Assi L.N.,University of South Carolina |
Deaver E.,Holcim Inc. |
Elbatanouny M.K.,Wiss, Janney, Elstner Associates, Inc. |
Ziehl P.,University of South Carolina
Construction and Building Materials | Year: 2016
Development of sustainable construction materials has been the focus of research efforts worldwide in recent years. Concrete is a major construction material; hence, finding alternatives to ordinary Portland cement is of extreme importance due to high levels of carbon dioxide emissions associated with its manufacturing process. This study investigates the effects of activating solution type, curing procedure, and source of fly ash in relation to the resulting compressive strength of fly ash-based geopolymer concrete. The fly ash-based geopolymer paste microstructure was observed and density, absorption and voids were measured. Two activating solutions were used: a) a mixture of sodium hydroxide, silica fume, and water; and b) a mixture of sodium hydroxide solution, sodium silicate, and water. Test results indicate that the resulting concrete has the potential for high compressive strength and the compressive strength is directly affected by the source of fly ash. Results further indicate that compressive strength is not significantly affected by the curing condition when silica fume is used in the activating solution in comparison to the use of sodium silicate. © 2016 Elsevier Ltd. All rights reserved.
Akhtar S.S.,Holcim Inc. |
Ervin E.,Holcim Inc. |
Raza S.,Cinar Ltd. |
Abbas T.,Cinar Ltd.
IEEE Transactions on Industry Applications | Year: 2016
In the North American energy market, natural gas (NG) prices have been gradually decreasing during the past several years, primarily due to advances in shale gas extraction techniques. The availability of cheaper NG, while seen as an attractive short-term fuel switching option, is viewed with caution by most cement plants due to long-term procurement concerns. Also, due to traditionally higher NG prices, cement plants have invested heavily into solid fuels, including storage, grinding, handling, and dosing systems - often achieving high thermal substitution rates (TSRs) of solid alternative fuels and raw materials (AFRs). As a result, a wealth of knowledge has been acquired on firing solid fuels, including some of the more difficult ones, e.g., higher sulfur petcoke and bigger size AFRs, where operational issues such as build-ups, emissions, and production losses have been and are being minimized. Switching to gas firing, however, requires readaptation of combustion and process guidelines for a fuel which, although in principal, is easier to burn, but has relatively lower radiative heat transfer and sharper burning characteristics than coal. As such, the plants, which have switched to NG firing, have observed inconsistent trends in production, energy, and emission performance, mainly due to the lack of sufficient information on combustion/process interactions of the two fuel types required for cost-effective optimization. An NG flame ignites earlier, releases intense heat but lacks dissipation of heat as compared with a solid fuel flame, thereby requires plant specific adjustments. This paper presents actual results of NG firing trials at selected cement plants along with mineral interactive computational fluid dynamics (MI-CFD) predictions, subsequent to validation from the plant data, on four kiln and four calciners. Recommendations are also made to improve and optimize NG firing by taking into considerations of the combustion and mineral interactions. © 2015 IEEE.
Lyons B.,Holcim Inc. |
Bierie G.,Global Conveyor Technologies and Training |
Marti A.,Technical Writer
IEEE Cement Industry Technical Conference (Paper) | Year: 2015
Belt conveyors are basically a thick rubber band, stretched at high tension and threaded through a thicket of rolling components, moving at high speed, carrying literally tons of unconfined material from where the cargo is thrown on the belt to the point where it is pitched off the belt. Accordingly, belt conveyors contain a variety of safety hazards. But because conveyors are an everyday fact of life in a cement plant, the hazards often go unrecognized, and personnel who must work on and around the conveyors go untrained. This presentation will look at the benefits of employee training to improve conveyor safety for those who work on or around belt conveyors, and for those or who manage the performance of belt conveyor systems. It will look at the fundamentals of adult educationsmall group, interactive, hands-on education-And how these principles can be applied to improve the worker training program covering belt conveyor operations, maintenance, and safety. The presentation will discuss conveyor training programs conducted recently at cement plants, detailing both how the training was supplied, and the lessons learned-by attendees and by plant management. © 2015 IEEE.
Howard I.L.,Mississippi State University |
Cost T.,Holcim Inc.
Geotechnical Special Publication | Year: 2014
Very high moisture content fine grained soils, or VHMS, stabilized with portland cement are the focus of this paper. The key item investigated is cement sulfate (SO3) content and the potential to improve very early strength of stabilized VHMS by reducing the SO3 content of a given cement facility relative to normal production. Sulfate solubility is inversely proportional to temperature, i.e., solubility decreases as temperature increases, and a typical cement could, in traditional uses, experience sulfate demands in excess of those that would occur in VHMS. Therefore, the objective of this paper is to present a laboratory study for VHMS where strength and stability properties are evaluated after curing specimens at different temperatures while stabilized with cements from one facility containing different SO3 contents. Complimentary thermal profile testing is also performed on cement paste. The key finding from unconfined compression testing was that SO3 contents from 2.2 to 4.7% responded in the same overall manner to temperature when used to stabilize VHMS. © 2014 American Society of Civil Engineers.
Sullivan W.G.,Mississippi State University |
Cost T.,Holcim Inc. |
Howard I.L.,Mississippi State University
Geotechnical Special Publication | Year: 2012
This paper's objective is to document thermal profile testing on soil slurries stabilized with portland cement. Thermal profile testing as used herein is sometimes referred to as semi-adiabatic calorimetry (SAC). SAC has become popular for cement paste and mortar evaluation but has seen little use for stabilized soil applications. Test mixtures included three fine grained soils with moisture contents of 100 to 233% and nine different portland cements at contents of 3 to 15% by unstabilized slurry mass. Five SAC equipment options were investigated to compare suitability. The most appropriate set of equipment was further evaluated over an extended range of conditions. Methods to extrude the specimens from plastic molds after one day of thermal measurement were also investigated to allow unconfined compression (UC) testing to be performed on the same specimens. The equipment devised is economical, portable, and requires minimal operator skill. Results demonstrate SAC techniques are effective means to observe thermal profiles of cement stabilized soil slurry and show merit for a variety of applications including quality control. © 2012 American Society of Civil Engineers.
Safariyeganeh S.,DuPont Company |
Lovett C.J.,Holcim Inc.
IEEE Transactions on Industry Applications | Year: 2015
The U.S. Environmental Protection Agency has adopted revised emission limits to the National Emission Standards for Hazardous Air Pollutants (NESHAP) for the Portland cement manufacturing industry and revised emission limits to the New Source Performance Standards (NSPS) for Portland cement plants. These changes revise the emission limits for specified air pollutants for new and existing cement plants. The NESHAP regulations address the emission limits for materials such as mercury, total hydrocarbons (THCs), hydrochloric acid (HCl), and particulate matter. The NSPS address particulate matter, opacity, nitrogen oxides (NOx), and sulfur dioxide (SO2). Herein, a case study is presented in which a novel environmental technology was utilized to help achieve SO2 removal efficiencies in excess of 97% for a cement plant located in the United States. A slurry scrubber was specified for this application due to its unique ability to achieve high removal efficiencies for SO2-rich waste gases, using a low-cost reagent. Additional capabilities of this system specific to the cement industry are also discussed, such as hot gas quenching, particulate removal, and resistance to the corrosive, abrasive, and thermally intense environments often found in cement plants. © 1972-2012 IEEE.
Lamare T.,Holcim Inc. |
Moser M.,Holcim Inc.
ZKG International | Year: 2015
With the use of remote-controlled drones, cement producers now have a new tool to help increase productivity in daily operations, by providing faster and more accurate results in various applications that previously required skilled and expensive external service providers. © 2015, Bauverlag GmbH. All rights reserved.
Jerrels J.,Holcim Inc. |
Walden K.,Holcim Inc.
IEEE Cement Industry Technical Conference (Paper) | Year: 2013
Cement operations increasingly depend on contractor companies to provide specialized skills and expertise. However, relying on contractors carries associated safety risks that are gaining the attention of organizations. If not managed, these risks can lead to regulatory issues, productivity issues, legal action, and eventually a serious injury or death. While cement companies and their contractors have the same objective as it pertains to safety to prevent all injuries and accidents it is ultimately the cement companies that determine whether contractors put safety first. This paper identifies methods through which cement operators may effectively manage the risks associated with utilizing contractors to improve safety results. Topics include managing the contractor during selection and qualification, setting site work expectations, setting enforcement guidelines, and establishing channels of communication. © 2013 IEEE.
Walden K.,Holcim Inc.
IEEE Cement Industry Technical Conference (Paper) | Year: 2010
The construction is almost complete on the largest single clinker production line in the world. At 12,000 metric tons per day clinker and 4 million metric tons annual cement capacity, this massive greenfield plant was built by Holcim in the United States along the Mississippi River in Ste. Genevieve County, Missouri. The uniqueness of this undertaking is not only the size, but also the strict efficiency goals and environmental regulations that apply to the site development, construction, and operation. Preliminary evaluation of the Ste. Genevieve project began in the late 1990's, and Holcim ultimately underwent a six year process of reviews and permits involving eight federal and state regulatory agencies. With all permits finally in hand, Holcim awarded a contract in early 2006 to engineering and equipment supplier for all the main and auxiliary mechanical and electrical equipment as well as engineering services, training, and commissioning The focal point of the plant is the single pyroprocess system with new generation clinker cooler and in-line preheater with low NOx and CO calciner. Furthermore, the supply of four (4) vertical roller mills for cement grinding reinforced this commitment for the most energy efficient solution setting a market standard for finish cement grinding. Because the plant is meeting emission limits among the lowest permitted for any cement plant in the United States and the world, any environmental impact is minimized. In addition, approximately 2200 acres (55% of the total property's acreage) is preserved in its natural condition for the entire life of the plant. The success of the Ste. Genevieve project was based on the strong partnership and open relationship that has been developed between Holcim and the supplier. Start-up of the plant occurred in August 2009. The kiln and all auxiliary circuits had achieved steady state operation by September 2009 at or above design parameters. With a foundation of a sound technical solution and combined worldwide resources, this extraordinary project is now a source of pride for all parties involved. The new facility in Ste. Genevieve County is operated by Holcim (US) Inc., a subsidiary of Holcim Ltd. of Switzerland. With majority and minority interests in over 70 countries on all continents, Holcim Ltd. is one of the world's leading suppliers of cement, as well as aggregates (gravel and sand), concrete and construction-related services. ©2010 IEEE.
Holcim Inc. | Date: 2013-07-16
computer application software for mobile phones and other electronic devices for use in the simulation of mortar and masonry images.