scholarly journals Assessing the effect of a white Portland cement admixture on the early frost-thaw resistance of NHL-based masonry mortar

2021 ◽  
Vol 55 (1) ◽  
Author(s):  
Frowin Ruegenberg ◽  
Martin Schidlowski ◽  
Franz Brunner ◽  
Erik Kirkwood ◽  
Thomas Bidner ◽  
...  
Keyword(s):  
Portland Cement ◽  
Setting Time ◽  
Winter Season ◽  
Weather Conditions ◽  
Atmospheric Conditions ◽  
Hydraulic Lime ◽  
Natural Hydraulic Lime ◽  
Excess Moisture ◽  
Speed Up ◽  
Framework Conditions

AbstractWell preserved mortars based on natural hydraulic lime are widely spread in historical buildings throughout the alpine area of Tyrol, Austria. These are frequently restored with mortars oriented on historical models. Portland cement is also commonly used to modify these materials on building sites to speed up the setting time to improve the early frost-thaw resistance, primarily when they are applied around the winter season. Therefore, it was our objective to specify the application potentials of those materials, respecting the intended use and the atmospheric conditions. Moreover, we tried to figure out the possible benefits and risks when using NHL-based materials, optionally modified by cement, yielding stable recommendations for the work with corresponding mortars. Hence, we examined the development of strength and water transport, also the frost-thaw durability in a temporal context. The obtained results were compared with findings of assessing both materials under variable weather conditions around the winter season. Accordingly, the use of pure NHL-based lime mortars resulted as being critical mainly until about two months before intense frost conditions. Cement effectively contributes to the rapid hydraulic setting reaction in NHL-based materials. Hence, we recommend measured cement additions in areas where strong frost is expected after a few weeks and especially targeted in areas where carbonation is hindered because of excess moisture. Nevertheless, the potential use of Portland cement should be properly controlled in historic building preservation. A systematical approach that considers the framework conditions and the corresponding application to an area is essential to assure an appropriate conservation outcome.

Lime-Based Materials and Practices for Surface Refitting of Cultural Heritage

2010 ◽  
Vol 133-134 ◽  
pp. 1241-1246 ◽  
Author(s):  
Shi Bing Dai ◽  
Jin Hua Wang ◽  
Yuan Hu ◽  
De Bing Zhang
Keyword(s):  
Cultural Heritage ◽  
High Performance ◽  
Weather Conditions ◽  
Historic Buildings ◽  
Material System ◽  
Hydraulic Lime ◽  
Historical Materials ◽  
Carbonation Process ◽  
Natural Hydraulic Lime ◽  
Optimal Material

The surface of cultural heritage and façade of historic buildings represent most values. The conservation of such surfaces need special cares, because most of them are non-structural exposed to extreme weather conditions. The refitting and consolidation delaminated surface were carried out using organic resins, like epoxy resins or cement suspension. However the evaluation in the recent years show such kinds of materials are not chemically compatible with historical materials. Based on inspection on cracks of Huashan’s Pictographs and other historic buildings in Shanghai and Hangzhou, a new system composed of adhesives and injection grouts based on natural hydraulic lime (NHL) has been developed for refitting and rehabilitation of delaminated surfaces made of natural stones, plaster and bricks. The laboratory researches and trial areas on site have shown the adhesives based on modified NHL have sufficient bonding strength to hold delaminated stone slices and blocks. Furthermore, they show slow setting and carbonation process, almost same heat expansion coefficient as the lime stone and inorganic historical materials. After exposure of 135days on site, the trial areas show neither cracking nor efflorescence. The application of developed adhesives and injection grouts in the restoration work of historic Shanghai plaster gates of Jiuxinli in Hangzhou, Zhejinag Province, has been observed positively. Because of high performance and competitive price against organic resins, they are expected to be an optimal material system in the future for façade restoration of architectural heritage and monuments.

scholarly journals Effect of Aluminium Dross on Workability and Setting Time of Cement and Concrete

2021 ◽  
Vol 9 (VII) ◽  
pp. 1851-1859
Author(s):  
Panditharadhya B J
Keyword(s):  
Portland Cement ◽  
Ordinary Portland Cement ◽  
Positive Impact ◽  
Setting Time ◽  
Waste Product ◽  
Weather Conditions ◽  
Industrial Wastes ◽  
Raw Material ◽  
Partial Replacement ◽  
Aluminium Dross

Aluminium dross is generated when resmelting process is done in an aluminium industry to recover residual aluminium, wherein primary dross is taken as a raw material. It is completely a waste product and hazardous to dispose it into landfills. This is rich in aluminium oxide and having traces of few heavy metals. It is necessary to check the eco-friendly methods of solidification of this material. One of the feasible methods of solidifying the industrial wastes is using them in production of cement concrete. In this study, behaviour of aluminium dross as a partial replacement for Ordinary Portland Cement is evaluated. Aluminium dross is replaced at 5, 10, 15 and 20% of Ordinary Portland Cement. Consistency and setting time of cement paste samples were determined which shows a lag in setting time of paste. Workability and setting time of concrete mixes with 5, 10, 15 and 20% of Aluminium dross as a binder, were evaluated. Retardation of setting time and increase in the workability are the main observations of this study. As the percentage of aluminium dross increases, the setting time also increases. This may be considered as a reason to utilize such concrete mixes in hot weather conditions wherein delayed setting time is an added advantage. Therefore, retardation of setting time is the positive impact of aluminium dross. Keeping in view of the fact that there can be a reduction in strength with increased binder replacement and the workability requirements, only up to 20% of aluminium dross was replaced in the present study.

scholarly journals Developing a Department of Transportation Winter Severity Index

2019 ◽  
Vol 58 (8) ◽  
pp. 1779-1798 ◽  
Author(s):  
Curtis L. Walker ◽  
Dylan Steinkruger ◽  
Pouya Gholizadeh ◽  
Sogand Hasanzedah ◽  
Mark R. Anderson ◽  
...  
Keyword(s):  
Winter Season ◽  
Weather Conditions ◽  
Severity Index ◽  
Meteorological Variables ◽  
Atmospheric Conditions ◽  
Department Of Transportation ◽  
Weather Sensitivity ◽  
Adverse Weather ◽  
Vehicular Crashes ◽  
Winter Severity

AbstractAdverse weather conditions are responsible for millions of vehicular crashes, thousands of deaths, and billions of dollars per year in economic and congestion costs. Many transportation agencies utilize a performance or mobility metric to assess how well they maintain road access; however, there is only limited consideration of meteorological impacts to the success of their operations. This research develops the Nebraska winter severity index (NEWINS), which is a daily event-driven index derived for the Nebraska Department of Transportation (NDOT). The NEWINS includes a categorical storm classification framework to capture atmospheric conditions and possible road impacts across diverse spatial regions of Nebraska. A 10-yr (2006–16) winter season database of meteorological variables for Nebraska was obtained from the National Centers for Environmental Information. The NEWINS is based on a weighted linear combination applied to the collected storm classification database to measure severity. The NEWINS results were compared to other meteorological variables, many used in other agencies’ winter severity indices. This comparison verified the NEWINS robustness for the observed events for the 10-yr period. An assessment of the difference between days with observed snow versus days with accumulated snow revealed 39% fewer snow-accumulated days than snow-observed days. Furthermore, the NEWINS results highlighted the greater number of events during the 2009/10 winter season and the lack of events during the 2011/12 winter season. It is expected that the NEWINS could help transportation personnel allocate efficiently resources during adverse weather events. Moreover, the NEWINS framework can be used by other agencies to assess their weather sensitivity.

scholarly journals Influence of Meteorological Conditions and Aerosol Properties on the COVID-19 Contamination of the Population in Coastal and Continental Areas in France: Study of Offshore and Onshore Winds

Atmosphere ◽  
2021 ◽  
Vol 12 (4) ◽  
pp. 523
Author(s):  
Jacques Piazzola ◽  
William Bruch ◽  
Christelle Desnues ◽  
Philippe Parent ◽  
Christophe Yohia ◽  
...  
Keyword(s):  
Atmospheric Transport ◽  
Weather Conditions ◽  
Meteorological Conditions ◽  
Sea Spray ◽  
Atmospheric Conditions ◽  
Virus Transport ◽  
Virus Propagation ◽  
Viral Particles ◽  
The Social ◽  
Aerosol Properties

Human behaviors probably represent the most important causes of the SARS-Cov-2 virus propagation. However, the role of virus transport by aerosols—and therefore the influence of atmospheric conditions (temperature, humidity, type and concentration of aerosols)—on the spread of the epidemic remains an open and still debated question. This work aims to study whether or not the meteorological conditions related to the different aerosol properties in continental and coastal urbanized areas might influence the atmospheric transport of the SARS-Cov-2 virus. Our analysis focuses on the lockdown period to reduce the differences in the social behavior and highlight those of the weather conditions. As an example, we investigated the contamination cases during March 2020 in two specific French areas located in both continental and coastal areas with regard to the meteorological conditions and the corresponding aerosol properties, the optical depth (AOD) and the Angstrom exponent provided by the AERONET network. The results show that the analysis of aerosol ground-based data can be of interest to assess a virus survey. We found that moderate to strong onshore winds occurring in coastal regions and inducing humid environment and large sea-spray production episodes coincides with smaller COVID-19 contamination rates. We assume that the coagulation of SARS-Cov-2 viral particles with hygroscopic salty sea-spray aerosols might tend to inhibit its viral infectivity via possible reaction with NaCl, especially in high relative humidity environments typical of maritime sites.

The influence of weather conditions on mid-field ponds situated in a reclaimed area in Sępopolska Plain

2010 ◽  
Vol 39 (1) ◽  
Author(s):  
Ireneusz Cymes ◽  
Iwona Cymes ◽  
Ewa Dragańska ◽  
Sławomir Szymczyk
Keyword(s):  
Weather Conditions ◽  
Negative Influence ◽  
Ammonium Nitrogen ◽  
Water Evaporation ◽  
Atmospheric Conditions ◽  
Natural Reservoir ◽  
Quality Of Water ◽  
Water Ph ◽  
Chlorine Ions ◽  
Agricultural Areas

The influence of weather conditions on mid-field ponds situated in a reclaimed area in Sępopolska PlainThe investigations were conducted in northeastern Poland near Lidzbark Warmiński (54° 08" N, 20° 36" E). Five mid-field ponds situated on grasslands were chosen: four of them were dredged and deepened, and one of them remained as a natural reservoir. The aim of this paper was to assess the influence of weather conditions on the quantity and quality of water in mid-field ponds situated in agricultural areas. It was found that the quantity of water in mid-field ponds was related much more to the air temperature, which was responsible for either water evaporation or snow melting, rather than to the amount of precipitation. The reduction in the volume of water stored in the ponds during very dry years had a negative influence on its quality. During the observation period, the dredged ponds were characterized by permanent water tables, whereas the natural reservoir dried out in very dry years. Atmospheric conditions influenced the concentrations of ammonium nitrogen and calcium and chlorine ions in the studied water bodies. The volume of water retained in mid-field ponds influenced the concentrations of phosphorus and sulphates. Increased precipitation sums caused lower water pH; however in warmer periods, at increased pH and COD

Preparation of Alternative Hydraulic Binder Based on Secondary Raw Materials

2014 ◽  
Vol 1000 ◽  
pp. 12-15
Author(s):  
Jiří Švec ◽  
Tomáš Opravil ◽  
Jiří Másilko
Keyword(s):  
Portland Cement ◽  
Raw Materials ◽  
Construction Materials ◽  
High Volume ◽  
Point Of View ◽  
Hydraulic Lime ◽  
Combustion Gases ◽  
Secondary Raw Materials ◽  
Hydraulic Binder ◽  
Massive Scale

Reusing and recycling of secondary raw materials from high-volume industrial productions (especially form construction materials and binders fabrications) is very important way of conserving environment and it is also interesting from the economical point of view. The production of common hydraulic binders, especially Portland cement, burdens the environment with considerable amount of combustion gases and consumes energy in massive scale. Alternative (low – energy) binder can be used as Portland cement substitution in applications with lower mechanical properties requirements. Mined limestone wash sediments contain large amount of clay components, but there is also indispensable share of fine calcite. This composition makes these sediments a promising material for the preparation of hydraulic binders as Roman cement or hydraulic lime.

scholarly journals Bond Properties of NHL-Based Mortars with Viscosity-Modifying Water-Retentive Admixtures

Minerals ◽  
2021 ◽  
Vol 11 (7) ◽  
pp. 685
Author(s):  
Tomáš Žižlavský ◽  
Patrik Bayer ◽  
Martin Vyšvařil
Keyword(s):  
Water Content ◽  
Adhesive Strength ◽  
Water Retention ◽  
Minor Role ◽  
Clay Brick ◽  
Hydraulic Lime ◽  
Natural Hydraulic Lime ◽  
Binder Ratio ◽  
Paste Viscosity ◽  
A Minor

This article studies the influence of biopolymeric viscosity-modifying admixtures with water-retentive function on the physico-mechanical properties of natural hydraulic lime-based mortars and their adherence to the traditional fired-clay brick substrate. The use of admixtures increases the water/binder ratio, which in turn leads to a decrease in the strength of the mortars. The viscosity-modifying function improves the adhesive strength between mortar and pre-wetter brick by increasing the binder paste viscosity, while the water-retentive function along with increased water content may lead to a decrease in adhesive strength. On the contrary, water retention and increased water content are beneficial on a dry surface, while paste viscosity plays only a minor role. When subjected to temperature-varying cycles, the mortars are more prone to in-mortar failure during the pull-off test. The air-entraining function of some admixtures improves the frost resistance of the mortars; however, it would negatively affect the adhesive strength by incorporating pores into the contact zone between the mortar and brick substrate. This study showed that the use of some of the studied admixtures may improve the adhesion of mortar to the brick substrate.

Utilization of Circulating Fluidized Bed Combustion (CFBC) Fly Ash and Coal-Fired Fly Ash in Portland Cement

2014 ◽  
Vol 629-630 ◽  
pp. 306-313 ◽  
Author(s):  
Mao Chieh Chi ◽  
Ran Huang ◽  
Te Hsien Wu ◽  
Toun Chun Fou
Keyword(s):  
Fly Ash ◽  
Portland Cement ◽  
Fluidized Bed ◽  
Building Materials ◽  
Circulating Fluidized Bed ◽  
Setting Time ◽  
Fluidized Bed Combustion ◽  
Initial Setting Time ◽  
Cfbc Fly Ash ◽  
Circulating Fluidized Bed Combustion

Circulating fluidized bed combustion (CFBC) fly ash is a promising admixture for construction and building materials due to its pozzolanic activity and self-cementitious property. In this study, CFBC fly ash and coal-fired fly ash were used in Portland cement to investigate the pozzolanic and cementitious characteristics of CFBC fly ash and the properties of cement-based composites. Tests show that CFBC fly ash has the potential instead of cementing materials and as an alternative of pozzolan. In fresh specimens, the initial setting time of mortars increases with the increasing amount of cement replacement by CFBC fly ash and coal-fire fly ash. In harden specimens, adding CFBC fly ash to replace OPC reduces the compressive strength. Meanwhile, CFBC fly ash would results in a higher length change when adding over 30%. Based on the results, the amount of CFBC fly ash replacement cement was recommended to be limited below 20%.

Sign in / Sign up

Export Citation Format

Share Document