Papers by Keyword: Eco-Cement

Abstract: Portland cement production leads to significant carbon dioxide emission and greenhouse effect. Magnesium oxide eco-cement, which is a mixture of Portland cement, magnesium oxide and fly ash, may be an alternative production. In this paper, the issue is focused on the carbon dioxide absorption ability and mechanical performance of this eco-cement. Several mix proportions of eco-cement were designed to conduct forced carbonation, strength and expansion tests. Also, microstructure analysis after carbonation was conducted. The results indicate that magnesium oxide eco-cement can efficiently absorb carbon dioxide and carbonation can improve mechanical performance substantially, also expansion of the eco-cement is found to fall within the safe limits and possesses good stability and soundness.

Abstract: The research program developed by the authors and presented in this paper designate the Bahlui clay Romania fitting the clays with specific behaviour such as the Addis Ababa clay, London clay, Dharwad clay, New Yorkshire clay, Ankara clay and Weald clay. Its behaviour is mainly characterized by high swells and shrinkages at moisture variations. The utilization of the Bahlui clay as good foundation soil or material for compacted soil cushion required the determination of the parameters characterizing its behaviour during moisture variation: swell-shrinkage, compressibility and respectively shear strength. The research experiments to define the physical and mechanical behaviour of the Bahlui clay were performed on both natural and remoulded samples with 2.5÷10% mix from the dry soil mass with Portland with/or eco-cement. The paper presents graphs and tables displaying the Portland/eco-cement stabilization influence on the main physical and mechanical indices characterizing the Bahlui clay behaviour during moisture variations as well as conclusions its usage.

Abstract: The main factor that governs the shrink-swell behavior of expansive soils is the change in water content and the amount and type of clay size in the soil. In this paper, the research made are focused in reducing the swell potential of the studied clay by improvement in two ways: first by stabilization with a combination of eco-cement and Portland cement (1:1 ratio), and second by synthetic fiber reinforcement. A series of laboratory tests were performed on synthetic fiber reinforced expansive soil to determine the potential for using synthetic fiber reinforcement to reduce swell potential of soils. Specimens tested were prepared at two different synthetic fiber dosages 0.2% and 0.4%. The treatment of expansive clay with 5% eco-cement and 5% Portland cement revealed a better improvement of the swelling potential. The synthetic fiber reinforcement of the expansive soil doesn’t lead to a significant improvement of the soil.

Abstract: The forming background, properties and classification of eco-cement as well as it’s characteristics are systematically expatiated in this paper and the application and research progress of eco-cement in and abroad are introduced. The domestic research status of eco-cement and some presently existing problems are analyzed and discussed. It’s believed that there are good prospect of eco-cement in our country, much more attention should be paid on the problem which conclude security production, exhaust gas emission and environmental pollution control regulations of the eco-cement production. In the development of eco-cement industry, it’s necessary to consider the factors of environment and city construction for the industrial plan. Furthermore, the performance and application field of eco-cement still have to be improved.

Abstract: The objective of this paper is to investigate the influence of curing time on expansive soil as a construction material when treated with eco-cement stabilizer, as partly substituting the Portland cement. Standard consolidation samples were prepared from treated soils with 10 % cement (5% eco-cement and 5% Portland cement), reported to the dry unit weight of soil, and cured for 1, 7 and 14 days. After this period the soil samples were then socked in water and standard consolidation tests were performed on them. The compressibility characteristics, for the improved soil with 10% cement, Eoed, mv and Cv have shown a significant improvement during the first 7 days. After 7 days curing time the variation of compressibility characteristics is less pronounced.

Abstract: Eco-cement produced from waste concrete was proved to be feasible in early research. The seed crystal of ground granulated blast furnace slag (GGBS) was utilized in this research to lower the sintering temperature of eco-cement clinker. The mineral compositions of clinker with GGBS seed crystal was analyzed by X-ray diffraction (XRD), and the mechanical properties of eco-cement with GGBS seed crystal was also tested. Four main cement minerals were all observed in eco-cement clinker and the compressive strength of the eco-cement pastes can approach to about 66 MPa at 28 curing days. The results showed that GGBS seed crystal was favourable for the formation of cement minerals at a lower temperature. It can help reduce by about 50~100°C for the sintering process of cement clinker. Content of GGBS seed crystal should better be in the rage of 5%~8%, and the suitable sintering temperature should be 1350°C.

Abstract: The raw materials from household garbage and industrial waste have increased its usage in the concrete and cement industries. These eco-materials have helped the environment, avoiding pollution, land filling or burning of waste and the usage of other natural resources. However, the cost of many eco-materials is still higher than that of common natural materials. It is necessary to study in detail its behavior and properties to decrease its cost and increase its performance. This research deals with Eco-cement and molten slag aggregate which main raw materials are household garbage and industrial waste. Concretes produced with Portland cement and Eco-cement were mixed with gravel, limestone, quartz and molten slag aggregates to compare its properties. The fracture energy, strength and modulus of elasticity tests were performed and discussed in this paper. The concretes produced with Eco-cement and molten slag aggregate show better results than those produced with Portland cement and natural aggregates.

Abstract: The disposal of circulating fluidized bed (CFB) fly ash has been a serious environmental problem in the development of our society. In this work, the feasibility of recycling CFB fly ash as a blended material incorporating blast furnace slag (BFS), clinker and gypsum for the preparation of Eco-cement has been investigated. The mechanical properties of CFB fly ash based Eco-cements, including CFB fly ash–clinker system, CFB fly ash–ground BFS system, and CFB fly ash–ground BFS–clinker system, were evaluated in this paper. Scanning electron microscopy (SEM) and X-ray diffraction (XRD) techniques were used to analyze the microstructural changes and the hydration products of the CFB fly ash based Eco-cement pastes. The results indicated that it is feasible to use CFB fly ash along with BFS and clinker to produce Eco-cement. The hydration products of CFB fly ash based Eco-cement are mostly ettringite and amorphous C-S-H gel, which are principally responsible for the strength and structure development of CFB fly ash based Eco-cement in the hydration process.

Abstract: In Japan, a majority of urban waste is incinerated to reduce the volume and the residue (incineration ash) is land filled. Japanese municipalities, however, are confronted with serious shortages of waste landfill sites. To mitigate this situation, Taiheiyo Cement Corporation has developed two technologies, which are Ash Rinsing Process and Ecocement. Incineration ash is a suitable material for cement production because it primarily contains essential chemical components of cement clinker. The problem is that chlorine and heavy metals accompanying primary components cause operational trouble and deteriorate quality and material safety of cement. Ash rinsing technology will be effective to remove chlorine and heavy metals in the ash. Therefore, for municipalities closely located existing Ordinary Portland cement plants, it is the simplest way to use waste incineration ash as a raw material in those cement plants. Ecocemet, on the other hand, will be an attractive option for the municipalities distant from cement plants. Ecocement is defined as cement that is produced from over 500 kg (dry base) waste incineration ash supplemented with other wastes (sludge, etc) per ton of Ecocement. According to the discharged amount of ash, correspondingly scaled Ecocement plant is needed. In Ecocement production process, chlorine in the ash is combined with intentionally added alkalis or heavy metals and is extracted. Extracted metal chlorides are recycled as metal sources. Two types of Ecocement can be used in the fields of ready mixed concrete, concrete blocks or soil stabilizer. The first commercial plant of Ecocement constructed in Chiba prefecture started operation in April 2001. In July 2002, Japanese Industrial Standard of Ecocement was published. Consequently, Ecocement has become an authorized product in Japan. The second Ecocement plant is now under construction in Tokyo.