Behaviour of different cementitious material formulations in sewer networks

2014 ◽  
Vol 69 (7) ◽  
pp. 1502-1508 ◽  
Author(s):  
J. Herisson ◽  
M. Guéguen-Minerbe ◽  
E. D. van Hullebusch ◽  
T. Chaussadent
Keyword(s):  
Ordinary Portland Cement ◽  
Environmental Parameters ◽  
Cementitious Materials ◽  
Cementitious Material ◽  
Material Degradation ◽  
Protective Mechanisms ◽  
Chemical Mechanisms ◽  
Sewer Network ◽  
Aluminate Cement ◽  
Sewer Networks

Sewer networks are subjected to degradation, including biodeterioration of materials, in the presence of biogenic sulfuric acid, leading to costly repairs. To ensure durable structures, it is essential to select the best adapted materials. Two cementitious materials based on ordinary Portland cement (OPC) or calcium aluminate cement (CAC), were subjected to biodeterioration in the headspace of an operating sewer network. After a few month OPC materials started to deteriorate whereas CAC materials were still intact. The better durability of CAC materials is due to the presence of alumina providing a combination of protective mechanisms. On-site environmental parameters were monitored and analysed in the context of the biological and chemical mechanisms involved in material degradation. These data will eventually feed into the development of a representative, reproducible and accelerated laboratory test.

scholarly journals Cement Equivalence of Metakaolin for Workability, Cohesiveness, Strength and Sorptivity of Concrete

Materials ◽  
2020 ◽  
Vol 13 (7) ◽  
pp. 1646 ◽  
Author(s):  
J.J. Chen ◽  
Q.H. Li ◽  
P.L. Ng ◽  
L.G. Li ◽  
A.K.H. Kwan
Keyword(s):  
Ordinary Portland Cement ◽  
Performance Testing ◽  
Cementitious Materials ◽  
Cementitious Material ◽  
Mix Design ◽  
Cube Strength ◽  
Slump Flow ◽  
Equivalent Mass ◽  
Equivalent Factor ◽  
Strength And Durability

A series of concrete mixes with metakaolin (MK) content ranging from 0 to 30% and water/cementitious materials (W/CM) ratio varying from 0.30 to 0.50 were produced for performance testing. The results showed that adding MK up to 20% as ordinary Portland cement (OPC) replacement best improved the 28-day and 70-day cube strengths, whereas adding MK up to 30% as OPC replacement always increased the cohesiveness and decreased the sorptivity, but impaired the workability. Moreover, the cement equivalent factor (CEF), i.e. the equivalent mass of OPC per mass of MK added, for each performance attribute, including workability and cohesiveness, was evaluated. Whilst the actual CEF of MK was generally higher at a higher W/CM ratio and lower at a higher MK content, overall, the average CEFs were found to be 1.98, 2.17, 3.83, 1.93, 2.12, and 4.70 for slump, flow, cohesiveness, 28-day cube strength, 70-day cube strength, and sorptivity coefficient, respectively. These CEF values indicated that the MK is a highly effective cementitious material for improving the cohesiveness, strength, and durability. Moreover, it has been demonstrated that the CEFs for workability and cohesiveness are useful parameters in aiding the mix design of MK concrete.

Study on Sulphate Resistance of Often-Used Cementitious Material of High Performance Concrete for Marine

2012 ◽  
Vol 450-451 ◽  
pp. 94-101
Author(s):  
Kun Peng Gu ◽  
Cheng Qi Wang
Keyword(s):  
Corrosion Resistance ◽  
Portland Cement ◽  
High Performance ◽  
Ordinary Portland Cement ◽  
High Performance Concrete ◽  
Cementitious Materials ◽  
Resistance Coefficient ◽  
Cementitious Material ◽  
Corrosion Mechanism ◽  
Better Than

Corrosion resistance coefficient and expansion ratio of different cementitious materials are tested under the sulphate corrosion experimental condition, sulphate resistance of often-used cementitious material of high performance concrete for marine is studied and evaluated. The results show that sulphate resistance of portland cement is better than ordinary portland cement, and both of them are low, often-used cementitious material of high performance concrete for marine have certain sulphate resistance, which are better than ordinary portland cement and portland cement, and some of them have strong or very strong sulphate resistance. The evaluation results of the sulphate resistance of often-used cementitious material of high performance concrete for marine are not unanimous completely by corrosion resistance coefficient method and expansion rate method. Sulphate corrosion mechanism of different kinds of cementitious material is analyzed.

scholarly journals A Review of the Mechanical Properties and Durability of Ecological Concretes in a Cold Climate in Comparison to Standard Ordinary Portland Cement-Based Concrete

Materials ◽  
2020 ◽  
Vol 13 (16) ◽  
pp. 3467
Author(s):  
Ankit Kothari ◽  
Karin Habermehl-Cwirzen ◽  
Hans Hedlund ◽  
Andrzej Cwirzen
Keyword(s):  
Carbon Dioxide ◽  
Portland Cement ◽  
Ordinary Portland Cement ◽  
Cementitious Materials ◽  
Cold Climate ◽  
Supplementary Cementitious Materials ◽  
Short Exposure ◽  
Chemical Admixtures ◽  
Composite Cements ◽  
Alkali Activated

Most of the currently used concretes are based on ordinary Portland cement (OPC) which results in a high carbon dioxide footprint and thus has a negative environmental impact. Replacing OPCs, partially or fully by ecological binders, i.e., supplementary cementitious materials (SCMs) or alternative binders, aims to decrease the carbon dioxide footprint. Both solutions introduced a number of technological problems, including their performance, when exposed to low, subfreezing temperatures during casting operations and the hardening stage. This review indicates that the present knowledge enables the production of OPC-based concretes at temperatures as low as −10 °C, without the need of any additional measures such as, e.g., heating. Conversely, composite cements containing SCMs or alkali-activated binders (AACs) showed mixed performances, ranging from inferior to superior in comparison with OPC. Most concretes based on composite cements require pre/post heat curing or only a short exposure to sub-zero temperatures. At the same time, certain alkali-activated systems performed very well even at −20 °C without the need for additional curing. Chemical admixtures developed for OPC do not always perform well in other binder systems. This review showed that there is only a limited knowledge on how chemical admixtures work in ecological concretes at low temperatures and how to accelerate the hydration rate of composite cements containing high amounts of SCMs or AACs, when these are cured at subfreezing temperatures.

scholarly journals Coupled Preparation of Ferronickel and Cementitious Material from Laterite Nickel Ores

Materials ◽  
2020 ◽  
Vol 13 (21) ◽  
pp. 4992
Author(s):  
Ruimeng Shi ◽  
Xiaoming Li ◽  
Yaru Cui ◽  
Junxue Zhao ◽  
Chong Zou ◽  
...  
Keyword(s):  
Direct Reduction ◽  
Cementitious Materials ◽  
Tricalcium Silicate ◽  
Cementitious Material ◽  
Raw Material ◽  
Tricalcium Aluminate ◽  
Thermodynamic Conditions ◽  
Nickel Ores ◽  
Main Components ◽  
Factsage Software

Nickel slags can be produced through ferronickel preparation by the pyrometallurgical processing of laterite nickel ores; however, such techniques are underutilized at present, and serious environmental problems arise from the stockpiling of such nickel ores. In this study, a modification to the process of ferronickel preparation by the direct reduction of carbon bases in laterite nickel ores is proposed. The gangue from the ore is used as a raw material to prepare a cementitious material, with the main components of tricalcium silicate and tricalcium aluminate. By using FactSage software, thermodynamic calculations are performed to analyze the reduction of nickel and iron and the effect of reduction on the formation of tricalcium silicate and tricalcium aluminate. The feasibility of a coupled process to prepare ferronickel and cementitious materials by the direct reduction of laterite nickel ore and gangue calcination, respectively, is discussed under varying thermodynamic conditions. Different warming strategies are applied to experimentally verify the coupled reactions. The coupled preparation of ferronickel and cementitious materials with calcium silicate and calcium aluminate as the main phases in the same experimental process is realized.

scholarly journals Influence of Dimethacrylate Monomer on the Polymerization Efficacy of Resin-Based Dental Cements—FTIR Analysis

Polymers ◽  
2022 ◽  
Vol 14 (2) ◽  
pp. 247
Author(s):  
Aleksandra Maletin ◽  
Ivan Ristic ◽  
Tanja Veljovic ◽  
Bojana Ramic ◽  
Tatjana Puskar ◽  
...  
Keyword(s):  
Spectral Analysis ◽  
Clinical Practice ◽  
Chemical Structure ◽  
Cementitious Materials ◽  
Degree Of Polymerization ◽  
Cementitious Material ◽  
Ftir Analysis ◽  
Dental Cement ◽  
Polymerization Mechanism ◽  
The Difference

The degree of polymerization for dimethacrylate resin-based materials (BisGMA, TEGDMA, UDMA, HEMA) ranges from 55 to 75%. Literature data indicate that polymerization efficacy depends, among other factors, on the type of methacrylate resin comprising the material. The aim of this study was to evaluate the polymerization efficacy of four dental cement materials characterized by different polymerization mechanisms using FTIR analysis. In the present study, the FTIR method was adopted to analyze the degree of polymerization efficacy of four resin-based dental cement materials, two of which were self-cured and two were dual-cured cements. The IR spectral analysis was performed 24 h after the polymerization of the cementitious material. RelyX ARC cement exhibits the lowest polymerization efficacy (61.3%), while that of Variolink II (85.8%) and Maxcem Elite is the highest (90.1%). Although the efficacy of self-cured cements appears to be superior, the difference is not statistically significant (p = 0.280). Polymerization efficacy largely depends on the chemical structure of the material in terms of the presence of a particular methacrylate resin and less on the polymerization mechanism itself, i.e., whether it is a self-cured or dually cured dental cement. Thus, in clinical practice, cementitious materials with a higher proportion of TEGDMA compared with BisGMA are recommended.

Long term pollution simulation in combined sewer networks

2001 ◽  
Vol 43 (7) ◽  
pp. 83-89 ◽  
Author(s):  
B. Masse ◽  
M. Zug ◽  
J. P. Tabuchi ◽  
B. Tisserand
Keyword(s):  
Conceptual Model ◽  
Combined System ◽  
Sewerage System ◽  
Sewer Network ◽  
Reference Flow ◽  
Combined Sewer ◽  
Stream System ◽  
Long Time ◽  
Sewer Networks

This paper presents results of long term pollution simulations on the example of the sewerage system of Grand-Couronne. This modelling work is part of a study where objective is to develop a method to define the reference flow of a WWTP. The model HYDROWORKS DM™ has been successfully validated in hydraulics and pollution for the sewer network, for long time simulations. A conceptual model has been built to model the pollution in the tank at the outlet of the combined system. One synthetic year of rain has been used to simulate the working of the “up stream system” of the WWTP (combined sewer + tank + separate sewer + pre-treatments) and has been successfully validated by measurements of the 1998-1999 year. If this paper is focused on the “up stream system”, the SIMBA/SIMBAD WWTP model has been successfully calibrated and validated too, and the combination represents a fully validated “Integrated Model” for the sewerage system.

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