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APPLICATION OF LIGHT WEIGHT AGGREGATES FOR AFFORDABLE HOUSING

PROF. ADNAN QADIRCO- CHAIRMANDEPARTMENT OF URBAN AND INFRASTRUCTURE ENGINEERING

INTRODUCTION This study presents Investigation of lightweight aggregate concrete containing Polypropylene fibresComparison with Normal weight aggregate concreteEconomic impact in terms of project costAGGREGATES HAVING Unit weight 1100 kg/cubic meter

NATURALLY EXISTENT such as Pumice and Scoria.

ARTIFICIALLY PREPARED from expanded shale, clay, slate and blast furnace slag upon heating in a rotary kiln at a temperature in excess of 1000 C.INTRODUCTION-LIGHTWEIGHT AGGREGATES Polypropylene fibres when added in concrete Enhance its mechanical properties Crack control, Shear and flexural strength

Fibres may be used in concrete at volume fractions varying from 0.1% to 3%(0.1 % in this study)

INTRODUCTION POLYPROPYLENE FIBRES OBJECTIVE

To determine the application of lightweight aggregate concrete in flexural members

To observe the improvement in the properties of LWAC upon the addition of polypropylene fibres

SCOPE

The scope included a comparative analysis of different aggregate concrete in terms ofLoad deflection behaviourNo. of cracks and their widthsStrainsCost estimation

LITERATURE REVIEWPP fibres are known and proven to improve the mechanical properties of concrete such as crack control, ductility, toughness, shear and flexural strength and impact resistance. The real advantage of adding fibres is its ability to bridge the cracks and undergo pull out processes [1].

The Chemical inertness of PP fibres have made them favourable as an additive to concrete at volume fractions varying from 0.1% to 5%. [2]. Though the addition of fibres decreases the concrete slump depending upon their length. However the lower slump did not affect the workability of fibre reinforced concrete and it is still adequate for placing, compacting and finishing the concrete at the same water content [1,3]. METHODOLOGYNWACLWACCASTINGTESTING2 POINT LOAD TESTEXPERIMENTAL RESULTS12 BEAMS27 CYLINDERSCOMPRESSIVE TEST OF CYLINDERSTRIAL BATCHES 48 CYLINDERSLWAFC6 BEAMSShear Failure6 BEAMSFlexure FailureCORE MATERIALSLIGHTWEIGHT AGGREGATES

Manufactured by Council for Works and Housing Research (CWHR) prepared from hard grey shale stone extracted from coastline of Baluchistan

POLYPROPYLENE fibres

Manufactured by DURACRETE MATRIX

PREPARATION OF LWA

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PREPARATION OF LWA

PREPARATION OF LWAPROPERTIES OF LWA

PROPERTYCOARSE LWAFINE LWAAbsorption3.8%1.3%Compacted density848 kg/m3929 kg/m3Loose density768 kg/m3897 kg/m3Moisture content0.5%0.65%Specific gravity1.81.9MIX DESIGN

Mix design of NWAC, LWAC and LWAFC were prepared for compressive strength of 21 MPaThe mix proportions and water-cement ratios were:Concrete sampleMix proportionsWater Cement RatioNWAC1:2.5:3.50.60LWAC1:3:2.50.65LWAFC1:3:2.50.70CASTING OF CYLINDERS

A total of 48 cylinders, 16 each of NWAC, LWAC and LWAFC were casted and tested for 3,7,14 and 28 days compressive strength with Forney Compressive Testing Machine.28 days compressive strength results were:Concrete samples28 days Compressive StrengthsNWAC23 MPaLWAC21.44 MPaLWAFC22.4 MPaCASTING OF BEAMS

Twelve (12) reinforced concrete beams were casted during the project. All beams, 4 of LWFAC, 4 of NWAC and 4 of LWAC were provided with two different types of reinforcement arrangement for flexure and shear, Six (6) beams were designed for flexural failure and Six (6) beams were designed for shear failure in which two deformed bars of 13mm were provided in the tension zone which was bottom fiber where as two deformed bars of 10mm were provided in the top fiber. Shear stirrups of 10mm bars were provided in beams that were designed for flexure.

BASICS OF THE EXPERIMENT

CYLINDERS (15 x 30 )BEAMS (180 x 15 x 20)

EXPERIMENTAL PROGRAM

R/F DETAIL OF BEAM TESTED FOR FLEXURE R/F DETAIL OF BEAM TESTED FOR SHEAR

CASTING AND CURING

Curing was again the pond curing as done for sample cylindersThe beams were casted in steel molds. The electric vibrator was used for better resultsExperimental ProgramCURING & TESTING OF BEAMSRESULTS CURINGPond Curing was adopted on the basis of its suitability

TESTING OF SAMPLESCompression Testing MachineModel # QC-50-TR Least count of 250 NCapacity 2000 kN

Experimental ProgramCURING & TESTING OF CYLINDERS

Experimental ProgramCURING & TESTING OF BEAMSOBSERVATIONStrainDeflectionCrack Pattern

Strain GaugeDeflectometerExperimental ProgramTESTING UTM Model #UH-500 KNI Capacity 500kN

TESTING AND MEASUREMENTBEAM UNDER TESTING

BEAM AFTER FAILURE

NWAC BEAM

LWAC FAILURE

LFWAC BEAM

FLEXURE FAILURE OF BEAMS IN THE STUDY

NWAC

LWAC

LWAFCLFWAC SHEAR FAILURE

Load-Deflection Behavior

EXPERIMENTAL ANALYSISThe result showed that approximately similar deflections occurred in NWAC and LWAC whereas upon the addition of polypropylene fibres in LWAC, deflection increased slightly suggesting a ductile behavior.CRACKS IN BEAMS

More cracks were observed in LWAC sample as compared to NWAC.The number of cracks in LWAFC beams decreased approximately half in number.

The first crack in LWAFC beam emerged at a higher load value than the other two concrete samples as evident LOAD VS NO. OF CRACKS

CRACK WIDTH:

The cracks width had increased slightly in LWAC then NWAC beams.In LWAFC there was a prominent declination in cracks widths as compare to both NWAC and LWAC beams.

YIELD LOADThe shear behavior of NWAC, LFWAC and LWAC was almost similar i.e. all beams failed by developing diagonal crack near support. Whereas the shear failure in LFWAC is not sudden due to addition of PP fibresMAXIMUM CRACKING LOADThe cracking load of LFWAC beam is higher in both types of beam i.e. beams design for shear and flexure, than the cracking load of NWAC and LWAC.SURFACE STRAINS

The surface strains were noted with the help of a demountable strain gauge at depths 50, 100 and 150 mm from top fibres of beams.

The surface strains developed in LWAFC beams were less than those developed in the other two specimens.LESS STRAIN IN LWAFCUNIT WEIGHT OF CONCRETEThe unit weight of LWAC and LWAFC decreased approximately 21% than NWAC which was of paramount importance during design of structure.

REDUCTION IN QUANTITY OF STEEL REINFORCEMENT

Due to decrease in dead load of structure steel requirement was reduced.

The steel required in LWAC beam reduced by 21 % as compared to NWAC beam.

COST ESTIMATION

Material cost including concrete, steel reinforcement and polypropylene fibres required in a single beam element made of NWAC, LWAC and LFWAC was estimated.

The results suggest that LWAC and LFWAC beams were 10 % and 14 % costly than NWAC beam. COST COMPARISON OF RC BEAMS

CONCLUSIONS

Similar deflectionsLess number of cracks in LWAFCMinimum crack width in LWAFCMore load required to produce crack in LWAFCSimilar yielding loadsMinimum surface strainsLesser unit weight concrete ultimately less steel required for Reinforcement(21% less )LWAFC beams were 14 % costly than NWAC beam.

RECOMMENDATIONSThe material need to be tested for its seismic behavior since it was critical in earthquake prone areas.Fire resistance response of the material was also to be evaluated to assure the safety measures.Certain other parameters such as impact resistance and insulation can also be assessed.

REFERENCES

[1] Litvin, A., Report to Wire Reinforcement Institute on Properties of Concrete Containing Polypropylene fibres, Available online at: http://www.amazon.co.uk/ Reinforcement-Institute-properties-containing-polypropylene/dp/B001AAUHI4

[2] Nemkumar B et.al, Fiber-reinforced concrete in precast concrete applications: Research leads to innovative products, Summer 2012 PCI Journal, Available online at: http://www.pci.org/pdf/publications/Journal/2012/Summer/JL-12-SUMMER-7.pdf [3] MALISCH WR, Polypropylene fibre ,PUBLICATION# C860363, The Aberdeen Group, Available online at: http://www.concreteconstruction.net/images/ Polypropylene %20Fibres%20in%20Concrete_tcm45-347135.pdfThe author would like to acknowledge the efforts made by the undergraduate students for carrying out the tasks with full dedicationThe cooperation of CWHR for providing light weight aggregate free of cost and for their continuous support.ACKNOWLEDGEMENTS