Development Of Concrete Technology Research Articles

Modified concrete: reality and prospects

Aim. To review the history of concrete technology over the past 30 years and to analyze current trends in the field.Reality. New concepts and terms that manifest the level of modern science in the field of concrete technology are given. It is shown that the use of complex organomineral modifiers produced on an industrial scale, which are characterized by unique compositions, forms, and processability, allowed Russia to organize promptly mass production of concrete with high performance properties in the amount of about 5 million m3. Examples of construction of unique structures from new modified concretes are presented. The list of such structures includes high-rise buildings, sports facilities, bridges, overpasses, tunnels, etc.Prospects. Priority tasks for further development of concrete technology in Russia have been formulated. Among them are the development and improvement of physical and technical characteristics of concretes; extended use of large-tonnage technogenic wastes in production of concrete mixtures; updating and development of new normative documents for calculation, design, and erection of modern structures with high operational reliability, durability, and aesthetic properties.

PENGARUH LIMBAH CANGKANG KERANG SEBAGAI SUBSTITUSI AGREGAT HALUS TERHADAP KUAT TEKAN BETON

The development of concrete technology in trials of adding mixed ingredients continues to be carried out to obtain the desired strength and quality of concrete. The clam shells contain pozzolanic chemical compounds, namely lime which is expected to be used as a substitute for fine aggregate in a mixture of concrete constituents. This research was conducted to determine the compressive strength of concrete by utilizing shell waste as a substitute for fine aggregate of 0%, 15% and 25% with aging observed at 7, 14 and 28 days. This research carried out several material tests such as sieving, aggregate specific gravity, moisture content, silt content, wear and tear, organic matter, slump test and concrete compressive strength test. Based on the results of the study, it was found that the optimum strength in mixed variations with shell waste as a substitute for 15% fine aggregate obtained a compressive strength value of 14.09 MPa at 14 days. From the results of the research conducted, it can be concluded that the use of shell waste as a substitute for fine aggregate is not recommended for the manufacture of concrete in the world of construction, because the strength value of the concrete obtained does not meet the requirements of Standard SNI 7656: 2012

Thermal Behavior and Energy Efficiency of Modified Concretes in the Tropical Climate: A Systemic Review

Concrete remains the most utilised construction material for building envelopes, which regulate the indoor temperature to achieve human thermal comfort. Often, the energy consumption for building performance appraisal is related to the thermal behaviour of building materials as heating, ventilation, and air conditioning systems all variously contribute to human comfort. Following the development of concrete technology, many types of concrete have been invented to serve several purposes in the construction industry. To clearly understand the concrete type tailored for the specifics of a construction project, the local climate, concrete mechanical properties, and concrete thermal behaviours should be primarily identified to achieve energy efficiency, which also suits the sustainability of global materials. This paper, therefore, reviews the modified concrete thermal behaviours in the tropical climate for more systematic city planning in order to achieve better energy efficiency. Urban heat islands in the tropics and contributing factors, as well as heat transfer mechanisms, are first highlighted. The requirements of concrete thermal behaviour for building envelopes are then discussed through specific heat capacity, thermal conductivity, thermal diffusivity, time lag, and decrement factor in the context of applications and energy consumption in the tropical regions. With a case study, it is found that concrete thermal behaviours directly affect the energy consumption attributed mainly to the use of cooling systems in the tropics. The study can be a reference to mitigating the urban heat island phenomenon in the planning of urban development.

MECHANICAL AND SHRINKAGE BEHAVIOR OF BASALT FIBER REINFORCED ULTRA-HIGH-PERFORMANCE CONCRETE

Ultra-High-Performance Concrete (UHPC) is considered to be a new development of concrete technology with excellent workability, high compressive strength, toughness, and long durability, etc. These characteristics are achieved by the synthetic application of strength enhancements such as the use of mineral additives, optimum particle distribution and especially the use of fiber reinforcement which greatly enhances flexural strength and toughness for the UHPC. In this paper, the influence of basalt fiber content on some properties of UHPC such as workability, compressive strength, flexural strength, elastic modulus and shrinkage were investigated. The results of this paper show that use of basalt fiber with reasonable content will not affect the workability of the concrete mixture while increasing the flexural strength, compressive strength, and elastic modulus of the UHPC. The compressive strength of concrete reaches over 120 MPa, flexural strength is over 10 MPa. UHPC sample using 1.5% fiber content will give the highest compressive and flexural strength values, this value increased about 8.5% compared to the control sample without fibers.

The Influence of the Use of Cement Brands on the Physical and Mechanical Properties of Reactive Powder Concrete (RPC)

The most popular building material today is concrete. Concrete is used for buildings, industrial structures, bridges, railroad sleepers, roads, dams and more. Along with the development of concrete technology is increasingly developing and innovative so as to achieve better characteristics, cheaper prices and environmentally friendly. In the early days of the development of concrete it is explained to us about the origin from ancient times to civilization to the present century of its development. In current developments, concrete already has a very high compressive strength up to 200-800 MPa, this is also called Ultra Hight Concrete (UHC). It is developed by the Reactive Powder concrete (RPC) method. Where in the research conducted, the manufacture of reactive material, namely Reactive Powder concrete (RPC) was given with a compressive strength of up to 52 MPa. The components of the RPC mixture consist of cement, fine aggregate, silica fume, superplasticizer and water. To produce a compressive strength of 52 MPa, the composition of the mixture used previous research. Detailed RPC concrete mix proportions are given in this study. Preparation and testing of materials are made in the laboratory of the Faculty of Civil Engineering in Untan. The results that will be obtained are the physical and mechanical properties of RPC Concrete. As previously explained, the manufacture of RPC concrete requires basic ingredients that include cement, fine aggregate, silica fume, superplasticizer and water mixed together. Of course, with basic ingredients with good and correct composition, the physical and mechanical properties of RPC concrete will reach the planned quality. Cement sold in the market today has PPC and PCC types. Therefore, the cement which is a binder of powder materials into a solid one plays a very important role in the formation of the best physical and mechanical properties of RPC concrete. With cement as a binding material, it is certain that the strength of RPC concrete is determined by the binding capacity of the type of cement to be used, thus RPC concrete will be obtained according to the planned quality of the plan. From the cement brands on the Indonesian market consisting of PPC and PCC cement types, it can be concluded that one of the cements using the PCC type cement brand has better physical and mechanical properties than the PPC type cement brand. And all brands of cement with PCC type produce compressive strength > 52 MPa. So, in the manufacture of RPC concrete it is recommended to use a cement brand with PCC type.

ECONOMIC REVIEW OF VARIATION OF PRESTRESSED GIRDER LENGTH ON BRIDGE CONSTRUCTION PRACTICES

In the last decade, long-span continuous beam bridges have been built to meet the need of the totalbridge length requirements for obstacle avoidance. In almost 100 years of development of bridge construction coupled with the development of concrete technology, the maximum bridge length, which was originally about 20 m, currently has reached a length of 50 m or longer with the use of prestressed construction. The longer girder length will reduce the number of pillars, minimize the possibility of damage to the pillars due to local scouring or expand the coverage of the free area under the bridge. This study aimed to evaluate the economical aspect of the use of prestressed girders with length variations of 40 m, 50 m, and 60 m. The analytical calculations were carried out based on the applicable standards of bridge design. The results of the study indicated that the most economical configuration for a long span bridge (200m-400m) is the use of a prestressed girder length of 50 m with a girder cross-section height of 2.10 m. However for 480m bridge lengths, 60m PCI girder lengths tend to start out lower. It can be concluded that for a longer bridge span, a longer PCI girder is also required.

PENGARUH PENAMBAHAN SILICA FUME DAN GLENIUM SKY TERHADAP KUAT TEKAN BETON K-400

In the development of concrete technology (Concrete Technology) today which is increasingly unceasingly, along with the development of the era hence the quality of concrete selection as the main raw material of building construction is very important. This research writer take silica fume and glenium sky as added concrete mixture to know the influence of the addition of silica fume and glenium sky to the compressive strength of concrete. The research is divided into three stages : material testing, test object making and test object. This research uses cube-shaped specimen with size 15x15x15 cm, with 5 variations, they are normal concrete, silica fume 5%, silica fume 5% + glenium sky 2%, silica fume 5% + glenium sky 4%, and silica fume 5% + glenium sky 6%, which every variations has 3 test specimens with 3 days, 7 days, and 28 days. From laboratorium testing, the characteristics of compressive strength of concrete at age 28 days of normal concrete is 407,2 Kg/Cm2, normal concrete with silica fume 5% is 418,5 Kg/Cm2, normal concrete with silica fume 5% + glenium sky 2% is 435,9 Kg/Cm2, normal concrete with silica fume 5% + glenium sky 4% is 451,9 Kg/Cm2, normal concrete with silica fume 5% + glenium sky 6% is 484,1 Kg/Cm2.

A model to characterize the effect of particle size of fly ash on the mechanical properties of concrete by the grey multiple linear regression

Fly ash has become an important component of concrete as supplementary cementitious material with the development of concrete technology. To make use of fly ash efficiently, four types of fly ash with particle size distributions that are in conformity with four functions, namely, S.Tsivilis, Andersen, Normal and F distribution, respectively, were prepared. The four particle size distributions as functions of the strength and pore structure of concrete were thereafter constructed and investigated. The results showed that the compressive and flexural strength of concrete with the fly ash that conforming to S.Tsivilis, Normal, F distribution increased by 5-10 MPa and 1-2 MPa, respectively, compared to the reference sample at 28 d. The pore structure of the concrete was improved, in which the total porosity of concrete decreased by 2-5% at 28 d. With regarding to the fly ash with Andersen distribution, it was however not conducive to the strength development of concrete. Regression model based on the grey multiple linear regression theory was proved to be efficient to predict the strength of concrete, according to the characteristic parameters of particle size and pore structure of the fly ash.

The Impact of Surface Preparation for Self-Compacting, High-Performance, Fiber-Reinforced Concrete Confined with CFRP Using a Cement Matrix.

With the development of concrete technology, the tendency to combine different materials with each other to achieve a greater efficiency and durability of structures can be observed. In the modern construction industry, various materials and techniques are increasingly being combined in order to achieve e.g., an increased resistance to dynamic impacts of a structure, or an increased scope of work of a selected constructional element, which translates into a significant increase in the energy of destruction. Thus, hybrid elements, known as composite ones, are created, which consist of concrete and reinforcements. This study examined the influence of the preparation of the concrete surface on the behavior of high-performance, self-compacting, fiber-reinforced concrete (HPSCFRC), reinforced with carbon fibers (CF) using a cement matrix. In the general lamination processes, this is preformed using epoxy resin. However, epoxy resin is sensitive to relatively low temperatures, and therefore the authors attempted to use a cement matrix in the lamination process. When connecting hardened concrete with a fresh concrete matrix or mixture, the type of the concrete surface is significant. In this research, three types of concrete surfaces e.g., unprepared, sanded and grinded were considered. All of the surfaces were examined using a 3D laser scanner, to determine the Abbott-Firestone profile material share curve. In this research, cylindrical concrete specimens were reinforced with one, two and three layers of laminates. They were then subjected to a uniaxial compressive test. The results of tests showed that the use of cement matrix in the lamination process, due to its low efficiency, should not be applied when reinforcing concrete elements with a high compressive strength. Moreover, the grinded surface of concrete showed the best cooperation with CF reinforcement.

An application of Taguchi experiment design methods on optimization of mortar mixture composition with Silica Fume as a partial substitute for cement

The development of concrete technology in infrastructure also triggers the progressive cement manufacture, where cement production also contributes significantly to the emission of CO2. To minimize the use of cement and increase mortar quality, the addition of additive substance material is needed with a quality control method. The purpose of this research is to establish the proportions of the materials with the optimum partial replacement of cement by silica fume to the compressive strength and physical properties of the 56 days old mortar using Taguchi Method design of experiment. This research uses 3 factors, which are silica fume proportion, sand proportion, and cement proportion. Each factor consists of 3 levels, with silica fume content is ±20% from the total weight of the cement. The mortar is based on 9 combinations of materials on the orthogonal matrix L9(34) created with dimensions of 50 x 50 x 50 mm cube. The results show that the optimum proportion is 150 gr of silica fume, 660 gr of cement and 1400 gr of sand which is equivalent to replacing 18.52 % cement with silica fume, which gains 54.00 MPa compressive strength, pH 9.75 and 5.369 % water absorption.

The processing, properties and optimum mix of fly ash based - self compacting geopolymer concrete

The development of concrete technology toward environmentally friendly concrete has become increasingly interest area. The production of Portland cement has a significant impact on greenhouse emissions. The fact triggers the research and the development of eco-friendly concrete, one of which is geopolymer concrete. The implementation of concrete casting sometimes faces the construction that requires the casting process without vibration. It is then when the self-compacting concrete technology was developed. Concerning the two main issues of eco-friendly self-compacting concrete mention above, fly ash based-self compacting Geopolymer concrete has become a research study and develops in the last decades. This paper identifies the process, properties, an optimum mix of fly ash-based self-compacting geopolymer concrete. The properties in this research are the workability of fresh concrete and compressive strength at 7 days. Compressive strength is reported with several NaOH molarities, Alkaline to fly ash ratio, curing time, Curing temperature, Superplasticizer, and Extra Water. Examination of the workability is done with a slump flow test, V-Funnel test, and L-Shape box test. The result shows the optimum mix of fly ash based self-compacting geopolymer concrete.

Neutron shielding concrete incorporating B4C and PVA fibers exposed to high temperatures

Traditionally, concrete has been used in radiotherapy rooms, in nuclear fuel containers, in nuclear power plant foundations and other structures using large thicknesses to shield the radiation. Currently, the development of concrete technology allows us to produce cement-based composite materials incorporating fibers, improving mechanical properties, additives and additions, increasing certain properties such as the shielding against ionizing radiation. This paper explores the possibility of building protective walls using different specialized concrete skins, which protect against neutron radiation generated by nuclear fuels. The paper validates a lightweight neutron protection concrete for high and low activity containers considering the worst conditions of use. It has been proven that the mechanical properties, durability and behavior under fast increases of temperature are suitable for purpose. The studied concrete incorporates natural limestone aggregate, polyvinyl alcohol fibers and boron carbide as a neutron absorber. After exposure to thermal gradients of 100 °C, 300 °C, 500 °C, 700 °C and 1000 °C, the concrete is characterized by its residual physical and mechanical properties and its microstructural topography. Results show a reduction in mechanical properties, a decrease in the continuity of the material detected by ultrasonic impulse propagation and an increase in the presence of voids in the microstructure.

Analisis Kuat Tekan Beton Ringan Dengan Subtitusi Material Kertas Koran Dan Fly Ash

Development in the field of construction in the modern era shows a very rapid development, including in the construction of housing, offices, hospitals and so on. Concrete as a construction material has long been used and widely applied by the community because it has advantages easily formed according to construction needs. The development of concrete technology has also continued to develop with the presence of high-strength concrete. The process of making lightweight concrete certainly requires mixed materials that have low specific gravity. One alternative material that can be used is newsprint and fly ash, both materials are materials that have a low specific gravity and are easy to work on, the addition of fly ash and newsprint so that the relationship of compressive strength and weight of concrete influence each other, the more addition of fly ash and newsprint, the compressive strength increases and the weight of the concrete increases.

Influence of polypropylene fiber on early strength of self-compacting concrete

One of the development of concrete technology in construction’s world is Self-Compacting Concrete. Self-Compacting Concrete (SCC) is an innovative concrete that able to “flow” and condensed by gravity and its own weight with little vibration or even without a vibration device at all. However, these concrete still have deficiencies like general concrete that is weak to tensile. To increase the tensile strength of the concrete is by adding fiber into the mix. One type of fiber that can be used as an additive to the mix is Polypropylene fibers. This study aims to determine the effect of adding polypropylene fibers to the mechanical properties and characteristics of SCC concrete and to know the optimal polypropylene fiber content in the manufacture of Self Compacting Concrete. Fiber addition variations are 0 kg / m3; 0.25 kg / m3; 0.5 kg / m3 and 0.75 kg / m3. The result of the research showed that the variation of 0.5 kg / m3 and 0.75 kg / m3 addition of fibers didn’t fulfill the requirements to be categorized as a SCC concrete. The results of hard concrete test showed the highest compressive strength that is on the SCC PP concrete of 22.31 MPa at the age of 1 day and 46.24 at the age of 28 days. The highest strength is on the SCC 0.25 PP concrete of 6.52 MPa at the age of 1 day and 10.07 at the age of 28 days. The highest flexural strength is on the SCC 0.25 PP concrete of 6.76 at the age of 1 day and 8.60 at the age of 28 days.

Environmental performance of ordinary and new generation concrete structures\u2014a comparative analysis

The development of concrete technology results in a new generation of cement-based concrete such as high-performance concrete, self-compacting concrete and high-performance, self-compacting concrete. These concretes are characterised by better parameters not only in terms of strength and durability but also rheology of the mixtures. Obtaining such properties requires the adoption of a different composition and proportion of ingredients than ordinary concrete. The greater share of cement in these concretes causes an increase in the energy consumption and emissions (per unit of concrete volume) at the production stage. However, use of new generation concrete allows for a reduction of overall dimensions of a structural element, due to the increased strength parameters. Such a solution may finally result in lower consumption of resources and energy, as well as a decrease of gas emissions. The article presents the results of a comparative environmental analysis of ordinary and new generation concrete structures.

The effect of steel slag as a coarse aggregate and Sinabung volcanic ash a filler on high strength concrete

The Development of concrete technology is continues to grow. The requisite for efficient constructions that are often viewed in terms of concrete mechanical behavior, application on the field, and cost estimation of implementation increasingly require engineers to optimize construction materials, especially for concrete materials. Various types of concrete have now been developed according to their needs, such as high strength concrete. On high strength concrete design, it is necessary to consider several factors that will affect the reach of the quality strength, Those are cement, water cement ratio (w/c), aggregates, and proper admixture. In the use of natural mineral, it is important for an engineer to keep an eye on the natural conditions that have been explored. So the selection of aggregates as possible is a material that is not causing nature destruction. On this experiment the use of steel slag from PT.Growth Sumatra Industry as a substitute of coarse and fine aggregate, and volcanic ash of mount Sinabung as microsilka in concrete mixture substituted to create high strength concrete that is harmless for the environment. The use of mount sinabung volcanic ash as microsilika coupled with the use of Master Glenium Sky 8614 superplasticizer. This experiment intend to compare high strength concrete based slag steel as the main constituent aggregates and high strength concrete with a conventional mixture. The research result for 28 days old concrete shows that conventional concrete compressive strength is 67.567 MPa, slag concrete 75.958 Mpa, conventional tensile strength 5.435 Mpa while slag concrete 5.053 Mpa, conventional concrete bending strength 44064.96 kgcm while concrete slag 51473.94 kgcm and modulus of conventional concrete fracture 124.978 kg / cm2 while slag concrete 145.956 kg / cm2. Both concrete slump values shows similar results due to the use of superplasticizer.

Effect of rock flour type on rheology and strength of self-compacting lightweight concrete

With the development of concrete technology, producing concrete products that have the ability to flow under their own weights and do not need internal or external vibrations is an important achievement. In this study, assessments are made on using travertine, marble and limestone rock flours in self-compacting lightweight concrete (SCLC). In fact, the effects of these powders on plastic and hardened phases of SCLC are studied. To address this issue, concrete mixtures with water to cementitious materials ratios of 0.42 and 0.45 were used. These mixtures were made with 0 and 10% silica fume (SF) replacement levels by cement weight. To achieve lightweight concrete, lightweight expanded clay aggregate (Leca) with the bulk density of about 520 kg/m3 was utilized. Also two kinds of water were consumed involving tap water and magnetic water (MW) for investigating the possible interaction of MW and rock flour type. In this study, 12 mixtures were studied, and their specific weights were in the range of 1660-1692 kg/m3. To study the mixtures in plastic phase, tests such as slump flow, J-ring, V-funnel and U-box were performed. By using marble and travertine powders instead of limestone flour, the plastic viscosities and rheology were not changed considerably and they remained in the range of regulations. Moreover, SCLC showed better compressive strength with travertine, and then with marble rock flours compared to limestone powders. According to the results of the conducted study, MW showed better performance in both fresh and hardened phases in all the mixes, and there was no interaction between MW and rock flour type.

The impact of coarse aggregate shape on the behavior of self-compacting high-performance concrete

Self-Compacting High Performance Concrete (SCHPC) presents a crucial step in the development of concrete technology. The most important features of self-consolidating concrete are flowability, segregation resistance and passing ability. Generally, the rheological properties are modified by effective superplasticisers and water to binder ratio. The aim of this study is to focus on the important aspect of the impact of shape of the coarse aggregate on fresh concrete mixture properties, strength and deformability of SCHPC. Coarse aggregate is a significant proportion of the concrete volume and therefore has a meaningful influence on its quality. By appropriate selection of the shape of the grain aggregate, it is possible to affect the rheological parameters of concrete. The results presented in this study indicated that the shape of the grains of coarse aggregate has an impact on the strength and stiffness of SCHPC. Moreover, the occurrence of irregular grains of coarse aggregate causes lower slump flow and higher plastic viscosity in comparison to concrete mixtures with regular grains only. The research presented in this article is part of the author's wider research devoted to this issue.

Research on Fracture and Durability of High Performance Concrete

The building structure is the main frame of the building and whose optimization and development promotes the renewal and development of building materials. Concrete has become more and more popular construction materials that are widely used in modern times. With the development of science and technology, all kinds of concrete structures emerge in an endless stream. These concrete structures should not only meet the requirements of structural load design but also the long-term work in a specific environment capacity. This produces a great demand of adequate durability of the concrete structure and this is the future direction of the development of concrete technology. Since the middle of twentieth Century, a number of accidents have happened at home and abroad. The cause of these accidents is the poor durability of concrete structures. It also makes people pay more and more attention to the durability of concrete structure. High performance concrete is a kind of concrete with a new type of high tech that has been widely used in all over the world in recent years, which can not only guarantee the durability and workability but also meet the requirements of application and economy. The high-performance concrete prepared by the eight groups was studied in this paper and the fracture and durability of high performance concrete were studied by two experiments of compressive strength and frost resistance.

High Performance Concrete for Environmentally Efficient Building Structures

Concrete is the most used man made material nowadays. The environmental impact associated with cement production is very significant due to the extent of concrete use. At the same moment cement production is associated with large energy consumption and high amount of greenhouse gas emissions. Development of concrete technology during last twenty years has lead to a significant quality shift of technical parameters and also of related environmental impacts. New types of optimized concrete mixes have significantly improved characteristics from the perspective of strength, mechanical resistance, durability and resistance to extreme loads. The use of alternative non-steel reinforcement from various types of fibres can increase reliability, durability and reduction of environmental impacts. Due to optimization of production technology, concrete is gradually becoming a building material appropriate and advantageous for sustainable construction of buildings. In this context increase of reliability and durability within whole life cycle is essential. New approaches in concrete technology like utilization of high performance and ultra high performance concretes, use of textile reinforcement, shape optimization and conceptual approach for integrated life-cycle assessment of concrete structures are presented in the paper. Some of principles are demonstrated on results of experimental research performed by author and his team at the Czech Technical University in Prague (CTU).