dosage increases, the increasing rate of which is evidently before 28 days, after that it is flat or become slow. It can be seen from SEM (scanning electron microscope), in the system of slag dosage below 30%, the gel-like structures bind with crystals which make the system very compact.

Durability of Sustainable Self-Consolidating Concrete

2018 ◽  
Vol 765 ◽  
pp. 285-289
Author(s):  
Osama Ahmed Mohamed ◽  
Waddah Al Hawat ◽  
Omar Fawwaz Najm
Keyword(s):  
Compressive Strength ◽  
Fly Ash ◽  
Silica Fume ◽  
Cementitious Materials ◽  
Chloride Penetration ◽  
Supplementary Cementitious Materials ◽  
Test Results ◽  
Self Consolidating Concrete ◽  
Human Footprint ◽  
Granulated Blast Furnace Slag

Supplementary cementitious materials such as fly ash, silica fume and ground granulated blast furnace slag (GGBS) have been used widely to partially replace cement in producing self-consolidating concrete (SCC). The production of cement is associated with emission of significant amounts of CO2 and increases the human footprint on the environment. Fly ash, silica fume, and GGBS are recycled industrial by-products that also impart favorable fresh and hardened properties on concrete. This study aims to assess the effect of the amounts of fly ash and silica fume on strength and chloride penetration resistance of concrete. Rapid Chloride Penetration Test (RCPT) was used to assess the ability of SCC to resist ingress of chlorides into concrete. SCC mixes with different dosages of fly ash and silica fume were developed and tested at different curing ages. Test results showed that replacing 20% of cement with fly ash produced the highest compressive strength of 67.96 MPa among all fly ash-cement binary mixes. Results also showed that replacing15% of cement with silica fume produced the highest compressive strength of 95.3 MPa among fly ash-cement binary mixes. Using fly ash and silica fume consistently increased the concrete resistance to chloride penetration at the early ages. Silica fume at all dosages results in low or very low levels of chloride penetration at all curing ages of concrete.

Basic Mechanics Properties Test of Fly Ash Concrete

2012 ◽  
Vol 238 ◽  
pp. 138-141
Author(s):  
Wei Xie ◽  
Hai Juan Zhang ◽  
Shu Shan Li
Keyword(s):  
Tensile Strength ◽  
Compressive Strength ◽  
Fly Ash ◽  
Ash Content ◽  
Early Age ◽  
Test Results ◽  
Fly Ash Concrete ◽  
Influence Mechanism ◽  
Normal Reference ◽  
Test Study

By the test study of basic mechanics properties of concrete with different fly ash content, the influence of the content of fly ash on the compressive strength, flexural strength, splitting tensile strength and static compressive elastic modulus of concrete are analyzed with the explaining of the influence mechanism of fly ash. The test results show that, comparing with the normal reference concrete, the early age strength of fly ash concrete enhances slowly, while the late strength develops rapidly, even overpasses the strength of normal reference concrete.

scholarly journals HYDRATION OF PLASMA-TREATED ALUMOSILICATE BINDERS

2014 ◽  
Vol 54 (5) ◽  
pp. 348-351
Author(s):  
Vít Šmilauer ◽  
Oleg Babchenko ◽  
Štepán Potocký ◽  
Alexander Kromka
Keyword(s):  
Compressive Strength ◽  
Fly Ash ◽  
Plasma Treatment ◽  
Material Science ◽  
Hydration Heat ◽  
Early Age ◽  
Hydrophilic Surface ◽  
Hydration Kinetics ◽  
Early Age Hydration

Plasma treatment offers several applications in material science. In this research, the potential of plasma treatment is explored on the hydration of hydrophilic CNT-enriched cement and hydrophilic fly ash. The evolution of the hydration heat and the compressive strength show that a hydrophilic surface slightly accelerates the early-age hydration kinetics, while the long-term properties remain unchanged.

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