Abrams Cone Research Articles

THE EFFECT OF POLYPROPYLENE FIBERS ON COMPRESSIVE AND SPLIT TENSILE STRENGTH OF LIGHTWEIGHT CONCRETE

This study was carried out to design lightweight concrete, which is enriched with polypropylene fibers using coarse pumice and sand fine aggregates. Lightweight concrete specimens were classified into distinct groups based on fibers content employed, namely a control group with 0 kg/m³ and the experimental incorporating 0.1 kg/m³, 0.3 kg/m³, 0.5 kg/m³, and 0.7 kg/m³ varying quantities of polypropylene fibers. Subsequently, after a curing period of 28 days, the hardened concrete test was conducted on cylinder specimens measuring 150 mm x 300 mm. The consistency of the fresh concrete mixture was tested using the Abrams cone test, which revealed a decrease in the workability of fibers-reinforced concrete with an increase in fibers volume in the mixture. The test aimed to determine the effect of polypropylene fibers on compressive and tensile strength of lightweight concrete. The optimal compressive and split tensile strength was observed at fibers volume fraction of 0.5, to obtain 7.84 MPa, or 56.68% increase in compressive strength, and 2.12 MPa or 42.86% rise in tensile strength. Based on compressive and split tensile strength obtained from this study, concrete was classified as highly lightweight structural concrete, which served as an insulator.

Automated Control of the Fresh State of Industrial Concrete Behaviour by Rheometer Test Adjustment

This study aimed to develop a rheometer prototype and define a procedure for adjusting the automated control of the fresh state of concrete. Sixteen batches were produced, and their fresh behaviour was measured at different testing times by applying the Abrams cone and flow curve test (FCT) as the rheological protocol. During this test, the yield stress and plastic viscosity of the concretes were measured in relative units. The rheometer prototype was used to define a new protocol to select the most suitable rheometer impeller arrangement and optimal FCT configuration. This protocol considers the torque at the end of the breakdown period, torque reduction during the breakdown period, segregation, and negative values of the yield stress in relative units. This protocol also enabled an iterative adjustment procedure, facilitating the use of a rheometer for the automated control of the homogeneity and behaviour of fresh concrete, as well as real-time decision making.

The use of superplasticizers in multicomponent concrete mixtures

In addition to the positive effect of the introduction of a superplasticizer, there are also negative ones: an increase in the period of structure formation, a significant air entrainment and, as a result, a decrease in strength. One of the ways to reduce the negative impact on the structure and properties of concrete composites is the method of preparing a suspension, which consists in first dissolving 10% of the amount of cement in all the mixing water in a concrete mixer for 1-2 minutes. Then load the rest of the cement and aggregate. Preliminary dissolution in water mixing with superplasticizer leads to the formation of a colloidal solution containing an increased amount of micro- and nanoparticles. When a superplasticizer is introduced into a cement-water suspension, particles with a high degree of dispersion are formed, as well as calcium hydrosilicate cristolites with a size of 1-3 nm. This sharply increases the activity of the superplasticizer and, consequently, improves the mobility of the concrete mixture. For example, from P2 to P3, from P3 to P5. This allows to reduce the consumption of the additive by 1.5 - 2 times. It has been established that the superplasticizer can be adsorbed only on hydrate neoplasms. For pre-treatment, it is necessary to use special equipment with high energy consumption such as RPA, fine grinding mills, disintegrators and various activators. Obtaining a cement-water suspension can be carried out in mortar, concrete mixers, in mixers of any type. The concrete mixture consists of cement, crushed stone, sand, water and superplasticizer C-3, determination of the draft of the cone using the Abrams cone, determination of the cubic strength using a hydraulic press in accordance with GOST 10180-2012. It becomes possible to increase the grade in terms of workability as a result of preliminary hydroactivation of the plasticizing additive, which leads to a decrease in its consumption. This method of hydroactivation of superplasticizers for the manufacture of cement concretes can be used to save the consumption of a plasticizing additive.

Using Natural Raw Materials and CEM Approach for the Design of Andean Volcanic Self-Compacting Concretes

Volcanic activity is characteristic of seismic zones. Consequently, volcanic material form part of the landscape in places where earthquakes are common natural phenomena. As volcanic wastes (VW) show pozzolanic activity, the substitution of manufactured Portland cement (PC) with VW is clearly a desirable option not only from an economical point of view but also to reduce the CO2 fingerprint. Therefore, designing concretes with volcanic Portland cements (VPC) clearly contributes to cleaner cement production. Construction and building activities in seismic zones need to use a specific kind of concrete—self-compacting concrete (SCC). The challenge we focused on was the design of SCC using VPC. The flow behavior of SCC is characterized by low yield stress, high plastic viscosity, and shear-thickening behavior at high shear. However, obtaining these striking properties of the concrete is not easy with traditional concrete flow tests (Abrams cone, etc.). Moreover, these methods are very costly in terms of time and material. An alternative that allows us to use absolute rheometry and which has been little explored consists in the substitution of concrete by an equivalent mortar. The so-named concrete equivalent mortar (CEM) approach was used in this study to obtain SCC formulations with VPC. Mini cone tests confirmed the absence of blend in some selected CEM formulations based upon the accomplishment of the criteria for SCC. Three concrete proposals were inferred from the respective CEM formulations. They adapted to the SCC European standard according to the Abrams cone spread test.

Influence of Soap Factory Wastewater on the Physical and Mechanical Performance of Concrete

The management of water resources is one of the major priorities in all countries of the world and even more so in developing countries such as Cameroon. The purpose of this research project is to assess the influence of the use of soap wastewater on the physical and mechanical performance of concrete. The experimental test program was designed to assess the impact of varying the concentration of soap factory wastewater as a replacement for tap water. Cylindrical concrete test pieces were made by varying the proportion of wastewater from soap factories at a rate of 0%, 40%, 60%, 80% and 100%; depending on the water/cement ratio of 0.5, 0.6 and 0.7. These cylindrical concrete specimens were tested at the ages of 3, 7, 28, 60 and 90 days; the load was applied consistently and the breaking stress was measured automatically at failure. The results of the experimental tests carried out in this project indicate that the use of wastewater from the soap factory for the preparation of concrete as a replacement for tap water induces a decrease in the value of the subsidence at the abrams cone of the concrete, delays the start of the setting of the cement, leads to a reduction in the compressive strength of the concrete, causes the formation of pores in the concrete matrix at early ages. Correlations have been developed to quantify the loss in the strength of concrete as a function of the polluted water content and the variation of the water / cement ratio.

Study of the effect of the addition of rubber aggregates on the behaviour of self-compacting sand concrete

This work mainly relates to promoting the use of concrete based on sand and the incorporation of rubber aggregates (0-1mm) from recycling of used tires in volume substitution of sand with rates of 10, 20 and 30% in order to obtain materials with low environmental impact. In order to meet this objective, an experimental approach was carried out, which consisted in incorporating different percentages of rubber aggregates in the formulation of sand concrete. These concretes are characterized in the fresh and hardened state in order to study the effect of adding these rubber aggregates on the properties of self-compacting sand concrete. The results found show that the fluidity of the SCSC (expressed by spreading with the Abrams cone and the flow at the V-Funnel) improves with the increase in the dosage of rubber aggregates and these values are located within the recommendations of the French Association of Civil Engineering. They also show that rubber particles can improve certain desired technical characteristics such as ductility.

Simulation of generalized Newtonian fluids with the Smoothed Particle Hydrodynamics method

AbstractIn this paper we examine Direct Numerical Simulation DNS of single phase non‐Newtonian fluids described by a generalized Newtonian rheology. Non‐Newtonian flow including large deformations and free surface flow could be observed in a wide range of industrial and environmental applications. For that reason, we choose the Lagrangian Smoothed Particle Hydrodynamics (SPH) as a simulation tool. The non‐Newtonian solver is implemented into the general purpose particle framework HOOMD‐blue [1,2], which allows for massive parallel CPU and GPU simulations. Numerical accuracy of the model is demonstrated by simulating confined Poiseuille flow between parallel plates. The validation has been done for a wide variety of shear strain–shear stress ratios where also the effect of the solid‐fluid interface boundary condition is examined. Furthermore, a comparison with the experimental results for the broken dam problem [3] showed good accuracy of the free‐surface flow prediction. Additionally, we have investigated a slump test (Abrams cone [4]), a relatively simple but in practice often performed experiment for non‐Newtonian yield‐stress fluids. Finally, we have investigated in further detail the cone diameter, height, flow time, the final shape and the influence of the rheological model parameters as well as the boundary conditions related to the stationary cone configuration.

Rheological characterization of self‐compacting concrete: New recommendation

AbstractThe most commonly used test to characterize the fluidity of self‐compacting concretes (SCC) is the Abrams cone spreading. However, this later, according to many scientific studies, contains some defects depending on the operator and the analysis of the found results. Further, the use of a concrete rheometer on building site is a very complex operation. In this regard, our laboratory has developed another practical, simple, and economical test able to measure, on building site, the plastic viscosity and the yield stress of the SCC. This is a “V‐Funnel coupled to a horizontal Plexiglas channel” test. The experimental results of our study show that the proposed tool can replace the LCPC‐box test, the concrete rheometer and other empirical tests recommended by the European standards.

Field-oriented tests to evaluate the workability of cob and adobe

Due to its low environmental impact, earth construction has received lot of consideration in recent years. Furthermore, in order to improve the quality of earth construction, there is a need for a better description and control of the earth consistency or rheology. Just as for concrete with the Abrams cone, there is need for a simple and robust test that is able to provide, under field conditions, the consistency of the earth and that has results that can be used to estimate the yield stress of a fine soil used for cob or adobe. Two types of field-oriented tests are optimized for field conditions: the first one is based on the cone penetration test as used for the determination of the Atterberg limits and the second one is the ball dropping test already used onsite to check the adequacy between the earth consistency and the construction process. Finally, an experimental validation carried out on two types of soil shows that the yield stresses computed from the field-oriented tests is in agreement with the yield stresses obtained in a conventional way using a vane rheometer.

Shrinkage and creep performance of concrete with recycled aggregates from CDW plants

This research analyses the shrinkage and creep performance of concrete with recycled aggregates from various Portuguese construction and demolition waste recycling plants, studying the influence of the properties and composition of each recycled aggregate source on the characteristics of concrete produced with them. Recycled aggregates from four plants were used in the concrete mixes produced in this research, of which two were coarse recycled aggregates and two were fine recycled aggregates. During this experimental campaign, the behaviour of the mixes with recycled aggregates was evaluated by three fresh-state concrete tests (slump using the Abrams cone, density, and air content) and two hardened-state concrete tests (shrinkage and creep). It was found that the incorporation of recycled aggregates caused a qualitative drop in the concrete's properties. The properties of the concrete mixes were significantly dependent on the source (and composition) of the recycled aggregates.

Thermal Performance of Concrete with Recycled Aggregates from CDW Plants

This investigation intends to analyse the thermal performance of concrete with recycled aggregates (RA) from construction and demolition waste (CDW) collected from several locations in Portugal. A total of 17 concrete mixes were analysed by means of thermal conductivity tests. Firstly, the composition and characteristics of the aggregates (natural and recycled) used in the production of the concrete mixes were analysed thoroughly, by means of several physical and chemical tests. Later, in order to evaluate the thermal behaviour of the mixes, several tests were performed and their results analysed, both on the fresh-state (slump with the Abrams cone test, density and air content) and the hardened state (compressive strength and thermal conductivity). The analysis of the thermal behaviour showed that the use of RA improves the thermal performance of the concrete mixes. The extent of this change was shown to be quite variable depending on the origin of the RA used.

Methodology for evaluation of mud rush risk in block caving mining

Mud rushes are sudden inflows of fine wet ore within underground mines; they can harm people and equipment as well as cause production delays. Block and panel caving mines are prone to mud rushes in their production levels, with mud flowing from the drawpoints. Different mines have developed methods to control drawpoint conditions and thus perform safe ore extraction. The aim of this study is to develop a decision matrix and apply it to samples from drawpoints for the Diablo Regimiento mine, Codelco, El Teniente Division (Chile). The Abrams's Cone was used to perform slump tests on mud samples and characterize their consistency by setting the saturation degree and packing. The unconfined strength for different saturation degrees and packing was then evaluated. The results show that conditions for fluid response in slump tests correspond to conditions for low strength in unconfined compression tests. We also found the water content value at which the flowing consistency changes from plastic to soft behaviour according to the slump test classification for each sample. This value varied between 12.2% and 16.9%, depending on the sample tested. Finally, a fluid security factor was defined in order to design an extraction pattern for the samples tested, based on the water content. We conclude that a very densely packed ore is not prone to flowing. The flow properties depend strongly on the specific properties of the ore tested, and consequently a specific criterion should be developed for different types of ore at a particular mine. The criterion developed for Diablo Regimiento ore provides critical water content values from 11% to 15%, depending on the ore type.

Self-compacting concrete obtained by the use of kaolin wastes

A self-compacting concrete (SCC) is characterized by its special capacity of filling ability, passing ability and resistance to segregation by the action of its own weight without the presence of other external forces. These fresh properties are obtained thanks to the use of filler, where the limestone one is mostly used. Numerous industries produce a great amount of solid wastes, some suitable for use as filler in the production of SCC. This study aimed to develop a SCC with inclusion of wastes from the manufacturing of kaolin, through an optimum dosage of kaolin wastes and superplasticizer (sp) which were well established from the experiments. The paste dosage was defined by Marsh funnel and mini-slump tests and fresh properties of concrete were measured by L box, U box, J ring, V funnel and Abrams cone. The use of kaolin wastes in SCC production is pioneering. The mix-design method used was successful and it was validated by the several fresh properties results which provided to the concrete a SCC characteristic flowing behavior. Finally, including industrial waste in SCC has brought significant environmental benefits.

High torque vane rheometer for concrete: principle and validation from rheological measurements

A high torque vane rheometer is used to measure the yield stress of cement-based materials. It is shown that this apparatus is suitable for the evaluation of the yield stress of various concretes and mortars in the fresh state in comparison with slump tests realized with ASTM Abrams cone. Then, the rheological properties (yield stress and shear flow behaviour) of a homogeneous kaolin clay suspension are studied with the apparatus and favourably compared with other rheometers and geometries.

Minimizing water dosage of superplasticized mortars and concretes for a given consistency

Workability and consistency are fundamental properties of cement-based materials: their control ensures a correct and easy casting of the material without segregation of aggregates. The workability of cementitious systems depends on their rheological behavior (also called “consistency”), which varies with the material composition and the mixing parameters. In this work, a method based on the analysis of mini-cone and Abrams cone test results was developed to optimize the binder volume and minimize the mixing water fraction of superplasticized mortars and concretes for a given consistency. A three-parameter empirical equation was proposed to simulate the relationship between water content and slump value in large ranges of water-to-binder ratios and superplasticizer dosages.

Correlation between Yield Stress and Slump: Comparison between Numerical Simulations and Concrete Rheometers Results

Results of numerical flow simulations for two slump geometries, the ASTM Abrams cone and a paste cone, are presented. These results are compared to experimental results in the case of a cone filled with cement pastes in order to validate the proposed numerical method and the chosen boundary conditions. The correlation between slump and yield stress obtained numerically for the ASTM Abrams cone is then compared to the experimental correlations obtained by testing concrete with different rheometers during comparative studies that were organized at LCPC Nantes (France) in 2000 and MB Cleveland (USA) in 2003.

Ecoulements d'affaissement et d'étalement

ABSTRACT This paper gathers results from several numerical, analytical and experimental studies in an attempt to answer most of the practical questions that rise when trying to quantify the workability of a given fresh concrete with empirical tests such as the Abrams cone test or the slump flow… Several physical phenomena are successively analyzed and asymptotical solutions of the flow are obtained in two extreme case (high and low slumps) and compared to experimental results in the case of concretes and cement pastes. Finally, the limits of the slump flow test used as a SCC reception test are demonstrated and an alternative test is presented.

From mini-cone test to Abrams cone test: measurement of cement-based materials yield stress using slump tests

Stoppage tests in civil engineering consists in measuring the shape of a fresh material deposit after flow occurred. This measured geometrical value (slump, spread) is linked to the plastic yield value of these yield stress materials. The most famous example is the Abrams cone for concrete. In this work, the flow induced by a smaller cone test for cement pastes and grouts is studied. In a first part, the spread is theoretically linked to the plastic yield value. Experimental results on several cement pastes validate the obtained relation but also shows the necessity to take in account the surface tension effects for low yield stress materials. The modified relation allows the prediction of the plastic yield value from the measured spread. The proposed method is then applied to the Abrams cone and fresh concrete. It is demonstrated that it is only suitable for high slumps (>20 cm).