CEMENT Influence of the porosity and pore solution on the microstrructural stability of cement paste, mortar and concrete The importance of the microstructural parameters: porosity and pore solution with regard to the cement paste, mortar and concrete properties is reviewed. Finally, the result the effect prodiced on the material stability is assessed. EQUIPMENT PROVIDERS How High Momentum Kiln Burners improve the combustion process Newer installations carried out by GRECO show that burners with higher flame impulse are more flexible to reach the challenging process targets of cement production. Check out what are the main benefi ts and how you can prepare your plant for the future. We tested them under hardest conditions to find out the difference. What is the superior technology? High momentum or low momentum burners? Recently some burner suppliers changed their designs to lower momentum burner, while GRECO constantly improved the high momentum burners to follow the increased requirements as multi-fuel combustion, enhanced flame control, controlling of sulfur circles, increased usage of alternative fuels and harder to achieve environmental emission limits. The experience, comparison and newer installations have shown that burners with higher flame impulse are more flexible to reach the described process targets of cement production. ANKRAL Q2 — An Innovative Solution In the last years, the cement industry has been unable to avoid the economic turbulences observed not only in Europe but worldwide. Although the impact has depended strongly on the regional context, demand for economic lining solutions, able to deal with alternative fuel firing, has increased. With the new ANKRAL Q2 brick type RHI addresses the altered requirements in the cement industry. With the experience gained during the development of ANKRAL QF and the increased use of RHI’s own raw material sources, together with an optimized raw material concept, it has been possible to develop a brick grade with unique properties at a very attractive price level. In order to design an economic product that is able to deal with alternative fuel firing, research and development focused on reducing the effect of decreased brick flexibility due to alkali salt infiltration rather than combating the corrosion effect itself. This enabled a reduction in the sensitivity to chemical attack without increasing the raw material costs. An extensive development project was launched focusing on fracture mechanics and flexibility in order to develop an optimal solution. The result of these developments is the ANKRAL T2 brick, which was launched in early 2011 and has been renamed ANKRAL Q2. All Q-type bricks are based on a further development of the hercynite technology, termed the Q-concept or hybrid spinel technology. The new technology exploits the effect of increased flexibility resulting from combining fused hercynite with an additional flexibilizer. Due to the new innovative brick concept, ANKRAL Q2 represents a highly economic brick grade with a broad application range in the basic zone of cement rotary kilns. Introduced into the market at the beginning of 2011, results of the first installations are reported in this paper. To date, all installations have met the high expectations of this new brick brand. Monolithic Material and Lining Solutions for cement plants with a high mechanical and chemical stress caused by increasing amount of secondary and/or alternative fuels Recently the widespread use of alternative fuels in cement production has forced many plants to reconsider their refractory lining concepts. The increasing amount of these secondary/alternative fuels leads to significant chemical and mechanical problems within the traditional refractory linings. Forced by this demand from our clients Refko and Reyma have developed a new range of products and lining concepts. These have been designed to withstand the severe conditions taking place in the refractory lining, specifically in terms of chemical attack, thermal shock and mechanical stress. CONCRETE PROBETHA-08, a new software for the concrete control PROBETHA-08 is a new software developed by the Spanish Institute of the Cement and its Applications (IECA) and the Public Works Agency of the Andalusian Government. This program allows automatize the control of the concrete in any kind of works (not only civil works), by dividing into batches, applying control criteria, compiling documentation and much more. The references for the software are in the Spanish standard EHE-08. This software can be downloaded for free from www.ieca.es and www.aopandalucia.es. Mechanical characterization of concrete with high fines content With the publication and entry into force of the EHE-08, the limit amount of limestone addition for concrete was modified. This article presents a study regarding the behaviour of one of the types of concrete most commonly used in the construction field (HA-25) with a higher content of filler than that defined in the EHE-08. The influence of adding this amount of filler is assessed at different ages of concrete and its influence in properties such as strength, shrinkage or creep is also analysed. SUSTAINABILITY Waste energy recovery in the cement industry In order to improve knowledge on waste energy recovery in the cement industry, CEMA Foundation have developed different communication materials: Comic: “Waste became energy”, aimed at young audiences. An information brochure with concise and schematic data regarding energy valorization in cement plants. A technical report “Waste energy recovery in the cement industry”, with technical information (question and answer format). All the materials available on CEMA website: www.fundacioncema.org. The Technical report “Waste energy recovery in the cement industry”, answer to the key questions regarding energy valorization: What is energy recovery?, Why experts and international governments support energy recovery in cement plants?, What type of wastes are being used in European cement plants? Which are the technical guarantees of waste combustion in a cement kiln? Why a cement factory is not the same that an incineration plant? Which are the scientific studies that show that waste energy recovery in cement plants is a safe activity? How energy recovery contributes to climate change prevention? WORKS A new road with micromilled concrete pavement and a bridge over the Esla river in Leon (Spain) The Castilla y Leon regional Government has built a new road between the towns of Castrofuerte de Campos - Toral de los Guzmanes, located in the South of the province of León. It includes a 324 m long and 10 m wide bridge allowing local traffic to avoid a long detour around the Esla river. The total length of the road is 3,787 m. The pavement is composed of 20 cm of concrete on 15 cm of crushed granular material. It rests on a capping layer of natural granular material. The subgrade has an E2/E3 category according to the Spanish specifications. A minimum 28 day flexural strength of 4.0 MPa was required for concrete when tested at 28 days. Transverse joints were placed at a sequence of distances of 3.4 - 3.6 - 3.8 m, as well as a longitudinal joint between traffic lanes. All of them were sawn and then sealed. Aiming to reduce noise levels, the texture was obtained by micromilling the surface. This was the first Spanish experience on the use of this technique in new pavements. In addition, evenness problems caused by stops of the paver were also corrected. Last but not least, speed of construction was increased with respect to that achieved when an exposed aggregate texture was selected at the beginning of the work, since the winter conditions prevailing at the jobsite hindered the removal of unset surface mortar and therefore the cutting of joints. As a result, a silent, high skid-resistant texture was achieved. All things considered, micromilling increases both comfort and safety of drivers.
Redaccion Cemento Hormigón -