Experimental Investigation on the Effectiveness of Truss-Shaped Punching Shear Reinforcement in Flat Slab

The use of reinforced concrete flat slabs in building construction increases the floor-to-floor clearance, expedites site operations, and offers aesthetically rewarding features. However, punching shear failure in a flat slab is brittle in nature and can be potentially catastrophic. Many studies have been conducted to improve the punching shear capacity of flat slabs but some of the proposed punching shear reinforcements were complicated and costly. This research aimed to evaluate the effectiveness of a simple and cost-effective; truss-shaped punching shear reinforcement embedded in a 1200 mm × 1200 mm × 175 mm thick flat slab specimen. Three types of truss-shaped punching shear reinforcements were prepared. All specimens were supported at the edges and subjected to gravity load tests. The results showed that the introduction of truss-shaped punching shear reinforcement increased the punching shear capacity in the range of 7.71% to 21.47%. The maximum deflection of these specimens exhibited an insignificant increase compared to the control specimen, suggesting that punching failure governed the ultimate behavior. The additional strength offered by truss-shaped punching shear reinforcement makes flat slabs as a construction material more appealing because they allow them to withstand higher design loads

Flexural Strength Behavior of Composite UHPFC-Existing Concrete

Article Preview Article Preview Ultra high performance fiber concrete (UHPFC) is an advanced formula concrete that is proven to be more superior than conventional concrete because it embrace the qualities of steel and concrete. Therefore UHPFC properties which include high durability and strength are fully exploited in the research of rehabilitation and strengthening in concrete and even non-concrete structures. This article presents the findings of an experimental study carried out to examine the bonding strength behaviour between normal concrete (NC) substrate and UHPFC as a repair material, under flexural strength test by using third-point loading beam test method. Three types of NC substrate surface preparation were used: as-cast (without surface preparation) as a reference, wire-brushed, and sand-blasted. The flexural test results clearly indicated that all failures occurred through the NC substrate and no

Experimental Investigation on the Effectiveness of Truss-Shaped Punching Shear Reinforcement in Flat Slab

The use of reinforced concrete flat slabs in building construction increases the floor-to-floor clearance, expedites site operations, and offers aesthetically rewarding features. However, punching shear failure in a flat slab is brittle in nature and can be potentially catastrophic. Many studies have been conducted to improve the punching shear capacity of flat slabs but some of the proposed punching shear reinforcements were complicated and costly. This research aimed to evaluate the effectiveness of a simple and cost-effective; truss-shaped punching shear reinforcement embedded in a 1200 mm × 1200 mm × 175 mm thick flat slab specimen. Three types of truss-shaped punching shear reinforcements were prepared. All specimens were supported at the edges and subjected to gravity load tests. The results showed that the introduction of truss-shaped punching shear reinforcement increased the punching shear capacity in the range of 7.71% to 21.47%. The maximum deflection of these specimens exhibited an insignificant increase compared to the control specimen, suggesting that punching failure governed the ultimate behavior. The additional strength offered by truss-shaped punching shear reinforcement makes flat slabs as a construction material more appealing because they allow them to withstand higher design loads

Strength of Binary and Ternary Blended Cement Pastes Containing Palm Oil Fuel Ash and Metakaolin Exposed To Sodium Sulphate

The compressive strength of binary (BBCP) and ternary blended cement pastes (TBCP) containing Palm Oil Fuel Ash (POFA) and Metakaolin (MK) exposed to 3 % sodium sulphate solution has been studied. The ordinary Portland cement (OPC) was partially replaced with POFA and MK on mass-for-mass basis. All specimens were first cured for 28 days in normal water and subsequently subjected to full immersion in sodium sulphate solution for 150 days for the compressive strength evaluation. The results show that partial replacement of cement with POFA and MK improved the durability of the cement pastes by reducing the damage caused by sulphate attack

The Effect of Na2SO4 and NaCl Solutions on the Moisture Movement of Fired Clay Masonry Wall

The influence of sodium sulphate and sodium chloride exposures on the moisture movement of masonry systems has been investigated. The investigation involved the measurement of moisture movement of single leaf masonry wall which were built with fired clay bricks in conjunction with grade (iii) mortar with proportions of 1: 1: 6 (OPC: lime: sand).  After being constructed, the masonry walls were cured under polythene sheet for 14 days in a controlled room with temperature of 25 ± 2ºC and 80 ± 5% relative humidity.  They were then exposed to sodium sulphate and sodium chloride solutions at different concentrations of 5, 10 and 15%. The moisture movement was monitored up to 210 days.  The moisture movement was also measured on the unbonded bricks and mortar prism so that the contribution of brick and mortar on the moisture movement of the masonry walls could be quantified. As a result, after the period of exposure to the soluble salt conditions, large expansion was observed in particular case of sulphate exposure. The composite model underestimated the moisture movement of fired clay masonry walls which were exposed to the soluble salts

Acoustic Emission (Ae) Techniques For The Damage Assessment Of Structures.

Reinforced concrete (RC) has been facing several types of damage mechanism during their lifetime. The types of common defects in concrete structures are crack formation, corrosion, scalling and etc. Therefore a non destructive evaluation method such as Acoustic Emission (AE) is required for assessing the condition of the RC structures. AE testing in RC structures shows great potential in monitoring and assessing the health conditions of structures. AE is used as a tool to detect, identify, locate and quantify a variety of damage mechanism

Influence of metakaolin as partially cement replacement minerals on the properties of cement and concrete / Muhd Norhasri Mohd Sidek ...[et al.]

Metakaolin is a manufactured pozzolan produced by thermal processing of purified kaolinitic clay using electrical furnace. This study has examined the effect of Metakaolin on the properties of cement and concrete at a replacement level of 0%, 5%, 10% and 15%. The parameters studied were divided into two groups which are chemical compositions, water requirement, setting time and soundness test were carried out for cementitous properties. Workability, compressive strength and bending strength were test for concrete properties. Hardened concrete was cured under different type of curing conditions and tested.. The result showed that the inclusions of Metakaolin as cement replacement minerals have change some of the cementitous and concrete properties. This research reveals, the optimum effect for cementitous and concrete properties for metakaolin was 10%

Performance of green high-strength concrete incorporating palm oil fuel ash in harsh environments

The corrosion of steel reinforcement by chloride is commonly recognized as a key factor that contributes to the degradation of durability in reinforced concreae structures. Using supplementary cementitious materials, such as industrial and agricultural waste materials, usually enhances the impermeability of the concrete and its corrosion resistance, acid resistance, and sulfate resistance. This study’s primary purpose is to examine the effects of replacing ordinary Portland cement (OPC) with ultrafine palm oil fuel ash (U-POFA) on the corrosion resistant performance of high-strength green concrete (HSGC). There were four HSGC mixes tested; the first mix contained 100% OPC, while the other mixes replaced OPC mass with 20%, 40%, and 60% of U-POFA. The performance of all HSGC mixes containing U-POFA on workability, compressive strength, porosity, water absorption, impressed voltage test, and mass loss was investigated at 7, 28, 60, and 90 days. Adding U-POFA to mixes enhances their workability, compressive strength (CS), water absorption, and porosity in comparison with mixes that contain 100% OPC. The findings clearly portrayed that the utilization of U-POFA as a partial alternative for OPC significantly enhances the corrosion-resistant performance of the HSGC. In general, it is strongly advised that a high proportion of U-POFA be incorporated, totaling 60% of the OPC content. This recommendation is the result of its significance as an environmentally friendly and cost-effective green pozzolanic material. Hence, it could contribute to the superior durability performance of concrete structures, particularly in aggressive environmental exposures. Highlights: The corrosion resistance performance of high-strength green concrete was investigated. Ultrafine palm oil fuel ash as a partial alternative of cement mass with 20%, 40%, and 60% was used. HSGC performance was evaluated in terms of workability, compressive strength, water absorption, porosity, impact stress testing, and mass loss

Performance of high strength concrete containing Palm Oil Fuel Ash and Metakaolin as Cement Replacement Material

The release of carbon dioxide (CO2) from the cement industry into the atmosphere and the increasing amount of oil palm waste from industrial plants lead to the problem of the greenhouse effect and environmental pollution. Studies on palm fuel ash (POFA) and metakaolin (MK) as a semi-substitute for cement can reduce the problem of the greenhouse effect and environmental pollution, as well as increase and improve the level of strength of concrete. Using mechanical and transport test methods as well as assisted by comparative X-ray Diffraction (XRD) analysis can prove the use of pozzolanic material as a catalyst to the compressive strength of concrete. In this study, slump test, compressive strength test, and water absorption test were conducted on samples containing total cement substitution up to 40% of POFA and MK as cement substitutes. The partial replacement of cement with MK and POFA reduced the workability of the concrete. However, binary and ternary blended concrete containing MK and POFA provide better compressive strength compared to OPC concrete up to 9.5% after 28 days age. Moreover, it was found that, the compressive strength of concrete containing POFA was better than the concrete containing MK up to 4%

Physicomechanical assessments and heavy metals’ leaching potential of modified asphalt binders incorporating crumb rubber and tin slag powders

Industrial solid waste has been widely used as an alternative additive for bituminous material modification. This study aims to evaluate the basic properties and quantify the leaching potential of modified asphalt binders incorporating crumb rubber powder (CRP) from waste tires and tin slag (TS) for a local smelting company. Three percentages of CRP and TS, at 5, 10, and 15%, were considered. The conventional asphalt binder (PEN 60/70), CRP, and TS-based modified asphalt binders were analyzed for toxicity, softening point, penetration value, elastic recovery, torsional recovery (TR), and coatability index. The findings indicated that the addition of the waste materials led to no significant heavy metal content in the asphalt binder mix. Moreover, the basic and physical properties of the asphalt binders were also improved by 5, 10, and 15% of the waste, respectively. However, TS waste exhibited limited effects on all the parameters and had a 5% optimum dosage. The modified binders’ results showed that the CRP modified asphalt binders had fewer heavy metals and responded more to elastic recovery and coatability