Several experiments were conducted to observe various properties of concrete such as compressive strength, surface hardness, ultrasonic pulse velocity (UPV) and splitting stress test. The same proportion also gave the optimal result for the tensile strength of concrete. Silica Fume is also a reactive pozzolan that can be added to cement to improve compressive strength, bond strength and wear of concrete.
This project aimed to study the performance of the concrete by adding rice husk ash, silica fume and powdered fly ash as a multiple binder. The experiments were conducted to observe the strength of the concrete using a different mix and proportions of waste product. Various experiments were determined to observe different properties of the concrete, such as compressive strength, ultrasonic pulse velocity test, surface hardness test and splitting stress test.
The final result of this project was to obtain some output data that can prove whether the addition of the waste product to the concrete can improve its performance and can be used as a substitute material for cement. The project mainly consisted of determining the strength of the concrete using rice hulls, silica vapor and pulverized fly ash (PFA) as multiple binders. The final outcome of this project was to obtain some output data that can prove whether adding the waste product to the concrete can improve its performance so that the use of the cement can be reduced.
CHAPTER 2 LITERATURE REVIEW
A pozzolan is a powdered material, and added to the cement in a concrete mix, it reacts with the lime, released by the hydration of the cement, to create compounds that improve the strength or other properties of the concrete. These materials can give additional strength to the concrete by reacting with Portland cement hydration products to create additional C-S-H gel, the part of the paste responsible for concrete strength [3]. RHA resulting from the combustion process of paddy husk is one of the cement replacement materials (CRM) produced from agricultural waste.
In general, the reactivity of the pozzolanic material can be achieved by increasing the fineness of the material. Ordinary Portland cement (OPC) is expensive and unaffordable for a large part of the world's population. The result from the table shows that the addition of RHA causes an increase in compressive strength due to the capacity of the pozzolan to fix the calcium hydroxide generated during the cement hydrate reactions.
As a microfiller, the extraordinary fineness of silica allows it to fill the microscopic voids between the cement particles. In short, it can reduce the permeability and improve the bond between the paste and the aggregate of the resulting concrete compared to conventional concrete. Silicon dioxide is formed when the SiO gas released during the reduction of quartz mixes with oxygen in the upper parts of the furnace.
Today, it is widely used, as its use by replacing part of the cement enables significant savings in the costs of concrete production. Generally, for use in high-strength concrete, fly ash is used in dosages of about 15% of the cement content. Due to the variability of fly ash produced even from a single plant, quality control is particularly important.
The addition of RHA causes an increase in compressive strength due to the capacity of pozzolan to fix calcium hydroxide, created during cement hydrate reactions. The maximum value of the tensile stress, calculated at failure from the theory of elasticity, is the splitting tensile strength, ff, which is usually assumed in standards as a material property. Therefore, the pulse rate can be used to evaluate the quality and uniformity of the material.
The method is least accurate when both transducers are applied to the same face of the test piece, or.
CHAPTER 3 METHODOLOGY
5. concrete samples will have a combination of OPC, Silica Fume, PFA and also MYRHA. Determine all properties of concrete; cube and cylindrical concrete were produced and tested in the second experiment. The results for each property of the different mixture were then compared to prove the hypothesis of the project.
A concrete cylinder formwork set consisting of a formwork and a tubular support member is fixed inside the concrete formwork before the concrete is placed. The height of the upper edge of the mold is adjusted to correspond to the plane of the finished surface of the slab. The formwork support prevents direct contact of the slab concrete with the outside of the formwork and allows its easy removal from the hardened concrete.
This test method covers the determination of the splitting tensile strength of cylindrical concrete specimens. Plywood strips are used so that the load is uniform along the length of the roller. The maximum value of tensile stress calculated at failure from elasticity theory is.
Pulses of compression waves are generated by an electro-acoustic transducer which is kept in contact with one surface of the concrete under test. This ASTM test method involves the determination of the pulse propagation velocity of compression waves in concrete. Before starting the test, start the test within 5 minutes of obtaining the last portion of the composite sample.
Concrete is then filled into the cone in three layers, each approximately one-third the volume of the cone from the composite sample taken and resting on the legs of the two cone sections. Remove excess concrete from the slide cone opening using the pry bar in a rolling motion until it is level.
CHAPTER 4
As we can see in Table 9, the strength of the concrete that was added with MIRHA mixtures had a higher strength at the age of 28 days. There was also a difference in the strength development of concrete when additional admixtures of PFA and silica fume were added. Concrete with PFA and silica fume had a higher strength at the age of 28 days.
It was therefore proven that additional admixtures had an effect on the concrete strength. This was because the pozzolanic reaction takes place between pozzolan materials; MIRHA, PFA and Silica Fume, with the Calcium Hydroxide to produce a stronger C-S-H gel bond. The optimum response as we can see from the table was when 5% of MIRHA was added.
Perhaps by the excess amount of MIRHA; 7.5% and 10%, were added, it had caused the reaction to go slower and caused the strength development. From the table we can also see that the concrete having a mixture of MIRHA 5% with added PFA and Silica Fume had the highest strength at the age of 28 days which was 86.53 MPa. So we can say that this was the optimal mixture that can be used to get a stronger concrete.
The development of concrete strength at is also clearly shown on the graph (Figure 17 and Figure 18). He observed from the table that the concrete to which MIRHA was added had a higher tensile strength at the age of 28 days compared to the normal concrete. The tensile strength becomes higher when additional admixtures of PFA and Silica Fume are added, and the optimum value again when it contains 5% MYRHA, which is 16.22 MPa.
The surface hardness of the concrete also differs depending on the admixtures added to the concrete. Table 11 shows that concrete to which MIRI-IA, PFA and Silica Fume have been added can add strength to the concrete.
CHAPTER 5
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APPENDICES
A non-porous wooden or metal platform, a pair of shovels, a steel hand scoop, a measuring roller and a small concrete mixer (if using a machine mix). If they are wet, look up the aggregate content to determine the amount of water needed. The compressive strength is considered as the maximum compressive load it can withstand per unit area.
Compressive strength tests for concrete with a maximum aggregate size of up to 40 mm are typically performed on 150 mm cubes. Carefully center the cube on the lower plate, ensuring that the load is applied to two opposing cast faces of the cube. Without jerking, continuously apply the load and continuously increase it at a rated rate within the range of 02 N/mm2s to 0.4 N/mm2 until no more load can be tolerated.
Calculate the compressive strength of each cube by dividing the maximum load by the cross-sectional area. The UPV test is designed to study the quality of concrete in existing structures. It can also be used to determine the dynamic modulus of elasticity, dynamic Poisson's ratio, homogeneity, estimated compressive strength, crack depth, thickness of damaged layers and density of concrete.
Part of the Non-DestrucBW concrete testing method is the measurement of the velocity of ultrasonic pulses in concrete. The pulse of longitudinal vibrations is generated by an electro-acoustic transducer (transmitter) and received by a similar receiver, which is placed on the opposite side of the tested concrete element. The equipment (PUNDIT) used to determine the tra*onic pulse velocity in concrete consists of a transducer, a receiver and a main control unit.
When testing concrete elements for quality, various controls are possible to determine ultrasonic pulse speeds. The depth of the cracks in the test can be determined by placing the transducers over the crack as IL city in Figure Dow.
