Lab Report on Reinforced Concrete Design

1469 Words Apr 12th, 2011 6 Pages
Introduction:
In this laboratory experiment, we were required to produce a concrete mixture based on the BRE Manual Design of concrete mixtures which is attached to this report. It is then used to produce concrete cubes and prisms.
The objective of this experiment is to learn the methods of producing concrete and concrete characteristics as well as comparing the theoretical values of the concrete’s Young’s Modulus with experimental values.

Procedure for concrete mix:
A concrete mix was designed based on the BRE Manual Design of concrete mixtures. Then, a total of 40kg of the required proportions of Ordinary Portland cement which includes water, fine aggregate, and 20mm size crushed gravel coarse aggregate was weighed out. The materials
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calculated by using the formula:
Ec(t)=4n2L2ρ × 10-15 (kN/mm2)
Where L = 500mm n = first natural resonant frequency (Hz)
The static modulus Ecm is determined using Eurocode 2 equation:
Ecm=Ec(t)1.05 (kN/mm2)
The direct static method is:
Ecm=22 ((fck+8)/10)0.3 (kN/mm2) fck = 0.8 fcu (N/mm2)

The Flexural Tensile Strength of the prisms is calculated by using the formula:

Where P= Failure load a= Breadth, Depth & Shear Span of prism
Calculations are tabulated in table 3.1 & 3.2: Test | Prism | ρ (kg/m3) | V (m/s) | n (Hz) | Ec(t) (kN/mm2) | Ecm (kN/mm2) | Deviation (%) | Pundit | Air cured | 2282 | 3851.83 | - | 28.21 | 26.87 | -13 | | Water cured | 2339 | 3563.67 | - | 24.75 | 23.58 | -12 | Erudite | Air cured | 2282 | - | 2.33 | 12.42 | 11.82 | -156 | | Water cured | 2339 | - | 3.87 | 35.09 | 33.42 | 19 |
Table 3.1: Modulus of prisms using Pundit and Erudite Tests

Test | Ecm (kN/mm2) | Air cured cylinder | 11.85 | Water cured cylinder | 10.56 |
Table 3.2: Static modulus for air and water cured cylinders

Average values of Ecm six cases above = 19.68 kN/mm2
Difference with theoretical values = 32% less

Sieving Results: Fine aggregate | Weight (kg) | Percent retained | Percentage passing | Pan lid | 0 | 0% | 100% | 10mm | 0 | 0% | 100% | 5mm | 0.002 | 0% | 100% | 2mm | 0.019 | 4% | 96% | 1.18mm | 0.041 | 8% | 87% | 600μm | 0.128 | 26% | 61% | 300μm | 0.187 | 38% | 23% | 150μm | 0.078 | 16% | 7% | Base | 0.034 | 7% | 0% | Total |
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