Different Types Of Aggregates Research Articles

Experimental Analysis of MOC Composite with a Waste-Expanded Polypropylene-Based Aggregate.

Polypropylene (PP) is one of the most widely produced types of plastic worldwide, but its recycling is limited. This work presents a study of the utilization of expanded polypropylene (EPP) waste in a magnesium oxychloride cement (MOC) composite usable in the building industry. MOC is formed by mixing magnesium oxide powder and a concentrated solution of magnesium chloride and is characterized by excellent bonding ability to large quantities of different types of aggregates. A developed air-cured MOC composite, where an EPP-based aggregate was used for the full replacement of natural aggregate, was investigated in terms of its basic physical, mechanical, thermal and water resistance properties. The results demonstrate that incorporation of EPP waste greatly improved the thermal insulation properties, while the mechanical resistance was reduced to an acceptable level. The developed MOC composite containing EPP waste can be considered as an alternative thermal insulation material applicable for the construction of floor or envelope construction systems.

A Rapid Colorimetric Method to Visualize Protein Interactions

As key molecules in most biological pathways, proteins physically contact one or more biomolecules in a highly specific manner. Several driving forces (i.e., electrostatic and hydrophobic) facilitate such interactions and a variety of methods have been developed to monitor these processes both in vivo and in vitro. In this work, a new method is reported for the detection of protein interactions by visualizing a color change of a cyanine compound, a supramolecule complex of 3,3-di-(3-sulfopropyl)-4,5,4',5'-dibenzo-9-methyl-thiacarbocyanine triethylammonium salt (MTC). Nuclear magnetic resonance (NMR) studies suggest that the hydrophobic nature of the protein surfaces drives MTC into different types of aggregates with distinct colors. When proteins interact with other biomolecules, the hydrophobic surface of the complex differs, resulting in a shift in the form of MTC aggregation, which results in a color change. As a result, this in vitro method has the potential to become a rapid tool for the confirmation of protein-biomolecule interactions, without the requirements for sophisticated instrumentation or approaches.

Standardization the effect of shape of aggregates with respect to compressive strength of concrete

It is proved that aggregate’s types have the severe effect on physicomechanical properties of concrete as aggregate covered almost 70 to 80 percent of the total volume of concrete. The effect of Flaky and Elongated aggregates on strength, durability, and workability of concrete has often been qualitatively expressed. The aim of this work is establishing the same quantitatively. M25 grade concrete for different ratios of weights of Elongated to normal aggregate, Flaky to normal aggregate and combined Flaky & Elongated aggregate to normal aggregate was tested for compressive strength at 28 days concrete. Three different types of aggregates were employed in the investigation, namely; normal aggregate, Elongated aggregate, and Flaky aggregate. Density and water absorption also kept constant to identify the effects on properties of concrete only for differences in shape. Thirty-six concrete cylinder was cast at 28 days. Varying dosages of Normal aggregate (60%, 65%, 70%, 75%,80% 85%), flaky aggregate (40%, 35%, 30%, 25%, 20%, 15%), elongated aggregate (40%, 35%, 30%, 25%, 20%, 15%), by mixture volume and length of 12inch (304.8 mm) & diameter of 6inch (152.4 mm) cylinder were used to test. Compaction was done by temping rod. Concrete cylinder was tested at the age of 28 days of curing. This study proposed of mixing three different types of aggregate in concrete. Compressive strength of concrete was measured by the effect of three different shapes of aggregates of varying dosages.

EFFECTS OF BASALT AGGREGATES ON CONCRETE PROPERTIES

Concrete is one of the most important building materials of engineering structures and especially construction applications. Since compressive strength is the most effective parameter for determining the strength of concrete, it is one of the most important mechanical properties to be determined in concrete. Aggregate grain strength, aggregate granulometry, cement strength, water/cement ratio, and concrete fill rate are the most important factors affecting the compressive strength of concrete. The quality of concrete is directly related to the aggregate that is volumetrically found most in the concrete. It is suggested that high strength, hard, easy to obtain and easy to access basalt aggregates are preferred to obtain high-performance concrete. The present study aims to investigate the fresh and hardened concrete properties of the concrete produced by the basalt aggregates extracted in the Elazig region. For this purpose, concrete mixtures containing cement dosages of 300, 350 and 400 kg/m 3 and containing different sizes of basalt aggregates were prepared. The concrete compressive strengths were tested for cubic samples of 150x150x150mm and 100x100x100mm, while the tensile splitting strengths were tested for cubic samples of 150x150x150mm. As a result of the tests performed, as the cement dosage increased, the slump values of the concrete mixtures and the strength of the concrete increased. The micro-structural structure of existing aggregates was investigated, and strong molecular bonds were observed with SEM analysis conducted within the scope of this study. In addition, a comparison was made with reference to the concrete samples prepared with different types of aggregates used in previous studies. It was seen that the compressive strength of the concrete containing the basalt aggregate was generally higher. In this experimental study, it was concluded that the concretes produced with basalt aggregates might have better mechanical properties and be environmentally friendly and economical.

Effect of pore structure on the performance of photocatalytic lightweight lime-based finishing mortar

The present paper aims to evaluate the performance of photocatalytic lightweight indoor hydraulic lime-based finishing mortars, with Portland cement-based finishing mortar as a reference. Two different types of aggregates, expanded glass and expanded silicate, are utilized to achieve the lightweight character and their contributions are investigated. The pore structure of the developed mortars is determined by mercury intrusion porosimetry (MIP) and BET methods. The mechanical strength, drying shrinkage, thermal physical properties and air pollutant removal ability of the mortars are investigated and the effects of pore structure on these properties are evaluated.Due to the higher porosity, lime-based finishing mortars possess a higher capillary water absorption and higher drying shrinkage, which can be explained by the Kelvin-Laplace mechanism. The lime-based mortar shows very good thermal properties, with a thermal conductivity of 0.15 W/(m·K). The lime-based mortar shows a better ability of removing air pollutants, up to 46% under indoor air conditions laboratory test, compared to the cement-based mortar, which is attributed to the lower content of gel pores present in the lime-based mortar. Expanded glass shows positive influences concerning thermal properties and air pollutant removal ability compared to expanded silicate.

Draining capability of single-sized pervious concrete

Six mixtures of single-sized pervious concrete were prepared with three different types of aggregates (dolomite, diabase, and steel slag from a Croatian landfill near the town of Sisak) and with two different aggregate fractions (4–8 mm and 8–16 mm). Each pervious concrete mixture contained 10% of sand from the Drava River. The hydrologic properties of the pervious concrete mixtures are compared in order to define the aggregate type that will ensure the best drainage properties. The draining capability was tested by three methods: the constant head and falling head methods on the small samples, and the standard test method for testing the infiltration rate of in-place pervious concrete by ASTM C 1701-09. The possibility of pervious concrete application as a surface layer in pavement construction in the European area is estimated according to the achieved mechanical properties. The optimal aggregate type for preparing pervious concrete from the hydrologic point of view is diabase because of its sharp grain edges, which allow the water to pass smoothly through the pore system. None of the studied mixtures satisfied the set criteria on the mechanical properties of concrete for the surface layer of pavements in the European area. However, it is observed that the coarser aggregate fraction will result in better hydraulic and mechanical properties of pervious concrete.

Simple model for time-dependent bond transfer in pretensioned concrete using draw-in data

Time evolution of prestress loss and bond transfer length holds vital information concerning long-term performance of pretensioned prestressed concrete. In this paper, it is proposed to utilize long-term measurements of strand draw-in to extract this time-varying information, which could be more effectively obtained than concrete or strand surface strain measurements. Theoretical investigations combined with numerical studies of experimental data are carried out for this purpose. This study builds on Guyon’s boundary value problem (BVP) model which quantifies draw-in for instantaneous elastic response. A one-dimensional linear viscoelastic standard solid model is employed to model the creep of concrete, which is a simple but effective model of the time-dependent response of concrete. Guyon’s BVP model is generalized to include time dependence and then combined with an existing initial value problem (IVP) model for post-tensioned concrete leading to a new mixed model for time-dependent prestress loss and bond transfer in pretensioned concrete.Analysis is undertaken in this study to (i) quantify long-term prestress loss and bond-transfer behaviors by applying the proposed model and directly utilizing measured draw-in time history data, (ii) validate the proposed quantitative analysis by using scaled pretensioned concrete beams with different types of aggregates and strengths of concrete - among other factors, and (iii) offer discussion of future work. For example, introducing concrete drying shrinkage into the proposed simple model seems promising and is necessary to provide an improved representation of the time-dependent behavior of prestressed concrete.

Evaluation of Fine Aggregate Surface and Fracture Surface by Confocal Microscope

The gypsum mortars with different types of aggregate were studied. The surface roughness of fine aggregates and the fracture surface roughness were evaluated by a confocal laser scanning microscopy. Four gypsum mortars and one gypsum paste were tested. The results from the confocal laser scanning microscopy (CLSM) are compared with the pictures of grain surface taken by a scanning electron microscopy (SEM) and both methods seem to be appropriate for surface evaluation. The influence of the surface aggregate roughness on some gypsum mortar properties is demonstrated.

Wearing characteristics assessment of pervious concrete pavements

Seven different concrete mixtures were prepared to estimate the possibility of using pervious concrete for light traffic urban areas. The total porosity, density, compressive strength, flexural strength, abrasion resistance, and traffic noise absorption capacity were tested for all the concrete specimens. The first mixtures corresponded to a standard dense concrete mixture (M1), while the other mixtures were pervious concrete mixtures involving two different types of aggregates (dolomite and steel slag) and different proportions of aggregate fractions. The total porosity, density, compressive strength, flexural strength, abrasion resistance, and traffic noise absorption capacity were tested in the case of all concrete specimens. The total porosity increased, whereas the compressive and flexural strength decreased simultaneously with an increase in the share of coarse aggregate fractions. The abrasion resistance and acoustic characteristics improved if only a fraction of the aggregate was used in pervious concrete preparation.

PH driven fibrillar aggregation of the super-sweet protein Y65R-MNEI: A step-by-step structural analysis

BackgroundMNEI and its variant Y65R-MNEI are sweet proteins with potential applications as sweeteners in food industry. Also, they are often used as model systems for folding and aggregation studies. MethodsX-ray crystallography was used to structurally characterize Y65R-MNEI at five different pHs, while circular dichroism and fluorescence spectroscopy were used to study their thermal and chemical stability. ThT assay and AFM were used for studying the kinetics of aggregation and morphology of the aggregates. ResultsCrystal structures of Y65R-MNEI revealed the existence of a dimer in the asymmetric unit, which, depending on the pH, assumes either an open or a closed conformation. The pH dramatically affects kinetics of formation and morphology of the aggregates: both MNEI and Y65R-MNEI form fibrils at acidic pH while amorphous aggregates are observed at neutral pH. ConclusionsThe mutation Y65R induces structural modifications at the C-terminal region of the protein, which account for the decreased stability of the mutant when compared to MNEI. Furthermore, the pH-dependent conformation of the Y65R-MNEI dimer may explain the different type of aggregates formed as a function of pH. General significanceThe investigation of the structural bases of aggregation gets us closer to the possibility of controlling such process, either by tuning the physicochemical environmental parameters or by site directed mutagenesis. This knowledge is helpful to expand the range of stability of proteins with potential industrial applications, such as MNEI and its mutant Y65R-MNEI, which should ideally preserve their structure and soluble state through a wide array of conditions.

The influence of aggregates type on W/C ratio on the strength and other properties of concrete

The influence of different types of aggregates and W/C ratio on concrete properties is analysed. In order to achieve this aim, lightweight (with expanded clay aggregate) and normal concrete (with gravel aggregate) mixtures are prepared with different W/C ratios. Different W/C ratios are selected by reducing the amount of cement when the amount of water is constant. The following properties of concrete have been determined: density, compressive strength and water absorption. Additionally, the statistical data analysis is performed and influence of aggregate type and W/C ratio on concrete properties is determined. The empirical equations indicating dependence between concrete strength and W/C and strength of aggregate are obtained for normal concrete and light-weight concrete.

NMR and Rheological Study of Anion Size Influence on the Properties of Two Imidazolium-based Ionic Liquids

NMR self-diffusion and relaxation, coupled with viscosity, were used to study the properties and structure of two imidazolium-based ionic liquids, 1-ethyl-3-methylimidazolium acetate [C2MIM][OAc] and 1-ethyl-3-methylimidazolium octanoate [C2MIM][OOct]. The experimental results point to the formation of different types of aggregates in each ionic liquid. These aggregates are small and stable under flow and temperature in [C2MIM][OAc], whereas the aggregates are large and sensitive to flow and temperature in [C2MIM][OOct]. In the latter case the size of aggregates decreases both under flow and temperature increase.

Influence of a hydrophobic core on thermoresponsive behavior of dendrimer-based star-shaped poly(2-isopropyl-2-oxazoline) in aqueous solutions

The behavior of eight-arm, star-shaped poly(2-isopropyl-2-oxazoline) (PiPrOx8) with a hydrophobic dendrimer core was studied in aqueous solutions by light scattering and turbidimetry methods. In order to reveal the influence of the star-shaped structure, model linear PiPrOxs were investigated for comparison. The experiments were carried out within a 100-fold concentration interval at temperatures from 15 to 63 °C. Dendrimer core interaction lead to the formation of different types of aggregates at low temperatures as compared to star-shaped PiPrOx with different cores. The temperatures of the phase separation interval were determined and analyzed depending on concentration. It was shown that macromolecule shrinkage and aggregation occur below the phase separation onset which results from the specific chemical nature of macromolecules and their hydrophilic-hydrophobic balance.

Asphalt binder adsorption by aggregates: a microscopic study

Asphalt adsorption by aggregates is an important parameter in hot mix asphalt mix design. In the present study, a comparison is made between asphalt binder adsorption obtained from volumetric calculations with that of from microscopic observations. Four different types of aggregates (of sieve size 50–80 mm) are used in the study. Volumetric measurements are carried out on individual aggregates to calculate the percentage of adsorbed asphalt binder. On the other hand, the depth of asphalt binder penetration (obtained from microscopic observation) is used to quantify the amount of adsorbed asphalt binder. From the results, it appears that microscopic studies consistently over-estimate the percentage of asphalt binder adsorbed. Scanning electron microscope with energy dispersive X-ray spectroscopy is used to further investigate some possible reasons for such a discrepancy.

Endoplasmic reticulum proteins SDF2 and SDF2L1 act as components of the BiP chaperone cycle to prevent protein aggregation.

The folding of newly synthesized proteins in the endoplasmic reticulum (ER) is assisted by ER-resident chaperone proteins. BiP (immunoglobulin heavy-chain-binding protein), a member of the HSP70 family, plays a central role in protein quality control. The chaperone function of BiP is regulated by its intrinsic ATPase activity, which is stimulated by ER-resident proteins of the HSP40/DnaJ family, including ERdj3. Here, we report that two closely related proteins, SDF2 and SDF2L1, regulate the BiP chaperone cycle. Both are ER-resident, but SDF2 is constitutively expressed, whereas SDF2L1 expression is induced by ER stress. Both luminal proteins formed a stable complex with ERdj3 and potently inhibited the aggregation of different types of misfolded ER cargo. These proteins associated with non-native proteins, thus promoting the BiP-substrate interaction cycle. A dominant-negative ERdj3 mutant that inhibits the interaction between ERdj3 and BiP prevented the dissociation of misfolded cargo from the ERdj3-SDF2L1 complex. Our findings indicate that SDF2 and SDF2L1 associate with ERdj3 and act as components in the BiP chaperone cycle to prevent the aggregation of misfolded proteins, partly explaining the broad folding capabilities of the ER under various physiological conditions.

Punching shear behavior of recycled aggregate reinforced concrete slabs

Preservation of environment and natural resources has recently attracted researchers to study the use of recycled aggregates from demolished concrete in new concrete structures. This paper presents an experimental study on punching shear behavior of simply supported natural and recycled coarse aggregate concrete slabs. The punching shear behavior of interior slab–column connection in flat plates is tested in “The Reinforced Concrete Laboratory of the Faculty of Engineering, Alexandria University”. Eight two-way slab specimens using two different types of aggregate “natural and recycled” and two aggregate nominal sizes (12.5 and 25mm) were cast and tested to failure. The slabs were designed such that they would fail in punching shear only. The experimental work was conducted on (6) recycled coarse aggregate concrete (RCAC) slab specimens and (2) natural coarse aggregate concrete (NCAC) slabs. All the slabs were simply supported on four edges and tested under a central patch load. The ACI mix design procedure was adopted to achieve strength of concrete at 28days of 35MPa. Four concrete mix proportions were used with (0%, 30%, 60% and 100%) replacement of natural coarse aggregate with recycled coarse aggregate for each aggregate size. The test results showed that the first punch crack load, ultimate punch load, stiffness and energy absorption decrease as the replacement of natural coarse aggregate with recycled coarse aggregate increases. Also as the recycled aggregate size increases the cracking and failure load increases. The measured ultimate failure loads have been compared with code predictions (ECP 203, ACI 318, JSCE code, Euro code 2 and yield line theory). The Euro code – 2 equations gave the best correlation with the experimental results.

An Experimental Investigation on the Thermal Effect on the Mechanical Behavior of Concrete

The paper shows an experimental investigation carried out to study the thermal effect on the short-term mechanical properties of concrete. This study presents some experimental results of mechanical-test specimens that were subjected to cold temperatures (-10°C and -20°C), average temperatures (10 and 30°C) and to high temperatures such as 40, 50 and 60°C during 24 hours. Three concrete mixes obtained using different types of aggregates were considered. All the tests for the experimental program have been carried out after cooling of the material. The concrete samples are tested to determine the compressive strengths and modulus elasticity and were then compared with those obtained at room temperature (20°C). The results demonstrated that the performance of concrete considerably falls with the increase of temperature until 60°C. Those results were also completed by scanning the electron microscope observations of the microstructure.

Experimental study on short eccentrically loaded column of recycled aggregate concrete filled square steel tube

To investigate the mechanical properties of recycled aggregate concrete filled square steel tubular column under bias voltage, and to analyze the effects of three influencing factors (steel ratio, eccentricity and different types of aggregates) on mechanical properties of test specimens. The experimental results indicated that recycled aggregate concrete filled square steel tubular column had high bearing capacity and excellent deformation performance, and its final fracture morphology was similar to that of common concrete-filled steel tube, which was bending failure. Steel ratio, eccentricity and different types of aggregates had significantly effects on the mechanical properties of bias column. Mid-span longitudinal strain distribution of the test specimens could basically satisfy the plane cross-section assumption, the calculated value according to standard GB 50936-2014 was close to the measured value, which was more suitable for calculating the bearing capacity of bias column.

Load Sensitivity Studies in Power Systems With Non-Smooth Load Behavior

One of the most important aspects of time-domain simulations for power system planning studies is load modeling. For a realistic representation of the load, the Western Electricity Coordinating Council (WECC) model validation and working group developed the composite load model. The composite load model represents the aggregation of different types of loads at the substation level. However, there exists some uncertainty in determining the load parameters and the percentage composition of the different components. Trajectory sensitivity (TS) analysis provides a systematic approach to study the impact of parameter uncertainty on power system response to disturbances. The non-smooth nature of the composite load model may present some additional challenges to sensitivity analysis in a realistic power system. This paper presents an application of TS analysis to study the impact of load parameter uncertainty on the system response. The impact of the non-smooth nature of load models on the sensitivity analysis is also addressed. This paper further suggests a method to determine the perturbation size limit for which accurate linear approximations can be made. The study was performed using the WECC system model.

Synthesis, Characterization, and Investigation of Thermosensitive Star-Shaped Poly(2-isopropyl-2-oxazolines) Based on Carbosilane Dendrimers

tar-shaped poly(2-isopropyl-2-oxazolines) with dramatically hydrophobic dendrimer core are synthesized using carbosilane dendrimers of first to third generations as macroinitiators. It is observed that half of the initiator functional groups are incorporated in polymerization process. The polymerization degree of polyoxazoline arms is about 25. Strong arm folding results in small molecule dimensions in both aqueous and organic solutions. Thermosensitive properties are studied for second generation-based star solution with the concentration of 0.00095 g cm−3. Model linear poly(2-isopropyl-2-oxazolines) are investigated for comparison. Carbosilane dendrimer core interaction leads to the formation of different types of aggregates at low temperatures. The temperatures of the beginning (T1 = 42–43 °C) and finishing (T2 = 50 °C) of phase separation are determined. It is shown that macromolecule compactization and aggregation take place even far from the phase transition interval and alternately prevail on heating.