Compressive Strength Research Papers - Academia.edu (original) (raw)

- by
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- Human Computer Interaction, Structural Engineering, Concrete, Foundations

Nowadays, the usage amount of the concrete is increasing drastically. The construction industry is a huge consumer of natural consumer. It is also producing the huge wastage products. The usage of concrete has been charged to be not environmentally friendly due to depletion of reserve natural resources, high energy consumption and disposal issues. The conservation of natural resources and reduction of disposal site by reuse and recycling waste material was interest possibilites. The aim of this study is to determine the physical and mechanical properties of sand cement brick containing recycled concrete aggregate and to determine the optimum mix ratio containing recycled concrete aggregate. An experiment done by comparing the result of control specimen using 100% natural sand with recycled concrete aggregate replacement specimen by weight for 55%, 65%, and 75%. The sample was tested under density, compressive strength, flexural strength and water absorption to study the effect of using recycled concrete aggregate on the physical and mechanical properties of bricks. The result shows that the replacement of natural sand by recycled concrete aggregate at the level of 55% provide the highest compressive and flexural strength compared to other percentage and control specimen. However, if the replacement higher than 55%, the strength of brick was decreased for compressive and flexural strength, respectively. The relationship of compressive-flexural strength is determined from statistical analysis and the predicted result can be obtained by using equation f f,RCA = 0.5375 (f c) 0.3272 .

- by Faisal Sheikh Khalid
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- Sand Cement Brick, Compressive Strength, Fine Aggregate
- by Joseph Palamara
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- Engineering, Chemistry, Dentistry, Calcium

At Centralised Waste Management Facility (CWMF) 160m3 of radioactive chemical sludge, generated from treatment of several batches of category-II and category-III radioactive liquid wastes by chemical precipitation method was stored in clariflocculator (CF) for downstream processing. The sludge needed conditioning before disposal. The analysis of the sludge samples collected at different radial locations and depths from the CF showed suspended

- by A G Shanmugamani
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- Process Control, Waste Management, Compressive Strength, Mass Transport

The purpose of this study was to analyze, in an animal model, the histologic and biomechanical phenomena at the bone-implant interface of implants inserted with high torque (HT) as compared to low torque (LT) during the first 6 weeks of healing. Forty tapered-screw-form implants were placed in five hybrid sheep. The implant sites were placed in the mandible, using an extraoral approach; four were placed with HT (test: mean 110 Ncm) on one side and four were placed with LT (control: mean 10 Ncm) on the contralateral side. After 1, 2, 3, 4, and 6 weeks of healing, removal torque testing and resonance frequency analysis were performed and the animals were sacrificed for histologic examination. Implants from the HT group showed significantly higher bone apposition than implants from the LT group at all examined healing times. Similarly, removal torque was consistently higher for the HT as compared to the LT group. A significant loss of primary stability in the HT group was evident 7 day...

- by Ugo Consolo
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- Dentistry, Biomedical Engineering, Wound Healing, Osseointegration

... In the case of cement paste containing up to 20% replacement of bentonite together with 4% CW ... 3. YM Zhang, W. Sun and HD Yan, Hydration of high-volume fly ash cement pastes. ... 4. M. Cheriaf, JC Rocha and J. Pera, Pozzolanic... more

- by Asım Olgun
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- Civil Engineering, Materials Science, Compressive Strength, Building

The main aim of the environmental protection agencies and the government are to seek ways and means to minimize the problems of disposal and health hazards of by-products. Some of the industrial by-products have been successfully used in the construction industry for the production of cement and concrete. Copper slag is one of the materials that is considered as a waste material which could have a promising future in construction industry as partial substitute of either cement or aggregates. Many researchers have already found it possible to use copper slag as a concrete aggregate. But not much research has been carried out concerning durability and corrosion studies of copper slag admixed concrete. This paper presents the results of an experimental study on various corrosion and durability tests on concrete containing copper slag as partial replacement of sand and cement. For this research work, M20 grade concrete was used and the tests were conducted for various proportions of cop...

- by Dr D Brindha
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- Engineering, Compressive Strength, Civil/Structural Engineering, Copper Slag

A process for interconnecting a three-dimensional pattern of self-propagating polymer waveguides was used to form micro-truss structures with two new unit cell architectures. The structures were formed using a two-dimensional mask with a hexagonal pattern of apertures. Distinct unit cell architectures were possible by exposing the mask to a different number of incident UV exposure beams, which are used to form the waveguides. One unit cell design featured three intersecting waveguides per node, resulting in a structure with threefold symmetry. The second unit cell design had six-fold symmetry and was characterized by primary nodes with six intersecting waveguides and secondary nodes with two intersecting waveguides. Compression loading experiments were conducted on micro-truss samples with comparable relative density values (q/q s = 6.5%), but different unit cell architectures. The addition of secondary nodes in the structures based on the second design led to an increase in compressive modulus of up to 70% and an average increase in peak strength of 42%. The increase in compressive strength and modulus was attributed to a reduction in the truss-member slenderness ratio achieved through increased waveguide connectivity.

The reduction in the sources of natural sand and the requirement for reduction in the cost of concrete production has resulted in the increased need to identify substitute material to sand as fine aggregates in the production of concretes. Quarry dust, a by-product from the crushing process during quarrying activities is one of the materials being studied. This paper reports the experimental study undertaken to investigate some properties of quarry dust and discusses the suitability of those properties to enable quarry dust to be used as partial replacement material for sand in concrete. The properties of quarry dust that were determined are aggregate crushing value, flakiness index, pH value, soundness, specific gravity, absorption and fineness modulus. Besides, the 28 th day compressive strength of concrete specimens, in which partial replacement of river sand with quarry dust were practiced, is also reported for comparison purposes. Results obtained indicate that the incorporation of quarry dust into the concrete mix as partial replacement material to river sand resulted in lower 28 th day compressive strength. This can partly be attributed to the properties of the quarry dust which might contribute to the negative effects in the strength of the concrete. The results of the study also indicates that quarry dust can be utilised as partial replacement material to sand, in the presence of silica fume or fly ash, to produce concretes with fair ranges of compressive strength.

- by Hilmi Mahmud
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- Compressive Strength, Fly Ash, Experimental Study, Specific Gravity

The first part of this study verifies that static compressive strength of new wooden pallets decreases as temperature increases. The drop of compressive strength is at a small rate of 0.61 psi per 1°F of temperature increase within the temperature range of 80°F to 160°F. This is consistent with the current timber structural design practice. The strength reduction is small and has little effect on pallet static compression performance. The second part of this study investigates impact acceleration from free-fall drop tests performed at temperatures ranging from 80°F to 160°F. As temperature rises, specimens become weaker thus they absorb more impact energy, which results in lower impact acceleration. The drop of impact acceleration is also at a small rate of 0.034g per 1°F of temperature increase. When temperature rises from normal temperature of around 80°F to a high temperature of 160°F, the impact acceleration reduces about 2.72g. This rise results in less potential damages on products on the pallet. The third part of this study looks at the impact acceleration due to horizontal impact due to a forklift at a lower range of temperature of 33°F to 72°F. The drop of impact acceleration is at a faster rate of 0.674g per 1°F of temperature increase. When temperature drops from 59°F to 48°F, the impact acceleration increases about 7.41g. This increases the damage potential of products on pallets.

- by Phyo Zaw Aung
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- Compressive Strength

a b s t r a c t 22 Artificial neural network analysis was performed to establish a relationship between microstructural 23 characteristics and compressive strength values of cement mortar in this study. Pore properties such 24 as pore area ratio, total pore length, total dendrite length and average roundness, and paste properties 25 such as hydrated part area and unhydrated part area ratios were approached as microstructural charac-26 teristics obtained by digital image analysis. These microstructural quantities were correlated with com-27 pressive strength values of cement mortar incorporating with the chemical admixtures by different 28 dosages, which resulted as several microstructural characteristics. Artificial neural network (ANN) anal-29 ysis indicated that by using ANN as non-linear statistical data modeling tool, a strong correlation between 30 the microstructural properties of cement mortar and compressive strengths can be established.

- by Okan Önal
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- Engineering, Software Engineering, Microstructure, Compressive Strength

The clinical performance of light polymerised dental composites is greatly in#uenced by the quality of the light-curing unit (LCU) used. Commonly used halogen LCUs have some speci"c drawbacks such as decreasing of the light output with time. This may result in low degree of monomer conversion of the composites with negative clinical implications. Previous studies have shown that blue-light-emitting diode (LED) LCUs have the potential to polymerise dental composites without having the drawbacks of halogen LCUs. Despite the relatively low irradiance of current LED LCUs, their e$ciency is close to that of conventional halogen LCUs with more than twice the irradiance. This phenomenon has not been explained fully yet. Hence, more tests of the LED LCU's e!ectiveness and of the mechanical properties of oral biomaterials processed with LED LCUs need to be carried out. This study investigates the #exural properties of three di!erent composites with three di!erent shades, which were polymerised with either a commercial halogen LCU or an LED LCU, respectively. In most cases no signi"cant di!erences in #exural strength and modulus between composites polymerised with a halogen LCU or an LED LCU, respectively, were found. A simple model for the curing e!ectiveness based on the convolution absorption spectrum of the camphorquinone photoinitiator present in composites and the emission spectra of the LCUs is presented.

- by Richard Vowles
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- Biomedical Engineering, Composites, Dental Materials, Polymerization

Arches, vaults and pillars generally experience eccentric normal force. As a consequence, the classical theories of masonry collapse, developed for concentrically compressed brickwork, are not directly applicable. In this paper experimental data on solid clay brick and limemortar masonry prisms, eccentrically loaded, are presented. Comparing the results to the response of a FEM model, some hints on the collapse mechanism of masonry show that the edge effects greatly affect the load carrying capacity of the brickwork. Besides, the plane section assumption is found to be acceptable up to the ultimate compressive strength, allowing relatively simple models to be used for arch-type structures.

- by Luigi Gambarotta
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- Compressive Strength, Carrying Capacity, Experimental Data

Objectives: The objective was to validate an existing theoretical model for the mechanics of constant peak displacement cardiopulmonary resuscitation (CPR) using experimental data taken using various back support surfaces at different... more

- by Kiran Dellimore
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- Spine, Compressive Strength, Clinical Sciences, Cardiopulmonary Resuscitation

High strength cements can be synthesised by alkali activation of materials rich in Al2O3 and SiO2. In this study, amorphous aluminosilicate polymers produced by sodium silicate activation of metakaolinite were studied, with particular reference to chemical optimisation of the compressive strength according to the relative
concentrations of Si, Al and Na in the polymer. The sodium silicate was manufactured from silica fume and sodium hydroxide. The compressive strengths of polymers with Si :Al molar ratios of 1.0–3.0 and Na :Al molar ratios of 0.5–2.0 were considered. The polymers were cured at 75 uC for 24 h and their compressive strengths measured after aging for 7 days. The strength was found to depend systematically on the relative amounts of Si, Al and Na, with the maximum being 64 ¡ 3 MPa for an Si :Al : Na molar ratio of 2.5 : 1 : 1.3. X-Ray diffraction/scattering data indicate qualitatively that the bonding network in the amorphous aluminosilicate
alters systematically with composition.

- by Matthew Rowles
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- Engineering, Materials Chemistry, Compressive Strength, CHEMICAL SCIENCES

In Europe, cement paste compressive strength models are frequently described by a power law similar to that of Féret. The French LCPC has also adopted this mathematical approach in its recent concrete mixture proportioning model. However the coefficient k and exponent b of the adopted power law were calibrated with only one Portland cement clinker, starting from pure pastes with various concentrations. These parameters do not take into account the chemical properties of the clinker. The purpose of this work was to check if the clinker chemical nature had an influence on the mechanical performances of the pastes (at 28 days). Complementary tests with eight cements coming from six different cement plants were then carried out. The mathematical treatment of the results made it possible to connect coefficient k to the silica content of the clinkers and more particularly to their C 3 S rates. It is linked to the strength of hydrated cement paste. Thus, the suggested approach significantly improves the accuracy of paste strength calculation. These results can be used to calculate concrete strength.

- by Jean-Michel Mechling
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- Civil Engineering, Materials Science, Compressive Strength, Silica

Purpose: The aim of this study was to determine effect of compressive cyclic loading on fatigue resistance and microleakage of monolithic CAD/CAM molar ceramic and composite crowns. Materials and Methods: Thirty-two extracted molars were... more

- by Amr Kassem
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- Materials Science, Dentistry, Prosthodontics, Computer Aided Design

Stress distribution in human tooth structure can be visualized through the use of Moiré fringes, which has improved the clinical understanding of recently identified anatomical structures in molar occlusal surfaces. This article discusses the concept of a "peripheral rim of enamel" and describes the manifestation of compressive and tensile fractures within the peripheral rim of enamel and dentin. It also emphasizes the benefits of microdentistry techniques and minimally invasive preparation designs in the long-term preservation of the natural tooth structure.

- by J T Rainey DDS
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- Materials Science, Dentistry, Medicine, Elasticity

Geopolymer is now a more advanced alternative to cement and available substitute for OPC while graphene nanoplatelets (GnP) are new nanomaterials with extraordinary properties that can enhance and improve the strength of cementitious materials. Although graphene reinforced concrete has intriguing potential, its implementation in construction requires better knowledge of the impact of GnP on the properties of concrete related to durability. Studies on the compressive and tensile strength performance of geopolymer concrete (GPC) containing GnP are needed. The present study investigated the influence of reinforcing GPC with varying percentages of GnP on the compressive and split tensile strengths of GPC. The addition of GnP ranged from 0.0%, 0.25% and 0.5% by weight of total binder. It has been observed that the addition of GnP increased the compressive strength by 30% and the tensile strength by 22% in comparison to a reference sample with a specified composition of fly ash and sodium metasilicate. In addition, the effect of GnP on enhancing the compressive strength of the geopolymer was shown to diminish as the amount of sodium metasilicate increased.

- by Nadzhratul Husna
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- Materials Science, Graphene, Geopolymer Concrete, Compressive Strength

A cross-linking reagent is required to improve mechanical strength and degradation properties of biopolymers for tissue engineering. To find the optimal preparative method, we prepared diverse genipin-cross-linked chitosan/collagen scaffolds using different genipin concentrations and various cross-linking temperatures and cross-linking times. The compressive strength increased with the increasing of genipin concentration from 0.1 to 1.0%, but when concentration exceeded 1.0%, the compressive strength decreased. Similarly, the compressive strength increased with the increasing of temperature from 4 to 20°C, but when temperature reached 37°C, the compressive strength decreased. Showing a different trend from the above two factors, the effect of cross-linking time on the compressive strength had a single increasing tendency. The other results also demonstrated that the pore size, degradation rate and swelling ratio changed significantly with different cross-linking conditions. Based on our study, 1.0% genipin concentration, 20°C cross-linking temperature and longer cross-linking time are recommended. Long Bi and Zheng Cao contributed equally to this work.

- by Monica Sandri
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- Materials Engineering, Materials Science, Biomedical Engineering, Chitosan

Curing techniques and curing duration have crucial effects on the strength and other mechanical properties of mortars. Proper curing can protect against moisture loss from fresh mixes. The objective of this experimental work is to examine the compressive strength of ordinary Portland cement mortars (OMs) under various curing regimes and cement fineness. Six different curing methods including water, air, water

- by William Walsh
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- Nursing, Fracture, Dogs, Injury

An experiment to investigate the potential of a laser-induced plasma method for determining concrete compressive strength was conducted by focusing a Nd:YAG laser on concrete samples with different degrees of compressive strength. This technique was developed in light of the role of the shock wave in the generation of a laser-induced plasma. It was found that the speed of the shock front depends on the hardness of the sample. It was also found that a positive relationship exists between the speed of the shock front and the ionization rate of the ablated atoms. Hence, the ratio of the intensity between the Ca(II) 396.8 nm and Ca(I) 422.6 nm emission lines detected from the laser-induced plasma can be used to examine the hardness of the material. In fact, it was observed that the ratio changes with respect to the change in the concrete compressive strength. The findings also show that the ratio increases with time after the cement is mixed with water.

- by Nasrullah Idris
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- Mechanical Engineering, Optics, Analytical Chemistry, Medical Imaging

The aim of the study was to assess, compare and evaluate the adhesive strength and compressive strength of different brands of glass ionomer cements to a ceramometal alloy. (A) Glass ionomer cements: GC Fuji II (GC Corporation, Tokyo), Chem Flex (Dentsply DeTrey, Germany), Glass ionomer FX (Shofu-11, Japan), MR dental (MR dental suppliers Pvt Ltd, England). (B) Ceramometal alloy (Ni–Cr: Wiron 99; Bego, Bremen, Germany). (C) Cold cure acrylic resin. (E) Temperature cum humidity control chamber. (F) Instron Universal Testing Machine. Four different types of Glass ionomer cements were used in the study. From each type of the Glass ionomer cements, 15 specimens for each were made to evaluate the compressive strength and adhesive strength, respectively. The 15 specimens were further divided into three subgroups of five specimens. For compressive strength, specimens were tested at 2, 4 and 12 h by using Instron Universal Testing Machine. To evaluate the adhesive strength, specimens were surface treated with diamond bur, silicone carbide bur and sandblasting and tested under Instron Universal Testing Machine. It was concluded from the study that the compressive strength as well as the adhesive bond strength of MR dental glass ionomer cement with a ceramometal alloy was found to be maximum compare to other glass ionomer cements. Sandblasting surface treatment of ceramometal alloy was found to be comparatively more effective for adhesive bond strength between alloy and glass ionomer cement.

- by sunit jurel
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- Silicon Carbide, Compressive Strength, Bond Strength, Surface treatment

Cement-based materials are brittle and highly sensitive to cracking, particularly shrinkage cracking. It is well documented that a fibre reinforcement restrains crack opening and thus limits their detrimental effects on the durability and serviceability of structures. However, a better solution to limit brittleness and prevent shrinkage cracking is to design a cimentitious composite exhibiting a high level of deformation before macrocracks appear. The present paper focuses on this challenge. It is based on the use of lowdeformation-modulus aggregates, actually rubber aggregates. The results given here concern mortars. A conventional mortar was compared with ones incorporating rubber tyre particles, partly replacing the natural sand aggregates. In all cases, the size of the particles was smaller than 4 mm and two ratios of sand replacement by rubber aggregates were considered: 20% and 30% by volume. The compressive and tensile properties of these cement composites were investigated.

- by J.-l. Granju
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- Architecture, Compressive Strength, Building, Building Environment

Simulated spent clinoptilolite was immobilised in a monolithic glass composite wasteform (GCM) produced by a pressureless sintering for 2 hours at relative low temperatures 750 deg. C. The GCM utilises the high durability of alkali borosilicate glass to encapsulate the Cs-impregnated clinoptilolite (Cs-Clino). With this approach mobile radionuclides are retained by a multi-barrier system, comprising the crystalline form of the clinoptilolite and the borosilicate glass Wastes loading ranging from 1:1 up to 1:10 glass to Cs-clino volume ratios corresponding to 37- 88 mass % were studied. Water durability of GCM was assessed in 7, 14 and 28 days leaching tests in deionised water at 40 deg. C based on ASTM C1220-98 standard. It was found that the normalised leaching rates of Cs remaining below 6.35 10 g/cm² day in a GCM with 73 mass % waste during a leaching test for 7 days. However, at higher waste loading of {>=}80 mass %, the normalised leaching rate of Cs was as high as 9.06 10 g...

Brick is the oldest building material. It is a standard sized weight bearing unit. The earliest bricks were dried which are formed from clay or mud. During 2007 the new fly ash bricks were created using by products from coal plants. A sustainable development is an important task to the cement industry. To avoid cement as a huge construction material to reduce the environmental issues, replaced with Fly ash, GGBS, Silica fume, Kadapa slab powder. For bonding polymers, limited water content is used. Hence, resulting hybrid geo-polymer brick with multi-material combination is effective. In this experimental approach, initially we were considered 75% and 25% Fly ash and GGBS respectively as a base and then varied silica fume and kadapa slab powder ranging from 2 to 5% in GGBS. Mechanical properties of the materials are giving effective values to replace. Through compressive strength results we can find optimum proportions based on silica fume and kadapa slab powder.

- by Dr. Sunandana Reddy Machireddy and +1
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- Compressive Strength, Fly Ash Bricks

In this experimental study, the effect of zeolite on the properties of autoclaved aerated concrete (AAC) was investigated. Zeolite was used as a quartzite replacement in conventional AAC mixtures. The zeolite containing AAC (ZAAC) specimens were prepared at bulk densities of 270-500 kg/m 3. The specimens were examined by X-ray diffraction, X-ray fluorescence, and thermal analysis. Bulk density, compressive strength and thermal conductivity parameters were investigated. According to the results of research, the commercial AAC is mainly composed of tobermorite, quartz and anhydrite, but the specimens of ZAAC, besides tobermorite and quartz, contain unreacted anhydrite and clinoptilolite phases. XRD patterns of ZAAC obtained after treatment at 700-1000 1C show that wollastonite, gehlenite and orthoclase are the new phases formed. It was observed that application of zeolite in AAC significantly lowered the thermal conductivity of autoclaved products (0.08-0.12 kcal/m h 1C) providing the compressive strength at the level of 1.22À3.34 N/mm 2 .

Porous cordierite ceramics with controlled porosity were fabricated via a reaction sintering using expandable microspheres as sacrificial templates and ceramics-filled polysiloxane as a precursor for cordierite ceramics. The influence of the sintering temperature, the template content, and the additive composition on the microstructure, porosity, and compressive strength has been investigated. The results showed that the template content, the sintering temperature, and the sintering additive composition have a significant effect on the porosity. By controlling the template content, the sintering temperature, and the sintering additive composition, it was possible to produce porous cordierite ceramics possessing a wide range of porosities ranging from 11! to 72!. The compressive strength was influenced by both the porosity and the additive composition. The compressive strength of the porous cordierite ceramics containing 6 mass! kaolin as a sintering additive was Ĭ150 MPa at 35! porosity.

- by Young-Wook Kim
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- Materials Engineering, Mechanical Engineering, Microstructure, Manufacturing

Research on concrete made with hemp is part of a sustainable development policy in the building field. The very low apparent density of the hemp hurds confers to lime and hemp concrete lightness and low thermal conductivity, however compared to usual construction materials, it has low mechanical strength. The presence of fibres in the hemp, the optimization of the granular to binder ratio, and the compaction during the casting process represent parameters which could significantly increase the compressive strength and change the mechanical behaviour of the material. A brief study of these parameters is presented and discussed in this paper. RÉSUMÉ. Les recherches concernant le béton de chanvre s'inscrivent dans le cadre d'une politique de développement durable dans le domaine de la construction. La très faible masse volumique apparente de la chènevotte confère au béton de chanvre une légèreté notable et une faible conductivité thermique, cependant elle entraîne une résistance mécanique relativement faible. La présence de fibres issues de la tige dans la chènevotte, l'optimisation du dosage granulat/liant, et le compactage réalisé à la mise en oeuvre constituent des paramètres qui peuvent augmenter significativement la résistance à la compression et modifier aussi le comportement mécanique du matériau. Une étude succincte de ces paramètres est présentée et discutée dans cet article.

This paper investigated the influence of ground granulated blast furnace slag (GGBS) on the setting time and compressive strength of one-part geopolymer binders (OPGB). Powdered sodium metasilicate activator was utilized in the range of 8-16% by weight of the total binder. The central composite design method was used in designing the mixtures. Experimental investigation revealed that both the initial and final setting times of the OPGB decreased drastically with the increase in the GGBS and the activator content. The inclusion of GGBS in the binder influences the setting time of the binders thereby resulting in quick setting time. The variance analysis of the established models demonstrated that the setting and compressive strength models could be predicted using quadratic models with a high R 2 coefficient. Optimization results revealed that the optimum mixture can be obtained by substituting 95.8 % fly ash with GGBS and 13.4 % solid activator.

- by Haruna Sani
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- Compressive Strength, Setting Time, Geopolymer

This paper investigates the effect of latex modified systems and combination of latex and polypropylene fibre on the performance of concrete. In this study, the polypropylene fibre volume fraction and the amount of added latex, are varied and compressive strength, splitting tensile strength, flexural strength, impact resistance, abrasion resistance, and water absorption are measured. Increasing the volume fraction of the fibre and amount of added latex increases the flexural strength, splitting tensile strength, impact resistance, and abrasion resistance. As an application of this work, paving blocks of size 200 × 100 × 60 mm were casted and tested.

Fly ashes do not have the same properties for different size fractions. It can be accepted that the effect of a fly ash on mortar strength is a combined effect of its size fractions. Therefore, it was concluded that by separating the size fractions and replacing cement with them, the combined bulk effect of a fly ash on strength can be better analysed. In this study, different size fractions of fly ash were used to replace cement partially in standard compressive strength mortars. We attempted to interpret the strength of Portland cement-fly ash mortars in terms of the chemical, minerological, morphological, and physical properties of different fly ash size fractions used. Strengths of the mortars were compared at 2, 7, 28, and 90 days. Also strength of mortars with all-in ash (original ash containing all the fractions) were estimated by using strength of mortars with size fractions and the suitability of this estimation was discussed.

- by Cem Erdogdu
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- Civil Engineering, Materials Science, Compressive Strength, Building

Exact detection of lithologic boundaries is one of the main challenges in exploration, drilling operations, and geology. Investigation of facies discontinuities has been performed using petrophysical data regarding sharp changes along the wellbore. Due to the fact that recorded well logging signals contain lots of high-frequency waves (noise), detection of the layer boundaries comes with some uncertainties that should be eliminated by denoising those signals. Wavelet transform analysis is a good approach to denoise the signals and its ability has been proven in several studies. In this study, implementation of wavelet transform analysis resulted in an innovative approach for exact differentiation of neighborhood lithologic units.

- by Emad Jamshidi
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- Neural Network, High Frequency, Wavelet Transform, Compressive Strength

The permeability and strength of pervious concrete depend on the particle sizes and proportions of the constituent materials of which the concrete is made of. In this paper, structural property and permeability of pervious concrete made with different coarse aggregate sizes is presented. For the different aggregate/cement ratio used in this study, coarse aggregate size 9.375 mm has higher compressive strength values compared to those made from 18.75 mm aggregate size while 18.75 mm aggregate size had higher permeability value compared to that of 9.38 mm. The average specific gravity of the two aggregates sizes used was 2.7. Aggregate/cement ratio of 6:1, 8:1 and 10:1 respectively were used to produce three different batches of fresh concrete using 18.75mm aggregate size and same ratios were used for 9.375mm coarse aggregate size to produce another three different batches. In each case, aggregate/cement ratio of 6:1 gave the highest compressive strength compared to other aggregate/ce...

- by Johnson Oluremi
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- Materials Science, Porosity, Permeability, Compressive Strength

Rice husk ash (RHA) has been used as a highly reactive pozzolanic material to improve the microstructure of the interfacial transition zone (ITZ) between the cement paste and the aggregate in high-performance concrete. Mechanical experiments of RHA blended Portland cement concretes revealed that in addition to the pozzolanic reactivity of RHA (chemical aspect), the particle grading (physical aspect) of cement and RHA mixtures also exerted significant influences on the blending efficiency. The relative strength increase (relative to the concrete made with plain cement, expressed in %) is higher for coarser cement. The gap-grading phenomenon is expected to be the underlying mechanism. This issue is also approached by computer simulation. A stereological spacing parameter (i.e., mean free spacing between mixture particles) is associated with the global strength of the blended model cement concretes. This paper presents results of a combined mechanical and computer simulation study on t...

- by Piet Stroeven
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- Civil Engineering, Computer Simulation, Compressive Strength, Building

In this investigation, structural type mortars reinforced with corn fibers were elaborated; these fibers were previously treated with flaxseed oil and paraffin, cut to lengths of 1, 2 and 5 cm, and weighed, in order to obtain a ratio of 0.5% and 1% by weight with respect to the quantity of cement. The fibers were physic chemically characterized by Thermogravimetric Analysis (TGA), Derivative Thermogravimetry (DTG) and Fourier Transform Infrared Spectrometry (FTIR), and their chemical resistance was evaluated by exposing them to a concentrated solution of Ca(OH)2 that simulated the alkaline medium of the cement. The fiber-reinforced mortars were mechanically characterized by compression and bending tests, which were performed 7, 21 and 28 days after processing. The results show that after 28 days the paraffin-coated corn fiber reinforced mortars, with 1 cm in length and 0.5% in weight presented the best results, an increase in the compressive and flexural strength of 16.92% and 38.51% respectively was noted, compared to the unreinforced mortar.

- by OSCAR FABIAN HIGUERA COBOS
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- Compressive Strength, Flexural Strength, CORN FIBER
- by Martin P Stewart
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- Atomic Force Microscopy, Methods, Compressive Strength, Clinical Sciences

The aim of the present research work was to systemically device a model of factors that would yield an optimized sustained release dosage form of an anti-hypertensive agent, losartan potassium, using response surface methodology by employing a 3-factor, 3-level Box-Behnken statistical design. Independent variables studied were the amount of the release retardant polymers -HPMC K15M (X 1 ), HPMC K100M (X 2 ) and sodium carboxymethyl cellulose (X 3 ). The dependent variables were the burst release in 15 min (Y 1 ), cumulative percentage release of drug after 60 min (Y 2 ) and hardness (Y 3 ) of the tablets with constraints on the Y 2 = 31-35%. Statistical validity of the polynomials was established. In vitro release and swelling studies were carried out for the optimized formulation and the data were fitted to kinetic equations. The polynomial mathematical relationship obtained Y 2 ¼ 32:91 À 2:30X 1 À 5:69X 2 À 0:97X 3 À 0:41X 1 X 2 þ 0:21X 1 X 3 À 0:92X 2 1 À 1:89X 2 2 ðr 2 ¼ 0:9944Þ explained the main and quadratic effects, and the interactions of factors influencing the drug release from matrix tablets. The adjusted (0.9842) and predicted values (0.9893) of r 2 for Y 2 were in close agreement. Validation of the optimization study indicated high degree of prognostic ability of response surface methodology. Tablets showed an initial burst release preceding a more gradual sustained release phase following a non-fickian diffusion process. The Box-Behnken experimental design facilitated the formulation and optimization of sustained release hydrophilic matrix systems of losartan potassium.

A cement-bonded moulding sand system takes a fairly long time to attain the required strength. Hence, the moulds prepared with cement as a bonding material will have to wait a long time for the metal to be poured. In this work, an... more

- by Dr. Mahesh Parappagoudar
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- Materials Engineering, Materials, Linear Model, Compressive Strength

The properties of concrete containing fine recycled aggregate are investigated. Recycled aggregate consisted of crushed concrete (CC) or crushed brick (CB) with particles less than 5 mm in diameter. The free water/cement ratio was kept constant for all mixes. The fine aggregate in concrete was replaced with 0%, 25%, 50% and 100% CC or CB. Generally, there is strength reduction of 15 -30% for concrete containing CC. However, concrete incorporating up to 50% CB exhibits similar long-term strength to that of the control. Even at 100% replacement of fine aggregate with CB, the reduction in strength is only 10%. Beyond 28 days of curing, the rate of strength development in concrete containing either CC or CB is higher than that of the control indicating further cementing action in the presence of fine recycled aggregate. More shrinkage and expansion occur in concrete containing CC or CB. D

- by Jamal Khatib
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- Civil Engineering, Nondestructive testing, Recycled Materials, Compressive Strength

SUMMARY Disc-shaped specimens are frequently tested in order to establish an understanding of the properties of ceramic material. In this study three-dimensional finite element stress analysis has been used to investigate the loading characteristics of this shape of specimen and the effect of incorporating scratches and voids into its structure. The results indicated that stress increased as loading was carried out nearer to the centre of the specimen. The presence of cracks did not affect these stresses whereas the presence of a void resulted in a very high stress concentration.

- by Hammad Hassan
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- Dentistry, Biomedical Engineering, Finite Element Analysis, Porosity

This study evaluated the structural, mechanical, and cytocompatibility changes of three-dimensional (3D) printed porous polymer scaffolds during degradation. Three porous scaffold designs were fabricated from a poly(propylene fumarate) (PPF) resin. PPF is a hydrolytically degradable polymer that has been well characterized for applications in bone tissue engineering. Over a 224 day period, scaffolds were hydrolytically degraded and changes in scaffold parameters, such as porosity and pore size, were measured nondestructively using micro-computed tomography. In addition, changes in scaffold mechanical properties were also measured during degradation. Scaffold degradation was verified through decreasing pH and increasing mass loss as well as the formation of micropores and surface channels. Current methods to evaluate polymer cytotoxicity have been well established; however, the ability to evaluate toxicity of an absorbable polymer as it degrades has not been well explored. This study, therefore, also proposes a novel method to evaluate the cytotoxicity of the absorbable scaffolds using a combination of degradation extract, phosphatebuffered saline, and cell culture media. Fibroblasts were incubated with this combination media, and cytotoxicity was evaluated using XTT assay and fluorescence imaging. Cell culture testing demonstrated that the 3D-printed scaffold extracts did not induce significant cell death. In addition, results showed that over a 224 day time period, porous PPF scaffolds provided mechanical stability while degrading. Overall, these results show that degradable, 3D-printed PPF scaffolds are suitable for bone tissue engineering through the use of a novel toxicity during degradation assay.

- by Martha O Wang and +2
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- Biomedical Engineering, Cell line, Porosity, Mice

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,... more

- by Hilmi Mahmud
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- Southeast Asia, Malaysia, Leaching, Eurasia

Fly ash is generated in large measures, especially by thermal power plants. A great batch of inquiry has been channeled out for efficient utilization of fly ash in the structure industry. Use of fly ash in manufacturing brick is one such thing which is being studied by many research scholars and engineers. The aim of the present study is to investigate the durability and water absorption features of fly ash bricks made up with different percentage of lime (L), local soil (S) and fly ash (FA). The experiments were conducted by both Pressure molded fly ash bricks. It was found that none of the L-S-FA bricks satisfy all the demands of standard codes. While some of the bricks satisfy the provisions in respect of intensity level only the L-S-FA (40-0- 60) bricks satisfy the demand of Indian Standard Code in respect of intensity as easily as water absorption features.

Thirty concrete mixes of differing water-binder ratio containing 0, 10, 20, 30, 40 and 50 % laterite as a partial replacement for sand were used to prepare laterized concrete specimens for the study of the effect of nonstandard curing methods on the strength of specimen. The effectiveness of a curing method was measured quantitatively as the ratio of the compressive strength of specimen cured using the non-standard method to those cursed using the standard water-curing method specified in the BS1881: Part 3:1970 (control). The results of the investigation show that with continuous wetting of the nonstandard curing media by sprinkling with water, the strength of the concrete obtained could be comparable to those cured using the control method. Of the four nonstandard curing methods considered in the study it was observed that the strength of sand- and sawdust-cured specimen were in some instances the same as or higher than those of the standard cured specimens at early age (7 days). ...

- by F. Udoeyo
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- Materials Science, Compressive Strength, Control Method

Soil blocks are usually stabilised with cementing materials, fibres or chemicals to improve their performance properties for construction purpose. This study investigates the properties of compressed earth blocks stabilised with a liquid chemical (Pidiproof LW+). Experiment was conducted using 0.5, 1 and 1.5% weight contents of Pidiproof LW+ to produce compressed earth blocks and cured at 7, 14, 21 and 28 days. The blocks were tested for density, absorption coefficient, compressive strength and splitting tensile strength. It was found that with the exception of density test, the chemical inclusion in the other tests significantly improved the performance properties of the compressed earth blocks. Furthermore, the higher chemical content (1.5%) inclusion in the compressed earth block provided better performance properties. The paper concludes that the inclusion of the liquid chemical in the compressed earth blocks generally improved the performance properties of the blocks. Recommendation is made to the use of other chemicals for applicability in earthen construction.

- by Shahzaib Khan
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- Engineering, Concrete, Materials, Sustainable Building Materials

This paper investigates the applicability of artificial neural network model for strength prediction of fibers' self-compacting concrete under compression. The available 99 experimental data samples of fibers self-compacting concrete were used in this research work. In this paper, computational-based research is carried for predicting the strength of concrete under compression and model was developed using ANN with five input nodes and feed-forward three-layer back-propagation neural networks with ten hidden nodes were examined using learning algorithm. ANN model proposed analytically was verified, and it gives more compatible results. Hence, the ANN model is proposed to predict the strength of fibrous self-compacting concrete under compression.

An experimental investigation into the behaviour of composite column-to-beam connections using ten large-scale connections has been conducted, four under monotonic loading and six under cyclic loading. This paper presents the details and results of the four preliminary monotonic tests. Details and results of the cyclic tests are reported in a companion paper. All connections consisted of a circular concrete-filled steel tubular column, a compact universal beam section and a shop fabricated connection stub. It is a direct connection of the beam to the tube wall (using flange connection plates, and web cleat plates) and four straight reinforcing bars welded to the top and bottom flanges and embedded into the concrete core. It was found that the connection strength increased as the capacity of the embedded bars increased, to a stage where no connection failure occurred, and the beam formed a plastic hinge outside the zone of influence of the bars. The bars were very effective in transferring both compressive and tensile loads directly into the column, and connection behaviour in terms of strength and stiffness was adequate to classify it as a rigid connection.

- by David Thambiratnam
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- Civil Engineering, Anchoring, Compressive Strength, Large Scale