Cement

With the advent of nano technology, materials have been developed that can be applied to high performance concrete mix designs. Nano silica reacts with calcium hydroxide (CH) to develop more of the strength carrying structure of cement: calcium silica hydrate (CSH). In this paper, relationships have been developed to distinguish the benefits when using different sizes of nano silica in cement paste. An extensive regime of experimental analysis was carried out to determine the effect of nano silica. Through these experiments the heat of hydration of multiple cement mix designs was measured. After that, the concentration of CH was recorded through X-ray diffraction. Then, the grain structures were examined through Scanning Electron Microscopy. Finally, the compressive strength was determined for each cement paste mixture. Through these experiments it was found that as the silica particles decreased in size and their size distribution broadened, the CSHs became more rigid; this increas...

The global cement industry produces over four billion tonnes annually. In recent years, the quest for increasing energy efficiency has led this industry to test and use "waste" materials as alternative fuels (AF). The objective of this study was to examine the use, as alternative fuel, of the shredded non-recycled plastics and paper residue (NRPP) of a materials recovery facility at the Balcones plant in San Antonio, Texas; this material has a Lower Heating Value (LHV) of about 17 MJ/kg and is called "engineered fuel" (EF). The results showed that EF consists of mostly paper fiber, a biogenic material, so its use helps to decrease CO 2 emissions from cement production. In the US, on an average about 4.3 MJ of thermal energy are used to dry, decompose, and sinter the carbonate minerals to produce one kg of "clinker" that is then ground to cement powder and mixed with other compounds. If the maximum amount of EF that can be used by the U.S. cement industry (83 million tonnes of cement per year) were to be separated at Material Recovery Facilities and used as alternative fuel in cement kilns, the diversion of non-recycled paper and plastics from landfills would amount to 17.7 million tonnes of EF. The general methodology used for the Life Cycle Assessment (LCA) is Eco-indicators 99 that uses the SimaPro database and four scenarios were assessed. The corresponding chemical structure of the EF was calculated and the associated emissions during combustion were determined. The laboratory analyses determined the average makeup of the sampled fuels consisted of 20% fossil based carbon and 80% biogenic. The use of EF in the cement industry reduces greenhouse gas emission by up to 3 tonnes of CO 2 per tonne of EF used in place of a highquality coal. The study also found that use of EF in cement production has no adverse effect on the stack emissions of cement plants, nor on the quality of cement produced. The mercury concentration in the stack gas of U.S. cement kilns is well below the U.S. standard and the total dioxin emissions of all cement plants amount to only 0.05% of the dioxins emitted by all U.S. sources. Furthermore, the cement process incorporates the residual ash in the EF into the final clinker, thus resulting in both energy and materials recovery.

Ozone treatment of steel rebar, together with latex addition (20% by weight of cement) to concrete, resulted in a 39% increase in the shear bond strength between rebar and concrete, compared to a 25% increase resulted from either ozone treatment alone or latex addition alone. Ozone treatment and latex addition resulted in similarly small increases in the contact electrical resistivity between rebar and concrete. Methylcellulose addition (0.4% by weight of cement) to concrete gave slightly less bond strength increase than the latex addition, but did not affect the contact resistivity.

The Solidification/Stabilization (S/S) of heavy metal soils using Ordinary Portland Cement (OPC) is studied as a hazardous waste treatment technology prior to landfill to lower the leaching rate. Cement is the most adaptable binder currently available for the immobilization of heavy metals. The decision to select of cements and operating parameters depends upon an understanding of chemistry of the system. This paper reviews the literature on the interferences between heavy metals and cement phases in the solidification/stabilization process. It provides a clarification of heavy metal effects on cement hydration and the fundamental chemical mechanisms by which the inhibition of cement takes place. Hence; it is possible to reach some conclusions about the potential effects of most waste constituents even in the absence of particular studies on specific compounds.

1Lecturer, Department of Building, University of Jos, Nigeria 2Lecturer, Department of Building, University of Jos, Nigeria ---------------------------------------------------------------------***--------------------------------------------------------------------Abstract – This research is aimed at determining the suitability of millet hush ash (MHA) as partial replacement of cement in the production of sandcrete blocks. This study examined the physical and chemical properties of locally sourced millet husk ash as a pozzolana. Mix ratio 1:6 (cement: sand) was used in this study for sandcrete block production. Cement was partially replaced with MHA in varying percentages of 0, 10, 20, 30 and 40% by weight. The blocks were molded and cured for 7, 14 and 28 days. The compressive strengths of the blocks were determined at 7, 14 and 28 days by crushing using compressive strength testing machine. The result of the chemical analysis of the locally sourced millet husk ash showed that it is...

In this study, the strength development and lechability aspects of metal-contaminated soil treated with ordinary portland cement (OPC) were investigated. The soil was collected from a scrap metal yard within the outskirts of Kuala Lumpur, Malaysia. Metal composition analysis indicated that the predominant metals present in the soil were iron (42,194 mg/kg), aluminium (8874 mg/kg), zinc (690 mg/kg), lead (428 mg/kg), copper (107 mg/kg) and chromium (52 mg/kg). The contaminated soil was treated with OPC using cement-to-dry soil (C/Sd) ratios of 0.5, 1 and 2. The effectiveness of the treatment was evaluated by performing unconfined compressive strength (UCS) as well as crushed and whole block leaching (WBL) tests on the treated soil. The treatment results were compared to the solidified waste acceptance criteria which were compiled based on the regulatory waste disposal limit at a disposal site in the United Kingdom and the maximum concentration of contaminants for toxicity characteristic of solid wastes from United States Environmental Protection Agency. Results indicated that chemical stabilization of metal-contaminated soils using OPC was effective for prevention of metal leaching from both disintegrated samples subsequent to years of weathering (crushed block) and intact samples (whole block) into the environment. © 2005 Elsevier Ltd. All rights reserved.

www.sciencedirect.com/science/article/pii/S0360132305003987

This contribution investigates the effects of seawater and colloidal silica (NS) in the amounts of 1, 3 and 5 wt%, respectively, on the hydration, strength development and microstructural properties of Portland cement pastes. The data reveal that seawater has an accelerating effect on cement hydration and thus a significant contribution to early strength development was observed. The beneficial effect of seawater was reflected in an improvement in compressive strength for up to 14 days of hydration, while in the 28 days compressive strength values were comparable to that of cement pastes produced with demineralized water. The combination of seawater and NS significantly promotes cement hydration kinetics due to a synergistic effect, resulting in higher calcium hydroxide (CH) production. NS can thus react with the available CH through the pozzolanic reaction and produce more calcium silicate hydrate (C-S-H) gel. A noticeable improvement of strength development, as the result of the s...

Concrete is a construction material composed of Cement, fine aggregate, coarse aggregate, and water with or without admixtures. The concrete industry is one of the heaviest consumers of natural resources due to which sustainability of concrete industry is under threat. The biggest problem facing the concrete industry is the environmental and economic concern. In this research Paper , the Ordinary Portland Cement (Grade 43) has been partially replaced by Waste Glass Powder (GLP) and in Second stage Natural sand and cement replaced by stone dust and waste glass powder accordingly in the proportion of 0%, 10%, 20%, 30%, 40% & 50%, at constant 15 % of Waste glass powder by weight of M-30 grade concrete. Concrete mixtures were produced, tested and compared in terms of Compressive Strength, Split Tensile Strength and Flexural Strength of the conventional concrete at a period of 28 days. It is observed that glass Powder and stone dust gives better results as compared to conventional concrete. It is found that strength and workability of mixes increases significantly when glass Powder and stone dust is used.

The use of air entraining agents have been accepted practice in cement technology for many years. A large number of uniform and stable micro bubbles is intentionally entrained to improve the durability and reduce the potential for damage from freezing and thawing, but these bubbles are inversely affected the hardened cement paste compressive strength. The Physiochemical and Mechanical Properties of cement pastes containing synthetic nonionic surfactant Lauryl glucoside (LG) as air-entraining agents are investigated. Different cement pastes with and without LG are prepared for five interval times (3, 7, 28, 90 and 360 days).
The influence of the different surfactant concentrations on the air content of the pastes and accordingly the bulk density, compressive strength and microstructure of the hardened cement specimens is discussed. The optimal level of factors to achieve the desired goals are determined. The results show that LG causes a uniform distribution of small air voids in the cement paste, beside its ability to accelerate the hydration reaction, which may greatly improve the compressive strength of the pastes.

Abstract Different weight ratios of microemulsion-based gelatin uniform microspheres (GMs) were added to the tetra calcium phosphate (TTCP)-based cement (CPC) to investigate the physical, mechanical and apatite-forming ability of the CPC. The GMs contained 20 wt% of glycidoxypropyltrimethoxysilane (EPPTMS) as a crosslinking agent. The average size of GMs was on the order of 35 μm. For CPC, the initial and final setting times were 10 min and 21 min, respectively. These values were prolonged up to 18 min and 28 min, respectively, for CPC containing 10 wt% of GM (CPC-10GM). The highest injectability percentage and injection time was related to the CPC-10GM. The highest mechanical values were related to CPC-5GM while CPC-10GM possessed the lowest compressive strength and Young's modulus. Apatite formation on the surfaces of all samples was confirmed by acellular in vitro bioactivity experiment after various periods of soaking time in simulated body fluid (SBF). Needle-like HA precipitates were manifested on the surface of CPC-5GM. According to MTT colorimetric assay, the viability rate of cells on the surfaces of CPC-5GM and CPC increases significantly with time. An appropriate attachment of G-292 cells on the surface of both samples after 48 h was observed by DAPI staining and SEM imaging methods. There was considerable difference in the ALP activity per cell basis between CPC and CPC-5GM at intervals of 7–21 days. These results indicate the potential of the CPC–5GM composites to be used in bone replacement.

Abstract The carbon dioxide (CO2), in the presence of water, forms a corrosive medium that reacts with the Portland cement hydrated products in a process denominated carbonation. Carbonation is a topic of great interest for the oil and gas industry due to deleterious and negative effects caused by formations that contain CO2 in their pores to the cements used in cementing operations, as primary and remedial cementing. The corrosive compound present in subsurface can be originated from geological processes, injection techniques for enhanced oil recovery and geological storage. This work evaluated characteristics of CO2 attack in class G Portland cement slurries formulated with different densities: 1890 kg/m3 (15.8 ppg), 1970 kg/m3 (16.5 ppg) and 2030 kg/m3 (17.0 ppg). The slurries were prepared, cured, and subsequently exposed to CO2 during periods of 30, 60 and 90 days in an autoclave with controlled temperature and pressure conditions. After the times inside the autoclave, the samples were analyzed with a pH indicator solution, sedimentation test and scanning electronic microscopy (SEM). The results showed an inversely proportional pattern: the higher the density, the lower the carbonation. The higher content of reactive solids contributed to make the matrix more closed and with a greater availability of hydrated cement products, acting as a barrier to the carbonation advancement.

In the present study, an investigation was conducted to evaluation of tile, brick, fire brick, plaster and concrete wastes derived from construction and demolition (C&D) wastes in Portland cement raw meal production as secondary raw material. Clinker test results showed that using of these wastes in cement was suitable. Then, cement production was performed with using 1, 2.1 and 3.9 wt. % mix C&D waste addition ratios in the cement factory. Desired phases like belite and alite, which are essential for the cement products, were observed at the micrographs. Also, obtained cement products supplied required and standard properties; however, strength and hydration heat values were lower. Finally, optimum C&D waste addition ratio was determined and results were found as practicable. It was shown that mix C&D waste materials can be utilized as secondary raw material in cement production.

In the challenging quest for a solution to reduce the risk of implant-associated infections in bone substitution surgery, the use of silver ions is promising regarding its broad spectrum on planktonic, sessile as well as multiresistant bacteria. In view of controlling its delivery in situ at the desired dose, we investigated its encapsulation in carboxymethyl cellulose (CMC) microparticles by spray-drying and included the latter in the formulation of a self-setting calcium phosphate bone cement. We implemented an original step-by-step methodology starting from the in vitro study of the antibacterial properties and cytotoxicity of two silver salts of different solubility in aqueous medium and then in the cement to determine the range of silver loading able to confer anti-biofilm and non-cytotoxic properties to the biomaterial. A dose-dependent efficiency of silver was demonstrated on the main species involved in bone-implant infection (S. aureus and S. epidermidis). Loading silver in microspheres instead of loading it directly inside the cement permitted to avoid undesired silver-cement interactions during setting and led to a faster release of silver, i.e. to a higher dose released within the first days combining anti-biofilm activity and preserved cytocompatibility. In addition, a combined interest of the introduction of about 10% (w/w) silver-loaded CMC microspheres in the cement formulation was demonstrated leading to a fully injectable and highly porous (77%) cement, showing a compressive strength analogous to cancellous bone. This injectable silver-loaded biomimetic composite cement formulation constitutes a versatile bone substitute material with tunable drug delivery properties, able to fight against bone implant associated infection. STATEMENT OF SIGNIFICANCE: This study is based on two innovative scientific aspects regarding the literature: i) Choice of silver ions as antibacterial agent combined with their way of incorporation: Carboxymethylcellulose has never been tested into bone cement to control its drug loading and release properties. ii) Methodology to formulate an antibacterial and injectable bone cement: original and multidisciplinary step-by-step methodology to first define, through (micro)biological tests on two silver salts with different solubilities, the targeted range of silver dose to include in carboxymethylcellulose microspheres and, then optimization of silver-loaded microparticles processing to fulfil requirements (encapsulation efficiency and size). The obtained fully injectable composite controls the early delivery of active dose of silver (from 3h and over 2 weeks) able to fight against bone implant-associated infections.

This study aimed to determine the cement industry's impact on ambient air quality inside and around a Saudi Arabian cement plant. Air quality has assessed in terms of several indicators: carbon dioxide, carbon monoxide, nitrogen dioxide, sulfur dioxide, PM10, PM2.5, ozone, and volatile organic compounds. AERMOD model was used to predict the concentrations of pollutants in the surrounding area. Results obtained revealed that the concentration of all impurities is within the standard limits for ambient air quality. In comparison with OSHA guidelines, only PM10 concentration exceeded the allowable limit. The higher concentrations of pollutants are recorded at the site closest to the plant site (S1, a housing compound located 0.8km ESE from the plant). Concentrations at the other monitoring sites decreased significantly. Except for PM10, the calculated hazard quotient (HQ) of all pollutants was <1which indicated no health effects are expected. The HQ of emissions can be ranked as...

The fused deposition principal of additive manufacturing (AM) involves the deposition of a material one layer at a time allowing the creation of an object from 3D digital design. The associated reduction in the amount of material wastage offers benefits to the construction industry and over the last decade, investigations have been carried out using cementitious materials for AM in construction. Central to the profile of the technology increasing in the industry is the development of a suitable cementitious material which may be deposited without formwork. Research currently consists of ground based gantry or robotic arm methods reliant upon suitable terrain and environmental conditions. This paper presents development of fibrous cementitious mortars and pastes suitable for a miniaturised deposition system designed for use in a multiple agent AM approach. Synthetic PVA, aramid and kevlar fibres along with natural fibres from the banana plant were investigated to evaluate contributions to the workability, buildability, mechanical strength and mechanism of failure of cementitious composite material. The addition of fibres to a cementitious matrix augmented by synthetic hydrocolloids results in compressive and flexural strength increases and transforms the method of failure from brittle to ductile. Results suggest PVA and kevlar fibres are suitable for a composite cementitious material with optimised rheology specifically designed for a multiple-agent, miniaturised deposition approach for AM.

Ordinary Portland Cement is recognized as a major construction material throughout the world. Researchers all over the world today are focusing on ways of utilizing either industrial or agricultural waste, as a source of raw materials for industry. This waste utilization would not only be economical, but may also result in foreign exchange earnings and environmental pollution. wastes, such as blast furnace slag, fly ash and silica fume are being used as supplementary cement replacement materials. A few studies have been carried out on the ashes obtained directly from the industries to study pozzolanic activity and their suitability as binders, partially replacing cement. This project analyses the effect of SCBA in concrete by partial replacement of cement at the ratio of 0%, 5%, 10%, 15% and 20% by weight by using magnesium sulphate solution. The bagasse is an important by-product of the sugar cane industry and most of it is used to produce steam and electricity in a co-generation plant at the ethanol plant.. This experimental study examines the compressive strength of concrete. The main ingredients used are Portland cement, SCBA, river sand, coarse aggregate and water. After mixing, concrete specimens were casted and subsequently all test specimens were cured in water at 7 days, 28days, 56days, 90days, and 180days.

The objective of this paper is to evaluate the effect of silica aerogel on the thermal conductivity of cement paste for the construction of concrete buildings in sustainable cities. Samples consisting of Ordinary Portland Cement (OPC), free water and different volumes of silica aerogel were prepared and cured for three (3), seven (7) and 28 days. Compressive strength tests were performed on samples at three (3), seven (7) and 28 days of curing. Porosity and thermal conductivity tests were conducted on samples at 28 days of curing. The lowest thermal conductivity measured was 0.076 W/mK, which was achieved by sample mix with 20 ml of silica aerogel (M20), which represents a 93.58% reduction in thermal conductivity relative to the control mix. The highest permeable porosity measured for cement paste incorporated with silica aerogel was 25.6%, which was also obtained by sample M20. However, the highest compressive strength measured was 54.33 MPa, which was obtained by sample mix with 10 ml of silica aerogel (M10) at 28 days of curing. The addition of silica aerogel as filler in cement paste can reduce the thermal conductivity of cement paste at the expense of reduced compressive strength and increased permeable porosity.

The paper presents the results of the studies performed on the influence of redispersible powders and of the cellulose ethers in mineral plasters applied as the last layer in exterior thermal insulation composite systems. Starting from traditional recipes, using polymeric additives specific for ETICS, there were developed original products in which the polymer additive (redispersible powder) concentration was modified with impact on physical and mechanical characteristics. The using of the cellulose ether led to obtaining some light compositions (smaller density) and good workability at application. The using of the redispersible powders has contributed to obtaining some mortars with low water permeability, high water vapour permeability and good support adherence, significant advantages for the products durability. There have been highlighted the chemical interactions between the redispersible powders and the Ca 2+ ions released during the cement hydration process. The redispersible powders act as a second binder in the system, thus leading to improved performance. În prezenta lucrare a fost studiată influenţa pulberilor redispersabile şi a eterilor de celuloză în tencuielile minerale aplicate ca ultim strat în sisteme de izolare termică la exterior. Pornind de la reţete tradiţionale, utilizând aditivi polimerici specifici pentru sistemele ETICS au fost concepute produse originale în care s-a modificat concentraţia de aditiv polimeric (pulbere redispersabilă) cu impact asupra caracteristicilor fizico-mecanice. Utilizarea eterului de celuloză a condus la obţinerea unor compoziţii uşoare (densitate mai mică) şi lucrabilitate bună la aplicare. Utilizarea pulberilor redispersabile a contibuit la obţinerea unor mortare cu permeabilitate la apă scăzută, permeabiltate mare la vapori şi aderenţă bună la suport, avantaje semnificative pentru durabilitatea produselor. Au fost puse în evidenţă interacţiuni chimice între pulberile redispersabile şi ionii de Ca 2+ eliberaţi la procesul de hidratare a cimentului. Pulberile redispersabile acţionează ca un al 2-lea liant în sistem conducând astfel la performanţe îmbunătăţite.

Early-age cracking affects the structural integrity of concrete structures and, if not inhibited, would lead to a reduction in service life. Plastic cracks are observed in the first few hours after placing the concrete, a time period well within the initial stages when the drying process is controlled by the rate of evaporation of concrete surfaces, which is roughly constant and similar to the rate of evaporation from water surfaces. In the absence of a theoretical method, this rate is commonly estimated using a nomograph based on Dalton's law. In this paper, a fluid mechanicsebased approach for water evaporation based on the boundary-layer theory, mass transfer, diffusion, and convection is described. A parametric study is conducted on the effect of boundary-layer temperature, wind speed, relative humidity, and evaporation characteristic length on the calculated evaporation rates. Predicted evaporation rates are verified by recent experiments. Results show that given appropriate environmental parameters, evaporation rates can be predicted with a good degree of accuracy.

 EN 206-1 Avrupa'da ilk kez 2000 yılı içinde yayınlandı, daha sonra 2005 ve 2010 yıllarında gözden geçirme ile bazı küçük değişiklikler yapıldı.  Diğer taraftan 2010 yılında EN 206-9 KYB ile ilgili bir standard yayınlandı.  2013 yılı sonunda ise EN 206-1 ve EN 206-9 birleştirildi ve diğer konular ile birlikte EN 206 standardı nihai haline önemli değişiklikler ile dönüştürüldü. EN 206: 2013 TS 13515 Çevresel Etki Sınıfları X0 Korozyon veya zararlı etki tehlikesi olmayan etki sınıfları, XC1 ila XC4 Karbonatlaşmanın sebep olduğu korozyon tehlikesi olan etki sınıfları, XD1 ila XD3 Deniz suyu dışındaki klorürlerin sebep olduğu korozyon tehlikesi olan etki sınıfları, XS1 ila XS3 Deniz suyundaki klorürlerin sebep olduğu korozyon tehlikesi olan etki sınıfları, XF1 ila XF4 Zararlı donma çözülme etkisine sahip etki sınıfları, XA1 ila XA3 Zararlı kimyasal etkiye sahip olan etki sınıfları, XM1 ila XM3 Aşınma sınıfları eklenmiştir, XWF ila XWS Alkali agrega reaktivitesi sınıfları eklenmiştir, Bileşen çevre etkilerinin değerlendirmesi yapılmıştır

“Đại dịch Covid-19 đặt ra thách thức lớn đối với ngành xi măng VIệt Nam. Không chỉ là sự kiện làm gián đoạn tới các hoạt động của ngành trong một tháng hoặc quý, dịch Covid-19 còn tác động trực tiếp đến quá trình thoái trào về nhu cầu tiêu thụ xi măng đã diễn ra trong nhiều năm trở lại đây. Điều này đồng nghĩa với việc, tiêu thụ xi măng trên các thị trường hiện tại sẽ có thể giảm sâu trong năm 2020, đặt áp lực lên khả năng cạnh tranh và duy trì hoạt động của các doanh nghiệp xi măng Việt Nam trong thời gian tới.”

h i g h l i g h t s Fiber distribution testing methods in cement-based composites are considered. The Optical Microscope, Scanning Electron Microscope, Fluorescence Microscopy and X-ray computed tomography are explained. The relationship between fiber distribution and properties of fiber reinforced cement-based composites (FRCs) are discussed. Fluorescence microscopy is more widely used for studying fiber dispersion in FRCs.

Ceramic dust is produced as waste from ceramic bricks, roof and floor tiles and stoneware waste industries. Concrete (M35) was made by replacing % (up to 30%) of cement (OPC 53) grade with ceramic dust (passing 75µm) shows good workability, compressive strength, split-tensile strength, flexural strength and elastic modulus. In this experimental investigation, concrete specimens were tested at different age for different mechanical properties. The results show that with water-cement ratio (0.46), core compressive strength increase by 3.9% to 5.6% by replacing 20% cement content with ceramic dust. It was observed that no significant change in flexural strength and split-tensile strength when compared to the conventional concrete.

The Cost as well as the time taken by the construction work has always attracted attention of Civil Engineers to be supplemented by some cheaper and fast settling construction material. This paper focuses the advantages of using Concrete canvas or Concrete cloth for Rapid and fast construction of structures like canals and many other which are made for temporary purpose. In the paper the engineering properties of the material is also discussed. This material being ceramic is fire resistant as well as water proof.

The use of cement and concrete is becoming increasingly widespread all over the world. However, the high energy consumption required for the production of clinker and the greenhouse gas emissions generated during production negatively affect both the economy and the environment. In the studies conducted for many years, researchers have found that the substitution of various pozzolans with cement provides both technical advantages and environmental benefits. The use of pozzolans in cementitious composites provides advantages such as the improvement of the physical and mechanical properties of the material, the conservation of the environment and the economy in terms of the evaluation of industrial wastes. In recent years, studies on the use of nanoparticles in cementitious composites are positively. In this study, it was aimed to investigate the properties of fresh and hardened cement mortars using micro silica as pozzolan and nano silica as nanoparticle. For this purpose, four different cement pastes and mortars mixtures were prepared by substituting 0%, 1%, 2%, 3% nano SiO2 (silica) cement in mortar mixtures containing 5% micro silica. The effects of the nano silica on the micro silica-containing cement paste on the consistency and setting time were investigated. The mortar mixtures produced were subjected to flexural and compressive strength tests on days 7, 28 and 90 th. SEM images of mortar mixtures were taken. As a result, it was found that 2% nano silica ad-mixture of 5% micro silica containing cement admixture affects the flexural and com-pressive strength positively, whereas 2% nano silica admixture increased the flex-ural strength by 13% and compressive strength by 7%.

An exhaustive study of available literature on use of activated carbon in cement
composites was done. Adsorptive nature of activated carbon can be effectively used to
remove toxic air pollutants such as nitrogen oxide, volatile organic compounds by
adsorbing to concrete elements (chimneys, tunnels etc.). Experimental research work
carried out on cement composites containing activated carbon revealed its potential
ability to improve physical, mechanical and durability properties of cement
composites. A comprehensive review of selected literature was carried out and the
significant findings are presented in this paper. Researchers across the globe had
experimentally showed that presence of activated carbon at 1 to 4% in cement
composites positively influence various properties of cement composites.

A laboratory testing programme was carried out to investigate the influence of Locust Bean Waste Ash (LBWA) on cation exchange and plasticity characteristics of Ordinary Portland Cement (OPC) modified lateritic soil. Preliminary tests were carried out on the natural soil to determine its properties. Other tests were carried out on soil-cement mixtures with up to 4% OPC admixed with 8% locust bean waste ash content by dry weight. Improvement in the plasticity characteristics of the soil was reflected in the decrease of liquid limit, increase in plastic limit and decrease in plasticity index with increased cement and locust bean waste ash content. The results using analysis of variance showed statistical significance. These results showed that modification with cement and locust bean waste ash blend significantly improved the plasticity characteristics through cation exchange of the lateritic soil.

Cilt/Volume : 7 Sayı/Number: 2 Yıl/Year: 2018 Sayı/Pages: 75-85 Alınış tarihi (Received): 09.02.2018 ÖZET: Bu çalışmada Artvin-Borçka'da bulunan Muratlı çay fabrikasına ait yakma ünitesi kuru tip toz siklon filtre sisteminde tutulan kömür külünün endüstriyel bir atık olarak beton üretiminde kullanılabilirliği araştırılmıştır. Farklı oranlarda çimentoya ikame edilmiş kömür külü atığının betonun taze ve sertleşmiş özelliklerine etkisinin belirlenmesi amaçlanmıştır. Bu amaca yönelik olarak, %0, %5, %10 ve %15 oranlarında kömür külü atık olarak çimento ikamesi ile C20/25 sınıfı 4 farklı beton karışımı hazırlanmıştır. Taze beton üzerinde slump deneyi, sertleşmiş beton örnekleri üzerinde ise Schmidt çekici, ultrases geçiş hızı ve basınç dayanımı testleri yapılmıştır. Çalışma sonunda erken yaşta (7. Gün) %5 atık ikamesinin referans betona göre ultrases geçiş hızını (%3.40) ve basınç dayanımını (%19.70) arttırdığı; 28. günde ise atık malzemenin C20/25 tasarımında beton içerisinde çimento ikamesi ile % 15'e kadar kullanılabileceği görülmüştür. Anahtar Kelimeler: Beton, endüstriyel atık, çay fabrikası, kömür külü. ABSTRACT: In this study, the possibility of using coal ash which held in dry powder cyclone filter system in combustion unit of Muratli tea factory in Artvin-Borcka, in concrete production has been researched. It is aimed to determine fresh and hardened concrete properties of cement substituted waste coal ash added concrete at different ratios. For this goal, four different concrete mixes of C20/25 class substituted with 0%, 5%, 10% and 15% dust is prepared. Slump experiment on fresh concrete, on the hardened concrete specimens, Schmidt hammer, ultrasound transit speed and compressive strength tests were carried out. At an early age (on 7th day), 5% waste residues increase the ultrasonic pulse velocity (3.40%) and compressive strength (19.70%) compared to the reference concrete; On the 28th day, it is seen that waste material can be used up to 15% with cement substitution in concrete in C20 / 25 design.

15 Secondo il Fumagalli questa incorporazione non venne direttamente fatta dalla stessa Italiana Cementi, ma tramite la costituzione di un'ulteriore società "dedicata". Fumagalli C., (1976), p. 472. 16 Dalla documentazione indagata non si hanno documenti riportanti la suddetta acquisizione e nemmeno il periodo certo, in cui questa sia avvenuta. Si ha conferma dell'interessamento della stessa società cementi per Tregnago fino ad aprile 1917, ritrovando notizie nel 1919 dell'avvenuta acquisizione dei terreni a Tregnago tramite una lettera di lamentela del presidente Pesenti all'avvocato Danieli del 22 agosto 1919, cfr documento n.10 del Regesto. Si evidenzia inoltre che dalla documentazione storica indagata non si è riscontrato l'appartenenza dello stabilimento di Tregnago a questa società. L'appartenenza viene segnalata esclusivamente nel testo del Fumagalli C., (1976), p. 472. 17 229,39 aree erano pari a 22.939 mq.

Thermal activation of Ga’ara kaolin is used to produce a good quality metakaolin. Portland cement clinker is ground
and blended with 3% gypsum. In this study, two types of mixes are made: the first using 10% hydrated lime and
different percentages of metakaolin as replacement by weight of the blended cement; in the second type, only
metakaolin is used, without hydrated lime, in mixes as a replacement by weight of the blended cement. The aim of
this study is to make a new type of environmentally friendly, blended cement with good fresh and hardened
properties. Energy savings can be achieved by using materials produced as industrial by-products (metakaolin,
hydrated lime). The compressive strength is 42.1 MPa for the mix with 12% metakaolin and 0% hydrated lime, and
38.8 MPa for 12% metakaolin with 10% hydrated lime, as compared to the reference mix value of 37.9 MPa at age
90 d. Blended cement can be made with 86% Portland cement fineness, adding 22% metakaolin + hydrated lime as a
replacement by weight of the blend, to give almost the same compressive strength as the reference mix, with
excellent soundness properties. This could reduce the annual production of cement, as well as the associated
emission of gaseous pollutants from factories during the cement production process.

Avec l’évolution technologique et démographique de l’homme et son besoin vital des zones arides et semi arides, il envahit le désert pour exploiter ses richesses, ce qui conduit à une présence des eaux plus importante qu’avant ; que ce soit pour les besoins agraires ou pour les besoins industriels. La présence des eaux dans ces régions favorise la création de l’environnement idéal pour l’effondrement des sols et, par conséquent, la ruine des constructions. Ceci nous oblige à proposer des solutions de traitement économique et faciles à mettre en œuvre. Cette étude expérimentale présente le cas de traitement par le ciment d’un sol affaissable, reconstitué au laboratoire, en utilisant la méthode double consolidation. Les résultats obtenus montrent qu’il est possible de diminuer le potentiel d’affaissement de ce sol à un niveau acceptable par l’ajout d’une faible teneur en ciment avec différentes teneurs en eau initiales et sous l’effet de plusieurs énergies de compactage.

It is well known that the production of cement is extremely resource and energy intensive process producing an equal amount of CO 2 per ton of cement. Hence, due to growing environmental concerns of the cement industry, there is a need to develop alternative materials such as fly ash, Ground granulated blast furnace slag (GGBS). Also there is a need to develop masonry units using these alternative materials for sustainability. Geopolymer technology makes use of fly ash which is a byproduct of thermal power plants. In the present research, cement and geopolymer blocks are produced by the same method. The basic properties of these masonry units such as compressive strength, density, modulus of elasticity, Initial rate of absorption (IRA) and water absorption are determined and compared. The results indicate that Geopolymer blocks posses superior properties compared to traditional cement blocks. Geopolymer blocks can be recommended for the use as masonry units for structural masonry. Thus the use of conventional cement can be eliminated.

This paper aims to provide background information on raw materials included in the cement industry that have chemically examined. The raw materials entering the factory examined, which include stone, crude oil, iron dust, sand, and gypsum, as it found that the total carbonate ratio is 89 percent as a weight ratio and the sulfide is smaller or equal to 1 percent as a weight ratio, and the magnesium carbonate is smaller or equal to 3 percent. For iron dust with sand, the total carbonates of the mixture were smaller or equal to 85 percent, and magnesium carbonate was smaller or equal to 3 percent. Silica oxide also examined in the sand were the results of the examination were greater than 85 percent. For sulfide oxide smaller than 1 percent, as well as for iron dust, the proportion of oxide Ferric is higher than 55 percent, the percentage of alumina oxide is less than 10 percent, silica oxide is less than 20 percent, as well as for crude oil, as it contains less than 4 percent of sulfide oxide, as well as primary and secondary gypsum examination, and it found that sulfide oxide is greater than 31 percent if the gypsum is Secondary and greater than 42 percent if the gypsum is primary. Materials are non-soluble smaller than 8 percent if it was secondary gypsum and less than 5 percent if the primary gypsum. Where these models examined and analyzed, and the storage location of the models examined were determined.

Dolomite cement is a significant and widespread component of Phanerozoic sucrosic dolomites. Cements in dolomites that were never deeply buried are limpid, have planar faces (non-saddle forms), often distinct zonation in cathodoluminescence and form syntaxial overgrowths on crystals facing pores. Five samples of sucrosic dolomites, interpreted as having had mostly limemudstone or wackestone precursors in four carbonate aquifers, provide insights into the abundance of planar cements in sucrosic dolomites. Such cement comprises 11% to 45% (32% mean) of peritidal to sub-tidal dolomites on an outcrop in the Edwards aquifer (Early Cretaceous) of central Texas; 19% to 33% (25% mean) of ramp dolomites in the Hawthorn Group (Oligo-Miocene) and 50% to 70% in shelf dolomites of the Avon Park Formation (Eocene) in the Upper Floridan aquifer of sub-surface peninsular Florida; 18% to 45% (32+% mean) of sub-tidal shelf dolomites in quarry sections of the Burlington-Keokuk Formation (Early Mississippian) in south-eastern Iowa; and 18% to 76% (50% mean) in shallow cores and outcrops of outer-shelf dolomites from the Gambier Limestone (Oligo-Miocene) of South Australia. Backstripping the cement phases revealed by cathodoluminescence colour photomicrographs documents the effects of cements on textural coarsening, pore-space reduction, induration and general 'maturation' of these dolomites. Most pre-Holocene dolomites are multiphase crystalline rocks composed of: (i) seed crystals or 'cores'; (ii) crystal cortices that concentrically enlarged the cores; and (iii) free-space, syntaxial precipitates of limpid cement around the crystals. Remaining CaCO 3 grains and micrite can be replaced by dolomite, but typically they are dissolved between stages (ii) and (iii), creating systems of intercrystal and mouldic pores typical of sucrosic dolomites. Networks of cement overgrowths, aided by water-filled pore systems under hydrostatic to lithostatic pressure, are judged to slow or prevent compaction in sucrosic dolomites. It can be argued that cortex growth involves both replacement of CaCO 3 particles and microcementation of their interparticle pores. This interpretation, and the abundance of cements in so many dolomites, would obviate the controversy over the volumetrics of 'replacement dolomitization'. Limpid, planar and syntaxial dolomite cements of early diagenetic origin are interpreted to have precipitated from clear pore waters, at low temperatures (<30 to 35°C) and shallow burial depths (<100 m), in water-saturated networks of dolomite 'silt' and 'sand'. Cements in many dolomites in island and continental-aquifer systems appear to result from event-driven processes related to sea-level highstands. Cementation events can follow 'replacement 1

We conduct the initial valuation of VICEM Ha Tien Cement (hereby called “HT1”) shares, listed on Ho Chi Minh Stock Exchange (HSX). Using discounted cash flow and peer multiples valuation method, we determine target price for HT1 shares at 13,460 VND/share (4% lower than March 6th 2020 closing price). Therefore, we recommend to SELL HT1 shares for short and medium-term goals based on key thesis:

► Lack of potential growth in 2020. For year 2020 and following period, HT1’s revenue growth is constrained by the decline of material demand in Vietnam’s Southern construction market due to (1) Slow progress in public’s infrastructure investment and (2) Tighten in government license for regional residential building. (more details)

► Increasing competition due to:
(1) Significant capacity expansion from competitors in HT1’s key selling markets. In 2020, HT1 faces increasing competitive pressure in two important markets: HCM City and Binh Duong. There will be two new cement plants launched by An Phu & FICO Tay Ninh with total capacity of 3.3 million tons/year (48% HT1’s capacity). Additionally, other regional players are also planning to further expand capacity, thus may create intense market competition. (more details).

(2) Declining in Vietnam’s cement export. Recently, the imposition of tariffs in a number of Vietnam's main cement export markets such as the Philippines and Bangladesh is causing a significant decline in export ability of many domestic companies. If this situation prolonged, pressure in the domestic market may increase, affect market demand for domestic players such as HT1. (more details)

► Negative outlook for company on-going investment projects:

(1) Most plans for capacity expansion are currently not feasible. As most factories and grinding stations have been operating at full capacity, HT1 is planning to invest in new production lines in the upcoming period. However, most expansion plans are currently not feasible to implement due to limited investment capital and lack of necessary investment permits. (more details)

(2) Previous non-core investment face significant delay. Two non-core investment projects: (1) VICEM complex building, which currently in conflict with new Public Investment Law (No. 167/2017 ND-CP) and (2) BOT Phu Huu, which is yet to be approved by HCM City People's Committee. We assess that these non-core project could be seriously delayed and difficult to recover capital in the near future. (more details)

This study examined the use of the locally available building materials such as sawdust and palm kernel shell as possible substitutes for fine and coarse aggregate in concrete. The physical properties such as specific gravity, Bulk density, Absorption test and sieve analysis test of these local materials were examined. The materials were batched by volume for the production of concrete and slump test were done on concrete to compare and control the water content. Four sets of concrete were casted (cement: sawdust: granite, cement: sand: granite, cement: sand; palm kernel shell and cement: sawdust: palm kernel shell) into cubes of size 150 x 150 x 150 using a mix ratio 1:2: 4 and 1:3:6.The concrete cubes were cured by sprinkling method for different time duration (7, 14, 21, and 28 days). The compressive strength tests were carried on the concrete. Compressive strength result for 1:2:4 and 1:3:6 concrete mixes show an overall reduction in compressive strength in all the mixes containing sawdust and palm kernel shell as compared to normal concrete mix (cement: sand: gravel). Also, there was a progressive reduction in compressive strength with age. Absorption test carried out showed that the rate of water absorbed by sawdust and palm kernel shells are higher compared to sand and gravel respectively. This indicates that the water absorption capacity in both sawdust and palm kernel shells would need to be modified in order to improve its compressive strength and durability. The quality of concrete with palmkernel shells can be improved by breaking into smaller sizes before using the palmkernel shell to produce a well graded sample of various sizes which in turn will help in proper interlock of the particles in concrete mass.

Code: (ASTM C191)
2.1 Purpose
          The purpose of this test is to determine the initial and final setting time of hydraulic cement by Vicat needle apparatus.
2.2  Significance and Use
1) According to weather we define setting time by adding retarder or accelerator.
2) We arrange the formwork according to setting time.
3) It is helpful in deciding the mixing time duration of concrete.
4) The knowledge of setting time is helpful in deciding the time to transport, place and compact the concrete effectively.

Leaving the waste materials to the environment directly can cause environmental problem. Hence the reuse of waste material has been emphasized. Waste can be used to produce new products or can be used as admixtures so that natural resources are used more efficiently and the environment is protected from waste deposits. Marble stone industry generates both solid wastes and stone slurry. This paper focus on the utilization of waste of Marble dust powder in concrete and enhancement of strength of concrete more economically. The Marble dust powder was added in M20 grade of concrete at (0%, 5%, 10%, 15%, 20%, 25% & 30%) with partial replacement by weight of cement. Water/Cement ratio (0.50) was kept constant, in all the concrete mixes. The concrete samples (cube & cylinder) were tested for compressive strength and split tensile strength after 7 & 28 days of proper curing. The results of the laboratory work showed that replacement of cement with Marble dust powder increases up to 10% for both compressive strength and split tensile strength of concrete.

This work compares a range of limestone extended cements, classifies each blend according to their respective cement specifications, and assesses the effect of the limestone on the strength development, water demand and plastic properties in concrete with a given target strength of 38MPa. Furthermore, the interaction that limestone has in the hydration process is evaluated.
The scope of this experiment is to determine the maximum level of limestone in a given mix before it starts to negatively affect the performance of the concrete whilst comparing the benefits in CO2 emission savings per ton of cement and translating this to an effective CO2 contribution per cubic meter of concrete.