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Thực trạng và giải pháp cải thiện hoạt động logistics trong ngành sản xuất xi măng Việt Nam

Nghiên cứu này phân tích tình hình dịch vụ logistics trong ngành xi măng ở Việt Nam (VN) như thế nào, những ưu điểm, hạn chế cũng như nguyên nhân phát sinh trong dịch vụ logistics ngành công nghiệp xi măng là gì. Trên cơ sở phân tích đó, nghiên cứu đề xuất một số giải pháp, khuyến nghị hoàn thiện các hoạt động logistics phục vụ ngành sản xuất xi măng của Việt Nam trong thời gian tới.


Nghiên cứu sử dụng xỉ thép tái chế gia cố xi măng làm lớp móng đường ô tô

Bài viết này trình bày vắn tắt kết quả nghiên cứu giải pháp sử dụng xỉ thép tái chế từ các nhà máy luyện thép khu vực Bà Rịa - Vũng Tàu (BRVT), gia cố xi măng để làm móng đường ô tô. Các chỉ tiêu thử nghiệm, đánh giá như đối với vật liệu cấp phối đá dăm gia cố xi măng: Cường độ chịu nén (Rn), cường độ ép chẻ (Rech) và mô đun đàn hồi vật liệu (E). Đây là các chỉ tiêu cơ bản phục vụ cho công tác thiết kế, thi công và nghiệm thu lớp móng đường ô tô sử dụng vật liệu gia cố xi măng.


Bài tập Kỹ thuật thuỷ khí - Chương 2

Tài liệu cung cấp với hơn 60 bài tập chương 2 môn Kỹ thuật thủy khí với một số nội dung như: áp suất trên thềm đại dương, xác định áp suất tương đối, áp suất khí, biểu thức xác định độ sâu của áp suất, xác định độ sâu trong tâm của áp suất, định độ lớn của lực tác dụng lên một phía và độ sâu của trọng tâm áp suất... Mời các bạn cùng tham khảo tài liệu để nắm chi tiết nội dung các câu hỏi.


급냉 제강슬래그를 재활용한 EVA-폴리머 시멘트 모르타르의 특성

급속 냉각 된 강철 슬래그의 재활용을 위해, 다양한 대체 비율의 급속 냉각 된 강철 슬래그를 갖는 EVA- 폴리머 개질 된 모르타르의 기계적 강도 및 물리적 특성을 조사 하였다. 5 개의 상이한 양의 EVA- 중합체 개질제 (0, 5, 10, 15, 20 wt %) 및 급속 냉각 된 스틸 슬래그 (0, 25, 50, 75, 100 wt %)로 중합체 개질 모르타르 25 개의 표본을 제조 하였다. ). 중합체 개질 된 모르타르의 특성을 조사하기 위해, 물-시멘트 비율, 단위 부피 중량, 신선한 모르타르 및 압축 강도를위한 공기 함량, 굴곡 강도, 내수성, 내열성, 다공성 및 SEM 조사와 같은 측정 물을 경화시킨다. 수행되었다. 결과적으로, 급속 냉각 된 강철 슬래그의 대체 비율이 증가함에 따라, 물-시멘트 비율은 감소했지만 단위 부피 중량은 현저하게 증가 하였다. EVA- 폴리머 개질제가 증가하고 급속 냉각 된 스틸 슬래그의 교체 비율이 증가함에 따라 수분 흡수율은 감소했지만 압축 및 굴곡 강도는 현저하게 증가했습니다. 내열 테스트에 의해 기계적 강도는 감소했지만 총 기공 부피 및 기공률은 현저하게 증가했습니다. SEM 관찰에서, 시편의 성분은 내수성 시험 전에 공-행렬 상 형태로 서로 달라 붙는 것으로 나타 났지만, 공-매트릭스상의 중합체 개질제는 내수성 시험 후에 분해 또는 열화되었다.


Experimental study on properties of polymer-modified cement mortars with silica fume

This paper discussed the flexural and the compressive strengths of polyacrylic ester (PAE) emulsion and silica fume (SF)-modified mortar. The chloride ion permeability in cement mortar and the interfacial microhardness between aggregates and matrix were measured. The chemical reactions between polymer and cement-hydrated product were investigated by the infrared spectral technology. The results show that the decrease of porosity and increase of density of cement mortars can be achieved by the pozzolanic effect of SF, the water-reducing and -filling effect of polymer. Lower porosity and higher density can give cement mortars such properties as higher flexural and compressive strength, higher microhardness value in interfacial zone and lower effective diffusion coefficient of chloride ion in matrix. D 2002 Elsevier Science Ltd. All rights reserved.


Long-term chloride-induced corrosion monitoring of reinforced concrete coated with commercial polymer-modified mortar and polymeric coatings

The efficiency of four commercial concrete coatings (a polymer modified cementitious mortar and three elastomeric coatings) against chloride-induced corrosion is discussed by means of steel corrosion longterm monitoring and by chlorides penetration profiles in concrete. The cement-based coating shows the best effect on delay chlorides penetration in concrete by acting as a physical barrier in addition to concrete cover. Despite its lower polymer content, the higher thickness guarantees a longer time-to-corrosion with respect to organic coatings. Once corrosion has started, corrosion rate is lower in the presence of coatings, due to their ability to reduce water ingress in concrete.


Preparation and properties of an environment friendly polymer-modified waterproof mortar

A new type of environment friendly polymer-modified waterproof mortar (PMWM) was developed through adding ethylene vinyl acetate (EVA)/vinyl acetate–vinyl ester of versatic acid (Va–VeoVa) mixture (re-dispersible emulsion powder), mine tailings, quartz sand and additives to the eco-cement, which was prepared by grinding the mixture of steel slag, blast-furnace slag, fly ash and activator. The optimal material proportioning of PMWM was obtained based on the Orthogonal experiment: re-dispersible emulsion powder, 11 wt.%; cement–sand ratio, 1:3.5 (tailings/quartz sand = 1:3); EVA/Va–VeoVa ratio, 1:1; water reducing agent (based on the cement weight), 1.5 wt.%. The product conforms to JC/T 984- 2005 (China professional standard: Polymer–cement waterproof mortar). Some factors influencing the characteristics of the mortar were discussed.


Resistance to biogenic sulphuric acid corrosion of polymer-modified mortars

The use of polymer-modified mortar and concrete (PMM and PMC) is investigated to improve the durability of concrete sewer pipes. The aim of the research is to ameliorate the resistance of concrete to biogenic sulphuric acid attack through polymer modification. Prior to the durability tests, experimental research is carried out to reveal the influence of polymer modification on the physical and mechanical properties of mortar and concrete...


Porosity, pore structure and water absorption of polymer-modified mortars: An experimental study under different curing conditions

The porosity and pore size distributions are pore structure parameters which have a direct effect on the permeability of cement paste as well as its durability. This paper is based on laboratory programs comparing the porosity, pore size distributions and water absorption with varying ageing processes of three commercial polymer-modified mortars (SBR, PAE and VAE) as well as unmodified conventional mortar mixes exposed to different curing conditions. It was found that an increase in polymer loading has resulted in a significant reduce in porosity and water absorption in polymer-modified mortars. Furthermore, the SBR3 mix exhibited the most superior properties of the study in all conditions at different ages of curing.


Prevention of air void formation in polyme

The air voids that form when cement and aggregates are mixed with an aqueous polymer solution are not easily removed because they tend to be stabilized by the polymer. Antifoaming agents can be used to prevent air void formation, but they often cause problems of poor adhesion. An alternative approach is suggested for reducing air void formation in polymer-modified mortar, which is to pre-wet the cement and sand with water, and then add a concentrated polymer solution. The air content of a PVA-modified cement mortar prepared in this way was as low as 6%, which was lower than the 13% air content of the PVA-modified mortar with an antifoaming agent, and it was much lower than the 32% air content when a PVA solution was mixed with dry cement and sand. 0 1997 Elsevier Science Ltd.


Properties of polymer-modified mortars using epoxy and acrylic emulsions

Water based polymer systems are often used for improvement in the properties of plain cement mortar or concrete. Presently, latexes of a single or combinations of polymers like polyvinyl acetate, copolymers of vinyl acetate–ethylene, styrene–butadiene, styrene–acrylic, and acrylic and styrene butadiene rubber emulsions are generally used. One of the limitations of these polymer systems is that they may re-emulsify in humid alkaline conditions. To overcome this problem, an epoxy emulsion based polymer system has been developed. In this paper the properties of the cement mortar modified with this newly developed epoxy emulsion are compared with those of the acrylic-modified mortar. The results showed that the mortars with the newly developed system have superior strength properties and better resistance to the penetration of chloride ions and carbon dioxide.


The advantage of natural polymer modified mortar with seaweed: Green construction material innovation for sustainable concrete

One important innovation of green construction material is natural polymer modified mortar. In this research, polymer modified mortar used natural polymer from seaweeds, they are Eucheuma Cottonii (gel) and Gracilaria Sp. The research conducted in two parts, pre-experiment and main-experiment. Pre-experiment aimed to investigate compressive strength of natural polymer modified mortar with seaweed gel (Eucheuma Cottonii) and seaweed powder (Gracilaria Sp.). The pre-experiment followed by main-experiment which investigated compressive strength and splitting tensile strength. The research has shown that natural polymer modified mortar with seaweed powder (Gracilaria Sp.) performed great compressive strength and splitting tensile with optimum mix composition of KM-0.5.


Mechanical behaviour of polymer modified mortars

We investigate the mechanical behaviour of a mortar and five polymer (latex styrene–butadiene) modified mortars (PMMs) with different polymer contents. The mechanical characterisation of the materials is based on compression and three-point bending tests. As expected, compression tests reveal a decrease of the PMMs rigidity and compressive strength for increasing polymer content. On the contrary, three-point bending tests show an increase of the flexural strength from a polymer-to-cement weight ratio higher or equal to 10 wt.%. After some considerations on material porosity and cement hydration, we establish that the main cause of the PMMs flexural strength increase is the latex percolation into a continuous network. Finally, analysis on damage initiation and material rigidity seems to indicate that latex addition limits skin and inner material micro-cracking due to sample drying out.


Experimental study on polymer-modified mortars with silica fume applied to fix porcelain tile

The combination of polymer and silica fume to produce mortars results in excellent properties, which are ideal for repairs and revetments requiring high performance. Such improvements justify its study for the installation of porcelain tiles. This article presents bond strength results for mortars containing different amounts of polymer and silica fume indicating the applicability of these mortars as a construction material. The interface between the porcelain and the mortars was analyzed by scanning electron microscopy (SEM) of flat polished sections and pore mean diameter was obtained by mercury intrusion porosimetry (MIP). r 2006 Elsevier Ltd. All rights reserved.


Experimental study on thermo-mechanical properties of polymer modified mortar

This paper presents the results of an experimental program devoted to the study of Polymer Modified Mortars’ (PMM) thermal conductivity, thermal diffusivity and calorific capacity at different temperatures and compressive and flexural strengths at room-temperature. For this purpose, Ordinary Mortar (OM) and PMM samples with different contents and through partial substitution of Portland cement were prepared. A real improvement of the PMM thermal properties was observed in comparison with those of OM despite the decrease of mechanical strength. X-rays Diffract Meter (XDM), Differential Scanning Calorimetry (DSC) and Scanning Electron Microscope (SEM) were also conducted to show the interaction of the polymer material considered.


Strength and elastic properties of powdered and aqueous polymer-modified mortars

The effectiveness of powdered emulsions (powdered cement modifiers) and aqueous polymer dispersions (aqueous cement modifiers) on improvements in strength and elastic properties of mortars is investigated in this paper. Polymer-modified mortars using various powdered and aqueous cement modifiers were prepared with variation in polymer-cement ratio, and tested for flexural strength, compressive strength, tensile strength, deflection, extreme tensile fiber strain and tensile strain. It is concluded from the test results that powdered cement modifiers affect the properties of mortars similarly as the aqueous cement modifiers and the powdered polymer-modified mortars can be used in the same manner as the aqueous polymer-modified mortars for practical applications.


Surface interactions of chemically active ceramic tiles with polymer-modified mortars

Adhesion mechanisms and interfacial strengths of poly(vinyl alcohol) (PVA) modified mortar and chemically active tiles with five different silane coupling agents were studied using the Fourier Transform Infrared (FTIR) technique and mechanical testing. The results revealed that small and hydrophilic silane functionalities and isocyanate groups improved interfacial strength between tiles and modified mortar while the silane bearing hydrophobic functional group decreased adhesion resistance. The adhesion mechanism performed by hydrophilic silanes suggested the contribution of covalent chemical bonds between PVA cement modifier and coupling agents at the interface.


Mechanical behavior of cement mortar with different polymer type

Mechanical property of cement mortar is closely related to polymer modifier type. Four kinds of polymer latex including Chloroprene Rubber (CR), Styrene Butadiene (SBR), Styrene Acrylic (SA) and Polyvinyl Acetate (PVAc) were selected to prepare the modified cement mortar in this study. Mechanical behavior of modified cement mortar was evaluated by flexural strength, Compressive Strength and Tensile Strength, respectively. The micro-morphology of modified cement mortar was observed by scanning electron microscope (SEM), which was useful to analyze the modification mechanism. The results show that the SBR and PVAc latex can effectively improve the flexural strength of cement mortar, while the compressive strength is reduced slightly. Tensile strength of modified cement mortar was increased, especially the PVAc latex modified cement mortar.


Mineralogical study of polymer modified mortar with silica fume

Experimental investigation on the effects of styrene acrylic polymer and silica fume on the mineralogical composition of pastes of high-early-strength portland cement after 28 days of casting are presented in this paper. Thermogravimetry and derivative thermogravimetry were used to study the interaction between polymers and cements, and the extent of pozzolanic reaction of mortars with silica fume. Differential scanning calorimetry and X-ray diffraction were also used to investigate the cement hydration according to the additions. The results showed that the addition of silica fume and polymer reduces the portlandite formation due to delaying of portland cement hydration and pozzolanic reaction.


Effects of lignin cellulose and expansive agent on microstructure and macro-property of polymer-modified mortar containing fly ash

The influence of polymer-modified mortar with fly ash was researched, when lignin cellulose and calcium sulphoaluminate expansive agent was added into mortar. The consistency, mechanical properties and shrinkage performance of mortar were studied by orthogonal experiment. Lignin cellulose was wrapped by the hydration products of binding materials. As the expansive agent and fly ash increasing, the consistency of mortar can be improved. Moreover, the influence of cement-based self-leveling material containing fly ash was also studied, when the different quantity of calcium oxide added into the material. The proper added quantity of CaO can largely improve the mechanical property and restrain the shrinkage of self-leveling material.


Polymer film formation in cement mortars modified with water-soluble polymers

The modification of cement mortars with small amounts of water-soluble polymers (polyvinyl alcoholacetate, methylcellulose and hydroxyethylcellulose) is studied. During hardening, two processes can take place, i.e. cement hydration and polymer film or bridge formation. Due to the very low polymer contents, the formation of polymer films is generally not considered. In this paper, evidence is given of the presence of polymer films or bridges in mortars modified with 1% of polyvinyl alcohol-acetate or methylcellulose. A contribution to the flexural strength of these mortars is found. By means of SEM investigation, polymer bridges are detected between the layered Ca(OH)2 crystals. Additional bonds are created which strengthen the preferential cleavage sites. Furthermore, polymer films or bridges are intergrown within the cement matrix on a submicron scale.


Polymer modified jute fibre as reinforcing agent controlling the physical and mechanical characteristics of cement mortar

Polymer modified alkali treated jute fibre as a reinforcing agent, substantially improves the physical and mechanical properties of cement mortar with a mix design cement:sand:fibre:water::1:3:0.01:0.6. The workability of the mortar is found to increase systematically from 155 ± 5 mm (control mortar) to 167 ± 8 mm (0.2050% polymer modified mortar). The density of the mortar is increased from 2092 kg/ m3 to 2136 kg/m3 with a concomitant reduction of both water absorption and apparent porosity. Optimal polymer content in emulsion (0.0513%) is found to increase the compressive strength, modulus of rupture and flexural toughness 25%, 28%, 387% respectively as compared to control mortar. Based on the X-ray diffraction and infra-red spectroscopy analyses of the mortar samples a plausible mechanism of the effect of modified jute fibre controlling the physical and mechanical properties of cement mortar has been proposed.


The effects of silica fume and polypropylene fibers on the impact resistance and mechanical properties of concrete

Impact resistance and strength performance of concrete mixtures with 0.36 and 0.46 water–cement ratios made with polypropylene and silica fume are examined. Polypropylene fiber with 12-mm length and four volume fractions of 0%, 0.2%, 0.3% and 0.5% are used. In pre-determined mixtures, silica fume is used as cement replacement material at 8% weight of cement. The results show that incorporating polypropylene fibers improves mechanical properties. The addition of silica fume facilitates the dispersion of fibers and improves the strength properties, particularly the impact resistance of concretes. It is shown that using 0.5% polypropylene fiber in the silica fume mixture increases compressive split tensile, and flexural strength, and especially the performance of concrete under impact loading.


Mechanical properties and microstructure of high strength concrete containing Polypropylene fibres exposed to temperatures up to 200 °C

High strength concrete has been used in situations where it may be exposed to elevated temperatures. Numerous authors have shown the significant contribution of polypropylene fibre to the spalling resistance of high strength concrete. This investigation develops some important data on the mechanical properties and microstructure of high strength concrete incorporating polypropylene fibre exposed to elevated temperature up to 200 -C. When polypropylene fibre high strength concrete is heated up to 170 -C, fibres readily melt and volatilise, creating additional porosity and small channels in the concrete. DSC and TG analysis showed the temperature ranges of the decomposition reactions in the high strength concrete. SEM analysis showed supplementary pores and small channels created in the concrete due to fibre melting. Mechanical tests showed small changes in compressive strength, modulus of elasticity and splitting tensile strength that could be due to polypropylene fibre melting.


Mechanical properties of high-strength concrete subjected to high temperature by stressed test

Recently, the effects of high temperature on compressive strength and elastic modulus of high strength concrete were experimentally investigated. The present study is aimed to study the effect of elevated temperatures ranging from 20 ℃ to 700 ℃ on the material mechanical properties of high-strength concrete of 40, 60 and 80 MPa grade. During the strength test, the specimens are subjected to a 25% of ultimate compressive strength at room temperature and sustained during heating, and when the target temperature is reached, the specimens are loaded to failure. The tests were conducted at various temperatures (20−700 ℃) for concretes made with W/B ratios of 46%, 32% and 25%, respectively. The results show that the relative values of compressive strength and elastic modulus decrease with increasing compressive strength grade of specimen.


Ebook New hotels - Alejandro Bahamon

The ebook introduces new hotels with unique architecture in the world: Side hotel, Mandarin Oriental Miami, design Suites and towers, Emiliano, W hotel Times Square, hotel Bauzá, West street, St. Paul hotel, The Muse, Icehotel, hotel Tulbingerkogel, Black Spa, Anton, hotel Post... This is a useful reference for those who want to learn about architecture and architects and invite you to consult.


Bài giảng Kiến trúc truyền thống các vùng nhiệt đới

Bài giảng bao gồm 3 phần: mở đầu, kiến trúc truyền thống các vùng khí hậu nhiệt đới, các đặc điểm thích ứng khí hậu trong kiến trúc truyền thống Việt Nam. Bài giảng phân tích quá trình phát triển kiến trúc ở các khu vực khí hậu khác nhau đã đem lại cho người thiết kế những bài học và kinh nghiệm quý giá. Mời các bạn cùng tham khảo bài giảng để nắm chi tiết kiến thức.


Ebook Kengo Kuma selected works - Botond Bognar

Ebook present the content: acknowledgments, introduction, an architecture of dissolution the work of Kengo Kuma, Kiro San observatory, Noh stage in the forest, museum of Ando Hiroshige, Takasaki parking building, Gizan Onsen hot spring bath house, plastic house, paint house building, baiso in temple, Soba restaurant at Togakush shrine, Horai Onsen bath house, Shinonome apartment building.


Bài giảng Kiến trúc sinh khí hậu - Ths.KTS. Trần Công Danh

Bài giảng bao gồm 4 chương: khí hậu toàn cầu và những đặc điểm khí hậu Việt Nam; mối quan hệ giữa kiến trúc, khí hậu, con người; tiện nghi sinh khí hậu; các giải pháp thiết kế kiến trúc thích ứng với khí hậu Việt Nam. Để nắm chi tiết nội dung kiến thức mời các bạn cùng tham khảo bài giảng.


Đáp án tự luận chứng chỉ đấu thầu

Tài liệu cung cấp với hơn 60 đáp án cho các câu hỏi tự luận trong chứng chỉ đấu thầu với những tình huống được mô phỏng sát với thực tế. Mời các bạn cùng tham khảo tài liệu để nắm chi tiết nội dung đáp án.


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