scholarly journals Effects of Using Pozzolan and Portland Cement in the Treatment of Dispersive Clay

2013 ◽  
Vol 2013 ◽  
pp. 1-10 ◽  
Author(s):  
A. H. Vakili ◽  
M. R. Selamat ◽  
H. Moayedi
Keyword(s):  
Portland Cement ◽  
Cement Content ◽  
Construction Material ◽  
Curing Time ◽  
Clay Sample ◽  
Optimum Amount ◽  
Simultaneous Treatment ◽  
Long Term Performance ◽  
Term Performance

Use of dispersive clay as construction material requires treatment such as by chemical addition. Treatments to dispersive clay using pozzolan and Portland cement, singly and simultaneously, were carried out in this study. When used alone, the optimum amount of pozzolan required to treat a fully dispersive clay sample was 5%, but the curing time to reduce dispersion potential, from 100% to 30% or less, was 3 month long. On the other hand, also when used alone, a 3% cement content was capable of reducing dispersion potential to almost zero percent in only 7 days; and a 2% cement content was capable of achieving similar result in 14 days. However, treatment by cement alone is costly and could jeopardize the long term performance. Thus, a combined 5% pozzolan and 1.5% cement content was found capable of reducing dispersion potential from 100% to zero percent in 14 days. The results indicate that although simultaneous treatment with pozzolan and cement would extend the required curing time in comparison to treatment by cement alone of a higher content, the task could still be carried out in a reasonable period of curing time while avoiding the drawbacks of using either pozzolan or cement alone.

Long-term performance of moderate heat Portland cement with double-expansive sources

2007 ◽  
Vol 22 (1) ◽  
pp. 35-39 ◽  
Author(s):  
Qing Ye ◽  
Huxing Chen ◽  
Deyu Kong ◽  
Shangxian Wang ◽  
Zonghan Lou
Keyword(s):  
Portland Cement ◽  
Long Term Performance ◽  
Term Performance

scholarly journals Alkali-activated materials: the role of molecular-scale research and lessons from the energy transition to combat climate change

2020 ◽  
Vol 4 ◽  
pp. 110-121 ◽  
Author(s):  
Claire White
Keyword(s):  
Portland Cement ◽  
Financial Incentives ◽  
Field Performance ◽  
Energy Transition ◽  
Combat Climate Change ◽  
Long Term Performance ◽  
Term Performance ◽  
Alkali Activated

Alternative (i.e., non-Portland) cements, such as alkali-activated materials, have gained significant interest from the scientific community due to their proven CO2 savings compared with Portland cement together with known short-term performance properties. However, the concrete industry remains dominated by Portland cement-based concrete. This Letter explores the technical and non-technical hurdles preventing implementation of an alternative cement, such as alkali-activated materials, in the concrete industry and discusses how these hurdles can be overcome. Specifically, it is shown that certain technical hurdles, such as a lack of understanding how certain additives affect setting of alkali-activated materials (and Portland cement) and the absence of long-term in-field performance data of these sustainable cements, can be mitigated via the use of key molecular- and nano-scale experimental techniques to elucidate dominant material characteristics, including those that control long-term performance. In the second part of this Letter the concrete industry is compared and contrasted with the electricity generation industry, and specifically the transition from one dominant technology (i.e., coal) to a diverse array of energy sources including renewables. It is concluded that financial incentives and public advocacy (akin to advocacy for renewables in the energy sector) would significantly enhance uptake of alternative cements in the concrete industry.

EFFECTS OF CLAY ON PROPERTIES OF CONCRETE

2017 ◽  
Vol 4 (1) ◽  
Author(s):  
Ayub Elahi ◽  
Atizaz Ali
Keyword(s):  
Construction Material ◽  
Harmful Effect ◽  
Clay Content ◽  
Acid Attack ◽  
Concrete Properties ◽  
Compressive Strength Of Concrete ◽  
Long Term Performance ◽  
Term Performance ◽  
Different Levels

Concrete is a versatile and most prevalent construction material. Its long-term performance depends on its interactions with the surrounding environment. The standards limit the ratio of the clay in aggregates due to its harmful effect on the concrete properties. This research paper presents the effect of different levels of clay addition on the concrete properties. Various levels of clay addition for different mixes were used in this experimental study. The effect of clay addition on workability, compressive strengths permeability and acid attack of concrete mixes was investigated. It has been seen that workability decreased by increasing the clay content to the mix. A drop in compressive strength of concrete up to 12% was observed by adding clay as compared with that of control samples. An adverse effect on resistance to permeability and acid attack of concrete was noted by increasing the clay content.

Estimation of Longevity of Portland Cement Grout Using Chemical Modeling Techniques

1989 ◽  
Vol 176 ◽  
Author(s):  
S. R. Alcorn ◽  
W. E. Coons ◽  
M.A. Gardiner
Keyword(s):  
Portland Cement ◽  
Empirical Relation ◽  
Practical Experience ◽  
Cement Grout ◽  
Chemical Degradation ◽  
Chemical Modeling ◽  
Fast Flow ◽  
Long Term Performance ◽  
Term Performance

ABSTRACTPortland cement has been identified as a likely candidate seal material by programs investigating the deep burial of nuclear waste as a disposal mechanism. The longevity of performance of cement grout is currently being investigated, along with bentonite, under the auspices of the Stripa Project. Coordinated laboratory, field, and modeling studies are underway to produce fundamental data, practical experience, and estimates of long-range performance, respectively. Long-term performance of cement grout is of particular concern. Since most of the solid phases of which grout is comprised are metastable, it is likely that grout performance will decrease with time. The question is whether performance will still be acceptable after this decrease. This issue is being addressed with the coupled use of geochemical and permeability modeling. For a simplified cement system, two mechanisms for chemical degradation have been considered: phase change and dissolution. For dissolution, both equilibrium (slow flow) and open (fast flow) systems have been analyzed as bounding scenarios. Granitic terrain groundwaters ranging from fresh to saline have been used in the analyses. To assess the consequences in terms of flow, an empirical relation between cement permeability and porosity has been developed. Performance changes with time have been predicted by making conservative estimates of local hydraulic head conditions for successive periods of repository history. For the granitic rock environments considered, preliminary results indicate that cement grout performance may be acceptable for tens of thousands to millions of years, providing its initial hydraulic conductivity is on the order of 10−12 m/s. Other conditions favoring long-term performance include minimizing the ettringite content of the grout, and emplacement at a site where the groundwater has an elevated TDS, and where the local hydraulic gradient is flat or repository resaturation times are short.

Practical Recycling Application of Power Plant Coal Ash for High Performance Shotcrete Material

2009 ◽  
Vol 620-622 ◽  
pp. 251-254
Author(s):  
Cheol Woo Park ◽  
Kyung Nam Kim
Keyword(s):  
Silica Fume ◽  
High Performance ◽  
Power Plants ◽  
Construction Material ◽  
Coal Ash ◽  
Test Results ◽  
Replacement Ratio ◽  
Long Term Performance ◽  
Term Performance

This study intends to increase the consumption of coal ash which is an industrial by-product from power plants. The coal ash used to be deposited in the ground and its recycling has been very poor comparing to the produced amount. This study aims to enhance practical application of coal ash as a shotcrete construction material. Derived were optimum mix proportions for high performance shotcrete using coal ash. In order to enhance long term performance, silica fume was also added. Experimental variables included replacement ratio of silica fume and coal ash. Compressive strength and potential hazardous contamination to soil were the primary factors in the performance evaluation. From the test results, when fly ash was replaced up to 10% of the cement, most required specifications were satisfied. Hazardous material content was shown to be well below the specifications. Therefore, when appropriate caution in handling is given in the field, it is strongly anticipated to increase the coal ash recycling as a shotcrete construction material.

Fine Particle Mass Monitoring with Low-Cost Sensors: Corrections and Long-Term Performance Evaluation

2019 ◽  
Author(s):  
Carl Malings ◽  
Rebecca Tanzer ◽  
Aliaksei Hauryliuk ◽  
Provat K. Saha ◽  
Allen L. Robinson ◽  
...  
Keyword(s):  
Performance Evaluation ◽  
Fine Particle ◽  
Low Cost ◽  
Particle Mass ◽  
Long Term Performance ◽  
Term Performance

Long-term performance of the Hancock bioprosthetic conduit for aortic root replacement

2008 ◽  
Vol 56 (S 1) ◽  
Author(s):  
CC Badiu ◽  
W Eichinger ◽  
D Ruzicka ◽  
I Hettich ◽  
S Bleiziffer ◽  
...  
Keyword(s):  
Aortic Root ◽  
Aortic Root Replacement ◽  
Long Term Performance ◽  
Term Performance
Sign in / Sign up

Export Citation Format

Share Document