A study of durable and reliable reactive powder concrete containing rice husk fibers

Natural fibers have seen a surge in popularity over the past decade as a direct response to the growing number of people who are concerned about the environment. The use of natural fibers has many advantages, including their low cost and their little impact on the environment. Rice husk is a byproduct of milling rice and is frequently regarded as a waste product by many people. However, it has a number of possible applications, one of which is the use of its natural fibers in the production of bio-composites. In this paper, experimental work was carried out to study the effect of Rice Husk Fibers with a volume fraction of one percent on the properties of Reactive Powder Concrete (RPC), utilizing various temperatures curing for four hours due two days after hardening the sample directly, and the optimal temperature that will give the highest strength will be adopted to study the effect on some mechanical properties. Rice Husk Fibers were added to the RPC mixture at a volume fraction of one percent. These characteristics include the compressive strength, dry density, and slump of the material. According to the findings, the compressive strength of the RPC grew by 7.4%, while the dry density reduced by 0.69 % after being heated to 60 °C for 28 days. On the other hand, the RPC's workability decreased by 5.62 % when compared to the reference mixture

The Effect of Type of Fiber in Density and Splitting Tensile Strength of SIFCON

SIFCON is characterized as a construction material of high ductility and very high strength. It is suitable for concrete structures used for special applications. However, the density of SIFCON is much higher than that of Fiber Reinforced Concrete (FRC) due to the need for a large amount of high-density steel fibers. This work examines the split tensile behavior of modified weight slurry infiltrated fiber concrete utilizing a mixture of two types of fibers, steel fiber, and polyolefin fiber. For the investigation, 30 cylinders and 15 cubes were poured. The used volume fraction (V.F) is (6 %) and the use of five series once as each type separately and once a hybrid in proportions of 2/3 polyolefin with 1/3 steel fiber and vice versa. The splitting tensile strength and the unit weight of SIFCON resulting from tests were studied. The results indicate that SIFCON produced from a mixture of 1/3 hook-end steel fibers with 2/3 polyolefin fibers achieved good results in reducing density while maintaining a high split tensile strength. It significantly decreased density by 140 kg per cubic meter and improved splitting tensile strength by 494%.

SOME FACTORS AFFECTING THE ULTRASONIC PULSE VELOSITY TEST RESULTS OF HIGH STRENGTH CONCRETE

The high strength concrete is characterized by its high strength, low porosity and good performance under aggressive environmental conditions. The paper presents some factors affecting the Ultrasonic Pulse Velocity test results for high strength concrete such as water/ cement ratio, type of aggregate, frequency level of transducers, dimension of the specimens and path length. An experimental equation has been derived for the prediction of compressive strength of high strength concrete from pulse velocity, which can be used for the estimation of strength. It provides more reliable prediction and can be used in precast concrete factories manufacturing precast concrete girders for bridge

The Effect of Using Different Aspect Ratios of Sustainable Copper Fiber on Some Mechanical Properties of High-Strength Green Concrete

To achieve sustainability, use waste materials to make concrete to use alternative components and reduce the production of Portland cement. Lime cement was used instead of Portland cement, and 15% of the cement's weight was replaced with silica fume. Also used were eco-friendly fibers (copper fiber) made from recycled electrical. This work examines the impact of utilizing sustainable copper fiber with different aspect ratios (l/d) on some mechanical properties of high-strength green concrete. A high-strength cement mixture with a compressive strength of 65 MPa in line with ACI 211.4R was required to complete the assignment. Copper fibers of 1% by volume of concrete were employed in mixes with four different aspect ratios (20, 40, 60, and 120). At 7, 28, and 60 days after typical curing, the samples' mechanical characteristics (compressive strength, flexural strength, and split tensile strength) are assessed. A reported increase in compressive strength of (2, 1.6, and 1.4) in (7, 28, and 60 days) for concrete with a high aspect ratio 120, compared to concrete with a low aspect ratio 20. The flexural strength of high-strength green concrete with fibers of a higher aspect ratio 120 was (23, 11, and 12.6%) times higher for all ages compared to low aspect ratio 20. The split tensile strength rose (1.7, 1.5, and 1.6%) for (7, 28, and 60 days), respectively, for concrete with a high aspect ratio 120, compared to concrete with a low aspect ratio 20. It was found that using fibers with a large aspect ratio improved the mechanical properties of concrete more than fibers with a small aspect ratio

Behaviour of Fire Exposed Reinforced Concrete Rigid Beams with Restrained Ends

This paper is devoted to investigate the effect of burning by fire flame on the behavior and load carrying capacity of rectangular reinforced concrete rigid beams. Reduced scale beam models (which are believed to resemble as much as possible field conditions) were suggested. Five end restrained beam specimens were cast and tested. The specimens were subjected to fire flame temperatures ranging from (25-750) ºC at age of 60 days, two temperature levels of 400ºC and 750ºC were chosen with exposure duration of 1.5 hour. The cast rectangular reinforced concretebeam (2250×375×375 mm) (length× width× height respectively) were subjected to fire. Results indicate remarkable reduction in the ultrasonic pulse velocity and rebound number of the rigid beams after cooled in water were (2-5 %) more than rigid beam specimens cooled in air. Load-deflection curves indicate deleterious response to the fire exposure. Also, it was noticed that the maximum crack width increases with increasing fire temperature

Effect of Petroleum Products on Steel Fiber Reinforced Concrete

This Investigation aims to study the effect of adding Steel fibers with different volume fractions Vf (o.5, 0.75, and 1% by volume of concrete) with aspect ratio 100 on mechanical properties of concrete, and also finding the influence of petroleum products (Kerosene and Diesel) on mechanical properties of Steel Fiber Reinforced Concrete (SFRC). The experimental work consists of two groups: group one consists of specimens (cubes and prisms) plain and concrete reinforced with steel fiber exposed to continuous curing with water. Group two consists of specimens (cubes and prisms) plain and concrete reinforced with steel fiber exposed to kerosene and diesel after curing them in water for 28 days before exposure. The results of all tests refer that the specimens (plain and reinforced concrete with steel fiber with different volume fraction) exposed to kerosene were better than the specimens (plain and reinforced concrete with steel fiber with different volume fraction) exposed to diesel

Optimisation of the Filament Winding Approach Using a Newly Developed In-House Uncertainty Model

The device under investigation in this paper consists of a float used to capture tidal energy, which is tethered by multiple flexible cables to a large barge-like reactor. The proposed float is made of a continuously wound glass-reinforced composite shell with stainless steel bolting plates integrated into the float walls to allow the connection of 5 stainless steel cables. Numerical computations are required to assess whether a delamination of the composite layers in the float is likely. The manufacturing of the device has various potential uncertainties that should be investigated, such as the number of the plies, the bond strength between the composite layers, and the fibre orientations of the composite material relative to the applied load. This paper provides a multi-level strategy to optimise the composite float system, which is manufactured from glass-reinforced plastic (GRP). In contrast to previous publications on the topic, the current work uses an efficient link between ANSYS Workbench and MATLAB through an in-house code that has been developed over 3 years. This allowed the whole process to be fully automated and to reduce the time and cost of the simulations. Previously, ANSYS APDL was linked to MATLAB, but limitations in terms of the geometry and boundary conditions made it impractical when compared to ANSYS Workbench for the simulation of complex features. This makes the current approach unique and rare when compared to the published work in the field. This approach allows the use of a huge number of trials and is able to reduce the number of parameters to be studied by selecting the most sensitive ones. Additionally, the developed tools may be used for the efficient, robust optimisation of the proposed structure. The current study has focused on exploring the effects of the fibre orientations and the optimum number of plies on the overall performance of the structure

Effect of Metakaolin on Properties of Lightweight Porcelinate Aggregate Concrete

Research in Iraq has expanded in the field of material technology involving the properties of the lightweight concrete using natural aggregate. The use of the porcelinate aggregate in the production of structural light concrete has a wide objective and requires a lot of research to become suitable for practical application. In this work metakaolin was used to improve compressive strength of lightweight porcelinate concrete which usually have a low compressive strength about 17 MPa . The effect of metakaolin on compressive, splitting tensile, flexure strengths and modulus of elasticity of lightweight porcelinate concrete have been investigated. Many experiments were carried out by replacing cement with different percentages of metakaolin. The metakaolin was replaced by 5%, 10%, 15% and 20%. A control reference mix without metakaolin was made for comparison purpose. For all mixes, compressive, splitting tensile, flexure strengths and modulus of elasticity were determined at 28-day. The results showed that the using of metakaolin improve the compressive, splitting tensile, flexure strengths and modulus of elasticity of lightweight porcelinate concrete. The higher compressive, splitting tensile, flexure strengths and modulus of elasticity were found for 15% metakaolin

BEHAVIOUR OF FIRE EXPOSED REINFORCED CONCRETE COLUMNS

This research is devoted to investigate the behaviour and load carrying capacity of reinforced concrete columns exposed to fire flame. The experimental program consisted of casting and testing of 128 column specimens divided into two series A and B with target compressive strength (30 and 40 MPa) and named series A and B respectively. Each series was divided into three main groups loaded eccentrically with eccentricities 30mm and 80mm. It was found that the predicted load carrying capacity of reinforced concrete columns by three codes (ACI-318/08, BS-8110/97 and Canadian/84), was unconservative after burning. The BS Code equation was found to predict load capacity after exposure to high fire temperature levels better than other codes. Load-deflection curves indicate deleterious response to the fire exposure. Also, it was noticed that the maximum crack width increases with increasing fire temperature and amount of spacing between lateral steel ties

Fabricating a new Rheometer for Concrete

A new concrete rheometer is introduced including its innovation, actual design, working rules, calibration, and reliability. A modified design of Tattersall two-point device is created. Some of components are purchased from local and foreign markets, while other components and the manufacturing process are locally fabricated. The matching viscosity method of determining the mixer viscometer constants is demonstrated and followed to relate torque and rotational speed to yield stress and viscosity (Bingham parameters). The calibration procedures and its calculation are explained. Water is used as a Newtonian fluid, while; cement paste (cement + water) with w/c ratio equal to (0.442) is used as a non-Newtonian fluid. The cement paste is tested in “Petroleum Research and Development Center” by “OFITE Model 800 Viscometer”. In order to verify the reliability of the new rheometer, an Artificial Neural Network (ANN) model with a well selected bank of data is constructed; and (16) Mixes of Self Compacting Concrete (SCC) are constructed, mixed and tested by the new Rheometer. The results from model (predicted) and those from the experimental work (measured) were found to have very good degrees of correlation and matching, which indicates that the new rheometer can be reliable