Concrete structures

This book deals with earthquake-resistant structures, such as, buildings, bridges and liquid storage tanks. It contains twenty chapters covering several interesting research topics written by researchers and experts in the field of earthquake engineering. The book covers seismic-resistance design of masonry and reinforced concrete structures to be constructed as well as safety assessment, strengthening and rehabilitation of existing structures against earthquake loads. It also includes three chapters on electromagnetic sensing techniques for health assessment of structures, post earthquake assessment of steel buildings in fire environment and response of underground pipes to blast loads. The book provides the state-of-the-art on recent progress in earthquake-resistant structures. It should be useful to graduate students, researchers and practicing structural engineers.

La Ópera de Sídney puede considerarse un paradigma en relación a la influencia que los métodos de representación gráfica y análisis estructural ejercen en la concepción y construcción de las obras de arquitectura. Se plantean posibles esquemas estructurales para las cubiertas de dicho edificio respetando la forma propuesta originalmente por Utzon, forma que se vio modificada durante el proceso de proyecto para hacer viable su construcción, poniendo en evidencia el impacto que los avances científicos y tecnológicos acaecidos durante la segunda mitad del siglo pasado han tenido en la manera de concebir y construir edificios.

Eine gute Primarschule zeichnet sich vor allem dadurch aus, dass sie den Schülern vielfältige Aussenräume bietet und sie mit den Mitteln der Architektur dazu auffordert, sich diese anzueignen – im digital dominierten Zeitalter mehr denn je. Überzeugend gelingt dies der Primarschule Schauenberg. Doch es gibt viele weitere Gründe, warum sie einer der besten Neubauten der Schweiz ist.

In the present paper, a numerical and experimental study about creep and shrinkage behavior of a high strength self-compacting concrete is performed. Two new creep and shrinkage prediction models based on the comprehensive analysis on the available models of both conventional concrete and self-compacting concrete are proposed for high strength self-compacting concrete structures. In order to evaluate the predictability of the proposed models, an experimental program was carried out. A concrete which develops 60 MPa within 24 h was used to obtain experimental results. Several specimens were loaded: (i) at different ages and (ii) with different stress-to-strength ratios. Deformation in non-loaded specimens was also measured to assess shrinkage. All specimens were kept under constant stress during at least 600 days in a climatic chamber with temperature and relative humidity of 208C and 50%, respectively. Results showed that the new models were able to predict deformations with good ac...

Corrosion of steel reinforcement has become a major concern for reinforced concrete structures in aggressive environments: It reduced service life of the structures. Fiber reinforced polymers (FRP) bars have gained the acceptance as a substitute of steel reinforcement in the last decades due to their advantageous properties such as corrosion resistance. To improve the ductility and meanwhile ensure satisfactory corrosion-resistant performance, a new form of Ultra High Performance Strain Hardening Cementitious Composites (UHP-SHCC) encased steel composite beams reinforced with basalt fiber reinforced polymers (BFRP) is studied. An experimental investigation on flexural behavior of the proposed beams was conducted by testing a total of four simply supported beam specimens subjected to four-point bending loads. The main parameters considered in this study were the type of the material encasing the steel section and the percentage of UHP-SHCC layer of the beam's depth. The test results indicate that using UHP-SHCC as an encasing material can provide an enhancement in load carrying capacity, ductility and energy dissipation capacity of tested beams. It is demonstrated that the structural performance of composite beams could be improved by replacing normal concrete with UHP-SHCC as the encasing materials. It is found that the combined use of UHP-SHCC and normal concrete could improve the overall ductility of the beams.

ABSTRACT This article presents the analysis of the structure, energy and cost efficiency of three lightweight structural systems–wood light frames (WLF), lightweight steel frames (LGSF) and 3D sandwich (3DSP) panels–during their useful life. The structural systems focussed upon in this study are commonly used in Eastern Europe with specific reference to Turkey. The structural analysis and design was carried out using ETABS while EnergyPlus was used in the analysis of the energy consumption of the buildings. The results of the structural analysis of the three alternative construction systems show that 3DSP has better structural behaviour in terms of resistance against lateral loads. The thermal performance evaluation of the walls and ceilings shows that the WLF and LGSF walls have better insulation values (12.5% lower U-value) while the roof construction of the 3DSP has much better insulation performance (70% lower U-value). Moreover, the building designed with 3DSP requires 11% less energy for total heating and cooling during one year. The information for the building industry in Turkey shows that the cost of construction for 3DSP construction is 34.6% lower than for WLF and 27.7% lower than LGSF.

This 1992 paper reports on work in progress in 'Design for Energy Efficiency,' one of fifteen task areas of the U.S. Department of Energy sponsored Energy Efficient Industrialized Housing research program. In this task, design studies establish visions of energy efficient housing systems and technologies for the year 2030 from which shorter term research activities can be defined. One study for a 'Multifamily Concrete Panel House in a Hot-Arid Climate,' a primarily passive solar design, responds to trends anticipating demand for small, minimum cost multi-family houses in sun-belt suburbs, diversifying household composition, declining wood resources, advancing concrete technology, increasing site density, and competition for cooling energy. Task background and progress is presented with an emphasis on passive solar systems and goals.

This research explore the rapid chloride permeability test (RCPT) on normal concrete incorporating supplementary cementitious materials (SCM). Rapid Chloride permeability test (RCPT) are conducted on cylindrical concrete specimens to recognize durability factors.fly ash and GGBS has been used as supplementary cementitious materials (SCM) and cement has been replaced with FA+GGBS. Compression test has been improved with substitution of supplementary cementitious materials and chloride ion permeability has been reduced with substitution supplementary cementitious materials (SCM) increase of water binder ratio also diminish the permeability value however compression value amplified.

The present case study investigates the capacity assessment and subsequent strengthening of pre-stressed concrete girders and provides additional information on the strengthening measures taken for the whole of the structure involved. It is based on an existing concrete building constructed in 1971. Structural modifications had to be made to ensure a proposed load-bearing capacity upgrade due to change of use. The building contains concrete girders pre-stressed with the post-tensioning method, the mechanical and geometric properties of which were not available, although it was known that the two-span girders were intended to meet high-capacity demands. Nonetheless, an accurate simulation of the structure was essential. For this purpose, non-destructive methods had to be employed, while safety factors were introduced in accordance with the corresponding code provisions, in order to minimize structural uncertainties. Subsequently, finite element models were created to evaluate the res...

The review article investigated failure, design issues, repair and strengthening of reinforced concrete (RC) silos, primarily in agricultural set-ups. The durability of RC structures was influenced by the nature of the bulk solids, materials used in the reinforcement of the structures. Traditionally, high-grade steel has been used in silo wall reinforcement because it is affordable and readily available. However, it is susceptible to corrosion. In contrast, fiber-reinforced polymers (FRP) have better mechanical properties (tensile strength, elastic modulus, and Poisson’s ratio) and are not corroded. Additionally, there are limited scalable and facile methods for commercial production. The low ductility elevates the risk of brittle fracture in external pre-stressing concrete repair/strengthening. Beyond the material factors, the existing silo design codes such as BS EN 1991-4:2006, Australian Standard AS 3774-1996, and American Society of Agricultural Engineers ANSI/ASAE EP433 DEC198...

Construction development at this point of modern time has growing up quite strongly, one of many critical elements in construction world is the material that used for construction activities. Concrete is one of the example of used material in construction work, but as a material that has other many composition within it and many of them are exploited from the earth, then it is our work as human to use it at optimum level by know and understand the properties and other ability of concrete itself.

Two novel demountable shear connectors for precast steel-concrete composite bridges are presented. The connectors use high-strength steel bolts, which are fastened to the steel beam with the aid of a special locking configuration that prevents slip of bolts within their holes. Moreover, the connectors promote accelerated construction and overcome typical construction tolerances issues of precast structures. Most importantly, the connectors allow bridge disassembly, and therefore, can address different bridge deterioration scenarios with minimum disturbance to traffic flow, i.e. (1) precast deck panels can be rapidly uplifted and replaced; (2) connectors can be rapidly removed and replaced; and (3) steel beams can be replaced, while precast decks and shear connectors can be reused. A series of push-out tests and a beam test were conducted to assess the behavior of the connectors and quantify the effect of important parameters. The experimental results showed that shear resistance and...

This research is a summary of previous researchers work done in this area There are numerous issues related to cantilever slabs such as the time-dependent deformation and erosion of steel support. There is a need for exploratory studies on the quality of fortified cantilever slabs. This paper presents an examination to evaluate the behavior of fortified concrete cantilever pieces after fortifying with different procedures. Six medium scale examples, separated into three bunches, were tested along a control piece. The primary gather comprises of two examples which were repaired and fortified utilizing strengthened concrete (RC) coat over with and without shear connector bars, while the moment bunch contained two slabs which were strengthened utilizing two strips of two layers of glass fiber fortified polymer (GFRP) covering 60% and 90% from the cantilever length. The final gather includes two specimens reinforced with two steel plates. In one example, the steel plates were glued to the surface utilizing epoxy gum. The moment example, the steel plates were affixed to the concrete surface utilizing development bolts. The stacking was conducted in two stages. Firstly, the tests were subjected to 40% of the extreme stack of the control slab. Furthermore, the examples reloaded after being reinforced up to failure. The load-deflection, steel strain, concrete strain, disappointment mode, durability, and ductility index are examined in this paper.

As of June 2020, you can preview book prelims and Chapter 1 here: https://issuu.com/casematepub/docs/foster_jones2020

The uploaded text comprises the full author accepted manuscript version of this book's Contents and introductory chapter 'The concrete and non-concrete'. Informed by this research, the concrete St John's Cross replica was listed at Category A by Historic Environment Scotland in March 2020. Keep reading for more details!

As the back cover says: 'In 1970 a concrete replica of the St John’s Cross arrived in Iona sitting incongruously on the deck of a puffer delivering the island’s annual supply of coal. What is the story behind this intriguing replica? How does it relate to the world’s first ringed ‘Celtic cross’, an artistic and technical masterpiece, which has been at the heart of the Iona experience since the eighth century? What does it tell us about the authenticity and value of replicas?

In this fascinating book, Foster and Jones draw on extensive interdisciplinary research to reveal the composite biography of the St John’s Cross, its concrete replica, and its many other scale copies.  They show that replicas can acquire rich forms of authenticity and value, informed by social relations, craft practices, creativity, place and materiality. Thus, the book challenges traditional precepts that seek authenticity in qualities intrinsic to original historic objects. Replicas are shown to be important objects in their own right, with their own creative, human histories — biographies that people can connect with.  The story of the St John’s Cross celebrates how replicas can ‘work’ for us if we let them, particularly if clues are available about their makers’ passion, creativity and craft.'

The publisher details are @ https://www.oxbowbooks.com/oxbow/my-life-as-a-replica.html

There's a related blog here: https://ionaresearchgroup.arts.gla.ac.uk/index.php/2020/01/13/letting-the-st-johns-cross-iona-speak/

Book contents:
Introduction
The concrete and non-concrete (SF)

I. Crafting lives
1. Life as a replica (SF & SJ)
Replication and authenticity
Analogue replicas still matter
The St John’s Cross and its copies matter
The lives and voices of replicas
Capturing lives - objects, texts, images and people
Piecing it all together

2. Loving Iona (SF & SJ)
Island of crosses
Multiple communities
A ‘thick’ place

3. ‘Priceless monuments’ (SF)
Early antiquarian interest
New stewards, new horizons
‘History versus Mystery; Science and Art versus Faith’
Island voices
Dead or alive?

II. Creating and cultivating the cross
4. Formation and reformation (SF)
Salvation, wounds and resurrection
Fragmentation
Antiquarian rebirth, earliest copies
Silent witness
The Fallen Cross

5. Birth of the concrete replica: ‘I can’t think of anything more worthwhile doing’ (SF)
A slow conception
Fertile possibilities
‘Miraculous success’: an ‘authentic prototype’ for an ‘authentic replica’
Erecting the replica in situ
For the love of Iona
Material matters, first impressions
Celebrating the ‘virtually impossible’
MacLeod and the St John’s Cross
New life, new values

6. From out of the shadows (SF)
Transformer
Reunited
Place in the world
The Iona brand

7. Glorious revelation: contemporary significance, values and authenticity (SF & SJ)
‘Loaded objects’: meanings and relationships
Place and space
Material evidence of ‘pastness’
‘Glorious revelation’

III. Celebration in concrete, celebration of concrete
8. New life, new thinking (SF & SJ)
Rethinking authenticity and value
Heritage implications
Creating knowledge and understanding
Understanding social value and authenticity
Securing for the future
Engaging and experiencing
New lives, new stories

High strength concrete (HSC) is a material often used in the construction of high rise buildings. In case of unexpected fire, building elements such as columns, slabs and walls will be subjected to extreme temperatures. In order to assess the performance of high-rise concrete members to such exposure, it is important to understand the changes in the concrete properties due to extreme temperature. This paper presents an experimental study undertaken to quantify the effect of elevated temperatures of 60, 75, 100, 200, 400 and 600°C with various exposure durations of 4, 8, 12, 72 hours and one month on HSC cylinders. HSC cylinders made of two strengths, namely 80 and 100 MPa are used. For comparing their performance with normal strength concrete, cylinders made with 40 MPa concrete are also investigated. Residual tensile and compressive strengths of concrete as well as weight loss values after high temperature exposures were determined. The detrimental effects of using silica fume for ...

The paper presents the new bridge over the river Acheloos in Greece. The position of the bridge poses several construction and design challenges, mostly due to the soil characteristics at the foundation, the increased seismicity of the region and the high flow of the river. The project involves the construction of a small balanced cantilever bridge with three spans of length 47.5m – 80m – 47.5m. The main innovation in the structure is that the deck is supported exclusively on high damping rubber bearings, a technique not commonly encountered in such bridges. The selection of this structural system was a result of the poor geotechnical / foundation conditions, which differed considerably among the piers, as well as their low height. This led to the design of special deck stabilizing systems for the various construction stages. The design included application of the principles of earthquake engineering, an advanced construction schedule and a displacement monitoring procedure. Informa...

Reactive MgO is produced at a lower kiln temperature compared to ordinary Portland cement (OPC) and gains its physical properties mainly as a result of carbonation processes. Use of reactive MgO as cement replacement has recently gained attention in context with precast concrete products subjected to carbonation curing. This study investigates pastes containing 0-40% reactive MgO and the effect of accelerated carbonation curing on the: formation of new carbonate phases, microstructural development, and microhardness. Outcomes from this study revealed that the primary Ca and Mg-bearing carbonates formed are calcite, aragonite, magnesium calcite, and nesquehonite. The combined effect of carbonation and reactive MgO resulted in: a reduction in pore size and total pore volume, increase in apparent density, and greater microhardness compared to OPC paste. The chemical processes, and physical properties revealed that the dense inter-connected network structure consisting of Ca and Mg carbonates is a significant factor that influences the microhardness.

This paper examines the conflict between François Hennebique and Armand Considère, centred on competing patents for reinforced concrete systems in early 20th-century French structures. In the 1890s Hennebique first patented in Belgium and then France, key aspects of monolithic structural framing using the new combined material of béton armé. He rapidly grew a commercial empire in France and abroad, centred on his main design studios in the heart of Paris, and using a global network of agents and contractors. Considère patented his own reinforced concrete system, béton fretté, in 1901 but could only benefit financially from commercial activity five years later when he retired as a senior French state civil engineer setting up in private consulting. The two men were to confront each other in the French courts over aspects of their respective systems for foundation piling. The paper also references the work of the French Commission on reinforced cement and concrete, on which both men sat between 1901 and 1905, in addition to two non-monumental buildings in and near Paris, which provide exemplary material for the key technical issues. The content is derived from aspects of the researcher’s current doctoral research on the influence of technical standards and associated regulations for steel and reinforced concrete on the development of modern architecture in Paris, Lille-Roubaix-Tourcoing and Brussels prior to WW1.

High Performance Concrete (HPC) is now a days used widely in the construction industry worldwide. To produce HPC with normal ingredients one use mineral admixtures like silica fume, fly ash and metakoline. In addition admixtures including Superplasticisers are also used. This paper investigates the effect of silica fume (SF), added in varying percentages (0, 3, 5, 7.5, 10, 12.5%), on concrete strength. Superplasticiser-(Viscocrete Tempo 12)-was added to the concrete mixtures as well. Compressive strength, shear strength and tensile strength tests were conducted, and the results were discussed. Results showed that the compressive strength changes with the varying percentage addition of silica fume. The highest compressive strength (88 MPa) was obtained when the percentage of silica fume was 7.5 % of the cement weight. Beyond 7.5 % silica fume, the compressive strength started descending. Tensile and shear strength were found to vary in an inverse relationship with the increasing percentage of silica fume. A significant reduction in tensile strength and shear strength were recorded when the silica fume percentage is increased. However, the 10% ratio between tensile and compressive strength for normal concrete, was not found to be, relevant for HPC with SF.

Over the past few decades, our research and technical skills has increased a lot. Even today we are innovating and developing the new trends in technology in pursuit of a safe and sustained future as the innovation leads to invention. Throughout this evolution, engineers are in constant research for new and better building materials and carbon fiber is one of these materials, which is used with some other fibers and a specific polymer to form a high performance composite mixture. The aim of this research paper is to study the benefits of using carbon fiber in different types of industry & this paper also overcomes the drawbacks of using other building materials.  The amazing properties of carbon fiber such as high tensile strength, high stiffness, low weight & high resistance to chemical and temperature makes it one of the most popular materials in construction industry due to these properties it has enormous applications in military, medical science, construction, automobile, aircraft industry etc. It actually works as a robust building material. It produces the structure that possesses both flexibility and durability. It is incredibly strong that’s why it can also withstand earthquakes. It is more flexible in wind than the regular structures. It is also listed in the top 20 engineering achievements of 20th century. It is definitely the next generation building material as it can replace steel in the many structures and can reduce its construction and maintenance cost.

Recently laser scanning technologies become widely used in many areas of the modern economy. In the following paper authors show a potential spectrum of use Terrestrial Laser Scanning (TLS) in diagnostics of reinforced concrete elements. Based on modes of failure analysis of reinforcement concrete beam authors describe downsides and advantages of adaptation of terrestrial laser scanning to this purpose, moreover reveal under which condition this technology might be used. Research studies were conducted by Faculty of Civil and Environmental Engineering at Gdansk University of Technology. An experiment involved bending of reinforced concrete beam, the process was registered by the terrestrial laser scanner. Reinforced concrete beam was deliberately overloaded and eventually failed by shear. Whole failure process was tracing and recording by scanner Leica ScanStation C10 and verified by synchronous photographic registration supported by digital photogrammetry methods. Obtained data were post-processed in Leica Cyclone (dedicated software) and MeshLab (program on GPL license). The main goal of this paper is to prove the effectiveness of TLS in diagnostics of reinforced concrete elements. Authors propose few methods and procedures to virtually reconstruct failure process, measure geometry and assess a condition of structure.

The purpose of this experiment is to obtain the tensile, known as “Modulus of Rupture”, strength of the concrete material and the wood material using flexural tests performed on concrete beams.
Tests specimen:
• two beams one with steel reinforcement and one without • two timber beams

Concrete; It is the most used material after water in the world. It is a non-alternative building element with its economical, abundant components in nature, high strength and durability, low cost, processability and many more features.
In order for a concrete to be good, it must be impervious concrete that can protect its physical and chemical integrity, against the loads and environmental effects it is exposed to, throughout its service life. The measure of quality in concrete is not resistance to compressive strength, but resistance to environmental influences and loads that concrete is
exposed to throughout its economic life.
The proof of concrete quality is field performance under actual loading and environmental conditions. But before concrete experiences much of this exposure, it’s necessary to determine its acceptability and make projections about its long-term performance. These judgments are based, in part, on the results of tests performed on hardened concrete.
This paper reviews that quality control of the hardened concrete in the building has been examined under two main titles. Destructive; Compressive strength, Flexural Strength and Splitting Tensile Test. Non-destructive; Rebound Hammer and Ultrasonic Pulse Velocity.

This paper looks at the evolution of slab forming systems over the past 60 years or so, primarily focusing on the systems' developed in North America and Europe. As you read this paper it will become clear that some present day manufacturing suppliers who claim "state of the art innovative solutions" are very often cases of history repeating itself. The paper confines itself to the study of slab forming systems used largely in the commercial, institutional and residential sectors. The systems discussed will have application on civil projects too but the very heavy systems, with leg load capacities in excess of 120kN (27,000lbs), are not the subject of this paper. Concrete construction/Formwork/Falsework/Shoring

In order to achieve greater stability and structural efficiency, engineers use
nature as an inspiration for their design. Considering the level of sustainability
in biological systems, they analyze their structural behavior, browse for
compatible analogies with technical systems, abstract the observed physical
and mechanical principles, and implement these principles into the final
product. This process defines the bionic design approach. The term “bionics”
refers to the scientific discipline that addresses the transfer of properties from
biology to technology. This thesis aims to study the theoretical fundamentals
of this concept, explain its methodologies, and demonstrate its applicability in
architecture. Through the assessment of bionically built shell structures, the
different steps of the design process are illustrated, and the elements of each
analogy are evaluated on both biological and technological ends. The chosen
examples in this thesis incorporate concrete, masonry, steel, and timber
structures. Multidisciplinary literature is reviewed to deliver a thorough
explanation for each design project. Based on this research, the structural
benefits that characterize certain biological systems can be transferred into
architectural design, and improve the load bearing capacity of shell structures
in particular, using the bionic approach.

The main objective of the present study is the assessment and retrofit of an existing road bridge that is located in Cyprus over the river Kouris. In particular the study concerns in a road bridge with seven spans of 10.5 m + 5 * 12.6 m + 10.5 m, a cross section width of 7.10 m and a 5 m piers height that was constructed in the early 50's. The structural system of the bridge comprises of cast in situ reinforced concrete T-beams and slab deck that is simply supported on masonry piers. According to the new urban plan to design the bridge should now accommodate two lanes per direction, a pedestrian walkway and a cycling lane with total cross section width of new deck 15.60 m. The deck of the bridge widened using for aesthetic reasons the same cross section type and the new T-Beams and slab deck connected monolithically to the existing one. The existing part of the deck was strengthened with reinforced concrete jacketing due to inadequacy in shear resistance. Major challenge of the project posed the existing masonry pier layout that was insufficient to carry the new design seismic forces. New piers, founded on piles, were designed adjacent to the existing piers in order to support the new widened part of the bridge, and also to bear all the horizontal loads arising from the masses of the total deck. Sliding bearings (free movement) placed in the part of the bridge over the existing piers and elastomeric bearings with movement only in the longitudinal direction placed in the new piers.

There has been a growth in extensive research aimed at examining the effects of seismic events on the performance of a structure. Buildings have a tendency to exhibit inelastic deformation in during seismic activities and post-elastic behavior. Hence, better insights of the performance of structure can be obtained by examining its post-elastic behavior. Non-linear static analysis (also known as Pushover Analysis) is an improved and effective modern way of examining structural performance in the event of potential seismic impact. Such an approach involves horizontally pushing a structure using a predetermined loading pattern which constantly increases over time thereby making it possible to determine the collapse conditions, associated lateral displacement and total applied shear force. It offers a sound Perception of Structural Performance against earthquake as well as damages suffered. Thus, pushover analysis makes it feasible to ascertain the responsive behavior of buildings in non-linear zones which is not catered for by conventional elastic designs.

An exploration of the origins and development of Queensgate Market; a 1970 covered retail market in Huddersfield in the United Kingdom.

The market’s roof of glazed reinforced concrete asymmetric hyperbolic paraboloid shell umbrellas and prominent artwork have led to never ending controversy. Proposed demolition of the building in 2003 and its listing on grounds of its architectural or historic importance in 2005 accentuated the community’s dichotomy over the market’s qualities.

Can the building be better understood by examining antecedents and historical practice?

Through a review of markets and market architecture and design, hyperbolic paraboloid shell roofs engineering, retail design and public art the research aims to explore aspects of the development of Queensgate Market;
• the trajectories of art, engineering and architectural practice
• the transfers of awareness, knowledge, empowerment and actualisation
• the mechanisms and vectors at play in such transfers; education and autodidactic learning and dissemination through publication and migration.
• the connections based on proximity, employment, meeting and travel.
It was carried out by site visits, primary and secondary sources and interviews with people involved with design and construction.

Queensgate Market is identified as the unique nexus and climax in the expression of markets, hyperbolic paraboloid shells and civic art.

The study concludes that the vagaries of human migration, challenge, proximity, education and friendship are informal but important vectors in addition to technology, commercial, legislative and societal norms to the realisation of the project.

In this study, material properties of calcium aluminate cement concrete (CACC) were investigated at various temperatures of 23, 200, 400, 600 and 800 °C. Material properties namely compressive strength, splitting tensile strength, elastic modulus, stress–strain response, mass loss and compressive toughness were measured using unstressed and residual test methods. High temperature performance of CACC was compared with conventional normal strength concrete (NSC). Data from high temperature tests of CACC revealed that the presence of alumina as a binding agent showed considerable enhancement in the mechanical performance compared to NSC. At elevated temperatures, reduction in the stress–strain response was observed in both CACC and NSC; however, increase in axial strain was more in case of CACC. Compressive toughness was higher in case of CACC as compared to NSC which increases up to 200 °C, but decreases beyond this temperature. Scanning electron microscope (SEM) was used to differentiate the microstructural changes in both types of concrete at temperatures up to 600 °C. Visual investigations after high temperature exposure revealed that CACC exhibits low cracking with less color changes as compared to NSC. Data generated from material property tests was utilized to develop simplified relations for expressing material properties of CACC as a function of temperature.

Test and analyses has been carried out to establish relationships among the compressive strength, split tensile strength and shear strength of concrete using recycled coarse aggregate. Two different arrangements have been used to determine the shear strength of concrete in order to study the variation of shear strength under different shear condition.

يهدف هذا البحث إلى دراسة تأثير إضافة ألياف الحديد على خواص الخرسانة وسلوك الانحناء في الكمرات الخرسانية المسلحة. حيث تضمن البرنامج العملي اختبار مجموعة من الكمرات الخرسانية المسلحة وعينات خرسانية محتوية على نسب حجمية مختلفة من ألياف الحديد لدراسة تأثير إضافة هذا النوع من الألياف على مقاومة الخرسانة في الضغط والشد الغير مباشر والانحناء. كما تضمن هذا البحث نمذجة ثلاثية الأبعاد للكمرات الخرسانية المسلحة المحتوية على ألياف الحديد باستخدام إحدى برامج نظرية العناصر المحدودة ويسمى (Midas FEA).
أظهرت النتائج المعملية أن إضافة ألياف الحديد لها أثر إيجابي واضح على تحسين خواص الخرسانة وسلوك الانحناء في الكمرات المسلحة. حيث سجّلت النتائج زيادة واضحة في مقاومتي الضغط والشد الغير مباشر وصلت إلى 60% و110% على التوالي بالمقارنة مع العينات المرجعية المصنعة بدون ألياف. وسجلت نتائج اختبار الكمرات الخرسانية المسلحة المحتوية على ألياف الحديد زيادة ملحوظة في قيم حمل التشقق الأول والمقاومة القصوى مع نقصان واضح في قيم الانحراف وصل إلى نسبة 40% في العينات المحتوية على ألياف. كما بينت النتائج المتحصل عليها من النمذجة ثلاثية الأبعاد باستخدام برنامج (Midas FEA) تطابقاً كبيرًا بالمقارنة مع النتائج المعملية مؤكدة دقة النموذج الرياضي المستخدم.

The waste materials utilization in concrete production is very much helpful in reaching the goal of sustainable construction. Therefore, this study intends to use coconut shells and fly ash by replacing coarse aggregate and cement, respectively, in concrete. The paper reports on the performance of M30 grade of concrete mixes containing different ratios of coconut shell having 20 mm maximum size as coarse aggregate. Ordinary Portland Cement 33 grade and coarse sand were used to produce standard concrete cubes. Compressive strength tests were carried out on concrete specimens of various ages. Test results indicate that except for the M30 mix, there is no significant effect on compressive strength of concrete up to 20 percent replacement of normal 20 mm coarse aggregates with coconut shells. But beyond that, strength started decreasing gradually with an increase in the proportion of CS aggregates in concrete.