Concrete Quality Research Articles

Stabilitas Pilar Beton Pracetak Segmental Pada Jembatan Standar Terhadap Beban Dinamik

The use of precast technology in the manufacture of segmental components for the bridge substructure is one application that can be used in the acceleration of bridge construction. Better concrete quality and precision are two advantages that can make precast technology a solution in accelerating bridge construction. Commonly, segmental precast concrete piers are not designed to resist earthquake loads; however, the use of segmental piers systems is still possible in seismic zones by limiting additional dead loads. This study discusses the load limitation using the dynamic response calculation methodology of segmental precast concrete pillar structures to the El Centro (1940) earthquake load by varying the slenderness of the piers/column between 22 to 100. Examination of the stress combination due to axial load (DL) and inertia load due to the earthquake is carried out to find out how much residual stress can be accommodated by the piers/columns. Additional dead load (WADD) is obtained by using Newton's second law by dividing the allowable additional inertial load based on the residual stress to the peak ground acceleration. The calculation results show a good correlation between piers’/columns’ slenderness and the proportion of additional dead load (WADD) to dead load (WDL), so that the applicability of using segmental precast concrete piers/columns in seismic zones can be predicted earlier through this correlation.

Effect of macrocell currents on rebar corrosion in reinforced concrete structures exposed to a marine environment

Autonomous corrosion monitoring systems in reinforced concrete structures tend to use sensors that are electrically isolated from rebars. This monitoring strategy ignores the macrocell currents that take place between active and passive areas of reinforcement. The effect of these currents has been studied on rebar corrosion in structures exposed to a marine environment. The results showed the existence of macrocell currents generates greater anodic polarisation in rebars’ active areas, which favours chloride migration towards steel surface. As a result, corrosion onset takes place sooner, the concentration of the chlorides is higher, and the corrosion rate increases. When a rebar is in passive state, steel mass loss is negligible due to macrocell currents. However, after corrosion onset, the influence of these currents is greater the worse concrete quality is, and the smaller cover is. The corrosion rate showed differences of almost two orders of magnitude in concrete C30 and of one order of magnitude in concrete C50. When the total corrosion rate is determined only by measuring microcell currents, the obtained values tend to underestimate the mass loss due to corrosion by 90%. Conversely, when the analysis includes macrocell currents, a good fit between the theoretical and real values is obtained.

ASSESSMENT OF COMPRESSIVE STRENGTH OF CONCRETE PRODUCED WITH FINE AGGREGATE FROM DIFFERENT LOCATIONS IN KADUNA STATE

Building Collapse from failure of structures has been a major concern for researchers today. This is traceable to several factors, one of which is the quality of the materials used during construction, as the quality of concrete is known to depend on the type of cement, water and aggregates used. Since coarse and fine aggregates occupy up to 70-75% of the concrete volume, it is necessary that the quality of aggregates be astutely ascertained. The objective of this research is to establish the best locations of fine aggregate in Kaduna state in order to facilitate its selection for construction purposes. A prescribed mix of 0.55/1:1.5:3 targeting a concrete of grade C20 was adopted for 100 x 100 x 100mm cubes. This research examined the engineering properties of fine aggregate which are used in concrete works in Kaduna. Fifteen sources from the three senatorial districts in Kaduna (Kaduna North, Kaduna South and Kaduna Central) were identified from which fine aggregate samples were collected and transported to the Nigerian Defence Academy, Afaka, for examination. The test results revealed that the specific gravity of the samples falls between 2.34 and 2.85 and fineness modulus between 2.36 and 3.3. The compressive strength after curing for 7 days varies between 18.5 N/mm2 and 26.4 N/mm2, and after 28 days curing varies between 23.3 N/mm2 and 30.1 N/mm2 all for same prescribed mix, cement grade and coarse aggregate type. Concrete produced with fine aggregate from Kaduna South L.G shows the highest strength after 28 days while the concrete from Kajuru L.G has the lowest compressive strength after 28 days.

Analysis of the Key Points of Concrete Pouring Maintenance and Quality Control in Cast-in-Place Box Girder Project

Analysis of the Key Points of Concrete Pouring Maintenance and Quality Control in Cast-in-Place Box Girder Project

Determining Concrete Structure Condition Rating Based on Concrete Compressive Strength

The need for concrete condition assessment for existing buildings increases because of high disaster vulnerability levels, as well as a large number of buildings that have reached their age of use. Currently, there is not any standard reference for assessing concrete condition rating yet, so a concrete condition assessment method that can be measured quantitatively needs to be developed. The developed concrete condition assessment method combines concrete condition assessment based on visual inspection and testing. Assessment measures start with an assessment of visual inspection results, which is continued with concrete compressive strength testing. This article contains a concrete condition assessment based on concrete compressive strength testing. This method determines the concrete condition rating scale using five condition ratings as a reference for building condition assessment. The limit value of each condition rating is taken from concrete compressive strength values that are structurally sufficient, according to the structural concrete requirement code for buildings. Concrete compressive strength values have resulted from non-destructive tests and destructive or loading tests. Building condition rating (BCR) value determination factors in the effect of structure element damage towards building structure and concrete testing result accuracy rating, and also can decrease inaccuracy towards concrete quality condition rating determination on scale limit values, and minimize error risks in determining damage condition rating. The resulting method has the advantage of assessing structure element condition rating and building condition rating (BCR) that can be measured quantitatively, has five assessment scale ratings that can portray building conditions having to be demolished, and calculates structure element critical weight.

Experimental Study of Effect of Silt in Fine Aggregates on Quality of Concrete

Abstract: Considering modern era of globalization and highly competitive world market, quality plays key role in every field. Quality plays even more critical role in construction industry where wrong doings cannot be reversed at later stage. Modern construction industry all over the world hinges around "cement concrete construction" and hence quality management of cement concrete construction plays key role in every country's development. Quality management for concrete involves design of concrete mix for a specific situation and purpose, testing materials and controlling concrete operations so as to get Concrete of desire quality. Keywords: Cement, Fine and Coarse Aggregates, Silt or dust, Factions, Compressive Strength, Durability, Workability, Quality.

Comparative Study on the Effects of Steel Slag Aggregate over Blended Cement Concrete

Abstract: Concrete is the most versatile construction material because it can bedesigned to withstand the harshest environments while taking on the most inspirational forms. Engineers are continually pushing the limits to improve its performance with the help of innovative chemical admixtures and alternative construction materials (ACM). Nowadays, most concrete mixture contains alternative construction materials which form part of the cementitious component. These materials are majority byproducts from other processes. The main benefits of ACM (alternative construction materials) are their ability to replace certain amount of cement or aggregates and still able to display major properties similarto concrete, thus reducing the cost of using traditional materials. The fast growthin industrialization has resulted in tons and tons of byproduct or waste materials, which can be used as ACMs (alternative construction materials) such as marble powder, silica fume, ground granulated blast furnace slag, steel slag etc. The useof these byproducts not only helps to utilize these waste materials but also enhances the properties of concrete in fresh and hydrated states. Most concrete produced today includes one or more ACM (alternative construction materials). For this reason, their properties are frequently compared to each other by mix designers seeking to optimize concrete mixtures. To design high strength concrete good quality aggregates is also required. Steel slag is an industrial byproduct obtained from the steel manufacturing industry. This can be used as aggregate in concrete. It has been usually used as aggregate in hot mix asphalt surface applications, but in the present work it has been used in conventional concrete mixture and performance is compared with normal aggregate concrete. Replacing all or some portion of natural aggregates with steel slag would lead to considerable environmental benefits. Steel slagaggregate generally exhibit a propensity to expand hence steel slag aggregates are generally not used in concrete making. However, use of blended cement concrete is reported to reduce the expansion of the concrete. In the present work a series of tests were carried out to make comparative studies of various mechanical properties of concrete mixes prepared by using normal cement concrete, marble powder and cement blend concrete (1:1 proportion ) with or without use of steel slag. The ingredients are mixed in 1: 1.5: 3 proportions. The properties studied are 7 days, 14 days and 28 days compressive strengths, workability and surface hardness. Keywords: Cement, Concrete, Steel Slag, Aggregates, Blended Cement,Marble Powder.

Investigation of Factors Causing Poor Quality of Concrete in Terms of Strength and Durability

Abstract: Considering modern era of globalization and highly competitive world market, quality plays key role in every field. Quality plays even more critical role in construction industry where wrong doings cannot be reversed at later stage. Modern construction industry all over the world hinges around "cement concrete construction" and hence quality management of cement concrete construction plays key role in every country's development. Quality management for concrete involves design of concrete mix for a specific situation and purpose, testing materials and controlling concrete operations so as to get Concrete of desire quality. Keywords: Cement, Fine and Coarse Aggregates, Silt or dust, Compressive Strength, Durability, Workability, Quality.

Studying the Impact of Imposed Actual Loads on the Non-Destructive Test Results for Evaluating the Compressive Strength and Other Properties of Concrete

Among all the concrete characteristics, the compressive strength is known as the most important feature and therefore, it is often utilized to quantify the quality of concretes. The assessment of concretes strength in existing constructions is important during their service life. Thus, in addition to destructive evaluation of strength, many non-destructive techniques have been adopted to assess the concretes strength. Ultrasonic Pulse Velocity (UPV) is one of the non-destructive techniques that involve measuring the speed of ultrasonic wave through concretes to predict concretes strength. According to the Griffith’s theory, the strength of the material is greatly affected by the defects’ existence (for example, small cracks). These cracks can be current prior to the application of any loading or could create throughout the load application. The presence of micro-cracks in concretes that generate due to the applied load may affect the UPV test results in comparison with unloaded concretes. An experimental investigation is conducted in order to assess the impact of the applied of load (ultimate load) on the measured ultrasonic wave velocity and compared with the results of compressive strength from destructive test. A total of thirty (150 mm × 150mm) cube specimens have been utilized with water to cement ratios (0.45). These cubes have been examined in ultrasound without any loads and then they have been tested in the same way with applied ultimate load which is approximately equal to half of the required design load (failure load) and then inspected or tested in the normal way (destructive test). In order to assess the compressive strength of concretes using UPV, loading condition is considered in order to study the impact of the applying load. In addition, the water absorption has been examined for thirty concretes samples under the impact of the applied loads (20%, 40% and 60%). The results of non-destructive tests of concretes samples under the influence of imposed loads (60%) have showed to be less by compressive strength 5 MPa than the results obtained from testing of unloaded concretes samples through the resulting equation and comparing them to the equation from previous research. This is consistent with the water absorption test of the specimens under the imposed loads (60%) where Absorption values have been greater than concretes models without applied loads.

Deep learning enabled particle analysis for quality assurance of construction materials

Microspheres in fly ash are critically important for determining the properties and performance of fly ash dosed concrete, but facile and cost-effective analysis and quality control of fly ash microspheres remain difficult on construction sites. This paper describes a deep learning method to segment and analyze fly ash spherical particles using a simple optical microscope and a path aggregation network. The proposed method accurately detects microspheres and predicts their particle size distribution and volume fraction, outperforming traditional methods for particle analysis. The predicted results are directly linked to key properties that determine the quality of fly ash. This research establishes an automated and efficient method for rapid job-site fly ash spherical particle analysis, so that inexpensive and handy construction material quality control and assurance can be achieved for infrastructure construction.

Construction and Demolition Waste-based Geopolymer Concrete: A Brief Review

Cement concrete and other cement-based composites find wide application in the construction industry. The manufacturing of cement releases a large amount of CO2, so the use of cement has become a major area of environmental concern. Attempts have been made to minimize the quantity of cement in con- crete by replacing it with supplementary cementitious materials. Geopolymer concrete is one of those potential candidates for alternative cementitious mate- rials. In today’s world, the production of Construction and Demolition (C&D) wastes has been increased worldwide which finds no suitable disposal and can- not be used in ordinary concrete due to potential deterioration of concrete quality. However, C&D waste can be safely used with geopolymer concrete with and without the usage of Supplementary Cementitious Materials (SCMs) and play a major role in improving the strength and durability properties of concrete.

Bending Behaviour of Prestressed T-Shaped Concrete Beams Reinforced with FRP-Experimental and Analytical Investigations.

Materials such as high performance (HPC) or ultra-high performance concrete (UHPC), and fibre-reinforced polymer (FRP) reinforcement can be used to improve the resource efficiency in concrete construction by, for example, enabling the production of thin-walled structures. When building filigree concrete beams two essential factors must be considered: the low stiffness of the structure and the bond between the materials. By prestressing the structural stiffness is improved while an adequate concrete cover ensures sufficient bond strength. Based on this the bending behaviour of prestressed T-shaped beams reinforced with FRP, focussing on determining the influence of four parameters on the bearing capacity, bond behaviour and failure mode, is investigated in this paper. Comprehensive experimental investigations prove the potential of the approach and show that a reduction of the web thickness down to 40 mm, a lower concrete quality, and the use of glass FRP instead of carbon FRP allow a more resource-efficient structure while the applied prestressing leads to a higher utilisation of the high performance materials.

Effect of Different Mineral Admixtures on the Performance of Pavement Quality Concrete Containing the Optimum Amount of Jarosite as Partial Replacement of Cement

Effect of Different Mineral Admixtures on the Performance of Pavement Quality Concrete Containing the Optimum Amount of Jarosite as Partial Replacement of Cement

EFFECT ON CONCRETE TENSILE STRENGTH OF DIFFERENT DISTRICT OF GROUND WATER

The quality of mixing water may affect the setting, hardening and strength of the concrete. Concrete is the most durable material and cement provides the large amount of energy to structural materials in concrete. Here the principal consideration is to mixing the quality and quantity of water into the concrete preparation. For the preparation of concrete quality of water always plays an major role. Quality of water may vary according to places; hence it may change the behaviour of concrete. It is seen that the water may affect strength, workability, setting time, tensile strength. According to IS3025 (PartII):1983, pH value of water should be potable between the range of 6.0 to 8.0 pH, it is favourable for construction work. The works aim is to provide a new approach of concrete tensile strength and also check the alkalinity, total suspended solids, sulphate, hardness etc. Samples are collected by different district (Durg, Rajnandgaon, Kawardha, Balod) of Chhattisgarh. Here we get different types of Minerals in every district. So This is done to determine the Split Tensile Strength Test of Concrete by making concrete cylinders. The samples of concrete (cylinder) were made for two different Grade i.e.mix design of M20 and M25. Keywords- Strength, Setting time, Water test, Impurity, pH value, Tensile Strength, Sieve analysis, W/C ratio, PPC cement, Workability test.

Effect of different district water sources on compressive strength on concrete

The quality of mixing water may affect the setting, hardening and strength of the concrete. Concrete is the most durable material and cement provides the large amount of energy to structural materials in concrete. Here the principal consideration is to mixing the quality and quantity of water into the concrete preparation. For the preparation of concrete quality of water always plays a major role. Quality of water may vary according to places; hence it may change the behaviour of concrete. It is seen that the water may affect strength, workability, setting time, compressive strength. According to IS3025 (Part II):1983, pH value of water should be potable between the range of 6.0 to 8.0 pH, it is favourable for construction work. The works aim is to provide a new approach of concrete compressive strength and also check the alkalinity, total suspended solids, sulphate, hardness etc. Samples are collected by different district (Durg, Rajnandgaon, Kawardha, and Balod) of Chhattisgarh. Here we get different types of Minerals in every district. So this is done to determine the Compressive Strength Test of Concrete by making concrete cubes. The samples of concrete (cube) were made for two different Grade i.e. mix design of M20 and M25 and with variable water cement ratio. The result after tests were compared and determination of various aspect of water were made if they are suitable to use for structural member of building and related structures Keywords- Compressive Strength, Setting time, Water test, Impurity, pH value, Strength, Sieve analysis, W/C ratio, PPC cement, Workability test, Structural member

Machine learning-based real-time tracking for concrete vibration

Proper concrete vibration is vital to the final quality and durability of concrete structures. There is a lack of objective methods to assess conformance to the requirements of vibration behavior in real time. Based on data fusion and machine learning, we propose a real-time tracking method for concrete vibration effort. The system combines the advantages of an ultra-wideband sensor and inclinometer—a simple structure, reliability, expandability, and low cost. A data processing algorithm and hybrid neural network recognition model are developed to process the data stream, enabling automatic derivation of the indexes related to the vibration effort and achieving active concrete vibration quality control. An evaluation method for the performance of the different vibration tracking systems is established using the error transfer formula. The feasibility and accuracy of the tracking method are experimentally verified. This proposed method provides a quality control tool that helps prevent potential quality problems during vibration.

Working state determination for concrete internal vibrator using genetic simulated annealing clustering method

The vibration duration is a key parameter for evaluating concrete consolidation quality. Based on the input current changing of internal vibrator drive motor when vibrator was inserted into concrete and pulled out concrete, this paper developed a device and proposed a method to determine the vibrator working state (insert or pull out). The current was collected through transformer and transmitted to single-chip microcomputer after rectified by current input module. The Chebyshev filtering method was adapted to filter the irregular fluctuation of the measured signal. The dual-threshold (idle current threshold and current difference threshold) method was proposed to determine the working state of vibrator. The current difference threshold was calculated using a genetic simulated annealing optimizing fuzzy C-means clustering method and it can distinguish normal current rise caused by inserting concrete and abnormal current rise caused by touching steel bar etc. when pulling out or moving vibrator. Considering vibrating concrete is a continuous process, the minimum vibrating time was flexibly set to correct the inserting state. Two misjudgment conditions were analyzed and proved that they had little effect on the overall accuracy. The identification accuracy and universality of the proposed method and device were verified by on-site application.

Analysis of the Variation in Different Nondestructive Testing and Standards

Non Destructive Testing (NDT) methods are used to review or measure the materials or designs without annihilating their surface, item uprightness and future handiness. The overall objective of the research is to assess the strength of concrete in existing structures using Nondestructive Tests at Kachankawal Rural Municipality, Jhapa District of Nepal.Rebound hammer test and ultrasonic pulse velocity tests were used for determining the compressive strength of concrete. The existing Reinforced Concrete Cement culverts were used for 9 existing structures. Average rebound number were taken and calculated from each sample. From the average rebound number were taken to determine the grade of concrete along with corresponding compressive strength. Similarly, the Ultrasonic Pulse Velocity tests were done on same existing structures and path length and time were noted for assessing the corresponding compressive strength and the quality of concrete. Triangulation among rebound hammer test, ultrasonic pulse velocity test and proposed initial grading were validated using chi square test. Relation between compressive strength with rebound hammer and ultrasonic pulse velocity were analyzed using linear regression model. Chi square confirms variation in compressive strength between calculated compressive strength and standard compressive strength. The relation of compressive strength (y) at R² = 1 with rebound number (x) and ultrasonic pulse velocity (x) could be expressed as y = 0.9306x - 2.7233 and y = 2.904 x + 10.119 respectively. The study is a guiding tool for concern authority and professionals to make effective decision regarding further structural development and budget allocation of the existing structures.

Compressive Strength Enhancement of Pervious Concrete Using Polymer Fiber

Pervious concrete is a unique kind of concrete having a high porosity, utilized for concrete flatwork application that permits water from perception and different sources to go legitimately through. This research study deals the improvement for strength quality and other necessary properties of pervious concrete in order to implement the same in high traffic roads. 0.15%, 0.20% and 0.25% polypropylene fibers were used to determine separate compressive strength qualities. The observed experimental test results indicated that there is direct variation between the compressive strength and percentages of polypropylene fiber. The present study concluded that an additional 35% increase in the compressive strength was observed in pavement as compared to plain pervious concrete.

Prospects for waste-free utilization of ore dressing tailings

The information about the state of the use of natural resources in Russia is given and the need to search for new sources of raw materials for industry is justified. There is a tendency to reduce the production capacity and the rate of extraction of metal ores, which does not allow the use of the infrastructure of mining enterprises and creates the problem of processing substandard ore deposits and disposal of accumulated waste. The concept of deep processing of substandard metal-containing raw materials and a strategy for the survival of mining enterprises, including the use of metal leaching technologies, is formulated. The advantages of technologies with the leaching of metals from mineral raw materials at the stages of its processing are characterized. The advantages of leaching in disintegrators are shown by comparison with the indicators of the basic variant. It is noted that mechanochemical activation improves the quality of concretes made on the basis of recycled tailings. Managing the properties of recyclable materials allows you to implement the principles of resource conservation with an economic effect. It is concluded that the recommended technology is the real direction of technological modification of production.