Different Failures in RCC Buildings

Priyanka Gupta

1.0 Introduction

In small residential buildings the quality of construction is seldom questionable. The reason varies from poor building material quality to lack of knowledge of good construction practices. Most of the times, engineers are ignored by individual house owners and masons are given sole responsibility of both design and construction. Almost all structural engineers practicing in India will agree that 99% of the failures of structures in India are not due to design failure.

Explaining the different aspect of construction that a normal home builder, engineer or contractor needs to remember.

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Prevention of corrosion in RCC by bacteria

Department of civil engineering,
IFET College of Engineering. Tamil Nadu, India.

Steel gets oxidise (corrosion) in the present of oxygen and water. Even present of oxygen in the concrete pore will not cause a corrosion at high alkaline environment. Concrete contains microscopic pores which contain high concentrations of soluble calcium, sodium and potassium oxides, this creates alkaline condition of pH 12–13. The alkaline condition leads to a ‘passive’ layer forming on the steel surface. The dense passive layer over the reinforcement prevents the alkalinity. This paper involves in the prevention of corrosion by maintaining alkalinity in concrete by using bacteria.

Key words: Reinforced concrete, corrosion, passive layer, alkaline, bacteria.

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Study On Behaviour Of Concrete Partially Replacing Quartz Sand As Fine Aggregate

E.Divya1 , R.Shanthini2, S.Arulkumaran3
Student, Dept. of civil engg., IFET college of engg., India1, 2
Asst. professor, Dept. of civil engg., IFET college of engg., India3

The use of quartz sand as replacement for sand is an economical solution for making the concrete resistant to weathering. The paper presents a concrete mix design procedure for partial replacement of sand with quartz sand. Present method was performed to evaluate the additional compressive, flexural strength with higher slump over conventional concrete in which sand is replaced with 0%, 25%, 50% and 100% of quartz sand by weight with 1% super plasticizers. The research also revealed that there is possibility of replacing fine aggregate with quartz sand in the production of structural concrete. The mix proportion adopted was 1:1.7:3 as per 10262:2009. Compressive and flexural strength tests were carried out to evaluate the strength properties of concrete at the age of 7 and 28 days. Modulus of elasticity tests were carried out at the age of 28 days.

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Materials Engineer
Kaushal Kishore is retired from IIT, Roorkee and now a Consulting Materials Engineer. He has over 50 years of experience in all types of Concrete Mix Design.

Vice President Project
Supertech Limited
Rakesh Sharma is Vice President Project of M/s Supertech Limited. He has 28 years of experience in Construction.

I.T. Park, Doon Square Mall at Dehradun, Uttarakhand is being constructed by M/s Supertech Ltd. For this site M-30 grade of concrete suitable for pumped concrete is required. Aggregates for construction was stored at site. Its analysis report is given in Table 2.

For laboratory trial 5 brands of PPC cement bags were taken from local market. They were identified as cement brand, 1, 2, 3, 4 and 5. Two reputed brands of normal superplasticizers based on sulphonated naphthalene formaldehyde (SNF) were taken for trials. They were identified as SP (A) and SP (B) to find their compatibility with the given 5 brands of PPC cement identified as cement brand 1, 2, 3, 4 and 5.

The behavior of concrete in the presence of superplasticizers is related to the amount and type of sulfate added to the clinker. The rheological and setting Behavior are changed depending on whether the sulfate is added as anhydrite, hemihydrates, or gypsum. The difference are explained by the different rates of dissolution of these sulfates.
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Concrete Strength Acceptance Criteria IRC:15-2011

Materials Engineer, Roorkee

For concrete roads, flexural strength of concrete is the design criteria. For all major projects, flexural strength of the mix shall be determine by third point loading of flexural beams size 150 mm x 150 mm x 700 mm as per IS: 516. Determination of flexural strength by correlating with cube strength (compressive strength) shall not be allowed for major projects, as the correlation is not well established.

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