scholarly journals Experimental Study of the Resistance to Influence of Aggressive Liquids on Lightweight Concrete

Materials ◽  
2021 ◽  
Vol 14 (15) ◽  
pp. 4185
Author(s):  
Marzena Kurpińska ◽  
Elżbieta Haustein
Keyword(s):  
Fly Ash ◽  
Lightweight Concrete ◽  
Negative Impact ◽  
Strong Acid ◽  
Weak Acid ◽  
Aqueous Salt Solution ◽  
Mineral Additive ◽  
Foamed Glass ◽  
One Year ◽  
Traditional Construction

In light of the scientific research, the corrosion of concrete structures is one of the main problems that may reduce their durability due to the negative impact of the natural environment. The paper analyzes the influence of the type of component on the selected properties of lightweight concrete subjected to the influence of aggressive liquids. Four concrete mixes were prepared with a granular aggregate made of foamed glass (GEGA) and aggregate made of sintered fly ash (GAA) with the use of a mineral additive: silica fly ash. The prepared lightweight concrete after one year was exposed for 60 days to the following environments: strong acid—HCl, 1% and 2% concentration, weak acid—CH3COOH, 1% and 2% concentration, and an aqueous salt solution of Na2SO4, 1% and 2% concentration. Then, the compressive strength was tested, and the microstructure analysis of the ready-made lightweight concrete (LWC) was performed. The degree of penetration of aggressive solutions into the cracks of the samples was assessed by means of applying 1% phenolphthalein solution. Changes in the weight of lightweight concrete samples after the test period were estimated. The obtained test results indicate that the decrease in the durability of lightweight concrete can be classified as a long-term process. Concrete with GEGA and GAA showed high resistance to aggressive environments. Moreover, the environment containing chlorides turned out to be the most aggressive, while the environment containing sulfates proved to be the least aggressive. The higher the concentration of the destructive factor was, the faster the corrosion process went. This has been proven by measuring the pH using phenolphthalein and carrying out microscopic examination. Concretes containing aggregates made of foamed glass and sintered fly ash are suitable for use both in traditional construction and in facilities exposed to an aggressive environment (e.g., in the chemical industry and at gas stations).

scholarly journals Influence of the Variability of Calcareous Fly Ash Properties on Rheological Properties of Fresh Mortar with Its Addition

Materials ◽  
2019 ◽  
Vol 12 (12) ◽  
pp. 1942 ◽  
Author(s):  
Artur Nowoświat ◽  
Jacek Gołaszewski
Keyword(s):  
Fly Ash ◽  
Bulk Density ◽  
Rheological Properties ◽  
Coefficient Of Variation ◽  
Negative Impact ◽  
Concrete Technology ◽  
Mineral Additive ◽  
Main Component ◽  
The Impact ◽  
By Products

One of the main by-products of brown coal burning is calcareous fly ash (CFA). Apart from other applications, it is used as a main component of cement, or as an active mineral additive to concrete. The present study involves the impact of the raw and processed calcareous fly ash (CFA) on the changes of rheological properties of mortars. The said impact was determined by using the coefficient of variation (CV) given in percentage. CFA samples collected from various sources were subjected to testing. The samples were collected from two electrofilters of blocks with boilers of different combustion parameters and from the retention tanks of the CFA sales department (CFA T) in which CFAs from various boilers are mixed. It has been demonstrated that the degree of the impact of CFA addition on the rheological properties of mortars depends on the source of this addition and on bulk density. The present work demonstrates the negative impact of raw CFA on mortar workability, and hence it is questionable to support its use in concrete technology.

scholarly journals The Influence of Cement Substitution by Biomass Fly Ash on the Polymer–Cement Composites Properties

Materials ◽  
2021 ◽  
Vol 14 (11) ◽  
pp. 3079
Author(s):  
Beata Jaworska ◽  
Dominika Stańczak ◽  
Joanna Tarańska ◽  
Jerzy Jaworski
Keyword(s):  
Fly Ash ◽  
Building Materials ◽  
Raw Materials ◽  
Combustion Process ◽  
Biomass Combustion ◽  
Cement Composites ◽  
Cement Mortars ◽  
Mineral Additive ◽  
Biomass Fly Ash

The generation of energy for the needs of the population is currently a problem. In consideration of that, the biomass combustion process has started to be implemented as a new source of energy. The dynamic increase in the use of biomass for energy generation also resulted in the formation of waste in the form of fly ash. This paper presents an efficient way to manage this troublesome material in the polymer–cement composites (PCC), which have investigated to a lesser extent. The research outlined in this article consists of the characterization of biomass fly ash (BFA) as well as PCC containing this waste. The characteristics of PCC with BFA after 3, 7, 14, and 28 days of curing were analyzed. Our main findings are that biomass fly ash is suitable as a mineral additive in polymer–cement composites. The most interesting result is that the addition of biomass fly ash did not affect the rheological properties of the polymer–cement mortars, but it especially influenced its compressive strength. Most importantly, our findings can help prevent this byproduct from being placed in landfills, prevent the mining of new raw materials, and promote the manufacture of durable building materials.

Ontology-Based Interorganizational Knowledge Management in Sustainable Construction Project

2011 ◽  
Vol 243-249 ◽  
pp. 6339-6343
Author(s):  
Guang Bin Wang ◽  
Gui You He ◽  
Li Bian
Keyword(s):  
Knowledge Management ◽  
Construction Industry ◽  
Negative Impact ◽  
Sustainable Construction ◽  
Construction Process ◽  
Application Process ◽  
Process Ontology ◽  
Knowledge Intensive ◽  
Traditional Construction ◽  
Industry Needs

Due to the great negative impact, the construction industry needs to undergo a paradigm shift from traditional construction to sustainable construction. To reach the goal of sustainable development, the construction industry needs to intensify its efforts to move to a knowledge intensive mode. Based on the analysis of e-Cognos and the concept of ontology, this paper proposes that e-Cognos ontology can be applied in the development of sustainable construction process ontology, which is a key part of knowledge management system (KMS). Following this, the application process of ontology-based KMS is analyzed using IDEF0 modeling method. Finally, this paper analyzes interorganizational collaboration model in sustainable project.

RESEARCH OF COMPLEX MODIFICATION OF HEAVY CONCRETE

2021 ◽  
Vol 96 (4) ◽  
pp. 107-112
Author(s):  
YU.S. FILIMONOVA ◽  
◽  
E.G. VELICHKO ◽  
Keyword(s):  
Compressive Strength ◽  
Fly Ash ◽  
Power Plants ◽  
High Efficiency ◽  
Thermal Power ◽  
Thermal Power Plants ◽  
Complex Chemical ◽  
Composition And Structure ◽  
Combined Use ◽  
Mineral Additive

Modification of the composition and structure of heavy concrete with the use of a complex chemical-mineral additive consisting of fly ash from thermal power plants, a superplasticizer, a high-valence hardening accelerator AC and a fine-dispersed clinker component is considered. Modified concrete is characterized by an increase in compressive strength at a brand age by 67%, a decrease in the water content of a concrete mixture by 13.6% and an improvement in its workability by 11-12 cm. With the combined use of a superplasticizer and a high-valence hardening accelerator AC a significant synergistic effect is observed in the format of enhancing their plasticizing effect. The high efficiency of the application of the mixed-dispersed clinker component has been established.

Impact of COVID19 pandemic on treatment outcome of locally-advanced head and neck squamous cell carcinoma (LA-HNSCC): IMPACCT study.

2021 ◽  
Vol 39 (15_suppl) ◽  
pp. 6061-6061
Author(s):  
Pau Guillen Sentis ◽  
Carmen Castillo Manzano ◽  
Beatriz Quirós ◽  
Francisca Morey Cortes ◽  
Sara Tous ◽  
...  
Keyword(s):  
Negative Impact ◽  
Locally Advanced ◽  
Standard Of Care ◽  
Stage Iii ◽  
Rank Test ◽  
Historical Cohort ◽  
First Semester ◽  
Kaplan Meier ◽  
Chi Squared ◽  
One Year

6061 Background: Treatment (ttm) of cancer patients (pts) was compromised during the first wave of COVID19 pandemic due to collapse of healthcare systems. Standard of care (SOC) for LA-HNSCC pts had to be adapted as operating rooms were temporarily unavailable, and to reduce risk of COVID19 exposure. The IMPACCT study evaluated the outcome of LA-HNSCC pts treated at the Catalan Institute of Oncology during the first semester of 2020 and compared it to a control cohort previously treated in the same institution. Methods: Retrospective single institution analysis of two consecutively-treated cohorts of newly-diagnosed HNSCC pts: from January to June of 2020 (CT20) and same period of 2018 and 2019 (CT18-19). Pt demographics and disease characteristics were obtained from our in-site prospective database. Ttm modifications from SOC as per COVID19-contingency protocol in CT20 for LA-HNSCC were collected. Chi-squared was used to compare variables and ttm response between cohorts. One-year recurrence-free survival (1yRFS) and overall survival (1yOS) of LA-HNSCC pts were estimated by Kaplan-Meier method and compared by Log-rank test. Results: A total of 306 pts were included: CT20=99; CT18-19=207. Baseline characteristics were balanced between cohorts (Table1). In pts treated with conservative ttm (non-surgical approach), persistence disease was higher in CT20 vs CT18-19 (26 vs. 10% p=0.02). Median follow-up of CT20 and CT18-19 was 6.8 months (IQR 5.1-7.9) and 12.3 (6.7-18.4), respectively. A trend towards lower 1yRFS and 1yOS was observed in CT20 vs CT18-19 (72 vs 83% p=0.06; 80 vs 84% p=0.07), respectively. Within CT20, 37 pts (37%) had one or more ttm modifications: switch from surgery to conservative ttm (n=13); altered radiotherapy fractionation (n=14); reduced cisplatin cumulative dose to 200mg/m2 (n=19); no adjuvant ttm (n=1). Pts who received modified ttm had no differences in 1yRFS vs those who did not (80 vs 66% p=0.31), but higher 1yOS was observed (97 vs 67% p<0.01). When stratified by stage, 1yOS difference remained significant in stage III/IVA (100 vs 61% p<0.01) but not in I/II (100 vs 77% p=0.28) or IVB (67 vs 50% p=0.54). Conclusions: COVID19 pandemic had a negative impact on ttm outcomes and survival in LA-HNSCC pts when compared to our historical cohort. Ttm modifications based on COVID19-contingency protocol did not compromise ttm efficacy in terms of RFS and was associated with better OS in Stage III/IVA.[Table: see text]

Fly ash from Coal-Combustion Waste as an Additive for Quality Improvement and Compressive Strength of Cement

2021 ◽  
Vol 27 (1) ◽  
pp. 127-134
Author(s):  
Roni Adi Wijaya ◽  
Yayuk Astuti ◽  
Septi Wijayanti
Keyword(s):  
Compressive Strength ◽  
Fly Ash ◽  
Coal Combustion ◽  
National Standard ◽  
Insoluble Residue ◽  
Chemical Components ◽  
Free Lime ◽  
Mineral Additive ◽  
Additional Mineral

A series of tests were carried out to determine the effect of the addition of coal combustion fly ash as an additional mineral (additive) on improving the quality and compressive strength of cement according to the Indonesian National Standard (SNI 15-2049-2004). Research methods include sample preparation, manufacture of cement with 0%, 5%, 8%, 12%, and 15% fly ash variations, chemical and physical properties of cement. The parameters measured were the level of chemical composition (%) using X-Ray Fluorescence Spectroscopy (XRF) ARL 9800 OASIS, free lime content (%) by volumetry, insoluble residue level (%) by gravimetry, compressive strength (kg/cm2), and smoothness cement (cm2/g). The results showed that the addition of fly ash increased the SiO2 content of cement, thereby increasing C3S and C2S compounds which are compressive strength components of a cement. Besides, the addition of fly ash is directly proportional to IR levels, compressive strength, smoothness, and inversely proportional to free lime levels. So the addition of fly ash can improve the quality of cement by increasing chemical components, increasing compressive strength, and reducing cracking or expansion of cement.

scholarly journals Total hip arthroplasty and lumbar spine disorders: Plain co-existence or mutual influence?

2020 ◽  
Vol 12 (2) ◽  
Author(s):  
Nils Wirries ◽  
Michael Schwarze ◽  
Dorothea Daentzer ◽  
Michael Skutek
Keyword(s):  
Lumbar Spine ◽  
Total Hip Arthroplasty ◽  
Hip Arthroplasty ◽  
Mutual Influence ◽  
Negative Impact ◽  
Clinical Signs ◽  
Clinical Results ◽  
Total Hip ◽  
One Year ◽  
Spine Disorders

Lumbar spine disorders (LSD) might influence the outcome after total hip arthroplasty (THA). Despite a known common prevalence of LSD and degenerative hip disorders, this study investigates their mutual influence in case of co-existence with the purpose to advance surgeons planning and patient’s prognosis. Patients with and without LSD were compared before and at the one-year postoperative examination. For clinical evaluation the WOMAC was assessed. The radiological analysis focused on cup anteversion and inclination. The total group included 203 consecutive patients. The overall incidence of LSD was 51.0%. Patients with LSD were on average 4.3 years older and had a 1.8 higher BMI than non-LSD patients (P<0.05). The cup positioning and the clinical results were comparable between both groups before and at the last time of follow up (P>0.05). No hip dislocations nor clinical signs of impingement were seen.We can conclude that there is a high degree of co-existence of LSD and hip disorders. However, a strong negative impact of LSD to clinical or radiologic results could not be confirmed in our study.

Utilization of Fly Ash Cenosphere for Production of Sustainable Lightweight Concrete

2019 ◽  
Vol 101 (1) ◽  
pp. 179-194 ◽  
Author(s):  
Sudeep K. Patel ◽  
Hara P. Satpathy ◽  
Amar N. Nayak ◽  
Chitta R. Mohanty
Keyword(s):  
Fly Ash ◽  
Lightweight Concrete ◽  
Fly Ash Cenosphere

scholarly journals Magnesium Salt Influenced Strength Behavior of Lime-Fly Ash Stabilized Fine Grained Soil

2020 ◽  
Vol 26 (3) ◽  
pp. 373-378
Author(s):  
Zhirong JIA ◽  
Luxin FU ◽  
Lizhi WANG
Keyword(s):  
Fly Ash ◽  
Negative Impact ◽  
Base Material ◽  
Test Dose ◽  
Underground Water ◽  
Magnesium Salt ◽  
Material Strength ◽  
Fine Grained ◽  
Fine Grained Soil ◽  
Mgcl2 Solution

The fine grained soil subgrade in coastal areas has the characteristics of high underground water level and serious salinization, and the lime-fly ash stabilized soil (LFSS) often used as the road base material. In order to study the effect of magnesium salt on the material strength, 5 % MgCl2 solution was used to simulate the groundwater magnesium salt environment, and specimens with 7 d, 14 d, 28 d, 60 d and 90 d curing ages were tested in MgCl2 solution for 1 d, 5 d, 10 d, 15 d or 30 d. A controlled test was also conducted in purified water. Strength mechanism of LFSS was analyzed; SEM test was taken; and the influence mechanism of MgCl2 medium was analyzed. The results showed that MgCl2 medium, immersing time, and curing age have effects on compressive strength of LFSS. More specifically, although the early strength is low, the strength of LFSS maintains slow and steady growth from 7 d to 90 d. Long-term immersing in both MgCl2 solution and purified water will reduce the strength of LFSS, while the strength of specimen immersed in MgCl2 solution will decrease faster. Reactions between MgCl2 and LFSS destroyed the original gels and crystals, causing a negative impact on the strength of LFSS. However, with the test dose of MgCl2, the reduced strength of LFSS can still satisfy the sub-base requirement of second-class highway in China.

scholarly journals Alkali-Silica Reaction Resistance and Pore Solution Composition of Low-Calcium Fly Ash-Based Geopolymer Concrete

2020 ◽  
Vol 5 (11) ◽  
pp. 96
Author(s):  
Jiawei Lei ◽  
Jiajun Fu ◽  
En-Hua Yang
Keyword(s):  
Fly Ash ◽  
Pore Solution ◽  
Systematic Investigation ◽  
Alkali Silica Reaction ◽  
Geopolymer Concrete ◽  
Portland Cement Concrete ◽  
Solution Composition ◽  
Low Calcium ◽  
Underlying Mechanisms ◽  
One Year

Low-calcium fly ash-based geopolymer concrete is generally reported to be less vulnerable to alkali-silica reaction (ASR) than conventional ordinary Portland cement concrete. However, the lack of understanding of pore solution composition of the low-calcium fly ash-based geopolymer limits the investigation of the underlying mechanisms for the low ASR-induced expansion in the geopolymer concrete. This study presents a systematic investigation of the pore solution composition of a low-calcium fly ash-based geopolymer over a period of one year. The results show that the pore solution of the fly ash geopolymer is mainly composed of alkali ions, silicates, and aluminosilicates species. The lower expansion of the geopolymer concrete in the current study is most probably due to the insufficient alkalinity in the geopolymer pore solution as the hydroxide ions are largely consumed for the fly ash dissolution.

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