Physical Properties Of Concrete Research Articles

Mechanical and physical properties of concrete containing FGD waste

The work reported here forms part of a wide-ranging research project on the optimum use of waste from dry and semi-dry flue gas desulfurisation (FGD) processes in concrete. This study examined the influence of a typical simulated desulfurised waste (SDW) on the physical and mechanical and physical properties of concrete. SDW was chosen due to the wide variability in the composition of actual FGD waste. Two binder systems were investigated: cement and SDW (C-SDW) and cement, slag and SDW (C-S-SDW). The SDW content ranged from 0 to 70% and the slag from 0 to 90% as partial cement replacements. The properties examined included compressive and flexural strengths, water absorption, shrinkage and expansion. The results showed that replacing cement with SDW beyond 20% systematically reduces strength. An increase in SDW content reduces shrinkage. The presence of small amounts of slag allows the use of high proportions of SDW. The use of desulfurised waste in concrete applications is possible as adequate strength can be achieved.

Study on the anticorrosive behavior of new core-shell pigments for protection of reinforced concrete steel in sulfate environment

Sulfate exposure is considered high aggressive medium to reinforced concrete, therefore high efficient protection ways are needed to protect the steel rebars.In this work, new cheap eco-friendly anticorrosive pigments based on zinc, strontium, zinc.strontium phosphate/silica fume were prepared. These pigments contain thin shell of phosphates (10–20%) precipitated on silica fume waste (80–90%) using core-shell technique. These pigments were incorporated in anticorrosive paints to protect steel rebars from the sulfate ions effect in concrete. Tests were conducted to examine their corrosion protection efficiency and effect on the physical properties of concrete. Tests include (a) half-cell potential and electrochemical impedance spectroscopy to determine the corrosion protection of the coatings against corrosion and (b) bond strength between the coated rebar and concrete. The results showed that, the prepared core-shell pigments provided good corrosion protection to the rebars without affecting the bond between the rebar and concrete cover.

Assessment of the mechanical properties of a concrete made by reusing both: Brewery spent diatomite and recycled aggregates

Since last decades, building construction materials have been widely developed by adding different residues as substitutes of traditional raw materials. This with the aim of both: reducing environmental impact of certain residues and decreasing the carbon foot print regarding to building materials. This paper contributes to such trend by showing the effect of brewery spent diatomite and recycled aggregates on the mechanical properties of concrete when both matters are used together. Therefore mechanical and physical properties of concrete are tested and compared to concrete manufactured by replacing different amounts of cement and natural coarse aggregates with brewery spent diatomite (BSD) and recycled aggregates (RA), respectively. The combined effect of two residues on compressive strength, flexural strength and modulus of elasticity are highlighted. Results show that a 5% of BSD and a 25% of RA can be used as replacement of cement and natural coarse aggregates without significant loss in the mechanical properties when compared to a control concrete.

Non-Destructive Testing of Concrete with Fine Recycled Aggregate

This paper is focused on non-destructive testing of concrete containing fine recycled aggregate (FRA). FRA was obtained from demolished concrete structures and crushed in the laboratory on fraction 0 – 4 mm. There were prepared four concrete mixtures. The first concrete mixture was control, did not include FRA. In other mixtures was natural replaced natural sand by FRA. There were tested workability of fresh concrete mixture and physical properties of hardened concrete. Finally, it is possible to say that the use of FRA influences the physical properties of concrete. The physical properties of concrete are connected with the durability of concrete. Therefore, it is necessary to focus on durability testing of FRA concrete in further research.

Abrasion Resistance of Concrete Containing Selected Mineral Powders

In this study the results of research that focused on abrasion resistance of concrete containing selected mineral powders are presented. The influence of replacing part of the cement on the physical properties of concrete was studied in the article. The concrete mixtures were modified by addition of basalt, quartz and quartz-feldspar powders in amount of 10, 20 and 30% of the weight of the cement. The results showed that using mineral powders can reduce or increase concrete surface abrasion resistance depending on the type of mineral powder and its concentration in concrete mixture.

Tests of Selected Properties of Aggregates on Ceramic Wastes

The article analysed the results of comparative sampling of selected properties of concretes with addition of aggregates from sanitary ceramic wastes. For the need of the analyses there were created concretes of various w/c coefficients (0,35, 0,50, 0,75) and with diverse percentage participation of ceramic wastes aggregates (exchange of 50% and 100% coarse aggregates into ceramic). The range of performed samples and analyses included sampling of mechanical and physical properties of concretes and the aggregates used. What was under analysis: for aggregates – sampling of bulk density, absorbency, resistance to crushing; for concretes from ceramic wastes – sampling of density, absorbency, compressive strength, tensile strength and compressive strength after roasting. Roasting was performed according to defined temperature cycles: cycle I - from 0 to 150OC (vaporisation of free water), cycle II - from 150 to 550OC (separation of chemically combined water), cycle III - beyond 550OC (change of hydraulic combination into ceramic, sintering).

EXPLORATORY STUDY ON THE MECHANICAL AND PHYSICAL PROPERTIES OF CONCRETE CONTAINING SULFUR

This research is an exploratory experiment into sulfur concrete used not as a complete replacement of cement but as an additional material in percentage of the cement content. The aim of this research was to explore the possible appreciation of mechanical and physical properties of concrete containing sulfur with percentages of 1%, 5% and 10% of the cement content. The sulfur used here was not heat-activated, hence the binding effect in sulfur was absent. The experimental results revealed that concrete containing sulfur did not perform better in their strength properties, both compressive strength and flexural strength. The physical properties such as water penetration and water absorption for concrete containing sulfur also showed poor performance in comparison to ordinary Portland cement concrete. Such phenomena are very likely due to the sulfur not being activated by heat. Carbonation test did not show good results as a longer term of testing is required. Drying shrinkage property was found to be encouraging in that concrete containing 10% sulfur had quite significant reduction in drying shrinkage as opposed to ordinary Portland cement concrete.

PHYSICAL AND MECHANICAL PROPERTIES OF CONCRETE INCORPORATING INDUSTRIAL AND AGRICULTURAL TEXTILE WASTES

To reduce the impact on the environment, industrial and agricultural waste products such as carpet waste, sisal and flax have been added to the concrete. Usage of these materials in concrete does not only improve the strength of concrete but also leads to the proper disposal of these materials that leads to reduce the impact on environment. Fiber admixture can effectively improve the mechanical and physical properties of concrete. Utilization of recycled fibers from post-consumer, industrial waste and agricultural waste offer some benefits such as waste reduction, resource conservation, also low-cost materials and reduced need for land filling. Concrete is a tension weak building material, which is often cracked not ridden in plastic and hardened states, drying shrinkage and so on, low tensile strength limited ductility and resistance to cracking. In order to improve attempt has been made to study the effect of these materials on ordinary Portland cement concrete. In the experimental work, glass fibers, sisal, flax and waste carpet waste in different percentage (0.5%, 1% and 2 %) has been added by volume of concrete volume. The hardened concrete properties compressive strength, dry Shrinkage, Impact stress, The effect of temperature and Thermal conductivity of Concrete) were carried out. A total of Thirteen concrete mixtures were performed with cement content of 350 Kg/m 3 at water cement ratio = 0.525 , The amount of water was adjusted according to cement content, The super plasticizer dosage varied from 0.8% to 2.5% of cement content to achieve the required level of workability defined by a slump value of 10± 2cm.

Physical properties of self-curing concrete (SCUC)

In this study the effect of two different curing-agents has been examined in order to compare them for optimizing the performance of concrete. The first used type is the Pre-soaked lightweight aggregate (leca) with different ratios; 0.0%, 10%, 15% and 20% of volume of sand, and the second type is a chemical agent of polyethylene-glycol (Ch.) with different percentages; 1%, 2% and 3% of weight of cement. In the test programme performed in this study, three cement content; 300, 400 and 500kg/m3, three different water-cement ratios; 0.5, 0.4, and 0.3, and two magnitudes of silica fume as a pozzolanic additive; 0.0% and 15% of cement weight, were used. The physical properties of concrete were evaluated at different ages, up to 28days. The concrete specimens are subjected to dry-air curing regime (25°c) during the experiment.The results show that the use of self-curing agent (Ch.) in concrete effectively improves the physical properties compared with conventional concrete. On the other hand, up to 15% saturated leca was effective while 20% saturated leca was effective for permeability and mass loss but adversely affects the sorptivity and volumetric water absorption. Self-curing agent Ch. was more effective than self-curing agent leca. In all cases, both 2% Ch. and 15% leca were the optimum values. Higher cement content and/or lower water–cement ratio leads to more effective results of self-curing agents in concrete. Incorporation of silica fume into concrete mixtures enhances all physical properties.

Influence of silica fume on mechanical and physical properties of recycled aggregate concrete

Several studies related to sustainable concrete construction have encouraged development of composite binders, involving Portland cement, industrial by-products, and concrete mixes with partial replacement of natural aggregate with recycled aggregate. In this paper, the effects of incorporating silica fume (SF) in the concrete mix design to improve the quality of recycled aggregates in concrete are presented. Portland cement was replaced with SF at 0%, 5% and 10%. Specimens were manufactured by replacing natural aggregates with recycled aggregates. Two size fractions (4/12mm and 8/22mm) as recycled aggregates were used and four series of concrete mixtures were produced. In all concrete mixtures, a constant water/binder ratio at 0.50 was used and concrete mixtures with a target initial slump of S4 class (16–21cm) were prepared. Concrete properties were evaluated by means of compressive strength, tensile splitting strength, water absorption and ultrasonic pulse velocity and it was found that, using 10% SF as a cement replacement for recycled aggregate concretes enhanced the mechanical and physical properties of concrete. At all the test ages the tensile splitting strength gain of the natural aggregate concrete mixture (NA) with and without SF was higher than that of the recycled concrete mixtures. Continuous and significant improvement in the tensile splitting strength of recycled aggregate concretes incorporating SF was observed. Similar to compressive strength test results, concrete incorporating 10% SF and containing 4/12mm fraction recycled aggregates showed better performance among recycled aggregate concretes.

Microstructure analyses of autoclaved ground dune sand–Portland cement paste

In this study, SEM, EDX, XRD, DAT and TGA are used to perform microstructure analyses of autoclaved ground dune sand–ordinary Portland cement (GDS–OPC) pastes. Pastes containing 0%, 10%, 20%, 30% and 40% GDS as cement replacement were prepared for this purpose. The microstructure analyses were used to examine the microscale changes that occur in the GDS–OPC pastes with increasing GDS replacement levels. The SEM and EDX results showed the clear formation of dense and newly formed thin crystalline calcium silicate hydrate with a low CaO/SiO2 ratio. The XRD, DTA and TGA analyses revealed that the portlandite phase had been eliminated. The microstructure analyses reveal how GDS contributes to the strength and physical properties of concrete.

A Review on the Effects of Various Supplementary Cementitious Materials on Physical Properties of Hardened Concrete

The global development and current trends in social attitude are resulting in an increase in the amount of waste generated by society, the treatment and disposal of which are becoming a serious problem. Therefore, waste management is one of the most important aspects in ensuring sustainable development in todays world. Some of the industrial by-products, such as pulverised-fuel ash (PFA), ground granulated blast-furnace slag (GGBS) and microsilica (MS) can be used in concrete to improve its properties. In this paper the influence of various by-products on the physical properties of concrete is reviewed.

Vibration based damage identification of concrete arch dams by finite element model updating

Vibration based damage detection is very popular in the civil engineering area. Especially, special structures like dams, long-span bridges and high-rise buildings, need continues monitoring in terms of mechanical properties of material, static and dynamic behavior. It has been stated in the International Commission on Large Dams that more than half of the large concrete dams were constructed more than 50 years ago and the old dams have subjected to repeating loads such as earthquake, overflow, blast, etc.,. So, some unexpected failures may occur and catastrophic damages may be taken place because of theloss of strength, stiffness and other physical properties of concrete. Therefore, these dams need repairs provided with global damage evaluation in order to preserve structural integrity. The paper aims to show the effectiveness of the model updating method for global damage detection on a laboratory arch dam model. Ambient vibration test is used in order to determine the experimental dynamic characteristics. The initial finite element model is updated according to the experimentally determined natural frequencies and mode shapes. The web thickness is selected as updating parameter in the damage evaluation. It is observed from the study that the damage case is revealed with high accuracy and a good match is attained between the estimated and the real damage cases by model updating method.

Effect of Boron Carbide Addition on the Strength and Physical Properties of Concrete

Concrete currently has become a conventional material in construction of nuclear reactor due to its properties such as safety, strength and economical in cost. Boron carbide (B4C) was used as additives in concrete are characterized as a good neutron absorber for nuclear reactor applications. The effect of B4C addition on physical and strength properties of concrete samples were investigated. The samples were prepared with three different weight percent (wt%) of B4C powder. The concrete slump tests of fresh concrete have been done to investigate the workability of mixtures. Free B4C mixture shows the highest workability compare to 5 and 20 wt% B4C concrete mixture. The density of 0 wt% of B4C is the lowest compared to 5 and 20 wt%. However, after 28 days curing time, the compressive strength test of 20 wt% B4C shows the highest value compare to 5 and 0 wt% B4C concrete respectively. It is obvious that up to 20 wt% B4C can be added to concrete mixture and cause significant strength increases.

Evaluating Residual Mechanical and Physical Properties of Concrete at Elevated Temperatures

Evaluating Residual Mechanical and Physical Properties of Concrete at Elevated Temperatures

Acoustic methods in nondestructive testing of concrete: Review of foreign publications in the field of theoretical studies

This paper is devoted to the review and analysis of foreign publications in the field of acoustic methods in theoretical studies of problems of nondestructive testing as applied to the analysis of the physical properties of concretes. Methods that combine theoretical and experimental approaches are considered in the introduction and deterministic and stochastic methods are analyzed independently. The application of the finite- and boundary-element methods is then described and a new method for studying the considered problems is proposed.

Acoustic methods for the nondestructive testing of concrete: A review of foreign publications in the experimental field

Acoustic methods for experimental studies of the problems of nondestructive testing that are used in the analysis of the strength and other physical properties of concrete are reviewed on the basis of an analysis of foreign publications. The classical through transmission, pulse-echo, and impact-echo methods, changes in the internal structure of concrete under loading, and factors that influence the correlation between the strength and acoustic-wave velocity are considered.

The effect of foundation’s modulus of elasticity on concrete gravity dam’s behavior

Investigation on the behavior of dams against the seismic loads is a key factor for safety requirement. One of the most important problems in evaluation of seismic behavior of concrete gravity dams is dam-reservoir-foundation interaction. In this paper, we study the effect of dam-reservoir-foundation interaction on nonlinear behavior of concrete gravity dams, a two-dimensional approach was used including the finite element method and smeared crack approach. Effective parameters in the models are physical properties of concrete such as modulus of elasticity, tensile strength and specific fracture energy. Their importance in the nonlinear analysis was investigated in a parametric study. Different boundary conditions were used in foundation in order to determine the seismic response of concrete gravity dams. Results show that when the nonlinear analysis includes the dam- foundation interaction and the foundation's mass, flexibility and radiation damping, the seismic response of concrete gravity dam will be reduced to a realistic level. Decreasing in ratio of foundation's modulus of elasticity to dam's modulus of elasticity (EF/ES) causes increasing in dam crest displacement. The crack profile is expected to reduce due to mass of foundation and it's damping effects in massed foundation system.

타블렛 형태 급결제가 콘크리트의 응결시간 및 조기강도에 미치는 영향에 관한 연구

한중 콘크리트 타설시 발생되는 초기 동해로 인한 피해를 방지하고 조강성을 향상시키기 위해 열풍기 사용을 통한 보양, 결합수와 골재의 가열 및 시멘트 사용량을 늘리는 방법, 급결제 및 촉진제를 사용하는 등 다양한 방법이 사용되고 있다. 하지만 이러한 방법은 사용상의 어려움과 에너지 소비 및 생산비의 증가에 따른 경제성 감소 등의 문제점을 가지고 있다. 이중 급결제 및 촉진제의 사용은 경제적 이지만 수화 초기부터 급격하게 반응하여 급결하는 특성 때문에 작업성의 확보가 어렵다는 문제점을 가지고 있다. 이에 이 논문에서는 기존 의약 분야에서 주로 이용되는 약물의 고형 투여 형태인 정제(Tablet)화 방법을 이용하여 급결제와의 응결 시간을 비교하였고, 이 결과를 토대로 콘크리트의 물리적 특성 및 역학적 특성 시험을 실시하여 일정 시간 동안 작업이 가능하고 초기동해 방지 및 조강성이 향상 되는지 확인 하였다. 그 결과 급결제 및 타블렛의 경우 사용량이 증가 할수록 응결 시간이 줄어드는 것을 확인하였고, 콘크리트의 물리적·역학적 시험에서는 경시 변화에 대하여 Control과 비교 타블렛0.5%, 1.0%가 일정 시간 동안 작업 시간 확보가 가능함을 확인하였을 뿐만 아니라 조기 강도에서도 급결제 0.5%와 타블렛 0.5%, 1.0%가 뛰어난 조기 강도 발현 특성을 보여주었다.

Effect of rice husk ash fineness on the chemical and physical properties of concrete

The influence of grinding on the physical properties of rice husk ash (RHA) and Portland cement is examined. The optimum rice husk ash grinding time (i.e. to produce a highly reactive product with minimum grinding energy) was determined. Eight different fineness grades of rice husk ash were examined and it was found that rice husk ash ground for the optimum grinding time had a median particle size of 9·52 μm. A rice husk ash dosage of 15% by weight of binder was used throughout the experiments. It was found that the specific gravity and the fineness of the rice husk ash increase with an increase in grinding time. However, the morphology of the rice husk ash changed with grinding. There appears to be an optimum grinding time of approximately 90 min, during which time the compressive strength and strength activity index increase significantly. The use of rice husk ash ground for 90 min (to 9·52 μm particle size) produced concrete with good strength and low porosity.