scholarly journals Experimental Study on the Performance and Microstructure of Cementitious Materials Made with Dune Sand

2016 ◽  
Vol 2016 ◽  
pp. 1-8 ◽  
Author(s):  
Chaohua Jiang ◽  
Xiaobin Zhou ◽  
Guilan Tao ◽  
Da Chen
Keyword(s):  
Raw Materials ◽  
Cementitious Materials ◽  
Dune Sand ◽  
Ordinary Concrete ◽  
Granulated Blast Furnace Slag ◽  
The Matrix ◽  
Lower Porosity ◽  
Dry Shrinkage ◽  
Hydrate Products ◽  
Furnace Slag

This paper presents the results of an investigation on the utilization of dune sand from waterway regulation engineering as the main raw materials to produce cementitious materials. The mechanical and durability properties of the cementitious materials were studied. Furthermore, a scanning electron microscope (SEM) and mercury intrusion porosimeter (MIP) were used to identify the microstructure of the specimens. The results show that the compressive and splitting tensile strength of cementitious materials can be improved due to the addition of ground granulated blast-furnace slag (GGBS) which mainly attributes to a better grain size distribution and pozzolanic effect compared to the specimen added cement alone. The specimen with the addition of suitable cement, GGBS, and gypsum shows low dry shrinkage and excellent abrasion resistance. Correspondingly the specimens present a lower porosity and total volume of pores at different curing ages. The SEM observation indicates that there are quite a lot of hydrate products such as calcium silicate hydrate gel in the matrix which verifies the formation of cementitious compounds. The results obtained suggest that there is potential in manufacturing cementitious material with dune sand in substitution of ordinary concrete to use in hydraulic engineering.

Performance of Blended Cement Concrete against Seawater Attack

2010 ◽  
Vol 64 ◽  
pp. 19-24
Author(s):  
H.H. Seleem ◽  
A.M. Rashad ◽  
B.A. El-Sabbagh
Keyword(s):  
Blended Cement ◽  
Strength Loss ◽  
Synthetic Seawater ◽  
Strength Deterioration ◽  
Ordinary Concrete ◽  
Granulated Blast Furnace Slag ◽  
Concrete Mixtures ◽  
Concrete Permeability ◽  
Pozzolanic Materials ◽  
Furnace Slag

The current work reports the influence of synthetic seawater on some of the durability aspects of an ordinary concrete mixture (control) and six pozzolan-concrete mixtures. Three types of pozzolanic materials were employed; silica fume (SF), ground granulated blast furnace slag (GGBS) and metakaolin (MK). The pozzolanic materials were employed as an addition to cement in binary and ternary combinations. All mixtures were tested for strength deterioration ratio (SDR) after 3, 6, and 12 months of exposure to synthetic seawater, permeability was measured after 6 and 12 months of exposure. It was found through this investigation that pozzolans increase the ability of concrete to withstand aggressive environment and prevent most of the deterioration signs. The pozzolanic materials serve also to increase the strength and to minimize the strength loss (SDR) upon exposure to seawater. The pozzolanic materials led to reduce concrete permeability compared to control.

scholarly journals Synergistic Excitation Mechanism of CaO-SiO2-Al2O3-SO3 Quaternary Active Cementitious System

2021 ◽  
Vol 8 ◽  
Author(s):  
Fusheng Niu ◽  
Yukun An ◽  
Jinxia Zhang ◽  
Wen Chen ◽  
Shengtao He
Keyword(s):  
Blast Furnace ◽  
Blast Furnace Slag ◽  
Steel Slag ◽  
Cementitious Materials ◽  
Test Block ◽  
Hydration Reaction ◽  
Alkaline Environment ◽  
Granulated Blast Furnace Slag ◽  
Cementitious System ◽  
Furnace Slag

In this study, the influence of steel slag (SS) content on the strength of the cementitious materials was investigated. The quaternary active cementitious material (CaO-SiO2-Al2O3-SO3) was prepared using various proportions of steel slag (SS), granulated blast furnace slag (BFS), and desulfurized gypsum (DG). The mechanism of synergistic excitation hydration of the cementitious materials was examined using various techniques such as X-ray diffraction (XRD), scanning electron microscopy (SEM) and Fourier transform infrared spectrometry (FTIR). The strength of the mortar test block was initially increased and decreased later with the increase of the SS content. Mortar test block with 20% steel slag, 65% granulated blast furnace slag, and 15% desulfurized gypsum with 0.35 water-binder ratio showed the highest compressive strength of 57.3 MPa on 28 days. The free calcium oxide (f-CaO) in the SS reacted with water and produced calcium hydroxide (Ca(OH)2) which created an alkaline environment. Under the alkaline environment, the alkali-activated reaction occurred with BFS. In the early stage of hydration reaction, calcium silicate hydrate (C-S-H) gel and fibrous hydration product ettringite (AFt) crystals were formed, which provided early strength to the cementitious materials. As the hydration reaction progressed, the interlocked growth of C-S-H gel and AFt crystals continued and promoted the increase of the strength of the cementitious system.

Thermal Transmission Properties of Sustainable Concrete with Supplementary Cementitious Materials

2020 ◽  
Vol 853 ◽  
pp. 142-149
Author(s):  
Ahmad Khartabil ◽  
Samer Al Martini
Keyword(s):  
Thermal Properties ◽  
Cementitious Materials ◽  
Supplementary Cementitious Materials ◽  
Transfer Resistance ◽  
K Value ◽  
Sustainable Concrete ◽  
Granulated Blast Furnace Slag ◽  
U Value ◽  
R Value ◽  
Furnace Slag

Understanding the thermal properties of a construction material is necessarily to evaluate its heat transfer resistance that has a major contribution to the energy-efficiency required to achieve sustainable structure. Thermal properties are evaluated through three main parameters namely: thermal conductivity, thermal resistivity and thermal transmittance. The aforementioned parameters are commonly referred as K-value, R-value, and U-value respectively. Recent regulations by Dubai municipality enforced to use sustainable concrete in construction. This is by replacing cement with supplementary cementitious materials (SCMs), such as grand granulated blast furnace slag (GGBS) and fly ash. The use of grand granulated blast furnace slag (GGBS) at relatively high percentage replacement became a typical practice in ready-mixed concrete industry in Dubai. As such, it is essential to characterize the thermal properties of this sustainable concrete. The current paper investigates the thermal properties of sustainable concrete mixtures incorporating supplementary cementitious materials, air entrainment additives, polypropylene and hybrid synthetic fiber. K-value, R-value and U-value are evaluated in accordance with ASTM C518. Additionally, hardened density of all investigated mixtures are measured. The results show that the foamed concrete has better heat transfer resistance than that for the non-air entrained mixture.

Effect of Aggregate Max Size on the Rheological Properties of Self Consolidating Concrete

2020 ◽  
Vol 853 ◽  
pp. 193-197
Author(s):  
Samer Al Martini ◽  
Ziad Hassan ◽  
Ahmad Khartabil
Keyword(s):  
Blast Furnace Slag ◽  
Aggregate Size ◽  
Maximum Size ◽  
Cementitious Materials ◽  
Supplementary Cementitious Materials ◽  
Self Consolidating Concrete ◽  
Granulated Blast Furnace Slag ◽  
Concrete Mixtures ◽  
Time Period ◽  
Furnace Slag

The effects of aggregate size and supplementary cementitious materials (SCMs) on the rheology of self-consolidating concrete (SCC) were studied in this paper. Two main concrete mixtures with different maximum aggregate sizes were prepared and investigated. The first mix had a maximum size aggregate of 5 mm and the second mix was with 20 mm max size aggregates. All mixes incorporated different dosages of Ground granulated blast furnace slag (GGBS). The rheology of all mixes investigated was measured over 2 hour time period. It was found that the size of aggregates and GGBS dosage have influence on the yield stress of studied concrete mixes.

Influence of Artificial Aggregates on the ITZ's Microstructure of Recycling Concrete

2013 ◽  
Vol 743-744 ◽  
pp. 180-185
Author(s):  
Jun Hua Zhang ◽  
Zong Hui Zhou ◽  
De Cheng Zhang ◽  
Xin Cheng
Keyword(s):  
Fly Ash ◽  
Mineral Composition ◽  
High Performance ◽  
Raw Materials ◽  
Steel Slag ◽  
Interfacial Transition Zone ◽  
Hydration Products ◽  
Ordinary Concrete ◽  
Natural Aggregates ◽  
Furnace Slag

Artificial aggregates with high-performance were prepared by the methods including steel slag, furnace slag, fly ash and coal gangue, and the recycling concrete was prepared by artificial aggregates instead of natural aggregates. This kind of concrete abandoned was able to completely regenerate cement, which will make the reuse of concrete possible. The composition and characteristics of the artificial aggregates will produce a significant effect on the interfacial transition zone (ITZ) in recycling concrete. The morphological features and mineral composition of three artificial aggregates were analyzed by SEM and XRD, and the ITZ of three recycling concrete and one ordinary concrete was investigated by SEM and EDS. The results showed that compared with ordinary concrete, although the recycling concretes ITZ had a small amount of CH crystal, most of the space was filled with dense hydration products. The interface width was 40μm, which less than 50μm of ordinary concrete. Artificial aggregates with different ratio of raw materials had a great effect on recycling concretes ITZ. The ITZ of recycling concrete prepared with 30% steel slag, 50% furnace slag, 20% fly ash had the smallest Ca/Si and much more C-S-H. the structure of ITZ was much denser and the microstructure was relatively better.

scholarly journals Investigation of Erosion of Cement-Bentonite via Piping

2017 ◽  
Vol 2017 ◽  
pp. 1-8 ◽  
Author(s):  
Zijun Wang ◽  
Boming Zhao ◽  
A. C. D. Royal
Keyword(s):  
Blast Furnace Slag ◽  
Cementitious Materials ◽  
Water Erosion ◽  
Granulated Blast Furnace Slag ◽  
Curing Period ◽  
Erosion Test ◽  
Materials Used ◽  
Mathematical Relationships ◽  
Seepage Barriers ◽  
Furnace Slag

Cement-bentonite is one of the main materials used in the seepage barriers to protect earth dams and levees from water erosion. However, the current understanding of the erodibility of the cementitious materials and the interactions between cracked seepage barriers and the water flow is inadequate. Based on the laboratory pinhole erosion test, we first investigated the impacts of cement-bentonite treatments by using the ground granulated blast-furnace slag (GGBS) as replacement on the erosion characteristics, compared with the original mixtures; the inclusion of GGBS highlighted a potential advantage against water erosion. In addition, we proposed to calculate the erosion percentage and establish the mathematical relationships between the erosion percentage and different regimes, that is, different curing period, erosion time, and sizes of initial holes. Results showed that enough curing period was critical to avoid the increases of hydraulic conductivity in the macrofabric of the barrier; meanwhile, the materials were eroded quickly at the beginning and slowed down with the erosion time, where the enlargement of the initial creaks would be stabilised at some point in time. Moreover, the sizes of initial holes may affect the erosion situation varying from the sample curing periods.

scholarly journals Characterization of Supplementary Cementitious Materials and Fibers to Be Implemented in High Temperature Concretes for Thermal Energy Storage (TES) Application

Energies ◽  
2021 ◽  
Vol 14 (16) ◽  
pp. 5190
Author(s):  
Laura Boquera ◽  
David Pons ◽  
Ana Inés Fernández ◽  
Luisa F. Cabeza
Keyword(s):  
Tensile Strength ◽  
Blast Furnace ◽  
High Temperature ◽  
Blast Furnace Slag ◽  
Steel Slag ◽  
Cementitious Materials ◽  
Iron Silicate ◽  
Supplementary Cementitious Materials ◽  
Granulated Blast Furnace Slag ◽  
Furnace Slag

Six supplementary cementitious materials (SCMs) were identified to be incorporated in concrete exposed to high-temperature cycling conditions within the thermal energy storage literature. The selected SCMs are bauxite, chamotte, ground granulated blast furnace slag, iron silicate, silica fume, and steel slag. A microstructural characterization was carried out through an optical microscope, X-ray diffraction analysis, and FT-IR. Also, a pozzolanic test was performed to study the reaction of SCMs silico-aluminous components. The formation of calcium silica hydrate was observed in all SCMs pozzolanic test. Steel slag, iron silicate, and ground granulated blast furnace slag required further milling to enhance cement reaction. Moreover, the tensile strength of three fibers (polypropylene, steel, and glass fibers) was tested after exposure to an alkalinity environment at ambient temperature during one and three months. Results show an alkaline environment entails a tensile strength decrease in polypropylene and steel fibers, leading to corrosion in the later ones.

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