BACKGROUND TO THE PROBLEM• High rate of building collapse in Nigeria has been a source of concern to

Professionals and stake holders in the building construction industry.

• 100% of buildings collapsed in Nigeria were constructed from reinforced

concrete.

• Cement which is the main binder in concrete production is expensive,

thereby increasing the demand to explore pozzolanic potentials of clay

substitute for cement in the local construction industry.

• The Standards Organization of Nigeria (SON) specified that the silt and

clay impurities in sand should not exceed 8%.

PROBLEM STATEMENT• Shabby construction practices such as mixing concrete on the bare

ground adds to the impurities in concrete.

• Clay impurities from different sources have effect on the strength and

physical properties of concrete.

• Subjecting concrete structures to high temperature conditions lead to

uneven expansion of the structure, causes cracks and eventually, failure.

• Hence the need to assess the effect of temperature on concrete

containing clay impurities.

AIM OF THE RESEARCH• To assess by means of literature review and experiment the effect of

varying temperature on the properties of concrete containing clay

addition.

OBJECTIVES• To investigate the effect of temperature on the compressive strength of

concrete containing 5% clay addition.

• To analyse from data obtained from experiment whether the allowable

8% clay impurities specified by the SON will still be valid if concrete

containing 5% clay addition is subjected to temperature.

• What effects do clay impurities have on the properties of concrete?

• What effect does temperature have on the compressive strength of concrete with 5% clay addition?

JUSTIFICATION• In Nigeria, during fire outbreaks, buildings are subjected to high

temperatures for long periods of time due to delay or absence of fire service units.

• Little research has been done on the impact of temperature on concrete containing impurities such as clay, silt and organic matter.

SCOPE• 150x150x150mm Concrete cubes produced with Portland cement,

containing 5% clay addition and cured for only 28 days. • Cubes were subjected to varying temperatures of 100, 200, 300,400 and

500°C only.

RESEARCH QUESTIONS

• The incidence of building collapse have become a major concern in the development of this nation.

• A recent devastating case of building

failure case is the collapse of a 6-storey

guest house belonging to the SCOAN in

Lagos which occurred on the 12th of

September, 2014 resulting in the death

of 116 persons.

• 100% of buildings collapsed in Nigeria are made of reinforced concrete (Lekan 2011).

CAUSES OF BUILDING COLLAPSE

FINDINGS FROM LITERATURE.

Natural factors Poor SupervisionOperational Problem Socio-economic behaviours of NigeriansLow quality concrete.

EFFECT OF FIRE ON CONCRETE STRUCTURES

• In the building construction industry, adequate attention has not been paid to fire as a causative factor responsible for building collapse in Nigeria (Ayuba, Olagunju & Akande 2012).

• Temperatures up to 95°C have little effect on concrete.

• Above 95°C cement paste undergo shrinkage, aggregates expand, resulting to overall expansion of concrete and reduction in strength.

CONCRETE AS A BUILDING MATERIAL

• A relatively new material and now the most widely used building and civil Engineering construction material.

• Constitutes of Cement, fine aggregate, coarse aggregate and water.

ADVANTAGES OF CONCRETE

Low Cost Durability Thermal Insulation

Strength Fire resistance

FINDINGS FROM LITERATURE.

ADMIXTURES IN CONCRETE

• Admixture are materials added to concrete to modify its properties.

WHY USE ADMIXTURES?

• To reduce to cost of concrete.

• To maintain qualities of concrete during the stages of mixing, transporting, placing and curing in adverse weather conditions.

POZZOLANA

• Pozzolanic materials possess no cementitious properties but will chemically react to form compounds possessing cementitious properties. Eg. Calcined clay, metakaolin, silica fume, rice husk ash, fly ash etc.

WHY USE POZZOLANA?

• High demand of cement.

In Nigeria, annual cement consumption is 19.5 million metric tonnes.

Only 9.5 million metric tonnes are produced locally.

FINDINGS FROM LITERATURE.

MATERIALS

• Ordinary Portland cement

• Fine Aggregates

• Coarse Aggregates

• Clay

• Water

TESTS CONDUCTED• Particle size distribution test• Bulk density test• Water absorption test • Workability test• Density test• Abrasion resistance test• Compressive Strength test

MATERIALS AND METHODS.METHODSConcrete mixed homogeneously

With 5% clay Addition.

Steel formwork cleaned and

Lubricated.

Concrete cubes poured into moulds

And rammed for compaction.

Curing of cubes for 28 days

Subjecting of samples to varying

Temperatures.

• From the workability test results, there is reduction in the workability of concrete as the percentage of clay increase.

• The density test results showed reduction in density of concrete containing 5% clay as temperature increases.

• Water absorption capacity of concrete increases with increase clay percentage.

• At temperatures above 200°C, compressive strength decreases with increase in temperature.

RESULTS.

2320 2340 2360 2380 2400 2420 2440 2460 2480 2500 25200

100

200

300

400

500

600

Density of concrete with 5% clay

Density (Kg/m3)

Tem

pera

ture

(°C)

100 200 300 400 5000

5

10

15

20

25

30

35

25.33

29.92 28.89

21.92 20.74

Compressive strength of concrete with 5% clay

Temperature (°C)Co

mpr

essi

ve s

tren

gth

(N/m

m2)

• At temperatures above 400°C, the compressive strength of concrete

containing 5% clay addition will fail to meet the required 21N/mm2

• Therefore the 8% allowable clay impurities specification by the

standards organization of Nigeria will not stand at temperatures

above 400°C.

CONCLUSION.

• Further research should be done on the effect of temperature on

other properties such as tensile strength of concrete containing 5%

clay addition.

• Research should be done on the effect of varying temperature on

sandcrete blocks containing varying percentages of clay addition.

• Further studies should be done on the effect of chemical attack on

the properties of concrete containing varying percentages of clay

addition.

RECOMMENDATION.