scholarly journals The Influence of Zeolitic By-Product Containing Ammonium Ions on Properties of Hardened Cement Paste

Minerals ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 123
Author(s):  
Danutė Vaičiukynienė ◽  
Agnė Mikelionienė ◽  
Aras Kantautas ◽  
Algirdas Radzevičius ◽  
Diana Bajare
Keyword(s):  
Portland Cement ◽  
Ordinary Portland Cement ◽  
Petroleum Industry ◽  
Pozzolanic Reaction ◽  
Strength Development ◽  
Hardened Cement ◽  
Reaction Products ◽  
Ammonium Ions ◽  
Cement Pastes ◽  
By Products

Fluid catalytic cracking (FCC) catalysts, used in the petroleum industry, are sources of zeolitic by-products. These by-products are often used as sorbents for the removal of ammonium ions from wastewater. After a period of use, the zeolitic by-product loses its sorption properties and is no longer effective. The problem is the use of zeolitic by-product with ammonium ions. In this study, a zeolitic by-product containing ammonium ions and high contents of active SiO2 and Al2O3 was used as a supplementary cementitious material (SCM). Cement pastes containing 0.5%, 1%, 3%, 5%, and 10% of the by-product were prepared, and the compressive strength and density of the pastes were evaluated. Incorporation of the zeolitic by-product increased the cement strength by 17% and 32% after 7 and 28 days of hydration, respectively. Thus, incorporation of the zeolitic by-product with ammonium ions as an SCM has a complex effect on an ordinary Portland cement (OPC) system. Ammonium chloride accelerated cement setting after 7 days of hydration, and the pozzolanic reaction positively affected strength development after 28 days of hydration. The reaction products caused the cement to have a compact microstructure. The zeolitic by-product containing absorbed ammonium ions can be successfully reused to replace ordinary Portland cement in cement pastes.

scholarly journals Effect of Some Acrylate—Poly(Ethylene Glycol) Copolymers as Superplasticizers on the Mechanical and Surface Properties of Portland Cement Pastes

2005 ◽  
Vol 23 (3) ◽  
pp. 245-254 ◽  
Author(s):  
S.A. Abo-El-Enein ◽  
S. Hanafi ◽  
F.I. El-Hosiny ◽  
El-Said H.M. El-Mosallamy ◽  
M.S. Amin
Keyword(s):  
Ethylene Glycol ◽  
Portland Cement ◽  
Ordinary Portland Cement ◽  
Mechanical Characteristics ◽  
Hardened Cement ◽  
Poly Ethylene Glycol ◽  
Cement Pastes ◽  
Surface Areas ◽  
Poly Ethylene ◽  
Hardened Cement Pastes

Ordinary Portland cement (OPC) pastes with added superplasticizer were made using water/cement weight ratios of standard consistency. Three types of superplasticizer based on acrylate—poly(ethylene glycol) copolymers were used. The pastes were hydrated for various time lengths and the mechanical characteristics of the hardened cement pastes were studied and related to their pore structures. It was found that the addition of the superplasticizers to OPC improved the mechanical properties of the hardened pastes for all hydration lengths. The addition of such superplasticizers to OPC resulted in a decrease in the specific surface areas and total pore volumes of the hardened superplasticized cement pastes relative to the corresponding hardened neat cement pastes.

scholarly journals Strength development of cement-treated sand using different cement types cured at different temperatures

2018 ◽  
Vol 195 ◽  
pp. 01006
Author(s):  
Lanh Si Ho ◽  
Kenichiro Nakarai ◽  
Kenta Eguchi ◽  
Takashi Sasaki ◽  
Minoru Morioka
Keyword(s):  
Compressive Strength ◽  
Portland Cement ◽  
Ordinary Portland Cement ◽  
Cement Content ◽  
Bound Water ◽  
Pozzolanic Reaction ◽  
Strength Development ◽  
Different Temperatures ◽  
Early Strength

This study aimed to investigate the strength development of cement-treated sand using different cement types: ordinary Portland cement (OPC), high early strength Portland cement (HPC), and moderate heat Portland cement (MPC) cured at different temperatures. The cementtreated sand specimens were prepared with 8% of cement content and cured under sealed conditions at 20οC and 40οC, and mortar specimens were also prepared for reference. The results showed that the compressive strength of cement-treated sand increased in order of MPC, OPC, and HPC under high curing temperatures. It was interesting that the compressive strength of the specimens using HPC was much larger than that of the specimen using OPC and MPC under 20οC due to the larger amount of chemically bound water. Additionally, it was revealed that under high curing temperatures, the pozzolanic reaction was accelerated in the cement-treated sand; this may be caused by the high proportions of sand in the mixtures.

scholarly journals The effects of seawater on the hydration, microstructure and strength development of Portland cement pastes incorporating colloidal silica

2019 ◽  
Vol 10 (8) ◽  
pp. 2627-2638 ◽  
Author(s):  
Pawel Sikora ◽  
Krzysztof Cendrowski ◽  
Mohamed Abd Elrahman ◽  
Sang-Yeop Chung ◽  
Ewa Mijowska ◽  
...  
Keyword(s):  
Compressive Strength ◽  
Synergistic Effect ◽  
Portland Cement ◽  
Colloidal Silica ◽  
Cement Hydration ◽  
Pozzolanic Reaction ◽  
Strength Development ◽  
Hydration Kinetics ◽  
Cement Pastes ◽  
Noticeable Improvement

AbstractThis contribution investigates the effects of seawater and colloidal silica (NS) in the amounts of 1, 3 and 5 wt%, respectively, on the hydration, strength development and microstructural properties of Portland cement pastes. The data reveal that seawater has an accelerating effect on cement hydration and thus a significant contribution to early strength development was observed. The beneficial effect of seawater was reflected in an improvement in compressive strength for up to 14 days of hydration, while in the 28 days compressive strength values were comparable to that of cement pastes produced with demineralized water. The combination of seawater and NS significantly promotes cement hydration kinetics due to a synergistic effect, resulting in higher calcium hydroxide (CH) production. NS can thus react with the available CH through the pozzolanic reaction and produce more calcium silicate hydrate (C-S-H) gel. A noticeable improvement of strength development, as the result of the synergistic effect of NS and seawater, was therefore observed. In addition, mercury intrusion porosimetry (MIP) tests confirmed significant improvements in microstructure when NS and seawater were combined, resulting in the production of a more compact and dense hardened paste structure. The optimal amount of NS to be mixed with seawater, was found to be 3 wt% of cement.

Diffusion Behavior of Organic Carbon and Iodine in Low-heat Portland Cement Containing Fly Ash

2008 ◽  
Vol 1124 ◽  
Author(s):  
Taiji Chida ◽  
Daisuke Sugiyama
Keyword(s):  
Fly Ash ◽  
Organic Carbon ◽  
Portland Cement ◽  
Effective Diffusion ◽  
Cementitious Materials ◽  
Pozzolanic Reaction ◽  
Radioactive Waste Disposal ◽  
Hardened Cement ◽  
Cement Pastes ◽  
Engineered Barrier

AbstractThe diffusion of radionuclides in cementitious materials used as an engineered barrier is an important parameter in the performance assessment of the sub-surface repository system used for low-level radioactive waste disposal in Japan. In particular, organic carbon-14 and iodine-129 would provide large contributions to the dose evaluation, because of their low ability to be adsorbed on cementitious materials. In this study, the diffusion of acetate and iodide in hardened cement pastes was examined by through-diffusion experiments. Low-heat Portland cement containing 30 wt% fly ash (FAC), which is a candidate cement material for the construction of the sub-surface repository, was prepared for the diffusion experiments. The effective diffusion coefficients, De, of the trace ions for hardened FAC cement pastes were estimated to be on the order of 10-13 m2 s-1 at the beginning of the diffusion experiments. Then, the rate of diffusion of the trace ions decreased over the experimental period of 1-15 months. This is probably due to the change in the microstructure of the FAC as the result of a pozzolanic reaction. After a few months, the values of De were estimated to be on the order of 10-14 m2 s-1. These results suggest that an engineered barrier made of FAC can act as an effective barrier inhibiting the diffusion of trace ions such as organic carbon and iodine.

scholarly journals Strength Development and Elemental Distribution of Dolomite/Fly Ash Geopolymer Composite under Elevated Temperature

Materials ◽  
2020 ◽  
Vol 13 (4) ◽  
pp. 1015 ◽  
Author(s):  
Emy Aizat Azimi ◽  
Mohd Mustafa Al Bakri Abdullah ◽  
Petrica Vizureanu ◽  
Mohd Arif Anuar Mohd Salleh ◽  
Andrei Victor Sandu ◽  
...  
Keyword(s):  
Elevated Temperature ◽  
Fly Ash ◽  
Portland Cement ◽  
Ordinary Portland Cement ◽  
Raw Materials ◽  
Liquid Sodium ◽  
Strength Development ◽  
Elemental Distribution ◽  
Distribution Analysis ◽  
Geopolymer Composites

A geopolymer has been reckoned as a rising technology with huge potential for application across the globe. Dolomite refers to a material that can be used raw in producing geopolymers. Nevertheless, dolomite has slow strength development due to its low reactivity as a geopolymer. In this study, dolomite/fly ash (DFA) geopolymer composites were produced with dolomite, fly ash, sodium hydroxide, and liquid sodium silicate. A compression test was carried out on DFA geopolymers to determine the strength of the composite, while a synchrotron Micro-Xray Fluorescence (Micro-XRF) test was performed to assess the elemental distribution in the geopolymer composite. The temperature applied in this study generated promising properties of DFA geopolymers, especially in strength, which displayed increments up to 74.48 MPa as the optimum value. Heat seemed to enhance the strength development of DFA geopolymer composites. The elemental distribution analysis revealed exceptional outcomes for the composites, particularly exposure up to 400 °C, which signified the homogeneity of the DFA composites. Temperatures exceeding 400 °C accelerated the strength development, thus increasing the strength of the DFA composites. This appears to be unique because the strength of ordinary Portland Cement (OPC) and other geopolymers composed of other raw materials is typically either maintained or decreases due to increased heat.

scholarly journals Chloride Ingress in Chemically Activated Calcined Clay-Based Cement

2018 ◽  
Vol 2018 ◽  
pp. 1-8 ◽  
Author(s):  
Joseph Mwiti Marangu ◽  
Joseph Karanja Thiong’o ◽  
Jackson Muthengia Wachira
Keyword(s):  
Compressive Strength ◽  
Portland Cement ◽  
Ordinary Portland Cement ◽  
Strength Development ◽  
Chloride Ingress ◽  
Calcined Clay ◽  
Apparent Diffusion Coefficients ◽  
Apparent Diffusion ◽  
Lower Porosity ◽  
Lower Chloride

Chloride-laden environments pose serious durability concerns in cement based materials. This paper presents the findings of chloride ingress in chemically activated calcined Clay-Ordinary Portland Cement blended mortars. Results are also presented for compressive strength development and porosity tests. Sampled clays were incinerated at a temperature of 800°C for 4 hours. The resultant calcined clay was blended with Ordinary Portland Cement (OPC) at replacement level of 35% by mass of OPC to make test cement labeled PCC35. Mortar prisms measuring 40 mm × 40 mm × 160 mm were cast using PCC35 with 0.5 M Na2SO4 solution as a chemical activator instead of water. Compressive strength was determined at 28th day of curing. As a control, OPC, Portland Pozzolana Cement (PPC), and PCC35 were similarly investigated without use of activator. After the 28th day of curing, mortar specimens were subjected to accelerated chloride ingress, porosity, compressive strength tests, and chloride profiling. Subsequently, apparent diffusion coefficients (Dapp) were estimated from solutions to Fick’s second law of diffusion. Compressive strength increased after exposure to the chloride rich media in all cement categories. Chemically activated PCC35 exhibited higher compressive strength compared to nonactivated PCC35. However, chemically activated PCC35 had the least gain in compressive strength, lower porosity, and lower chloride ingress in terms of Dapp, compared to OPC, PPC, and nonactivated PCC35.

scholarly journals Physical Properties of Concrete Containing Graphene Oxide Nanosheets

Materials ◽  
2019 ◽  
Vol 12 (10) ◽  
pp. 1707 ◽  
Author(s):  
Yu-You Wu ◽  
Longxin Que ◽  
Zhaoyang Cui ◽  
Paul Lambert
Keyword(s):  
Tensile Strength ◽  
Compressive Strength ◽  
Graphene Oxide ◽  
Flexural Strength ◽  
Portland Cement ◽  
Physical Properties ◽  
Ordinary Portland Cement ◽  
Construction Materials ◽  
Split Tensile Strength ◽  
Cement Pastes

Concrete made from ordinary Portland cement is one of the most widely used construction materials due to its excellent compressive strength. However, concrete lacks ductility resulting in low tensile strength and flexural strength, and poor resistance to crack formation. Studies have demonstrated that the addition of graphene oxide (GO) nanosheet can effectively enhance the compressive and flexural properties of ordinary Portland cement paste, confirming GO nanosheet as an excellent candidate for using as nano-reinforcement in cement-based composites. To date, the majority of studies have focused on cement pastes and mortars. Only limited investigations into concretes incorporating GO nanosheets have been reported. This paper presents an experimental investigation on the slump and physical properties of concrete reinforced with GO nanosheets at additions from 0.00% to 0.08% by weight of cement and a water–cement ratio of 0.5. The study demonstrates that the addition of GO nanosheets improves the compressive strength, flexural strength, and split tensile strength of concrete, whereas the slump of concrete decreases with increasing GO nanosheet content. The results also demonstrate that 0.03% by weight of cement is the optimum value of GO nanosheet dosage for improving the split tensile strength of concrete.

Estimation and Measurement of Porosity Change in Cement Paste

2010 ◽  
Author(s):  
Eunyong Lee ◽  
Haeryong Jung ◽  
Ki-jung Kwon ◽  
Do-Gyeum Kim
Keyword(s):  
Ionic Strength ◽  
Portland Cement ◽  
Cement Paste ◽  
Thermodynamic Model ◽  
Ordinary Portland Cement ◽  
Type I ◽  
Hydration Products ◽  
Cement Pastes ◽  
Porosity Change ◽  
Dissolution Reaction

Laboratory-scale experiments were performed to understand the porosity change of cement pastes. The cement pastes were prepared using commercially available Type-I ordinary Portland cement (OPC). As the cement pastes were exposed in water, the porosity of the cement pastes sharply increased; however, the slow decrease of porosity was observed as the dissolution period was extended more than 50 days. As expected, the dissolution reaction was significantly influenced by w/c raito and the ionic strength of solution. A thermodynamic model was applied to simulate the porosity change of the cement pastes. It was highly influenced by the depth of the cement pastes. There was porosity increase on the surface of the cement pastes due to dissolution of hydration products, such as portlandite, ettringite, and CSH. However, the decrease of porosity was estimated inside the cement pastes due to the precipitation of cement minerals.

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