scholarly journals Properties of Calcium Acetate Manufactured with Etching Waste Solution and Limestone Sludge as a Cementitious High-Early-Strength Admixture

2016 ◽  
Vol 2016 ◽  
pp. 1-9 ◽  
Author(s):  
Deuck-Mo Kim ◽  
Hwa-Sung Ryu ◽  
Sang-Heon Shin ◽  
Won-Jun Park
Keyword(s):  
Flow Behavior ◽  
Setting Time ◽  
Calcium Nitrate ◽  
Construction Materials ◽  
Calcium Acetate ◽  
Initial Strength ◽  
Early Strength ◽  
Diffraction Patterns ◽  
By Products

Concrete is one of the most widely used construction materials. There are several methods available to improve its performance, with one of them being the use of high-early-strength admixtures (HESAs). Typical HESAs include calcium nitrate, calcium chloride, and calcium formate (CF). Industrial by-products, such as acetic acid and lime stone sludge (LSS), can be used together to produce calcium acetate (CA), which can subsequently be used as a cementitious HESA. In this study, calcium carbonate and LSS were mixed with cement in weight ratios of 1 : 1, 1 : 1.5, and 1 : 2, and the properties of the as-produced CA were evaluated. CA and CF were mixed with cement in different weight ratios (0, 1, 2, and 3 wt%) to obtain CA- and CF-mortars, respectively. The flow behavior, setting time, pH, and compressive strength of these mortars were evaluated, and their X-ray diffraction patterns were also analyzed. It was found that as the CF content in the CF-mortar increased, the initial strength of the mortar also increased. However, it impaired its long-term strength. On the other hand, when 1% CA was mixed with cement, satisfactory early and long-term strengths were achieved. Thus, CA, which is obtained from industrial by-products, can be an effective HESA.

scholarly journals Effect of Calcium Nitrate on the Properties of Portland–Limestone Cement-Based Concrete Cured at Low Temperature

Materials ◽  
2021 ◽  
Vol 14 (7) ◽  
pp. 1611
Author(s):  
Gintautas Skripkiūnas ◽  
Asta Kičaitė ◽  
Harald Justnes ◽  
Ina Pundienė
Keyword(s):  
Compressive Strength ◽  
Cement Paste ◽  
Setting Time ◽  
Calcium Nitrate ◽  
Curing Temperature ◽  
Hardened Concrete ◽  
Cement Pastes ◽  
Initial Setting Time ◽  
Initial Setting ◽  
Early Strength

The effect of calcium nitrate (CN) dosages from 0 to 3% (of cement mass) on the properties of fresh cement paste rheology and hardening processes and on the strength of hardened concrete with two types of limestone-blended composite cements (CEM II A-LL 42.5 R and 42.5 N) at different initial (two-day) curing temperatures (−10 °C to +20 °C) is presented. The rheology results showed that a CN dosage up to 1.5% works as a plasticizing admixture, while higher amounts demonstrate the effect of increasing viscosity. At higher CN content, the viscosity growth in normal early strength (N type) cement pastes is much slower than in high early strength (R type) cement pastes. For both cement-type pastes, shortening the initial and final setting times is more effective when using 3% at +5 °C and 0 °C. At these temperatures, the use of 3% CN reduces the initial setting time for high early strength paste by 7.4 and 5.4 times and for normal early strength cement paste by 3.5 and 3.4 times when compared to a CN-free cement paste. The most efficient use of CN is achieved at −5 °C for compressive strength enlargement; a 1% CN dosage ensures the compressive strength of samples at a −5 °C initial curing temperature, with high early strength cement exceeding 3.5 MPa but being less than the required 3.5 MPa in samples with normal early strength cement.

scholarly journals Properties of Cement Mortar Using Limestone Sludge Powder Modified with Recycled Acetic Acid

2019 ◽  
Vol 11 (3) ◽  
pp. 879
Author(s):  
Hwa-Sung Ryu ◽  
Deuck-Mo Kim ◽  
Sang-Heon Shin ◽  
Wan-Ki Kim ◽  
Seung-Min Lim ◽  
...  
Keyword(s):  
Acetic Acid ◽  
Cement Mortar ◽  
Surface Characteristics ◽  
Calcium Acetate ◽  
Raw Material ◽  
Limestone Powder ◽  
Low Carbon ◽  
Pore Filling ◽  
Initial Strength

One of the various methods of manufacturing low-carbon cement is substituting limestone powder as a raw material or admixture. Limestone sludge powder (LSSP) has the same composition as that of limestone powder. The surface characteristics of LSSP powder modified with recycled acetic acid (RAA) and the characteristics of cement using this modified LSSP as a substitute were investigated in this study. The surface of LSSP modified with RAA was converted into calcium acetate and had a large grain size. When conventional LSSP was used as a substitute for cement, the initial strength increased owing to improved pore filling; however, the strength after 28 days of aging was lower than that of non-substituted cement. In the case of modified LSSP being replaced with cement at up to 10% of the cement weight, however, the calcium acetate on its surface increased the amount of hydration products in the cement, thereby increasing both the initial and the long-term strength.

An overview on the activation of reactivity of natural pozzolans

2001 ◽  
Vol 28 (5) ◽  
pp. 778-786 ◽  
Author(s):  
Caijun Shi
Keyword(s):  
Chemical Activation ◽  
Setting Time ◽  
Construction Materials ◽  
Pozzolanic Reaction ◽  
Strength Development ◽  
Portland Cement Concrete ◽  
Cement Concrete ◽  
Natural Pozzolan ◽  
Natural Pozzolans ◽  
Early Strength

Natural pozzolan is one of the oldest construction materials. Lime-pozzolan cements have been used for several thousands of years and have an excellent reputation for their durability. Pozzolans are being widely used as a cement replacement in Portland cement concrete. The use of pozzolans has the advantage of lower costs and better durability, but the disadvantage of a longer setting time and a slower early strength development. Different techniques have been tried to increase the reactivity of natural pozzolans to overcome these disadvantages. This paper has reviewed various methods used to activate the pozzolanic activity of natural pozzolans. All activation methods can be classified into three catalogues: thermal, mechanical, and chemical activation. A comparison based on strength–cost relationship indicates that the chemical activation method is the most effective and cheapest one.Key words: activation, reactivity, natural pozzolans, pozzolanic reaction, calcination, elevated temperature curing, chemical activators, strength, cost.

Experimental Study of Influences of Initial Temperature on Cement Grout Performance

2015 ◽  
Vol 1095 ◽  
pp. 242-247 ◽  
Author(s):  
Jin Chao Yang ◽  
Wan Peng Wang ◽  
Shu Guang Wang ◽  
Jian Hua Chen ◽  
Wei Yang
Keyword(s):  
Experimental Study ◽  
Initial Temperature ◽  
Setting Time ◽  
Cement Grout ◽  
Curing Temperature ◽  
Term Strength ◽  
Bleeding Rate ◽  
Early Strength

Through the experiment, this paper studies and analyzes influence of different initial temperatures on cement grout performance. The results show initial temperature has influences on grout fluidity, bleeding rate, setting time and early strength. Under guaranteed curing temperature, initial temperature has no influence on long-term strength of grout.

Humus state of chernozem at different ways of tillage in the agrosystems of the left-bank forest steppe of Ukraine

2015 ◽  
Vol 2 (3) ◽  
pp. 61-77
Author(s):  
O. Demydenko ◽  
V. Velychko
Keyword(s):  
Soil Cover ◽  
Forest Steppe ◽  
Left Bank ◽  
Energy Reserves ◽  
Soil Resources ◽  
Global Soil ◽  
Humus Accumulation ◽  
By Products ◽  
The Way

The contemporary condition of soil cover in Ukraine is characterized. The attention is focused onto widespread degradation processes in soils. The causes that determine the development of these negative processes are considered. The contemporary informational support for the condition of soil cover in Ukraine is estimated. In general, the current available information is of narrow-departmental nature, obtained by different methods and non-correlated monitoring programs. As a rule, it is stored in under-structured databases, incompatible with other information systems; mainly recorded on paper media unusable with modern technologies, whereby such information resources are diffi cult to be compiled together. These disadvantages are strong constraints against consistent usage of materials for evaluation, forecast and management of changes in the soil cover. The Soil Observation program should thereby be combined with Agrochemical Passportization and ecology-ameliora- tive monitoring; in other words, the application of innovative soil-agrochemical methodology is considered. Each individual type of surveys shall complement the others, and taken altogether, they shall constitute a con- sistent Information System, capable of solving the problems of assessing the condition, forecasting, manage- ment, usage and protection of soil resources. The monitoring procedures should be conducted on the basis of a new soil concept in line with unifi ed programs and methods, so as to meet European approaches to the maxi- mum extent. Such a technical composition enables getting information on present-day processes in soils, and is the only combination that actually helps us to “ecologize” our knowledge of soils, which is the leading trend in the scope of global soil-science. Thus obtained results will serve as a State-owned tool which would subse- quently facilitate the use and protection of soil resources all over the country, to be involved in a united global soil-information scope. The attention is focused onto social signifi cance of the information on soils and their fertility in terms of land resources optimization, as well as the formation of sustainable land use in Ukraine. Aim. To demonstrate the long-term effect of different ways of tillage of typical low-humus chernozem on the change in humus content and composition and the direction of transformation processes of organic fertili- zers. To study the changes in the structure of energy reserves in group and fractional composition of humus in typical low-humus light-loamy chernozem of the Forest-Steppe of Ukraine. Methods. Field, laboratory, microbiological, computational, mathematical and statistical. Results. It was determined that in conditions of long-term subsurface tillage the most effi cient humus accumulation occurs in the 0–20 cm layer of chernozem with simultaneous increase in its content in the lower part of the processed layer without any accumulation differentiation. Surface tillage leads to expressed differentiation in humus accumulation in the 0–20 cm layer of soil (0.005 % per year). When 6 t/ha of humus are replaced by 7 t/ha of by-products the intensity of humus accumulation is decreasing regardless of the way of tillage, but humus accumulation was found to be the most effi cient for subsurface tillage. The application of subsurface tillage leads to the increase in the ratio of C HA : C FA , which is conditioned by the increase in the humifi cation of plant remains of by-products in the 0−20 cm layer of soil by 110–112 % – for subsurface tillage, and by 105 % – for surface tillage. Conclusions. It was established that systematic subsurface tillage of typical chernozem of the Left-Bank Forest-Steppe of Ukraine leads to the structuring both of the total reserves of energy С org , and its quality content, aimed at the increase in the intensity of the processes of humifi cation and accumulation of organic carbon, and the decrease in miner- alization. The ratio of energy reserves С org of humic acids to fulvic acids in the 0−30 cm layer of chernozem is 1.85−1.87 regardless of the way of tillage, which testifi es to the repeatability of humus accumulation, but the total reserves of energy С org was higher for subsurface tillage (+ 31 Teracalorie/ha) compared to deep plough- ing. As for the surface tillage, the energy enrichment was at the level of deep ploughing.

NEUROENDOCRINE TUMORS OF THE PANCREAS: ETIOLOGY, PATHOGENESIS, DIAGNOSIS, AND CURRENT TREATMENT APPROACHES

2018 ◽  
Vol 64 (6) ◽  
pp. 830-839
Author(s):  
Temuri Morgoshiya
Keyword(s):  
Neuroendocrine Tumors ◽  
Clinical Manifestations ◽  
Gastrointestinal Hormones ◽  
Current Treatment ◽  
High Potential ◽  
Long Term Results ◽  
Considerable Part ◽  
Treatment Approaches ◽  
By Products

The overview of literature on modem classification issues, diagnostics and treatments of neuroendocrinal tumors of a pancreas is provided. According to modern views all neuroendocrinal tumors of a pancreas having clinical manifestations (in the form of the syndromes caused by products of specific hormones; increases in level of hormones in blood of patients without clinical manifestations; in the form of signs of existence of volume education in various departments of PZh) and/or the researches (more than 5 mm) revealed by means of beam methods are malignant in the biology as they have high potential to innidiation. In article it is shown that a considerable part of neuroendocrinal tumors of a pancreas are nonfunctioning, i.e. not cosecreting various gastrointestinal hormones and polypeptides in blood and thereof not followed characteristic clinical manifestations. It is noted that diagnostics of neuroendocrinal tumors of a pancreas is extremely difficult task on which solution the choice of a method of treatment and its long-term results depends...

scholarly journals Mortars with Recycled Aggregates from Building-Related Processes: A ‘Four-Step’ Methodological Proposal for a Review

2021 ◽  
Vol 13 (5) ◽  
pp. 2756
Author(s):  
Federica Vitale ◽  
Maurizio Nicolella
Keyword(s):  
Building Materials ◽  
Thermal Analyses ◽  
Construction Materials ◽  
Physical And Mechanical Properties ◽  
Research Trends ◽  
Mix Design ◽  
Recycled Aggregates ◽  
Design Parameters ◽  
Natural Aggregates ◽  
By Products

Because the production of aggregates for mortar and concrete is no longer sustainable, many attempts have been made to replace natural aggregates (NA) with recycled aggregates (RA) sourced from factories, recycling centers, and human activities such as construction and demolition works (C&D). This article reviews papers concerning mortars with fine RA from C&D debris, and from the by-products of the manufacturing and recycling processes of building materials. A four-step methodology based on searching, screening, clustering, and summarizing was proposed. The clustering variables were the type of aggregate, mix design parameters, tested properties, patents, and availability on the market. The number and the type of the clustering variables of each paper were analysed and compared. The results showed that the mortars were mainly characterized through their physical and mechanical properties, whereas few durability and thermal analyses were carried out. Moreover, few fine RA were sourced from the production waste of construction materials. Finally, there were no patents or products available on the market. The outcomes presented in this paper underlined the research trends that are useful to improve the knowledge on the suitability of fine RA from building-related processes in mortars.

scholarly journals Application of Plastic Wastes in Construction Materials: A Review Using the Concept of Life-Cycle Assessment in the Context of Recent Research for Future Perspectives

Materials ◽  
2021 ◽  
Vol 14 (13) ◽  
pp. 3549
Author(s):  
Tulane Rodrigues da Silva ◽  
Afonso Rangel Garcez de Azevedo ◽  
Daiane Cecchin ◽  
Markssuel Teixeira Marvila ◽  
Mugahed Amran ◽  
...  
Keyword(s):  
Life Cycle Assessment ◽  
Life Cycle ◽  
Solid Waste ◽  
Building Materials ◽  
Construction Materials ◽  
Plastic Waste ◽  
Plastic Wastes ◽  
Solid Waste Generation ◽  
Alternative Processes

The urbanization process contributes to the growth of solid waste generation and causes an increase in environmental impacts and failures in the management of solid waste. The number of dumps is a concern due to the limited implementation and safe disposal of this waste. The interest in sustainable techniques has been growing in relation to waste management, which is largely absorbed by the civil construction sector. This work aimed to review plastic waste, especially polyethylene terephthalate (PET), that can be incorporated with construction materials, such as concrete, mortars, asphalt mixtures, and paving. The use of life-cycle assessment (LCA) is related, as a tool that allows the sustainability of products and processes to be enhanced in the long term. After analyzing the recent literature, it was identified that studies related to plastic wastes in construction materials concentrate sustainability around the alternative destination of waste. Since the plastic waste from different production chains are obtained, it was possible to affirm the need for a broader assessment, such as the LCA, providing greater quantification of data making the alternative processes and products more sustainable. The study contributes to enhance sustainability in alternative building materials through LCA.

THE EFFECT OF COMPOSITION CHANGE IN SOL-GEL SYNTHESIZED PSC

2008 ◽  
Vol 20 (01) ◽  
pp. 53-59
Author(s):  
Wen-Hsi Wang ◽  
Yuan-Ling Lee ◽  
Chun-Pin Lin ◽  
Feng-Huei Lin
Keyword(s):  
Setting Time ◽  
Sol Gel ◽  
Hydration Product ◽  
Xrd Pattern ◽  
Ph Variation ◽  
Initial Strength ◽  
Filling Materials ◽  
Retrograde Filling ◽  
Significant Difference ◽  
Sol Gel Process

Modified calcium silicate cement had previously been developed as a dental retrograde filling. It had great sealing ability, good biocompatibility, and anti-bacterial properties. However, its clinical application was limited by a long setting time and poor handling property. In previous study,1, 2 the setting property of PSC was greatly improved due the sol-gel process, without the addition of transition metal element. In this study, different ratio of starting material of PSC was prepared. The composition of each group was also altered with the ratio of the starting materials according to the result of XRD pattern. There is no significant difference in pH variation profile between each group. Even though low C 3 S / C 4 AF ratio (DX631 and DX541 groups) possessed high initial strength at first 24 hours after hydration, there was no increase in strength ever since according to the result of microhardness. However, the groups with high C 3 S / C 4 AF ratio (DX811 and DX721 groups) possessed relatively low initial strength at 24 hours after hydration, but the strength increased rapidly and continuously at least for the next six days of hydration. Moreover, the peak intensity of hydration product (Portlandite) on XRD pattern in DX811 group was much higher than other three groups, and this was also in agreement with the result of microhardness. DX811 group is determined to be the optimal one for the further development in the application as root-end filling materials.

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