Effects of Adding Neutralized Red Mud on the Hydration Properties of Cement Paste

Red mud is a highly alkaline waste by-product of the aluminum industry. Although recycling of red mud is being actively researched, a feasible technological solution has not been found yet. In this study, we propose that neutralization of red mud alkalinity could assist in its use as a construction material. Neutralized red mud (LRM + S; pH 6–8) was prepared by adding sulfuric acid to liquefied red mud (LRM; pH 10–12). After adding LRM and LRM + S to cement paste, the heat of hydration, compressive strength, and hydration products were examined. The experiments revealed that the calorific value of the cement paste with LRM was low, and its peak was delayed, when compared with that of plain cement paste (referred to as Plain), whereas the calorific value of the cement paste with LRM + S was similar to that of Plain. At the age of 28 d, the compressive strength of the cement paste with 10% LRM + S was 99% whereas that with 20% LRM was only 55% of the strength of Plain. Thus, our results help to resolve the issue of strength degradation of cementitious materials observed upon the addition of red mud and enable its reuse as a construction material.

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Hydration Properties of Cement with Liquefied Red Mud Neutralized by Nitric Acid

Materials ◽

10.3390/ma14102641 ◽

2021 ◽

Vol 14 (10) ◽

pp. 2641

Author(s):

Sukpyo Kang ◽

Hyeju Kang ◽

Byoungky Lee

Keyword(s):

Compressive Strength ◽

Nitric Acid ◽

Cement Paste ◽

Red Mud ◽

Positive Impact ◽

Low Cost ◽

Construction Material ◽

Construction Materials ◽

Aluminum Production ◽

Hydration Properties

An increasing amount of red mud (RM) is being generated globally due to the growth in aluminum production. To avoid RM pollution, low-cost methods for effectively recycling RM are being investigated. We propose a method for recycling RM as a construction material. Liquefied RM (LRM) was neutralized by nitric acid and added to cement paste, and the hydration heat, compressive strength, and hydration products were investigated. The cement paste with neutralized LRM had a higher compressive strength than that of plain cement paste and cement paste with LRM without neutralization at 1 day of aging; this indicates that nitric acid neutralization increases the early-age strength. Furthermore, the cement paste with 10% neutralized LRM showed 28 days-compressive strength and hydration heating curves similar to the plain mixture, indicating the positive impact of LRM neutralization on the strength. It was noted that a greater quantity of portlandite was produced earlier in cement paste with neutralized LRM than in that without. Therefore, the proposed method of using RM as a concrete additive has the potential to reduce the cost and environmental impact of both construction materials and RM waste management.

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Hydration–Strength–Workability–Durability of Binary, Ternary, and Quaternary Composite Pastes

Materials ◽

10.3390/ma15010204 ◽

2021 ◽

Vol 15 (1) ◽

pp. 204

Author(s):

Yi Han ◽

Seokhoon Oh ◽

Xiao-Yong Wang ◽

Run-Sheng Lin

Keyword(s):

Compressive Strength ◽

Cement Paste ◽

Carbon Emissions ◽

Cementitious Materials ◽

Heat Of Hydration ◽

Surface Resistivity ◽

Cement Industry ◽

Supplementary Cementitious Materials ◽

Limestone Powder ◽

Alternative Materials

At present, reducing carbon emissions is an urgent problem that needs to be solved in the cement industry. This study used three mineral admixtures materials: limestone powder (0–10%), metakaolin (0–15%), and fly ash (0–30%). Binary, ternary, and quaternary pastes were prepared, and the specimens’ workability, compressive strength, ultrasonic pulse speed, surface resistivity, and the heat of hydration were studied; X-ray diffraction and attenuated total reflection Fourier transform infrared tests were conducted. In addition, the influence of supplementary cementitious materials on the compressive strength and durability of the blended paste and the sustainable development of the quaternary-blended paste was analyzed. The experimental results are summarized as follows: (1) metakaolin can reduce the workability of cement paste; (2) the addition of alternative materials can promote cement hydration and help improve long-term compressive strength; (3) surface resistivity tests show that adding alternative materials can increase the value of surface resistivity; (4) the quaternary-blended paste can greatly reduce the accumulated heat of hydration; (5) increasing the amount of supplementary cementitious materials can effectively reduce carbon emissions compared with pure cement paste. In summary, the quaternary-blended paste has great advantages in terms of durability and sustainability and has good development prospects.

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Fracture Properties Evaluation of Cellulose Nanocrystals Cement Paste

Materials ◽

10.3390/ma13112507 ◽

2020 ◽

Vol 13 (11) ◽

pp. 2507 ◽

Cited By ~ 2

Author(s):

SeyedAli Ghahari ◽

Lateef N. Assi ◽

Ali Alsalman ◽

Kürşat E. Alyamaç

Keyword(s):

Compressive Strength ◽

Cement Paste ◽

Cellulose Nanocrystals ◽

Fracture Behavior ◽

Building Materials ◽

Weight Ratio ◽

Cementitious Materials ◽

Cellulose Nanocrystal ◽

Hydration Properties ◽

Fracture Properties

Due to the need for high-performance and sustainable building materials, the investigation of the determination of fracture toughness of cement paste using new and sustainable materials, such as cellulose nanocrystals (CNCs) is worthwhile. Contrary to other well-known nano-reinforcement particles, such as carbon nanotubes, CNCs are less toxic; therefore, they have less safety and environmental risks. Fracture behavior of cement paste has been studied intensively for a long time. However, the incorporation of new materials in the cement paste, such as cellulose nanocrystal materials (CNCs), has not been fully investigated. In this paper, the fracture behavior, compressive strength, and hydration properties of cement paste reinforced with cellulose nanocrystal particles were studied. At the age of 3, 7, and 28 days, a three-point bending moment test, and a calorimetry and thermogravimetric analysis, scanning electron microscopy (SEM), and energy dispersive x-ray spectroscopy (EDX) analysis were performed on the water-to-binder-weight ratio of 0.35 cement paste, containing 0.0%, 0.2%, and 1.0% volume cellulose nanocrystals. Results indicated that the fracture properties and compressive strength were improved for the sample containing 0.2% CNCs. Preliminary results indicate that CNCs can improve the fracture behavior of cementitious materials and can be considered as a renewable and sustainable material in construction.

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Effect of ultrafine natural steatite powder, super plasticizer and VMA on the fresh and hardened properties of self-compacting cement paste and mortar

International Review of Applied Sciences and Engineering ◽

10.1556/1848.2021.00279 ◽

2021 ◽

Author(s):

S. Christopher Gnanaraj ◽

Ramesh Babu Chokkalingam ◽

G. Lizia Thankam ◽

S.K.M. Pothinathan

Keyword(s):

Compressive Strength ◽

Cement Paste ◽

Water Demand ◽

Construction Material ◽

Setting Time ◽

Mineral Admixture ◽

Self Healing ◽

Chemical Admixtures ◽

Hardened Properties ◽

Viscosity Modifying Admixture

AbstractFor the past few decades innovation in construction material has grown a lot. This leads to special concrete such as self-compacting concrete, geopolymer concrete, self-healing concrete, etc. To prepare a special concrete apart from regular concreting material some sort of special materials was also needed, like mineral and chemical admixtures. Hence it is necessary to study the effect of these admixtures in cement paste and mortar before studying the same in concrete. Hence an attempt is made to study the effect of mineral and chemical admixtures in the fresh and hardened properties of cement paste and mortar. For this study ultrafine natural steatite powder is taken as mineral admixture and polycarboxylic based superplasticizer and glenium stream 2 were taken as chemical admixtures. Ultrafine natural steatite powder was used as additive to cement in various percentages like 0%, 5%, 10%, 15%, 20% and 25%. Superplasticizer and viscosity modifying admixture were taken as 1.5% and 0.5%, respectively. Then various combinations were worked out. To study the fresh property of cement paste consistency, initial setting time and miniature slump cone test were done based on the results yield stress of cement paste also calculated empirically. To study the hardened property compression test on cement mortar was done. Based on the test results it is clear that the addition of ultrafine natural steatite powder increases the water demand hence reduces the workability. On the other hand, it increases the compressive strength up to a certain limit. Adding superplasticizer increases the workability and reduces the water demand and viscosity modifying admixture reduces the bleeding and segregation effects hence increases the compressive strength.

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Use of Algerian Natural Mineral Deposit as Supplementary Cementitious Materials

International Journal of Engineering Research in Africa ◽

10.4028/www.scientific.net/jera.34.48 ◽

2018 ◽

Vol 34 ◽

pp. 48-58 ◽

Cited By ~ 1

Author(s):

Karima Arroudj ◽

Saida Dorbani ◽

Mohamed Nadjib Oudjit ◽

Arezki Tagnit-Hamou

Keyword(s):

Mechanical Strength ◽

Calcium Hydroxide ◽

Cement Paste ◽

Cementitious Materials ◽

Pozzolanic Reaction ◽

Heat Of Hydration ◽

Cement Industry ◽

Supplementary Cementitious Materials ◽

Natural Mineral ◽

Different Ages

Much of the current research on concrete engineering has been focused on including siliceous additions as supplementary cementitious materials (SCMs). Silica reacts with Calcium hydroxide release during cement hydration, and produces more C-S-H. The latter contributes to increase compactness, mechanical strengths and sustainability of concrete. This paper explores the hydration characteristics of cement paste based on various natural mineral additions, that are very abundant in Algeria and present a high silica content (ground natural pozzolana “PZ” and ground dune sand “DS”). For this purpose, several analyses were carried out on modified cement pastes and mortars. TheseSCMswere introduced by replacement levels of 15, 20 and 25 by weight of cement. We first, studied the effect of these SCMs on the heat of hydration and mechanical strength of mortars at different ages. The evolution of hydration of modified paste was studied, by using Thermal analysis (TG/TDA) at different ages, to analyze the Calcium Hydroxide (CH) content of the modified pastes. It is shown that the CH content of the mixes including SCMs is lower than that of the plain cement paste, indicating that silica reacts with the cement paste through a pozzolanic reaction. Increased pozzolanic activity results in higher amounts of Calcium Silicate Hydrate in the paste, which in turn results in higher compressive strength for modified cement mortars. Due to its crystalline morphology, the ground DS particles present a partial pozzolanic effect, compared to PZ which is semi-crystalline. Modified mortars by 20% DS can be the optimal composition. It presents satisfactory results: good mechanical strength and low heat of hydration. It can lead to an economic and sustainable concrete. Ground DS is very abounded in Africa and free of any impurities and can be a good alternativeSCMsin cement industry.

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Strength Development and Thermogravimetric Investigation of High-Volume Fly Ash Binders

Materials ◽

10.3390/ma12203344 ◽

2019 ◽

Vol 12 (20) ◽

pp. 3344 ◽

Cited By ~ 1

Author(s):

Zhiyuan Zhou ◽

Massoud Sofi ◽

Elisa Lumantarna ◽

Rackel San Nicolas ◽

Gideon Hadi Kusuma ◽

...

Keyword(s):

Compressive Strength ◽

Fly Ash ◽

Temperature Rise ◽

Bound Water ◽

High Volume ◽

Heat Of Hydration ◽

New Method ◽

Hydration Properties ◽

Adiabatic Temperature Rise ◽

High Volume Fly Ash

To address sustainability issues by facilitating the use of high-volume fly ash (HVFA) concrete in industry, this paper investigates the early age hydration properties of HVFA binders in concrete and the correlation between hydration properties and compressive strengths of the cement pastes. A new method of calculating the chemically bound water of HVFA binders was used and validated. Fly ash (FA) types used in this study were sourced from Indonesia and Australia for comparison. The water to binder (w/b) ratio was 0.4 and FA replacement levels were 40%, 50% and 60% by weight. Isothermal calorimetry tests were conducted to study the heat of hydration which was further converted to the adiabatic temperature rise. Thermo-gravimetric analysis (TGA) was employed to explore the chemically bound water (WB) of the binders. The results showed that Australian FA pastes had higher heat of hydration, adiabatic temperature rise, WB and compressive strength compared to Indonesian FA pastes. The new method of calculating chemically bound water can be successfully applied to HVFA binders. Linear correlation could be found between the WB and compressive strength.

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Synthesis and Characterization of Red Mud and Sawdust Based Geopolymer Composites as Potential Construction Material

Materials Science Forum ◽

10.4028/www.scientific.net/msf.923.130 ◽

2018 ◽

Vol 923 ◽

pp. 130-134 ◽

Cited By ~ 1

Author(s):

Ing Kong ◽

Kay Min Khoo ◽

Oliver Buddrick ◽

Abdul Aziz Baharuddin ◽

Pooria Khalili

Keyword(s):

Compressive Strength ◽

Red Mud ◽

Raw Materials ◽

Construction Material ◽

Testing Machine ◽

Industrial Wastes ◽

Sem Images ◽

Universal Testing ◽

Geopolymer Composites

The aim of this study was to synthesize the geopolymer composites formed by two industrial wastes, namely red mud (RM) and saw dust (SD). SD was chemically treated with alkali for the removal of lignin and subsequently bleached, before forming composite with acid-modified RM. The composites were then characterized by using scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), thermogravimetic analysis (TGA) and universal testing machine to study the morphology, chemical, thermal and mechanical properties. The FTIR spectrum showed that Si and Al from the raw materials played the major role in forming aluminosilicate geopolymer composites. The SEM images revealed that SD and RM particles aggregated to form fully condensed geopolymer matrices with high compressive strength of 8.3-138 MPa, which were comparable to Portland cement (compressive strength of 9-20.7 MPa).

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The Assessment of Strength of Cementitious Materials Impregnated Using Hydrophobic Agents Based on Near-Surface Hardness Measurements

Materials ◽

10.3390/ma14164583 ◽

2021 ◽

Vol 14 (16) ◽

pp. 4583

Author(s):

Martyna Nieświec ◽

Łukasz Sadowski

Keyword(s):

Compressive Strength ◽

Cement Paste ◽

Concrete Structures ◽

Surface Hardness ◽

Cementitious Materials ◽

Schmidt Hammer ◽

Near Surface ◽

Cement Ratio ◽

Water Cement Ratio ◽

The Impact

Recently, the surfaces of concrete structures are impregnated to protect them against the environment in order to increase their durability. It is still not known how the use of these agents affects the near-surface hardness of concrete. This is especially important for experts who use the near-surface hardness of concrete for estimating its compressive strength. The impregnation agents are colorless and, thus, without knowledge of their use, mistakes can be made when testing the surface hardness of concrete. This paper presents the results of investigations concerning the impact of impregnation on the subsurface hardness concrete measured using a Schmidt hammer. For this research, samples of cement paste with a water–cement ratio of 0.4 and 0.5 were used. The samples were impregnated with one, two, and three layers of two different agents. The first agent has been made based on silanes and siloxanes and the second agent has been made based on based on polymers. The obtained research results allow for the conclusion that impregnation affects the near-surface hardness of concrete. This research highlights the fact that a lack of knowledge about the applied impregnation of concrete when testing its near-surface hardness, which is then translated into its compressive strength, can lead to serious mistakes.

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Mechanical Properties of Concrete Containing Liquefied Red Mud Subjected to Uniaxial Compression Loads

Materials ◽

10.3390/ma13040854 ◽

2020 ◽

Vol 13 (4) ◽

pp. 854 ◽

Cited By ~ 1

Author(s):

Gyeongcheol Choe ◽

Sukpyo Kang ◽

Hyeju Kang

Keyword(s):

Mechanical Properties ◽

Compressive Strength ◽

Red Mud ◽

Construction Material ◽

Strain Curve ◽

Peak Strain ◽

Cement Type ◽

Mixing Method ◽

Relationship Of ◽

The Relationship

This study used liquefied red mud (RM) sludge, an aluminum industry by-product, as a construction material. Accordingly, various methods were examined that used the fabricated liquefied red mud (LRM) as an admixture for concrete, and the mechanical properties of concrete were then evaluated according to the cement type and the amount of LRM. The LRM mixing methods (replacement and addition) were compared, and the slump and compressive strengths of concrete were evaluated for each method. To examine the mechanical properties according to the cement type and the amount of LRM, two types of cement (ordinary Portland cement and slag cement (SC)) were used, and 20 and 40 wt% LRM (with respect to the cement weight) were added. The mechanical properties of the stress–strain curve (SSC), compressive strength, peak strain, and elastic modulus were quantified. When the slump and compressive strength of concrete were considered based on the experimental results, the addition LRM mixing method was recommended as the appropriate method for LRM. As the addition of LRM increased, the mechanical properties of concrete degraded. However, when SC was used, the mechanical properties did not significantly change when different amounts of LRM were added (up to 20%). In addition, the SSC of LRM concrete could be approximated based on the use of the relationship of the compressive strength and peak strain according to the cement type and the amount of LRM.

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Effect of Composition of Cementitious Materials on Alkalinity of Pore Solution and Strength of Cement Paste

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.671-674.1732 ◽

2013 ◽

Vol 671-674 ◽

pp. 1732-1735

Author(s):

Xiao Lu Yuan ◽

Shi Hua Zhou ◽

Dong Mei Liu

Keyword(s):

Compressive Strength ◽

Cement Paste ◽

Pore Solution ◽

Ph Value ◽

Cement Content ◽

Cementitious Materials ◽

Mineral Admixtures ◽

Aluminate Cement

Alkalinity of the surroundings is the basis to study the MICP technology. Alkalinity of pore solution and strength of cement paste made of various cementitious materials were studied. Results show that the alkalinity of pore solution of cement paste decreased with the increase of sulpho-aluminate cement content. pH value of cement paste was about less than 10 when sulpho-aluminate cement content exceeded 75%. Incorporation of sulpho-aluminate cement decreased compressive strength of paste obviously; however, compressive strength of paste was improved when the addition of sulpho-aluminate cement was more than 75%. Addition of mineral admixtures reduced the alkalinity of pore solution of cement paste and increased its compressive strength. Compressive strength of specimens was decreased when the content of mineral admixtures increased.

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