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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. Source

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. Source

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. Source

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. Source

Assi L.,University of South Carolina | Ghahari S.,Purdue University | Deaver E.E.,Holcim Inc. | Leaphart D.,100 Maple Shade Ln | Ziehl P.,University of South Carolina
Construction and Building Materials | Year: 2016

Sustainable concrete has reduced CO2 emissions, is durable, and is expected to have less detrimental effect on future generations, due to the fact that it utilizes waste materials. However, the need for external heat limits construction applications. The effects of sodium hydroxide ratio, external heat amount, and partial Portland cement replacement on fly ash-based geopolymer concrete were investigated. The early compressive strength, density, absorption, and permeable voids were measured, and the microstructure of the fly ash-based geopolymer paste was observed and characterized. The activating solution was a combination of silica fume, sodium hydroxide, and water. Experimentation showed that application of external heat plays a major role in compressive strength. Results also show that early and final compressive strength gains, in case of absence of external heat, can be improved by using Portland cement as a partial replacement of fly ash. The Scanning Electron Microscopy (SEM) results showed that the addition of Portland cement utilized the free water from the geopolymerization reaction. It not only led to a reduction in the microcracks formation due to less shrinkage, but also provided extra alkalinity, such as calcium hydroxide, which helped accelerate the fly ash and the activating solution reaction. Additionally, the permeable void ratio is affected by the Portland cement replacement, showing a significant reduction when the Portland cement ratio is increased. © 2016 Elsevier Ltd Source

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