Production of Normal Weight Portland Cement Concrete
Apart from water, concrete is the most available resource on Earth. The substance has been in use since the Roman Empire, and to this day it remains the most imperative constituent of most designs and buildings. The industry is approximated to be worth $37 billion and plays a role in the employment of more than 2 million people in the U.S (Concrete Helper- A Concrete Industry Resource Concrete Facts, para 1).
Moreover, nearly 10 billion tons of the industry products are manufactured annually (Concrete Helper- A Concrete Industry Resource Concrete Facts, para 1). It is a substance with high compressive strength and the capacity to be molded easily into any form. Arguably, it is versatile and durable, factors that make concrete a dependable product for construction. Concrete has four unique components: Portland cement, coarse aggregate, fine aggregate, and water.
For the desired use during construction, the ingredients that make concrete are combined carefully into ratios accordingly. The mixture of aggregate and paste obtains its characteristics through a process known as hydration, a chemical reaction between water and Portland cement. The resultant mixture act as a glue between other components of concrete. The most significant properties of concrete are workability and strength. The high water to cement ratio describes higher concrete workability. Admixtures permit concrete to establish more design and configuration opportunities, from accumulating color to reducing the application of water in concrete so that we can preserve the natural resource. After the concrete is assorted, it can be dispensed into any frame and molded so that it can be used for practically any project.
The objective of this experimentation, which is divided into two parts, occurring 28 days apart, is to investigate the compressive strength of diverse blends of concrete that have various proportions of water, cement, and aggregates. These measures modify the water-cement ratio, which is the most important ratio to reflect on while mixing concrete for compressive strength or workability determinations. The first section of this test is the actual mixing of the concrete, which is finalized during one lab period. Another part of this experiment, the strength test day, is concluded during the development of one lab period seven (7) days later after the concrete had partially cured
Materials and Methods
Cubes and cylinders.
Other cementitious materials (fly ash, slag, natural pozzolans).
The first step involved the selection of the slump.
Second, the determination of the maximum size of the aggregate was conducted by measuring the aggregates dimensions using a plastic measuring cup, coarse aggregate, fine aggregate and cement, which were restrained to the exact weight via the electronic scale.
Estimation of the water, air mixture ratio. The coarse aggregate, fine aggregate and cement were each placed into a Ziploc bag, where they were mixed physically until all the elements were well dispersed. Using the plastic measuring cup, water was measured according to the particular design and ratio added to the Ziploc bag containing the dry materials.
Determination of the Water- cement proportion. The bag comprising all the components of concrete was mixed until the color of the mix was uniform and all elements were combined properly.
Calculation of the cement content was approxiamted.
Approximation of the coarse aggregate content was done using the weighing machines.
Valuation of fine aggregate content was done using the weighing machines.
Adjustment for aggregate moisture content was then done by each member of the group.
Finally, adaptation of the trial batches completed.
The composition of the concrete and cement paste materials were determined using the formula provided by the lab manual.
Using the measuring and gauging tools, the solid materials were first measured and the results recorded.
The solid materials were then put in the container where they were combined , mixed thoroughly and scattered evenly.
Measured volume of water based on each particular mix desin was applied to the container, blending until a homogeneous consistent color was formed.
The release agent was added to the box and the the excess was extracted from the mix.
The box filled halfway and combined and kneaded 16 times to guarantee that no visible spaces were observed.
The residue was occupied and tamped 16 times.
A trowel was then used to smooth the cubic box.
The was then enfolded in a moisture setting for seven days to cure.
After 7 days, the dimensions of the specimens were taken and recorded before testing.
Using a hydraulic machine, the concrete cubes were loaded onto the analysis stand, after assembling steel plates on uppermost part of the loading platform to establish an adequate height for testing compressive strengths.
The machines was aligned such that the concrete cubes were at the center of the base platter of the machine, so that the load would be applied perpendicularly at the center of the cube.
The machine was switched on, and the load was applied constantly until the sample failed. The maximum load applied for each cube was recorded and tabled as shown in Table 1.
The loading machine was disemboweled and washed, and the broken concrete cubes were disposed of.
After completing the compressive testing for the concrete cubes on day 7 from curing of the concrete in the moisture room, compression testing data from the other section of mix designs were used and combined with current data to generate a table and a bar graph. Both of these graphs were used to identify the existence of an association between the maximum load of the mix design and the water-cement ratio of the concrete. Table 1indicates the maximum stress data attained from the compression tests of the concrete from the data acquired by the other mix designs. All the load data were accurately measured directly from the hydraulic machine, with the units of pounds. In this case, Table 1 contains the mix designs with their respective maximum stress tolerated before failure.
The resultant concrete should have enough compressive strength and durability. Initially, when the cement and paste were combined, the amalgamation was not heterogeneous. However, when the combination continued, the homogeneous color was attained, signifying that the proportions were now reasonable. In this regard, the final product was significant because it perfectly characterized the anticipated properties.
Cement suitability and reliability, as well as its eminence and routine performance, might differ based on the adhesive assortment and the configuration ratio. For instance, water- content ratio is usually the mass-water ratio to the mass of cement confined within a quantified concrete medium. When the ratio is smaller, the strength increases. However, according to Collivignarelli, extra water addition may result in reduced strength, inferior durability, and even cracking (7903). In this case, the addition of a superplasticizer is used to advances the hard concretes compressive strength by promoting the compaction to be effective.
The workability of cement paste and concrete differs from one another because each has its separate formulations, design for combinations of ingredients, and every constituent has discrete properties. Therefore, cement paste is applied in such repair and renovation works as grouting, plastering works, or in . It contains less heat of hydration, reduced strength, and hence decreased applicability. However, concrete with the high heat of hydration has increased strength and hence elevated workability. In this case, the predicted compressive power and tensile/flexural intensity are ASTM C496, C78.
As a consequence of the laboratory experiment, the association between workability and compressive strength of concrete in terms of the water-cement ratio was determined. Despite each group conducting a separate experiment with the mix designs, the data obtained from the other mix designs creates a noticeable trend that as the , the compressive strength rises. However, there is a limit to how low the water-cement ratio can be established. In this case, if there is too little water, the cement will not hydrate appropriately and instead of acting as glue, the concrete will be too dry and parched to resemble a lump of gravel rather than an even path.
Therefore, the water-cement ratio is essential to concrete production and construction, and the association between lesser water content and greater compressive strength was confirmed. Precisely, the laboratory experiment resulted in the production of Portland cement concrete. The homogenous color designates that the composition was reasonable. Hence, the strength and flexibility increase if the water content level is reduced.