Key Engineering Materials Vol. 517

Abstract: Precious Ecological Experience in Traditional houses should be inherited and developed. However, it is washing away as urbanization. In this study, based on the field study in villages in Turpan, the Climate Adaptability of traditional houses is summarized from building landform, function, internal space and construction mode. Then indoor thermal environment in winter is tested, and the results show that the traditional houses with earth-envelopment wall have the ecological properties, which can maintain a balanced indoor thermal environment. In addition, advice on sustainable development of these traditional houses is discussed.

Abstract: The implementation of the mechanism of Energy Management Contract is of great significance in promoting the energy saving for buildings in China. Combining relevant contents in the Twelfth Five-year Plan of Shaanxi Province, this dissertation introduces the operating mode of the mechanism of EMC, analyses the main problems existing in the field of energy saving in large-scaled public buildings in Shaanxi Province, brings forward the innovative mode for developing market-oriented energy saving with Shaanxi Provincial characteristics based on EMC mechanism, and hopefully provides theoretical bases for the applications of EMC mechanism in the field of energy saving in large-scaled public buildings in our province.

Abstract: Tu-zhang-fang, which is a kind of Yi minoritys residential buildings with most ecological advantageous, not only can save energy, but also adapt to local climate, soil conditions and environment. It has good regional adaptation. But now, Tu-zhang-fang is facing the demise. In this paper, the mainly work is analyzing the advantages and disadvantages of Tu-zhang-fang about its rammed earth material, and designing experiments, which are about the modification of the material, to improve the water resistance, anti-freezing, bonding, plasticity and strength of shear force of the materials, and then giving reasonable points and direction of the optimization. The ultimate goal is to enhance the seismic behavior, increase building layers, optimal land utilization, enrich the interior space and meet the growing living requirements of comfort. This paper provides an effective way, by considering from the "re-build conservation ideas of residential culture, for the revival of these traditional distinctive residences with high value to be extended, as Tu-zhang-fang.

Abstract: Yunnan is very rich in natural resources, and using natural materials for building is an ancient tradition in local minority. In the remote poverty national areas, we always concern about making use of appropriate technical means, following the tradition of local construction, and efficiently applying local natural building materials. In addition, we pay close attention to improving their living quality effectively by the techniques. In this article, from a specific practice casethe United Nations GEF small grants programme, we make multiple detailed comparative analysis with traditional houses at the first, next we discuss appropriate design in the new residential construction of Aini in Xishuangbanna. And then we focus on using the local natural building materials such as bamboo, wood, adobe and other materials, by which we can make the improved design on roof system, wall system and floor system, so as to reduce construction costs and technical complexity, as well as we can effectively improve the living quality of construction at the same time. A demo project was constructed to show how these natural materials were integrated into a system to form the whole building. Joint team consists of local craftsmen and engineers constructed the demo-project so that the technology can be localized.

Abstract: About 6% of global CO₂ emissions are due to cement production. Blending of Portland cement with a significant fraction of mineral admixture could therefore be instrumental in reducing such emissions. Use of an admixture of vegetable origin such as rice husk as will additionally contribute to waste management and its incineration produces energy. This paper will stress the importance of properly designing such blends. Preferably gap-graded concepts should be employed, since blending efficiency in terms of strength development is promoted as shown in earlier publications. The paper therefore only briefly covers these aspects. Assessment of this blending concept on durability of cementitious materials constitutes a far more complicated problem. This requires careful porosimetry. Mostly, this problem is approached by MIP or by quantitative image analysis. Both can provide 3D information, although that of MIP is generally significantly biased. Quantitative image analysis is however time-consuming and laborious, and thus expensive. Moreover, it does not provide information on continuity of pores. Present day computer facilities offer therefore a better alternative. When using a proper DEM system, the concrete can be simulated in a realistic way. The paper describes new methods for investigating the pore structure in virtual concrete and presents some data on pure cement and blended cement. Differences will have impact on durability risks.

Abstract: Paper presents and discusses data obtained in a testing program on the replacement of limestone powder in asphalt concretes by fly ashes. This would combine economic, environmental and technical benefits. The finest fly ash of Vietnamese origin scored best. This is proposed due to the gap-graded design of the particulate mixture of coarse crushed rock fractions, fine fluvial sand and the mineral admixture. The test program encompassed Marshall tests, creep tests and splitting tensile tests.

Abstract: Steel high performance concrete (SHPC) structural wall was a combination of steel and high performance concrete. They can give full play to the advantages of steel and high performance concrete and have better dynamic behavior. Several specimens of SHPC structural walls with different parameters were tested under constant axial loading and horizontal cyclic loading. The testing phenomena and failure mechanics of those walls were compared and analyzed. On the basis of theoretic formulas and testing data, the main characteristic points and the law of stiffness degradation were presented, then, the tri-linear and four linear restoring models were built and provided. At last, the calculation formulas of stiffness parameter in restoring force model at different stages of deformation were presented. The results show that the declined strength stage of skeleton curve of specimens is related to the yielding strain of boundary steel, axial load ratio and stirrup content. The restoring force model of SHPC structural wall is thus formed for the application of nonlinear dynamics analysis as well as static structural calculations.

Abstract: Cement blending with mineral admixtures, especially with byproduct or waste product powder, can effectively reduce consumption of cement and promote the ecology. Recently, an innovative concept was proposed to replace of coarse cement grains by the inert fillers for sustainable cement in the low w/c concrete cement. As a basic mechanism, particle packing plays an important role in such replacement or blending. In the first part of study, the paper discusses the particle packing aspect of cement grains, limestone filler (LF) and LF blended cement. The new developed wet packing method and a dry packing method are proposed for the evaluation purpose. The paper presents results of packing tests with the influences of PSD, cement type, vibration, mixing, blending proportions, etc. The advantages and limitations of two packing methods are also discussed in this paper.

Abstract: Papers presented at ICPIC 2010, Madeira Island, Portugal, dealing with the use of polymers in cementitious materials, show the need to combine different admixtures to optimize the properties of cement. This work is a continuation of a paper presented at NOCMAT 2010, Cairo-Egypt, about the incorporation of several materials in Portland cement to increase mechanical properties and workability. The best performance admixtures were chosen and they were combined considering the superposition of effects. Cement pastes were prepared with chalcedony and sulfonate (to increase compressive strength) and sugar (to increase workability). Two percent of cement was replaced by the admixtures. The water/cement ratio was constant and equal to 0.44. Results show that the combination of 0.05% of sugar and 1.95% of sulfonate and 0.10% of sugar and 1.90% of chalcedony produced a paste with the greatest compressive strength and good workability. Compression strength was respectively 27.4 MPa and 36.6 MPa, which represent increases of 33.5% and 78.6%, respectively, relative to the reference paste without admixtures. While increasing the paste compression strength with sulfonate has been significant, the results of the paste with chalcedony were the more surprising because the water/cement ratio of pastes was kept constant. The chalcedony is a type of crystalline silica, which shows deformation in their structure. So because of crystalline structure of chalcedony, there should be, probably, no significant reactivity of it with the cement hydrates, just the fact that its structure be deformed can explain this reactivity. The most important conclusion concerns is that the combinations of admixtures can improve a lot the properties of Portland cement paste.

Abstract: Cement industry is under stress for mitigating CO₂ emissions: it is responsible for around 5-7% of total global emissions due to the production that went over 2x10⁹ tones in 2006. And this prospect will aggravate since it is expected, for 2050, an increase of 2.5 times, which will make cement industry guilty for more than 30% of CO₂ emissions. Main actions for decreasing emissions are: energy efficiency in kilns, use of alternative fuels and clinker substitution. These, however, are not capable to decrease emissions in a satisfactory way. CO₂ capture is expensive and could increase cement costs. The pressure, which is increasing all over the world, will certainly strike concrete producers. The optimization of cement use in concrete is an undeveloped strategy that can provide a huge contribution. For its development an international and cooperative effort is crucial. This paper proposes to change the focus from the cement production optimization to optimization of concrete production industry, responsible for most of cement consumption. It is discussed the limits of clinker substitution by mineral admixtures, comparing the expected cement demand increase versus the availability of these alternative materials, concluding that, despite the importance of this strategy, it is actually not capable for mitigating cement CO₂ emissions in a satisfactory way. It is discussed and assessed technical possibilities and limits of optimization of cement content in concrete, based on literature data analysis using two new environmental indicators Binder Intensity and CO₂ Intensity. There is a potential to reduce significantly the cement content on concrete, being possible to increase concrete production without increasing cement production and CO₂ generation. This can impact significantly on concrete environmental load to global warming and also in its cost, making possible to increase popular habitations construction mainly in some developing countries which have a lack of different sort of infrastructure where concrete technology is still dominant.