INNOVATIVE TECHNIQUE FOR

DESIGN OF BAKED CLAY BEAMS AND ITS

USE IN BUILDINGSBy

DR. ABDUL AZIZ ANSARI, SALIM KHOSO & FARHAN HUSSAIN WAGAN

BACKGROUNDBACKGROUND

INTRODUCTIONINTRODUCTION Use of indigenous materials is an Use of indigenous materials is an

attractive option for low cost attractive option for low cost residential construction. Clay and pit residential construction. Clay and pit sand are abundant in Pakistan. Clay sand are abundant in Pakistan. Clay is fine grained, natural, firm, earthy is fine grained, natural, firm, earthy material that is plastic when wet at material that is plastic when wet at appropriate water content, hardens appropriate water content, hardens when dry and gains strength like a when dry and gains strength like a permanent solid when heated permanent solid when heated intensely.intensely.

Clay consists of hydrated silicates Clay consists of hydrated silicates of aluminum. It is natural. non-of aluminum. It is natural. non-toxic, easily available, recyclable, toxic, easily available, recyclable, environment friendly and energy environment friendly and energy efficient. It is easy to work with efficient. It is easy to work with and provides opportunities for and provides opportunities for creativity in developing variety of creativity in developing variety of forms. It may be viewed as forms. It may be viewed as primitive, inferior and dirty but it primitive, inferior and dirty but it does offer a viable option for use does offer a viable option for use in low cost residential in low cost residential construction.construction.

This study aimedThis study aimed

• The structural propertiesThe structural properties

• The best compositionThe best composition

• The appropriate water contentThe appropriate water content

• Extent of compactionExtent of compaction

• Extent of shrinkageExtent of shrinkage

Equipment and InstrumentationEquipment and Instrumentation

A large number of devices, A large number of devices, equipment and machinery were equipment and machinery were required for this research but required for this research but majority of items were not available. majority of items were not available. Therefore, the needed items were Therefore, the needed items were conceived, devised, designed and conceived, devised, designed and fabricated according to specific fabricated according to specific needs of various operations and they needs of various operations and they are such as…..are such as…..

STIFF STEEL MOULDSTIFF STEEL MOULD

RESTRAINING SYSTEMRESTRAINING SYSTEM

COMPACTION SYSTEMCOMPACTION SYSTEM

COMPACTION SYSTEMCOMPACTION SYSTEM

TROLLYTROLLY

PLATFORM LIFTPLATFORM LIFT

GROUTING SYSTEMGROUTING SYSTEM

CURING TUBCURING TUB

MOBILE LIFTMOBILE LIFT

PRECOMPRESSION SYSTEMPRECOMPRESSION SYSTEM

END FIXITY ATTACHMENTEND FIXITY ATTACHMENT

U.D.L. SIMULATORU.D.L. SIMULATOR

BAKED CLAY SPECIMEN CUTTERBAKED CLAY SPECIMEN CUTTER

PULLER SYSTEMPULLER SYSTEM

TWO POINT LOAD ATTACHMENTTWO POINT LOAD ATTACHMENT

KILNKILN

ThermocoupleThermocouple

Standard Equipment used.Standard Equipment used.• Clay Drying OvenClay Drying Oven• PulverizerPulverizer• Load CellLoad Cell• Digital Display SystemDigital Display System• Torsee Testing MachineTorsee Testing Machine• Universal Load Testing MachineUniversal Load Testing Machine• Dial-Gauges and Displacement Dial-Gauges and Displacement

TransducerTransducer• Proving RingProving Ring

MATERIALS1. Clay and Pit-Sand

2. Mixing Water

3. Cement Slurry

4. Reinforcement

5. Concrete

It may be re-iterated here that the total research work has been divided into two series i.e. Preliminary Test Series and Main Test Series. The latter is further sub-divided into five phases. The effective span of all the beams was 1670 mm (65.75 inch). Apart from baked clay beams four concrete beams were also cast, cured and tested for the sake of comparison.

Phase - IPhase - I

First phase consisted of twenty three beams, out of which fourteen were rectangular and nine were I-shaped. All were reinforced with two bars.

The beams were compacted by applying a compression of 3.5 N/mm2. During first phase the beam panels were fired for a total period of 19 hours. In few cases after testing the beams, it was observed that the inner core of about one inch thickness was not properly baked.

PHASE IIPHASE II

During this 2nd phase six beams During this 2nd phase six beams were cast, baked, post-reinforced, were cast, baked, post-reinforced, grouted and tested. The major grouted and tested. The major parameter was to increase of parameter was to increase of external compressive force applied external compressive force applied on freshly cast beams for on freshly cast beams for compaction from 3.5 N/mmcompaction from 3.5 N/mm22 to to 4.73 N/mm 4.73 N/mm22 and also the firing and also the firing period from 19 hours to 22 hours. By period from 19 hours to 22 hours. By increasing the firing period the increasing the firing period the problem was over comeproblem was over come

Phase IIIPhase III The purpose ofThe purpose of testing beams of testing beams of

phase III of Main phase III of Main Test Series was to Test Series was to check the behavior check the behavior of baked clay beams of baked clay beams with top steel and with top steel and vertical steel. A vertical steel. A compressive force compressive force

of 4.75 N/mmof 4.75 N/mm22 (690 (690 psi) was applied for psi) was applied for compaction. compaction.

Phase IVPhase IV

In continuation with the work that In continuation with the work that has been done regarding suitability has been done regarding suitability of replacement of concrete, more of replacement of concrete, more beams have been tested containing beams have been tested containing double longitudinal reinforcement as double longitudinal reinforcement as well as vertical reinforcement to well as vertical reinforcement to emulate the real structural actions emulate the real structural actions which occur in the buildings. which occur in the buildings.

Phase VPhase VInfact in the advanced Infact in the advanced stage of experimental stage of experimental investigations the idea investigations the idea emanated to apply a emanated to apply a certain intensity of certain intensity of compression on beam compression on beam panels so that their panels so that their shear strength could be shear strength could be improved without improved without inserting the shear inserting the shear reinforcementreinforcement

Although the actual ultimate condition could not be reached due to immature failure of the end connections anchorage system consisting of nuts and welding on threaded steel bars which were used to reinforce and apply pre-compression to the baked clay. However, from the results it appears that if the anchorage is to be properly designed and strengthened the system would definitely work and positive results could be achieved.

CONCLUSIONSCONCLUSIONSBaked clay has shown very good Baked clay has shown very good crushing strength of 35.37 N/mm2 crushing strength of 35.37 N/mm2 (5128 psi) which is reasonably (5128 psi) which is reasonably good. good.

The major aim of this research is to make it possible in the plane of Pakistan for every rich and poor to afford a home of his own, which may resist the rigors of climate, environment and must not cause a hazard to at least the occupants.

The human generation shall be best served if clay is used for roof over their heads.

It was observed that best results could be achieved when the clay is 70% and Pit sand 30%.

Poisson’s ratio was found to be 0.173 as compared with that of concrete

The modulus of elasticity for all tested beams was found to be 33.7 kN/mm2

Predominantly all the beams failed in shear and full flexure strength was not achieved.

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