双江口水电站碾压试验掺砾土料研究

按照设计方案,双江口水电站掺砾土料的生产采用系统生产的方式,但由于目前系统尚未完建,经参建各方商讨采用平铺立采的方式生产供碾压试验用的掺砾土料。正式生产前,分别进行室外掺合试验2次,室内掺合试验1次,确定掺配遍数按4遍控制,掺配比例则根据掺合试验结果及上一批次掺砾土料掺配结果适时调整。通过掺砾土料的生产可知,在掺砾土料的平铺立采生产过程中,为取得更优的掺配效果,需根据土料及砾石料的级配检测结果适时调整掺配比例。

Effective Utilization of Coal Fly Ash in Building Material Production

This paper is aimed at verifying utilization possibilities of alkaline modified coal fly ash as cement replacement in the concrete. The influence of alkaline activated coal fly ash originating from Slovakian power plant in Novsky （Si/Al = 3,1） as a partial cement replacement in concrete on compressive strength of hardened composites after 28 and 90 days was investigated. Alkaline activation of coal fly ash was realized in an autoclave at 130 ℃ and pressure of 160 kPa during 5 hours and in a reactor under normal conditions （equal temperature during 36 hours） at solid/liquid ratio of 0.5. Coal fly ash/cement mixtures were prepared with 25 % cement replacement by starting and modified coal fly ash and given in forms. Compressive strengths of composites after 28 and 90 days of hardening were compared to referential composite without coal fly ash and evaluated according to the standard of STN EN 450 by the value of relative strength KR （compressive strength of coal fly ash/cement composite to compressive strength of comparative concrete）. The final compressive strengths of hardened composites based on alkaline activated coal fly ash reached values in the range of 6 up to 50 MPa. In the set of experimental composites based on alkaline activated coal fly ashes, the highest value of relative strength after 28- and 90- days of hardening reached composite with cement replacement by coal fly ash zeolitized in autoclave （105% of compressive strength of referential sample）, what is connected with formation of zeolitic phases on surface of coal fly ash particles. The achieved results confirm that alkaline activation of coal fly ash in an autoclave under observed conditions can be successfully used as a partial cement replacement in concrete of C20/25 and C25/30 in accordance with requirements of standards （STN EN 450 and STN EN 206）.

Properties of Fresh and Hardened Self-compacting Concrete Produced by Using Locally Available Materials

Self-compacting concrete （SCC） is defined so that no vibration is necessary for the compaction. The main criteria of producing SCC have to satisfy the following characteristics [1, 2, 3]： （1） Ability to flow into and completely fill complex forms under its own weight; （2） Ability to pass through and bond to congested reinforcements; （3） High resistance to aggregate segregation. Self-compacting concrete presents a significant sign in improving the product quality and efficiency of the building industry. It also enhances the working conditions and the quality and appearance of concrete. Japan has been used self-compacting concrete in bridge, building and tunnel construction since the early 1990s. In the last decade, SCC has been produced a high potential for greater acceptance and wider applications in highway bridge construction in the Europe and U.S.. However, till now, there is no application of SCC in the construction industry in Egypt. Therefore, the main objective of this research is to produce SCC by using the locally available materials in our region such as basalt, gravel, sand, limestone powder and silica fume. Experimental programme was designed to characterize the properties of fresh and hardened SCC. It comprises different concrete mixes thbricated with different types and percentages of constituent materials. Three full-scale reinforced concrete beams were fabricated from the SCC mixes and tested under flexure. For the purpose of comparison, an extra RC beam was made of conventional normal concrete to serve as a reference beam. This study, in general, demonstrated that the applications of SCC in construction industry oiler products with enhanced characteristics as well as could be economical.

Analysis of Harnessing Waste Fine Aggregate for Sustainable Production of Concrete Elements

This paper focuses on cement composites based on waste fine aggregate obtained from hydroclassification all-in-aggregate in the Central Pomerania region in northern Poland. In the world there are regions with poor supplies of coarse aggregate, which is one of the most essential raw materials used for production of ordinary concrete. In these regions, instead of coarse aggregate, there are often very large deposits of fine aggregate such as natural sand and fine all-in-aggregate. These raw materials may be used for concrete production of standard mechanical properties. Manufacturing concrete based on locally available fine aggregate is inexpensive which encourages the local production of fine aggregate cement composites instead of ordinary concrete, requiring gravel transported from distant places.

The Applicability of Soil＇s Fertilizers in Increasing of Production Effects in Lolium Perenne and Lolium Multiflorum Cultivation

The aim of the study was to determine the effect of soil fertilizers, used on the background of NPK fertilization on the productivity of Lolium perenne and Lolium multiflorum in different time of harvest. In 2012-2013 the following species and varieties of forage grasses： Lolium perenne and Lolium multiflorum were cultivated. It was the fallowing experimental subjects： K-control （without fertilization and fertilizer）, NPK （N-150 kg hal as a 34% ammonium nitrate, P-80 kg P2O5 ha-1, K-120 kg K20 ha-1）, UG-UGmax bio-preparation, EU-Eco bio-preparation （fertilizer）, HA-Humus Active as bio-preparation.

Ash-and-Slag Wastes of Energy Sector as Raw Material for Production of Rare-Earth Metals and Alumina

The results to develop a complex technology of co-extraction of germanium and gallium from the ash-and-slag wastes of coal combustion in Ukraine were presented. Based on the study of phase changes occurring in initial raw materials as a result of its processing, it was proposed to carry out a preliminary enrichment of the raw materials in order to produce secondary sublimates. Their further processing involves a combination of leaching soluble material with distillation of germanium in the form of tetrachloride. The resulting acidic solutions are trended to the gallium extraction. Optimum conditions of carrying out of processes are recommended.The chemical and phase composition of the resulting dump products and solutions have been defined. On the basis of it ways of their processing for the purpose of reception of alumina and building materials are recommended.

Utilization of Recycled Coarse Aggregate in Concrete Mixes

In this paper, the effect of the source of recycled coarse aggregate on the properties of concrete is investigated. The tests were conducted on concrete made from three sources of recycled aggregates： （1） old concrete with unknown strength, （2） old concrete with a known compressive strength of 21 MPa, and （3） old concrete with a known strength of 42 MPa. The three sources of recycled aggregates were used to produce new concrete with a target compressive strength of 21 MPa. The first and third sources of recycled aggregates were used in producing concrete with target strength of 42 MPa. A control mix was designed with aggregates from natural sources. The research included two methods of making recycled concrete. One concrete mix was produced using the recycled aggregate and adding more water than the control mix, to reach the target slump, while the second concrete mix was produced using the same amount of water as the control mix but with additional superplasticizer to maintain the target slump. The results obtained in this research showed that the concrete compressive strength depends on the source of recycled aggregates; the stronger the source of recycled aggregate, the higher the compressive strength of the produced concrete. Furthermore, the compressive strength of the first concrete mix was about 10%-20% lower than the compressive strength of the control mix. However, when superplasticizers were used, the compressive strength was around the same value as the control mix.

Lightweight Concrete Using Local Industrial By-product

Construction is one of the largest users of energy, material resources and water and it is a formidable polluter. One of the major materials used in construction is concrete and ordinary concrete contains about 12% cement which is a major producer of greenhouse gas in the world. The use of waste materials as partial replacement of cement in concrete reduces greenhouse gases, frees up land fill space, and reduces raw materials consumption. This contributes towards sustainable development, as in a sustainable society, nature is not subject to systematically increasing concentrations of substances extracted from the earth＇s crust. This research work explores the possibility of replacing some percentage of cement in concrete with marble sludge powder to produce lightweight concrete. This was achieved by determining the compressive strength and some hardened properties of concrete like sorptivity and carbonation with marble sludge. The results so far have been able to prove that lightweight concrete can be produced when some percentage of cement is replaced with this waste.