scholarly journals The Strength Characterisation of Concrete Made with Alumina Waste Filler

2020 ◽  
Vol 12 (24) ◽  
pp. 10235
Author(s):  
Jonathan Oti ◽  
John Kinuthia ◽  
Blessing Adeleke
Keyword(s):  
Portland Cement ◽  
Heat Of Hydration ◽  
Reaction Process ◽  
Hydration Reaction ◽  
Splitting Strength ◽  
Concrete Mix ◽  
Cumulative Production ◽  
Tensile Splitting Strength ◽  
Salt Slag ◽  
Over Time

This study covers an in-depth investigation into the properties and practicality of the utilization of up to 40% Alumina Waste Filler (AWF) as a partial Portland Cement (PC) replacement material. AWF is a by-product from the recycling of aluminium, produced when salt slag is smelted and cleaned. Its use in concrete will lessen the landfill requirements for AWF disposal, and reduce the strain of the growing requirements and cost of PC. The results obtained from this study showed that the addition of AWF to the concrete mix caused a reduction in the compressive and tensile splitting strength values, and a less-workable concrete was achieved for every increase in the quantity of AWF added to each mix. The addition of AWF influenced the hydration reaction process and reduced the cumulative production of the heat of hydration over time, whilst the permeability of the concrete decreased.

MECHANICAL PROPERTIES OF RECYCLED COARSE AGGREGATE CONCRETE REINFORCED WITH STEEL FIBERS

2021 ◽  
Vol 8 (1) ◽  
Author(s):  
Nancy Kachouh ◽  
Hilal El-Hassan ◽  
Tamer El-Maaddawy
Keyword(s):  
Mechanical Properties ◽  
Elastic Modulus ◽  
Compression Strength ◽  
Recycled Concrete ◽  
Steel Fibers ◽  
Flexural Stress ◽  
Flexural Toughness ◽  
Splitting Strength ◽  
Concrete Mix ◽  
Tensile Splitting Strength

This paper presents the combined influence of natural aggregates (NA) replacement with recycled concrete aggregates (RCA) and incorporating steel fiber reinforcement on the mechanical properties of normal-strength (30 MPa) concrete mixes. Hooked-end steel fibers were added in a 2% volumetric fraction to promote 100% RCA replacement. Fine aggregates were in the form of locally-abundant desert dune sand. Mechanical properties of 28-day concrete samples were assessed, including compression strength, tensile splitting strength, elastic modulus, flexural stress, and flexural toughness. For plain concrete mixes, the replacement of NA by RCA resulted in 18, 27, and 5% reductions in the respective design compression strength, elastic modulus, and tensile splitting strength. Nevertheless, the addition of steel fibers could restore the aforementioned properties by up to 90, 77, and 164%. Compared to the control mix made with NA, the flexural strength of the plain RCA-based concrete mix decreased by 33%, while the flexural toughness increased by 100%. In turn, the corresponding flexural properties of RCA concrete mix reinforced with steel fibers were 2 and 56 times those of the control made with NA. Findings provide evidence of the ability to produce concrete made with 100% RCA and reinforced with steel fibers with comparable compression properties and improved tensile and flexural performance compared to those of NA-based concrete.

Heat of hydration of Portland Cement–Metakaolin–Fly ash (PC–MK–PFA) blends

2008 ◽  
Vol 38 (6) ◽  
pp. 832-840 ◽  
Author(s):  
David G. Snelson ◽  
Stan Wild ◽  
Martin O'Farrell
Keyword(s):  
Fly Ash ◽  
Portland Cement ◽  
Heat Of Hydration

Research Progress on the Hydration of Portland Cement with Calcined Clay and Limestone

2021 ◽  
Vol 1036 ◽  
pp. 240-246
Author(s):  
Jin Tang ◽  
Su Hua Ma ◽  
Wei Feng Li ◽  
Hui Yang ◽  
Xiao Dong Shen
Keyword(s):  
Mechanical Properties ◽  
Portland Cement ◽  
Cementitious Materials ◽  
Supplementary Cementitious Materials ◽  
Research Progress ◽  
Hydration Reaction ◽  
Hydration Products ◽  
Early Hydration ◽  
Calcined Clay ◽  
Dense Microstructure

The use of calcined clay and limestone as supplementary cementitious materials, can have a certain influence on the hydration of Portland cement. This paper reviewed the influence of limestone and calcined clay and the mixture of limestone and calcined clay on the hydration of cement. Both limestone and calcined clay accelerate the hydration reaction in the early hydration age and enhance the properties of cement. Limestone reacts with C3A to form carboaluminate, which indirectly stabilized the presence of ettringite, while calcined clay consumed portlandite to form C-(A)-S-H gel, additional hydration products promote the densification of pore structure and increase the mechanical properties. The synergistic effect of calcined clay and limestone stabilize the existence of ettringite and stimulate the further formation of carboaluminate, as well as the C-(A)-S-H gel, contributed to a dense microstructure.

Optimization of the Concrete Mix Proportions Centered on Performance after Exposure to High Temperature

2011 ◽  
Vol 268-270 ◽  
pp. 372-376 ◽  
Author(s):  
A. Chaboki-Khiabani ◽  
M. Bastami ◽  
M. Baghbadrani ◽  
M. Kordi
Keyword(s):  
Mechanical Properties ◽  
Elevated Temperature ◽  
Statistical Study ◽  
High Strength ◽  
Taguchi Approach ◽  
Effective Parameters ◽  
Mix Proportion ◽  
Concrete Mix ◽  
Tensile Splitting Strength ◽  
Considerable Loss

This paper presents the results of an experimental and statistical study on the effect of high temperatures on the retained mechanical properties of high-strength concretes (HSC). The mechanical properties of HSC significantly change during and later than exposure to elevated temperature. The compressive and splitting tensile strength of more than 400 HSC cylindrical specimens with sixteen mix proportion have investigated to study the effect of mix proportion on the retained mechanical properties of HSC specimens after heating. According to these results, a considerable loss was observed for all mixes and specimens in strength particularly in tensile splitting strength. In addition, these experimental data were investigated using Taguchi approach to find the effective parameters of mix proportion. Also, the most optimum mix proportion was found and checked experimentally. According to our results, by controlling some factors in the mix proportion, it is possible to reduce the retained destructive effects of elevated temperature on HSC specimens.

scholarly journals Hydration and Microwave Curing Temperature Interactions of Repair Mortars

2021 ◽  
Vol 03 (04) ◽  
pp. 1-1
Author(s):  
Pal S. Mangat ◽  
◽  
Shahriar Abubakri ◽  
Konstantinos Grigoriadis ◽  
Vincenzo Starinieri ◽  
...  
Keyword(s):  
Portland Cement ◽  
Heat Of Hydration ◽  
Curing Temperature ◽  
Early Age ◽  
Normal Density ◽  
Concrete Repair ◽  
Microwave Curing ◽  
Polymer Addition ◽  
Curing Period ◽  
Repair Materials

Microwave curing of repair patches provides an energy efficient technique for rapid concrete repair. It has serious economic potential due to time and energy saving especially for repairs in cold weather which can cause work stoppages. However, the high temperatures resulting from the combination of microwave exposure and accelerated hydration of cementitious repair materials need to be investigated to prevent potential durability problems in concrete patch repairs. This paper investigates the time and magnitude of the peak hydration temperature during microwave curing (MC) of six cement based concrete repair materials and a CEM II mortar. Repair material specimens were microwave cured to a surface temperature of 40-45 °C while their internal and surface temperatures were monitored. Their internal temperature was further monitored up to 24 hours in order to determine the effect of microwave curing on the heat of hydration. The results show that a short period of early age microwave curing increases the hydration temperature and brings forward the peak heat of hydration time relative to the control specimens which are continuously exposed to ambient conditions (20 °C, 60% RH). The peak heat of hydration of normal density, rapid hardening Portland cement based repair materials with either pfa or polymer addition almost merges with the end of microwave curing period. Similarly, lightweight polymer modified repair materials also develop heat of hydration rapidly which almost merges with the end of microwave curing period. The peak heat of hydration of normal density ordinary Portland cement based repair materials, with and without polymer addition, occurs during the post microwave curing period. The sum of the microwave curing and heat of hydration temperatures can easily exceed the limit of about 70 °C in some materials at very early age, which can cause durability problems.

scholarly journals Influence of Amount of Calcareous Fly Ash on Heat of Hydration of Portland Cement

2019 ◽  
Vol 603 ◽  
pp. 042081
Author(s):  
Patrycja Miera ◽  
Jacek Golaszewski ◽  
Zbigniew Giergiczny
Keyword(s):  
Fly Ash ◽  
Portland Cement ◽  
Heat Of Hydration

Zeolite Influence of Vibropressing Concrete Durability

2017 ◽  
Vol 908 ◽  
pp. 71-75 ◽  
Author(s):  
Giedrius Girskas
Keyword(s):  
Low Temperature ◽  
Aluminum Fluoride ◽  
Concrete Durability ◽  
Test Results ◽  
Low Temperature Synthesis ◽  
Temperature Synthesis ◽  
Absorption Increase ◽  
Splitting Strength ◽  
Tensile Splitting Strength ◽  
Durability Of Concrete

Durability is one of the main characteristics in the production of high-quality concrete paving blocks in the Baltic region climate zone. Concrete paving blocks are produced by means of vi bropressing , dimensions: 198×98×80 mm . The article describes tests with concrete paving blocks, the top layer of which contains 5% of zeolite admixture obtained from waste of aluminum fluoride production by low-temperature synthesis. The durability of concrete paving blocks was tested according to abrasion resistance, tensile splitting strength, absorption and frost resistance. The test results revealed that 5% of zeolite admixture added to the top layer of concrete paving blocks reduce the absorption, increase the tensile splitting strength and decrease abrasion. The zeolite admixture used in concrete paving blocks reduces the scaling about 4 times after 28 freeze-thaw cycles when 3% NaCl is used as the freezing solution. The test results proved that synthetic zeolite obtained from aluminum fluoride by means of low temperature synthesis can be used as a supplementary cementitious material to increase the durability of concrete pavement elements.

scholarly journals Time-Stability Dispersion of MWCNTs for the Improvement of Mechanical Properties of Portland Cement Specimens

Materials ◽  
2020 ◽  
Vol 13 (18) ◽  
pp. 4149
Author(s):  
Laura M. Echeverry-Cardona ◽  
Natalia Álzate ◽  
Elisabeth Restrepo-Parra ◽  
Rogelio Ospina ◽  
Jorge H. Quintero-Orozco
Keyword(s):  
Mechanical Properties ◽  
Carbon Nanotubes ◽  
Raman Spectroscopy ◽  
Portland Cement ◽  
Time Stability ◽  
Cement Pastes ◽  
Multi Wall Carbon Nanotubes ◽  
Vis Spectroscopy ◽  
The Stability ◽  
Over Time

This study shows the energy optimization and stabilization in the time of solutions composed of H2O + TX-100 + Multi-Wall Carbon Nanotubes (MWCNTs), used to improve the mechanical properties of Portland cement pastes. For developing this research, sonication energies at 90, 190, 290, 340, 390, 440, 490 and 590 J/g are applied to a colloidal substance (MWCNTs/TX-100 + H2O) with a molarity of 10 mM. Raman spectroscopy analyses showed that, for energies greater than 440 J/g, there are ruptures and fragmentation of the MWCNTs; meanwhile at energies below 390 J/g, better dispersions are obtained. The stability of the dispersion over time was evaluated over 13 weeks using UV-vis spectroscopy and Zeta Potential. With the most relevant data collected, sonication energies of 190, 390 and 490 J/g, at 10 mM were selected at the first and the fourth week of storage to obtain Portland cement specimens. Finally, we found an improvement of the mechanical properties of the samples built with Portland cement and solutions stored for one and four weeks; it can be concluded that the MWCNTs improved the hydration period.

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