Noridah Mohamad

Testing of Precast Lightweight Foamed Concrete Sandwich Panel With Single and Double Symmetrical Shear Truss Connectors Under Eccentric Loading

This paper reports the structural behavior of precast lightweight foamed concrete sandwich panel, PLFP, subjected to eccentric loading. An experiment was conducted to investigate the structural performance of PLFP under this load. Two PLFP panels, PE-1 and PE-2 were cast with 2000 mm in heights, 750 mm in width and 100 mm in thickness. The thickness of the wall is actually a combination of three layers. Skin layers were cast from lightweight foamed concrete while the core layer is made of polystyrene. The skin layers were connected to each other by 9 mm steel shear truss connector which were embedded through the layers. Panel PE-1 was strengthened with single diagonal shear truss connectors made of 6 mm steel rebar while panel PE-2 was strengthened with symmetrical diagonal shear truss connectors of similar steel diameter. Both panels were tested under eccentric load till failure. The results showed that panel with symmetrical double truss connectors, PE-2, is able to sustain higher load compared to panel with single shear truss connector. The load-deflection profiles indicate that both panels achieved certain degree of composite action especially during the later stage of loading where the wythes tend to move in the same direction until they reached failure. The load-strain curves for both panels highlight the inconsistent distribution of surface strain along the height of panels. The overall trend of the strain curves show that they are under compression.

Structural Behavior of Precast Lightweight Foam Concrete Sandwich Panel with Double Shear Truss Connectors under Flexural Load

This paper presents the structural behaviour of precast lightweight foam concrete sandwich panel (PFLP) under flexure, studied experimentally and theoretically. Four (4) full scale specimens with a double shear steel connector of 6 mm diameter and steel reinforcement of 9 mm diameter were cast and tested. The panel’s structural behavior was studied in the context of its ultimate flexure load, crack pattern, load-deflection profile, and efficiency of shear connectors. Results showed that the ultimate flexure load obtained from the experiment is influenced by the panel’s compressive strength and thickness. The crack pattern recorded in each panel showed the emergence of initial cracks at the midspan which later spread toward the left and right zones of the slab. The theoretical ultimate load for fully composite and noncomposite panels was obtained from the classical equations. All panel specimens were found to behave in a partially composite manner. Panels PLFP-3 and PLFP-4 with higher compressive strength and total thickness managed to obtain a higher degree of compositeness which is 30 and 32.6 percent, respectively.

Precast lightweight foamed concrete sandwich panel (PLFP) tested under axial load: preliminary results

A study is carried out to develop a Precast Lightweight Foamed Concrete Sandwich Panel, PLFP, as a new and affordable building system. Experimental investigation to study the behaviour of the panel under axial load is undertaken. The panel consists of two lightweight foamed concrete wythes and a polystyrene insulation layer in between the wythes. The concrete panels are reinforced with 9mm diameter high tensile steel bars. The rebars are tied to each other through the insulation layer by shear connectors which are made of 6mm mild steel bars bent to 45º angle. Total number of four specimens was tested with one specimen; PA1 was cast without capping at both ends. It was used as a pilot test. The other three specimens are capped with normal concrete at both ends to avoid end crushing during axial loading. Axial load test was conducted and the results are presented here, which include the ultimate load capacity, crack pattern and failure mode, strain distribution and load-deflection curve of the panels. The experimental ultimate strength achieved recorded lesser percentage difference with the formulae by Pillai and Parthasarathy when compared to formulae in BS8110. It is also observed that the strength of the panels are affected by the compressive strength of the foamed concrete forming the wythes, the presence of concrete capping at panel’s ends and the slenderness ratio, H/t. Specimens with capping at both ends recorded higher ultimate loads with no premature crushing. Failure of panels with slenderness ratio, H/t < 18 were by premature buckling near the supports whereas for panels with higher H/t ratio, slight bending was observed in the middle zone. The results also indicate that a certain degree of compositeness is achieved between the wythes.

The Structural Performance of Precast Lightweight Foam Concrete Sandwich Panel with Single and Double Shear Truss Connectors Subjected to Axial Load

The progressive research upon the issue on renewal technology that can improve the construction industry has initiated the study of Precast Lightweight Foam Concrete Sandwich Panel (PLFP) as an alternative to Industrialize Building System (IBS). This paper reports the analysis of structural behavior of PLFP with double shear connectors under axial load. The PLFP panel consists of two wythes which enclosed a layer of polystyrene layer. Six (6 mm) rebar was used as the vertical and horizontal reinforcement and 9 mm steel bar bent at 450 was used as the connector. Full scaled panel was tested under axial load till failure. It was found that PLFP panel with double shear truss connector has higher ultimate strength capacity compared to PLFP with single shear connectors ehen tested under axial load.

Contribution of RHA granules as filler to improve the impact resistance of foamed concrete

Foamed concrete as aerated concrete widely used in range of constructions application, no exception to structure shield. As structure shield is important to resist on impact loading. Whilst, Rice Husk Ash (RHA) as agro-waste potentials as filler for foamed concrete. RHA that is produced by uncontrolled burning under 700oC during ± 6 hours obtain the granules contain the carbon and porous. The granules of RHA may fill the porous in matrix foamed concrete without remove the characteristic the foamed concrete its self-as aerated concrete. This investigation RHA has been used as a replacement for fine aggregate. Target density 1800 kg/m3 of foamed concrete both of with and without RHA have been produced to compare their strength and characteristic of impact resistance. SEM and EDS test has been conducted to determine microstructure and chemical composition of foamed concrete with RHA. The results showed that granules of RHA filled the porous and bonded with the denser part into matrix. The presence of granules of RHA has been changing the role of the air cell of porous in foamed concrete when it was subjected to impact loading. Also the granules of RHA give the foamed concrete denser without losing its characteristic of porous entirely.

Potential of RHA in Foamed Concrete Subjected to Dynamic Impact Loading

In relation to the conventional concrete then foamed concrete (FC) is weaker. Therefore FC was added by Rice Husk Ash (RHA) to alter the strength without eliminating its characteristic as aerated concrete. Actually function of RHA is substitute the sand partly. The strength of concrete affects to prevent the dynamic impact loading. However FC as aerated concrete can absorb energy impact by its porosity. Both of characteristics were presented in this investigation. SEM and EDS detected that pozzolanic reaction was done when FC was processing hydration of cement in admixture. The presence of RHA increased the strength of concrete owing to cement hydration process and pozzolanic reactivity of RHA. The result of impact loading on slab FC target displayed that FC with RHA was more shallow than without RHA. Beside of that local damage showed that FC with RHA denser and is not impression of fragments than FC without RHA.

Investigation on Energy Absorption of Slab Foamed Concrete Reinforced by Polypropylene Fibre Subjected to Impact Loading

Polypropylene Fibre (PF) as reinforcement has contributed to the intensity of Foamed Concrete (FC) slab when subjected to impact loading. The presence of PF in the admixture reduces the micro-porosity that generates the micro-crack of the slab. However, the fibrillation of PF in the admixture enhances the bonding mechanism system between PF and the FC matrix. The impact test conducted uses an instrumented drop-weight impact tower. Results show that FC without PF produces a distinct radial crack and clear fragments within the crater field unlike FC with PF. However, both slab materials did not generate spalling nor scabbing upon impact and the influence of porosity produces only local damage due to the mechanism of brittle crushing effect of porous walls. In this study, the energy absorption between FC with and without PF was investigated and from observation produces only minor differences. Results also verify that FC with PF did not loss its ability to absorb energy upon impact.

The Use of Recycled Aggregate in a Development of Reinforced Concrete Container as a Retaining Wall: Preliminary Study

Construction waste has been increasing due to fast development of construction industries. These wastes usually end up on landfill or to be left nearby construction site. This paper focuses on the potential use of recycled waste aggregate in a development of reinforced concrete rectangular container, RACC, as a solid waste storage. The filled container is intended to be used as a retaining structure at riverbanks to control erosion. The experimental programme include cube and cylindrical specimens tested to determine characteristic properties of recycle aggregate concrete (Pc, Pt, E). The characteristic properties obtained were used in designing the RACC to function as storage container and also as a retaining wall as referred to BS 8110 and BS 8007. Results showed that recycle aggregate concrete has relatively high compressive strength, tensile strength and modulus of elasticity. RACC size of 1.0 m x 1.0 m x 1.0 m with 150 mm thickness is found to be suitable and safe to be used both as container and retaining wall. This is proven by the maximum deflection and crack widths achieved which are lower than the allowable limit values.

Leaching Behaviour of Organic Materials in Reinforced Concrete Artificial Reef with RAC

This paper reports the leaching behaviour of pineapple skins incorporated in the artificial reef fabricated from recycle aggregate concrete. Pineapple skin was mixed with the concrete as added material which produce nutrients to attract fish habitat. Material test was conducted on the concrete reef specimens to determine its compressive strength. The nutrients dispersed were measured by using total phosphorus and nitrate test of the water sample collected from each of the artificial reef within the six days duration. Results showed the compression strength of the reef decreased with the increase of percentage pineapple skin used. However, it was found that the total phosphorus and nitrate leached from the reef increased gradually with time as the percentage of pineapple skin used increased.

Study on shear strengthening of RC continuous T-beams using different layers of CFRP strips

Carbon fiber reinforced polymer (CFRP) laminates are externally bonded to reinforced concrete (RC) members to provide additional strength such as flexural, shear, etc. However, this paper presents the results of an experimental investigation for enhancing the shear capacity of reinforced concrete (RC) continuous T- beams using different layers of CFRP wrapping schemes. A total of three concrete beams were tested and various sheet configurations and layouts were studied to determine their effects on ultimate shear strength and shear capacity of the beams. One beam was kept as control beams, while other beams were strengthened with externally bonded CFRP strips with three side bonding and one or two layers of CFRP strips. From the test results, it was found that all schemes were found to be effective in enhancing the shear strength of RC beams. It was observed that the strength increases with the number of sheet layers provided the most effective strengthening for RC continuous T- beam. Beam strengthened using this scheme showed 23.21% increase in shear capacity as compared to the control beam. Two prediction models available in literature were used for computing the contribution of CFRP strips and compared with the experimental results.