Concrete Slump Research Articles

Effect of rubber crumb on the microstructural properties of concrete

This study evaluates the effect of rubber crumb on the microstructural properties of concrete which was used to partially replace fine aggregate by 0, 4, 8, 12, and 16% proportion and designated as M0, M4, M8, M12, and M16 respectively. The wet and hardened properties of concrete were investigated by conducting a slump test and a compressive strength test, and by measuring the concrete bulk density. The crack formed as a result of compressive strength was investigated using a digital microscope, while the micro-cracks formed in the concrete structure were investigated using a scanning electron microscope (SEM). The results showed that concrete slump for all the samples range between 25 and 10 mm, with M0 and M4 having the highest slump. The compressive strength and density of the concrete decreased as the amount of rubber crumb increased in the mixture, with M0 having a compressive strength of 51.88 N/mm2 and M16 having the lowest compressive strength of 19.40 N/mm2. The SEM analysis showed that there was a weak bond between the concrete paste and the rubber crumb, which resulted in to a weak adhesive force, and the development of micro-cracks which contributed to the week compressive strength in concrete with higher rubber crumb.

Performance of Concrete Containing Granulated Blast Furnace Slag as a Fine Aggregate

The present challenge in front of Civil Engineers is to find alternative materials for fine aggregates in concrete. Since, most of the State Govt. banned the dredging of river sand. The Granulated blast furnace slag is considered as a fine aggregate in concrete. At present, in India Steel Industry produces about 40 Million Tonnes by 2020 it is estimated to 60 million tonnes. The Author has investigated the effect of compressive strength of concrete, when Granulated blast furnace slag is used (GBFS) as a fine aggregate in concrete. The work includes the partially and fully replacement of river sand by granulated slag in M25 Grade of concrete with a constant 0.45 W/C ratio. Slag replacement of 50, 80, 100% are used. It has been observed that concrete made with 50% of river sand and 50% (GBFS) is nearer to Zero percent replacement. Objectives: To determine the optimum percentage slag replacement as a fine aggregate in concrete which helps in maintaining sustainability of concrete and balancing between the environmental problems due to construction industry as it is necessary to find out the alternative materials for use as fine aggregates because of restrictions by the local authorities. Methods: The experiments are planned to find out the optimum replacement percentage of GBFS against river sand as a fine aggregate in concrete. Mix design for M25 grade of concrete is made with OPC (Ordinary Portland Cement) and PPC (Port land Pozzolana Cement) is considered with a constant 0.45 W/C ratio and slag replacement of 50, 80, 100% are used. 30 Cubes for each cement category of 150 mm size are casted, cured by immersion and tested by CTM. Findings: In both the cement category, the compressive strength and slump of concrete is found reducing with the increase in the percentage of slag as a replacement to fine aggregate. In concrete made with OPC when compared with 50%, 80% and 100% replacement with GBFS reduction upto 96.50%, 87% and 77.5% in strength and 84.6%, 53.84% and 34.6% in slump respectively is observed. In concrete made with PPC when compared with 50%, 80% and 100% replacement with GBFS reduction upto 95.30%, 80% and 63% in strength and 82.7%, 51.7% and 34.0% in slump respectively is observed. Application/Improvements: This study using alternatives to fine aggregate in concrete will help in making concrete economical, reduction in environmental problems and saving the natural resources. The study may be extended to determine the concrete sustainability in saline conditions also.

Concrete Slump Classification Using GLCM Feature Extraction

Digital image processing technologies have been widely applies in analyzing concrete structure because the accuracy and real time result. The aim of this study is to classify concrete slump by using image processing technique. For this purpose, concrete mix design of 30 MPa compression strength designed with slump of 0-10 mm, 10-30 mm, 30-60 mm, and 60-180 mm were analysed. Image acquired by Nikon Camera D-7000 using high resolution was set up. In the first step RGB converted to greyimage than cropped to 1024 x 1024 pixel. With open-source program, cropped images to be analysed to extract GLCM feature. The result shows for the higher slump contrast getting lower, but higher correlation, energy, and homogeneity.

Effect on Workability of Concrete due to Partial Replacement of Natural Sand with Gold Mine Tailings

Objective: Availability of fine aggregates in its natural form is becoming very scarce. It is becoming a challenging task to meet the demand for fine aggregates in its natural form without exploiting the natural resources. To sustain the construction activity, it becomes very essential to explore the possibility of utilizing alternative materials for fine aggregates. Large quantity of inorganic industrial waste is generated annually. Coal mine wastes, blast furnaces lag, iron ore tailings, red mud, zinc tailings, goldmine tailings etc., are some of the inorganic waste products that are generated. Methods/Statistical Analysis: In this investigation, an attempt is made to replace partially naturals and with gold mine tailings and study the behavior of concrete in the green state. Mix proportion for M25 concrete was obtained as per IS: 10262 guidelines, for normal concrete and concrete containing gold mine tailings as fine aggregates. Findings: Natural fine aggregates were replaced with 10%, 20% and 30% goldmine tailings on weight basis. In all five mixes were obtained and workability studies in the form of slump and compaction factor test were carried out. The slump for normal concrete was 84.33 mm and that for concrete containing gold mine tailings was 16.33 mm. The low slump for concrete containing gold mine tailings alone may be attributed to the presence of fine particles. The slump values for 10%, 20% and 30% replacement levels are 63.6 mm, 44.33 mm and 22.6mm respectively. Similar behavior is observed in the case of compaction factor test also. The decrease in the workability of concrete may be attributed to the increase in the fineness of resulting fine aggregates. Applications/ Improvements: The application of the gold mine tailing in the high scale structures and reduce cement by GMT.

Evaluation of the viscosity of tropical soils for debris flow analysis: a new approach

To analyse the debris flow type of landslides it is necessary to know the viscosity of the fast-moving soil mass. Such rheological parameters are important in the evaluation of characteristics of propagation of the movement downhill. This paper presents a proposal for the assessment of soil viscosity based on a modified set-up of the well-known concrete slump test. Through the definition of shearing rates in the slump tests, soil viscosity was determined on a plate–plate rheometer. Four natural soils from Rio de Janeiro, Brazil, with differing grain size distribution and plasticity, were used in the investigation. The results obtained are compared with experimental data from the literature, and show that care must be taken in defining viscosities based only on data related to grain size. Correlations between soil moisture and shearing rates, defined in the modified slump tests, and viscosity, defined in the rheometer tests, were obtained. As a result, a fairly good relationship between shearing rate and viscosity was established. Comparing the obtained data with numerical results available in the literature it is concluded that the developed experimental methodology may provide a simple way to evaluate the viscosity of soils for debris flow analysis.

Impact of recycled gravel obtained from low or medium concrete grade on concrete properties

This paper investigates the effect of recycled gravel obtained from low (Gl) or medium (Gm) concrete grade on fresh property of concrete (slump), mechanical properties (compressive-splitting tensile strength) and mass transport properties (ISAT-sorptivity) of concrete containing dolomite as a natural coarse aggregate. Concrete specimens were prepared with cement, water, sand and dolomite admixed with recycled gravel. The percentage of recycled gravel/dolomite was 0:100, 25:75, 50:50 and 75:25 at w/c=0.50, 0.55 and 0.60. The effect of silica fume and bonding admixture at w/c=0.55 on concrete properties were also considered. The results indicated that, increasing the percentage of recycled gravel/dolomite led to decreasing the slump. All mechanical properties of concrete discussed were inversely affected by increasing percentage of recycled gravel/dolomite from low and medium concrete. Adding 10% SF or bonding admixture increased the mechanical properties of concrete. Mass transport properties of concrete (ISAT-sorptivity) were enhanced by decreasing the percentage of recycled gravel/dolomite. The optimum percentage of recycled gravel/dolomite=25%.

Concrete Slump Classification using GLCM Feature Extraction

Digital image processing technologies have been widely applies in analyzing concrete structure because the accuracy and real time result. The aim of this study is to classify concrete slump by using image processing technique. For this purpose, concrete mix design of 30 MPa compression strength designed with slump of 0-10 mm, 10-30 mm, 30-60 mm, and 60-180 mm were analysed. Image acquired by Nikon Camera D-7000 using high resolution was set up. In the first step RGB converted to greyimage than cropped to 1024 x 1024 pixel. With open-source program, cropped images to be analysed to extract GLCM feature. The result shows for the higher slump contrast getting lower, but higher correlation, energy, and homogeneity.

Representing a logical grading zone for self-consolidating concrete

For an aggregate source with certain geometrical characteristics, grading can highly affect the properties of self-consolidating concrete (SCC). This paper basically focuses on the effect of using different aggregates grading on the properties of SCC. For this purpose twelve aggregate proportions with three different cement contents (450, 500 and 550), three different water-to-cement ratios (0.35, 0.4 and 0.45) and either poly-carboxylate based super-plasticizer as admixture were used. In order to examine fresh concrete properties, slump flow, U-box, L-box and V-funnel tests were carried out; for achieving hardened properties of SCC, tests were limited to compressive strength. The principal objective of this survey is to determine an acceptable aggregates grading zone which can be used in production of SCC with ideal properties. From the experimental consequences, it is observed that aggregate proportions in this zone, will result a SCC with appropriate workability and compressive strength. The optimum curves could be selected with Cu values more than 9.5.

Drying shrinkage behaviour of structural lightweight aggregate concrete containing blended oil palm bio-products

Oil palm shell (or palm kernel shell) and oil-palm-boiler clinker are two solid wastes from palm oil industry in tropical region. They can be used as aggregate in concrete mixture. Lightweight aggregate concrete with high strength was successfully produced using oil palm shell as coarse lightweight aggregate. However, lightweight concretes containing oil palm shell with normal and high strengths have relatively high drying shrinkage at early and later ages. This study is an effort to reduce drying shrinkage of oil palm shell lightweight concrete. It was found from previous studies that increasing the volume of oil palm shell in concrete increased its drying shrinkage. Therefore, one method to reduce the drying shrinkage is the reduction of oil palm shell volume by substituting this aggregate with another type of aggregate. For this purpose, comprehensive experimental study was carried out to investigate the effect of partial replacement of oil palm shell with oil-palm-boiler clinker aggregate on the shrinkage behaviour of this type of lightweight concrete. Two sets of concrete mixes were designed in this study. In the first set, oil palm shell was replaced with oil-palm-boiler clinker from 0 to 50% with interval of 10% in oil palm shell concrete with a constant water to cement ratio of 0.36. In the second set, the replacement of oil palm shell with oil-palm-boiler clinker was 30–50% with reduced water to cement ratios from 0.36 to 0.295. The influence of curing conditions on drying shrinkage of concretes was also considered. The test results indicated that partially substitutions of oil palm shell with oil-palm-boiler clinker could significantly reduce long term drying shrinkage of concrete. Contribution of oil-palm-boiler clinker in oil palm shell concrete in the range of 30–50% significantly increased the slump of control oil palm shell concrete. Therefore, it was possible to reduce the water content of these concretes to achieve the same workability of the control mix. Reduction on water content further reduced the drying shrinkage of the concrete. Concrete specimens under 7-day moist curing showed higher drying shrinkage compared to air drying condition.

ARTIFICIAL NEURAL NETWORK MODEL FOR FORECASTING CONCRETE COMPRESSIVE STRENGTH AND SLUMP IN EGYPT

Slump and compressive strength of concrete are commonly used criteria in evaluating fresh and hardened concrete. Accordingly, prediction of such criteria is important for the quality assurance of the produced concrete. In this paper, a Neural Network (NN) model is developed to predict concrete compressive strength and slump in Egypt. The Artificial Neural Network (ANN) model is developed, trained and tested using 1000 different concrete mixes gathered from different batch plants distributed all over the Arab Republic of Egypt. Important parameters that have noticeable effect on the compressive strength and slump are identified and used as the inputs for the ANNs model. The developed model can be used either to predict the compressive strength and slump for a given mix or to estimate the different ingredients to achieve a targeted compressive strength after seven and twenty eight days. To verify the results of the ANNs model, seventeen concrete samples are prepared and tested at laboratory and the same ingredients of the mixes are used to predict the strength and slump using the developed ANN model. The Root Mean Square Error (RMSE) of the results for the slump and the compressive strength after 7 and 28 days equal 3.74, 1.79 and 3.05, respectively. These results showed the ability of the developed ANNs as an effective tool to predict and estimate the compressive strength and slump of concrete in Egypt. The analysis of the test results leads to the conclusion that this idea can be used for the development of valid systems for specifications and standards.

An experimental study on the lateral pressure of fresh concrete in formwork

Most of the accidents related to concrete formwork are triggered by improper construction operations and the unsound lateral pressure estimations detailed in concrete formwork specifications. In this study a series of experiments was conducted to reveal the effect of different factors on lateral pressure. The results show that concrete slump, casting speed, and vibration mode can greatly influence the pressure; and the data obtained in the experiments differ greatly from the values yielded by different specifications. A modification is proposed to the GB50666 specification in order to improve the accuracy and reliability of pressure estimations.

THE ROLE OF SPECIAL ADDITIVES INTHE STRENGTHENING OF REINFORCED CONCRETE

The study aims to identify the role of the special additives for strengthening reinforced concrete used in construction, as the researcher presented the theoretical frameworks for the definition of reinforced concrete and its components as well as the special additives used in concrete, identifying its types and components. The experimental method based on the experience was used to reach the role of special additives to strengthen reinforced concrete and the researcher performed an experiment using the substance (CF/ACC) in its liquid form. The study reached the following: Control batch (without additives), produced fresh concrete slump equals 7cm, and the experimental batch with additives (CF/ACC) produced fresh slump equals 7cm, the effect of additives on the level of concrete slump in the experimental batch, where the additives proved its effectiveness in concrete stability. The study also recommended the following: The need to use the additives to the concrete because of its active role in enhancing the properties the reinforced concrete. The additives should not be mixed to the concrete except after the approval of the engineer who responsible for the project. Determine the appropriate materials for the required operations. The need to make mini tests to make sure of the concrete and additives effectiveness before starting in casting the concrete in the site.

Impact of separated bottom ashes on the parameters of concrete mix and hardened concrete

Polish energy industry is based primarily on the combustion of coal in conventional boilers and increasingly in fluidised bed boilers. As a result of combustion, by-products are formed, such as fly and bottom ashes. In the case of fly ashes, a number of methods of utilising them have already been developed, e.g. for the production of cement, concrete and in other industries. With regard to bottom ashes, whose properties differ significantly from those of fly ashes, methods are still being researched for the possibility of their industrial application. Similarly to fly ashes, it seems reasonable to move in the direction of bottom ashes being used in the wider construction industry, including for the production of concrete.This paper analyses the impact of the addition of bottom ashes obtained from hard coal combustion in conventional and fluidised bed boilers on the properties of fresh and hardened concrete. A concrete mix composition was developed by an experimental method, which was then modified with the use of bottom ashes. The impact of the substitution of cement and aggregates with bottom ash on the concrete properties was examined. For all the obtained series of concretes, tests were performed for the consistency of the fresh concrete using the concrete slump test, the compressive strength and tensile strength of the concrete after 3, 7 and 28 days of maturing and their absorption. The experiments have shown significant declines in the strength parameters of the concretes being analysed in the case of the substitution of cement with separated bottom ash. However, substituting relevant aggregate fractions with separated bottom ash resulted in an increase in both the compressive strength and the tensile strength in the analysed concretes.

A comparative assessment of bagging ensemble models for modeling concrete slump flow

In the last decade, several modeling approaches have been proposed and applied to estimate the high-performance concrete (HPC) slump flow. While HPC is a highly complex material, modeling its behavior is a very difficult issue. Thus, the selection and application of proper modeling methods remain therefore a crucial task. Like many other applications, HPC slump flow prediction suffers from noise which negatively affects the prediction accuracy and increases the variance. In the recent years,ensemble learning methods have introduced to optimize the prediction accuracy and reduce the prediction error. This study investigates the potential usage of bagging (Bag), which is among the most popular ensemble learning methods, in building ensemble models. Four well-known artificial intelligence models (i.e., classification and regression trees CART, support vector machines SVM, multilayer perceptron MLP and radial basis function neural networks RBF) are deployed as base learner. As a result of this study, bagging ensemble models (i.e., Bag-SVM, Bag-RT, Bag-MLP and Bag-RBF) are found superior to their base learners (i.e., SVM, CART, MLP and RBF) and bagging could noticeable optimize prediction accuracy and reduce the prediction error of proposed predictive models.

Estimation Model for Concrete Slump Recovery by Using Superplasticizer

Estimation Model for Concrete Slump Recovery by Using Superplasticizer

Experimental evaluation of workability and compressive strength of concrete with several local sand and mineral additions

The evolution of civil engineering has recently resulted in new structural methods and greater consumption of aggregates, particularly sand. This evolution has led to an international dynamics of valuating local materials, such as crushed sand, which is not used sufficiently often due to the high rate of fine particles that it contains. The aim of this work is to study the influence of fine particles of crushed sands on the compressive strength and concrete slump. The experiments have been performed on crushed, river and dune sands and the results indicate that the behavior of concrete in the fresh and hardened states is different according to the composition and sands. The results were compared with “Concrete Lab Pro 3” outputs. The analysis of the resistances shows that the experimental values and the estimated values are not comparable, especially in concrete slump.

Preparation for retarding and high early strength concrete

The primary objective of this research was to determine optimum dosage of mixing concrete containing plasticizers and fly ash, consistent with desirable structural grade concrete properties. Factorial tests were also conducted to investigate the four main factors: water-cementing materials ratio, water content, content of superplasticizers (SP) and fly ash content. It was found that the requirement for setting time played the dominant role in shrinkage and anti-cracking, and fly ash played a critical role in workability and reducing heat of hydration but showed insignificant effects on slump, early strength and initial setting time of concrete.

Sugar beet fiber and Tragacanth gum effects on concrete

As natural concrete supplements, waste materials obtained from food industry plants can substitute synthetic supplements in concrete to help protect the environment. This is an experimental study for examining the effects of Tragacanth gum and sugar beet fiber additives on concrete behavior. Tragacanth gum and sugar beet fiber have numerous applications in industry. Concrete specimens were prepared at six different mixing ratios of additives and subsequently tested. Tensile and compressive strengths, modulus of elasticity, slump, air voids volume and failure modes of the concrete specimens were measured to determine the changes the concrete had undergone due to the addition of sugar beet fiber and Tragacanth gum. Compressive strengths of the samples were between 32 and 37 MPa while the obtained tensile strength is between 3.43 and 3.66 MPa. The results indicated that concrete slump in the specimens exhibited considerable flowability, as in the case of self-compacting concrete. Moreover, increasing the test parameters decreased compressive strength and increased the number of air voids in the concrete. Adding a combination of Tragacanth gum and sugar beet fiber increased air voids and flowability in the concrete. Finally, given the increased concrete slump and concrete setting time, a numerical model was presented using the obtained laboratory results for examining slump variations after mixing the concrete.

Performance of Softwood Soda-Anthraquinone Lignin–Polyethylene Glycol Derivatives as Water-Reducing Admixture for Concrete

We have developed a high-performance lignin-based water-reducing admixture. In this study, softwood soda-anthraquinone lignin was modified with mono-epoxide polyethylene glycols having chain lengths of 10, 25, and 50 mol (the number of repeating units of ethylene oxide). The mortar flow and concrete slump flow tests were used to investigate the performance of the lignin derivatives as a water-reducing admixture. All tested lignin-PEG derivatives performed considerably better than a commercial lignosulfonate water-reducing admixture in the mortar flow test. In particular, the derivative with a PEG chain length of 50 mol performed excellently in both tests. The optimum PEG content for mortar dispersion was approximately 40% for lignin derivatives with a PEG chain length of 50 mol; this content exhibited a dispersing effect that was four times higher than that of the lignosulfonate water-reducing admixture. The strength of concrete containing the lignin derivatives was almost the same strength as that of concrete containing the commercial lignosulfonate water-reducing admixture.

Effect of the cement paste volume on the consistency of mixes for high performance massive and self-compacting concretes

The article presents the results of research concerning the influence of the volume of cement paste and the w/c ratio on the consistency of concrete mixes for high-performance massive and self-compacting concrete. The research covered six types of concrete mixes containing from 220 to 420 dm3 of cement paste in a cubic meter. Three of them were designed as high-performance concrete and for comparison three conventional ones. The consistency was tested with two methods: concrete slump test and flow table test, also additional tests of self-compacting mix were made. Compressive strength test were conducted to prove that concretes are high-performance. A high influence of the volume of cement paste on the workability and consistency of fresh concrete mix has been found, while the influence of the w/c ratio is considerably lower due to the dosage of high-quality superplasticizer.