Cementa AB

Stockholm, Sweden

Cementa AB

Stockholm, Sweden
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Folli A.,Danish Technological Institute DTI | Folli A.,University of Aberdeen | Strom M.,Danish Technological Institute DTI | Madsen T.P.,Danish Technological Institute DTI | And 5 more authors.
Atmospheric Environment | Year: 2015

This paper reports the results of a field test study concerning the use of photocatalytic paving elements in Denmark to mitigate nitrogen oxides pollution. Prior to the installation, the photocatalytic concrete elements were tested in the lab, where conversions of NO reached values as high as 78% with low amount of NO2 formed. Once installed, nitrogen oxides concentration, temperature and relative humidity were monitored every minute for more than a year. The results of the field tests showed that under ideal weather and irradiation conditions, i.e. summer months, the monthly average NO concentration (based on day and night values) in proximity of the photocatalytic area was around 22% lower than the reference area. The close correlation between performance data and solar UV irradiance revealed that at such a latitude (55.68° N) adequate NO (hence NOx) conversions (monthly average) are achieved for total UV irradiance exceeding 600kJm-2day-1. Within this period, data relative to the solar noon showed instantaneous NO abatement in some cases higher than 45%, corresponding to a total NOx abatement higher than 30%. © 2015 .


Grant
Agency: European Commission | Branch: FP7 | Program: CP | Phase: ENV.2011.3.1.9-1 | Award Amount: 4.98M | Year: 2012

The goal of Light2CAT is to develop new, highly efficient visible-light-activated titanium dioxide for inclusion in concretes to be used in structures across the whole of Europe to improve ambient air quality independent, for the first time, of local climate conditions. The need to improve air quality in European Countries has been identified as a major requirement to be achieved within the next decade in the effort to control climate change, a key Europe 2020 strategy, and to improve human health. Despite vigorous efforts to reduce levels of hazardous substances in the air, targets remain a challenge. One of the most valid sustainable technologies explored so far is photocatalytic concrete. This technology is proven to reduce the amount of hazardous air pollutants up to 80 % . It also imparts self-cleaning properties to built structures which has a secondary effect of reducing harsh cleaning chemicals entering the water systems. However, the titanium oxide based photocatalytic building materials are activated by ultraviolet light so, to date, such environmental benefits are limited to countries with a high incidence of sunlight. The concept of this project is to extend the use of photocatalytic concretes to the whole of Europe by developing materials that can also be activated by visible light . The aim is to remove climate and seasonal considerations from the use of the materials and, through higher conversion efficiencies of the catalytic components, to reduce production costs facilitating further take up of the technology within existing markets. The results of the project are initially focused on use within the transport infrastructure where the greatest impact is expected. The consortium is well conceived to achieve the results, comprising research centres leading research in these materials and industry partners including SMEs able to develop, demonstrate and market the new materials in the sector.


Ekblad J.,NCC Roads AB | Lundstrom R.,NCC Roads AB | Simonsen E.,Cementa AB
Materials and Structures/Materiaux et Constructions | Year: 2015

Water affects asphalt pavements in a detrimental way and it is common knowledge that certain combinations of binder and aggregate can trigger premature failures. Asphalt manufacturing relies mainly on experience and continuous empirical testing. To reduce water sensitivity, adhesion promoters are frequently used. In this investigation, focus was on using portland cement and a by-product from cement manufacturing, cement kiln dust (CKD). The hypothesis was that water susceptibility is influenced by the grading of the hydraulically active fillers: a finer grading will give a stronger improvement. The experimental plan comprised, besides a reference material, 3 different cements and 2 CKDs. Water susceptibility was assessed with the tumbler abrasion test using mastic specimens. Potentially negative effects: decreased workability and degraded low temperature properties were investigated by measuring viscosity of filler/bitumen mixes and low temperature cracking properties, respectively. Admixing of hydraulic filler was made by partly replacing the base material filler with hydraulic filler, thus keeping the overall filler content unchanged. Results show that resistance to moisture damage is improved by adding hydraulically active fillers. However, the hypothesis of finer gradings giving stronger response was not supported; all three portland cements gave very similar results. Furthermore, it seems that fractions of added hydraulic filler above 1–1.5 % (mass of total aggregate) do not further increase abrasion resistance. Essentially, no potential drawbacks, decreased workability or increased low temperature cracking, were noted. © 2013, RILEM.


Hokfors B.,Umeå University | Hokfors B.,Cementa AB | Bostrom D.,Thermal Energy Conversion Laboratory | Viggh E.,Cementa AB | Backman R.,Thermal Energy Conversion Laboratory
Advances in Cement Research | Year: 2015

This paper describes the formation of a phosphorous belite solid solution and its impact on alite formation. A subsolidus phase relation for the ternary system silicon dioxide-calcium oxide-phosphorus pentoxide (SiO2-CaO-P2O5) is reported. The ternary system is based on Rietveld refinements of X-ray diffraction patterns from experimental tests. The overall picture is based on known phase diagrams, relevant Rietveld refinements models, stoichiometric relationships as a function of increasing phosphorus pentoxide concentration and vacancy theories for solid solutions of phosphate belites. A tool is developed for predicting the chemistry of the product as well as the chemistry during heating when producing Portland cement clinker. A thermodynamic database for phase chemistry calculations of clinkering reactions has been created and evaluated. Suitable compounds and solution species have been selected from the thermochemical database included in FactSage software. Some solution compositions have been uniquely designed to allow for the proper prediction of the cement clinker chemistry. The calculated results from the developed database for heating raw materials in cement clinker production and cooling of the product are presented in this paper. The calculated results provide a good prediction of the phases and quantities formed during heating and non-equilibrium cooling. The prediction of the amounts of alite, belite and aluminoferrite phases in the product according to the Scheil method is good. The temperature interval for the existence of all of the major phases is relevant. The thermodynamic data for a solution phase of alite with substituting ions of primarily magnesium oxide and phosphorus pentoxide would improve the predictability of the developed database. © 2015, Thomas Telford Services Ltd. All rights reserved.


Hokfors B.,Umeå University | Hokfors B.,Cementa AB | Viggh E.,Cementa AB | Eriksson M.,Umeå University
Advances in Cement Research | Year: 2015

A thermodynamic process model is used as an evaluation tool. Full oxy-fuel combustion is evaluated for circulation of 20-80% of flue gases to the burn zone of a rotary kiln. The full oxy-fuel combustion simulations exhibit altered temperature profiles for the process. With 60% recirculation of flue gases, the temperature in the burn zone is comparable to the reference temperature, and carbon dioxide concentration in the flue gases increases from 33 to 76%. If water is excluded, carbon dioxide concentration is 90%. The partial oxy-fuel combustion method is evaluated for 20 and 40% recirculation of flue gases from one cyclone string to both calciners. Fuel and oxygen feed to the burning zone and calciners are optimised for the partial oxy-fuel scenario. The lowest specific energy consumption is desired while maximising the amount of carbon dioxide theoretically possible to capture. By introducing partial oxy-fuel combustion with 20% recirculation of flue gases in the carbon dioxide string, total carbon dioxide emissions increases by 4%, with 84% possible to capture. Within the limits of the model, the introduction of full oxy-fuel and partial oxy-fuel combustion is possible while maintaining product quality. When simulating partial oxy-fuel combustion, the energy consumption will increase even when no power consumption for the production of oxygen is included. © 2015, Thomas Telford Services Ltd. All rights reserved.


Hokfors B.,Cementa AB | Hokfors B.,Umeå University | Eriksson M.,NorFraKalk | Viggh E.,Cementa AB | Viggh E.,Umeå University
Advances in Cement Research | Year: 2014

This paper presents a recently developed simulation model that can be used as a tool for evaluating sustainable development measures for cement and lime production processes. Examples of such measures are introducing new combustion technologies such as oxy-fuel combustion, using biomass fuel and using alternative materials in the raw material feed. One major issue when introducing process changes is the need to maintain product quality. In some ways, oxygen-enriched air combustion resembles oxy-fuel combustion. The model results were validated and found to be consistent with full-scale operational data for normal running conditions and for a full-scale test with oxygenenriched air. The model shows, for example, that with an additional 1500 m3/h of oxygen, fuel addition at the calciners can increase up to 108% and the raw material feed rate can increase up to 116% for a process with a raw meal feed of 335.5 t/h.


Lagerblad B.,Swedish Cement and Concrete Research Institute | Gram H.-E.,Cementa AB | Westerholm M.,Cementa AB
Construction and Building Materials | Year: 2014

Crushed rocks are, in general, more flaky and irregular in shape than natural aggregates. Especially granitic rocks display variable amounts or flaky free micas in the finer fractions when crushed. Moreover, the crushed rocks result in more fine material. Fillers can, in combination with superplasticizers and if the quality is appropriate be used to expand the paste phase of the concrete and thus be used to lower the cement consumption. To utilize the filler optimally one needs to evaluate the filler quality. There are several methods to evaluate the filler. In this article different methods both in regards to the material properties and the behavior in mortar and micro mortar tests are compared and evaluated. The analysis shows the importance of understanding the effect of both the particle shape and flakiness in the fine fractions and the properties of the material in the finest fraction i.e. <10 μm. This is very much related to the mineralogy of the rock. © 2013 Elsevier Ltd. All rights reserved.

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