Aggregate Replacement Percentage Research Articles

Importance of pumice amount in the design of self-compacting lightweight concrete

Although concrete has high compressive strength values, it has a heavy unit volume and low tensile strength. In this study, the normal-weight aggregate, which takes up the most space in concrete by volume and mass, was partially replaced with pumice aggregate, and macro steel fiber (30 mm) was also added to the mixtures. This experimental work aims to investigate the effect of pumice aggregate amount on the fresh and hardened properties, as well as the flexural performance of the self-compacting lightweight concrete (SCLC). The replacement proportions of pumice aggregate with crushed sand were arranged as 45%, 50%, and 55% of the entire aggregate by weight. Three mixtures, each with 1% macro steel fiber reinforcement and without fiber, were prepared for each mixture scenario. The mix design of these six mixtures was arranged to achieve the self-compacting ability and the workability tests recommended by EFNARC (slump-flow, T50, J-ring) were taken into account. To investigate the mechanical properties (compressive, splitting tensile, and flexural strengths) and flexural toughness of the samples, the specimens were cured in water at 23±2 °C for 28 days. As a result, the unit volume weights of the specimens produced from pumice-substituted mixtures decreased with the increase in the pumice dosage, while the compressive, splitting tensile, and flexural strengths decreased. However, it has been determined that all SCLC mixtures including pumice aggregate provided workability properties in general and had enough compressive strength to be used in the production of structural bearing elements, regardless of fiber content. As a result, the optimum pumice aggregate replacement percentage with crushed sand was found to be 45% and the best flexural performance values of the specimens having macro steel fiber were observed in the ones having 45% pumice aggregate substitution.

A Research on Fresh and Hardened Concrete Residences with Partial Replacement of Recycled Coarse Aggregates Obtained from Demolition and Construction Waste

The modern world is witnessing the development of extremely demanding structures right now. Concrete is an extremely important and widely used material. However, the reuse of construction waste is crucial when considering life cycle assessment (LCA) and the efficient recycling of construction materials. Given its potential to address sustainability and environmental challenges, using recycled materials in construction has attracted much attention. This study aims to examine what happens to concrete's compressive strength when recycled coarse aggregates (RCA) replace some of the conventional coarse aggregates. The aim is to study the impact of RCA content on the mechanical characteristics of concrete and determine its appropriateness for use in structural applications. The main objectives of this work is to determine and compare the Density, Workability, Compressive strength, split tensile strength, and Flexural strength of Recycled aggregate in relation to conventional aggregate also to ascertain the ideal percentage of aggregate replacement with recycled aggregate and to calculate the percentage change in strength for recycled aggregate at different levels of replacement. The research methodology involves carrying out laboratory experiments to examine the compressive strength, split tensile strength, and flexural strength of concrete specimens with different proportions of recycled concrete aggregate (RCA) substitutions. The typical coarse aggregates are substituted by recycled aggregates in various proportions (5%, 10%, 15%, 20%, 25%, and 30%) by weight in M25 grade concrete. The formulation of the concrete mix design is meticulously done to provide a consistent water-cement ratio and other crucial criteria. The study involves the process of casting and curing concrete specimens that contain varying amounts of recycled concrete aggregate (RCA). At certain curing ages (e.g., 7 days and 28 days), the specimens are tested for compressive strength, split tensile strength, and flexural strength in order to assess their mechanical capabilities. After that, the outcomes are contrasted with control samples made entirely of conventional coarse aggregates. Primary finding shows workability declines as the proportion of recycled trash rises, but it is kept stable with mixing.

Influence of recycled coarse aggregate on properties of fly ash and slag-based geopolymer concrete cured under oven and ambient temperature

Purpose The purpose of this paper is to investigate the effect of the replacement of natural coarse aggregate (NCA) with different percentages of recycled coarse aggregate (RCA) on properties of low calcium fly ash (FA)-based geopolymer concrete (GPC) cured at oven temperature. Further, this paper aims to study the effect of partial replacement of FA by ground granulated blast slag (GGBS) in GPC made with both NCA and RCA cured under ambient temperature curing. Design/methodology/approach M25 grade of ordinary Portland cement (OPC) concrete was designed according to IS: 10262-2019 with 100% NCA as control concrete. Since no standard guidelines are available in the literature for GPC, the same mix proportion was adopted for the GPC by replacing the OPC with 100% FA and W/C ratio by alkalinity/binder ratio. All FA-based GPC mixes were prepared with 12 M of sodium hydroxide (NaOH) and an alkalinity ratio, i.e. sodium hydroxide to sodium silicate (NaOH:Na2SiO3) of 1:1.5, subjected to 90°C temperature for 48 h of curing. The NCA were replaced with 50% and 100% RCA in both OPC and GPC mixes. Further, FA was partially replaced with 15% GGBS in GPC made with the above percentages of NCA and RCA, and they were given ambient temperature curing with the same molarity of NaOH and alkalinity ratio. Findings The workability, compressive strength, split tensile strength, flexural strength, water absorption, density, volume of voids and rebound hammer value of all the mixes were studied. Further, the relationship between compressive strength and other mechanical properties of GPC mixes were established and compared with the well-established relationships available for conventional concrete. From the experimental results, it is found that the compressive strength of GPC under ambient curing condition at 28 days with 100% NCA, 50% RCA and 100% RCA were, respectively, 14.8%, 12.85% and 17.76% higher than those of OPC concrete. Further, it is found that 85% FA and 15% GGBS-based GPC with RCA under ambient curing shown superior performance than OPC concrete and FA-based GPC cured under oven curing. Research limitations/implications The scope of the present paper is limited to replace the FA by 15% GGBS. Further, only 50% and 100% RCA are used in place of natural aggregate. However, in future study, the replacement of FA by different amounts of GGBS (20%, 25%, 30% and 35%) may be tried to decide the optimum utilisation of GGBS so that the applications of GPC can be widely used in cast in situ applications, i.e. under ambient curing condition. Further, in the present study, the natural aggregate is replaced with only 50% and 100% RCA in GPC. However, further investigations may be carried out by considering different percentages between 50 and 100 with the optimum compositions of FA and GGBS to enhance the use of RCA in GPC applications. The present study is further limited to only the mechanical properties and a few other properties of GPC. For wider use of GPC under ambient curing conditions, the structural performance of GPC needs to be understood. Therefore, the structural performance of GPC subjected to different loadings under ambient curing with RCA to be investigated in future study. Originality/value The replacement percentage of natural aggregate by RCA may be further enhanced to 50% in GPC under ambient curing condition without compromising on the mechanical properties of concrete. This may be a good alternative for OPC and natural aggregate to reduce pollution and leads sustainability in the construction.

Behavior of Shear-Critical Recycled Aggregate Concrete Beams Containing BFRP Reinforcement

The shear performance of recycled aggregates beams reinforced with basalt fiber-reinforced polymer (BFRP) bars is evaluated and compared with that of similar beams made with natural aggregates (NA). Six beams with a shear span-to-effective depth ratio (a/d) of 3.0 were tested to failure. Test variables consisted of the recycled concrete aggregate (RCA) replacement percentage (60 and 100%) and the presence of BFRP stirrups in the shear span. Experimental results showed that a RCA replacement of 60% marginally reduced (5%) the shear capacity. However, the reduction in the shear capacity was more pronounced (17%) for the specimen made with 100% RCA. The contribution of BFRP stirrups to the shear capacity decreased with an increase in the RCA replacement percentage. The width of the major shear crack at a given value of load was higher for the beams with RCA. The deflection values at the ultimate load were greater for beams made with RCA. A codified analytical approach as well as a model published in the literature were employed to predict the shear capacity of the tested beams. Predictions of the codified analytical approach were very conservative. The analytical model published in the literature provided a more reasonable prediction for the shear capacity of the tested beams than that of the codified analytical approach.

Treated recycled coarse aggregate concrete: A new mixture proportioning method based on packing densities

In this paper, recycled coarse and fine aggregate collected from concrete rubble are treated with acid to remove the adhered cement mortar on the aggregates. These treated recycled aggregates both in fine and coarse aggregates are used to prepare concrete with water-cement ratio of 0.55 based on newly developed mix design method using packing densities. In this study two different recycled coarse aggregate sizes of 10 mm (40 % by mass fraction) and 20 mm (60 % by mass fraction) are used for various replacement levels of natural aggregates. The ratios of aggregates mixture of CA20, CA10 and FA are 38.4:25.6:36.0 by mass. For various packing densities, the recycled aggregates content is evaluated. Quantities for recycled aggregate concrete mixes made with 100 % recycled fine aggregate (RFA) and various replacement percentages of recycled coarse aggregate (RCA) for 0.55 w/c ratio are arrived at. Workability of concrete made with 100 % RFA in terms of slump (mm) can be enhanced by adding 5 % GGBS by mass of cement. Compressive strengths of concrete made with 0 to 100 % replacement of treated recycled fine and coarse aggregate ranges from 27.21 to 19.05 MPa. But when cement or silica fume is added to the recycled aggregate concrete then the compressive strengths are comparable to that of concrete made with natural aggregates.

Residual alkali–silica reaction of coarse recycled concrete aggregate based on the application of a prescriptive measure from the Argentinian regulation

The potential reactivity of a coarse recycled concrete aggregate (CRCA) obtained from concrete damaged by alkali–silica reaction (ASR) was evaluated by the concrete prism test method. Different recycled aggregate replacement percentages and exposure conditions were considered. Moreover, the use of Portland-limestone cement (PLC) as a preventive measure to mitigate the deleterious effect of ASR according to the Argentinian regulation was considered to evaluate the residual expansion of the CRCA. Expansions were recorded up to the age of 156 weeks, and different mechanical properties were also determined. The use of ordinary Portland cement (OPC) leads to an increase in ASR expansions for recycled concretes as CRCA content increases, whereas when PLC is used, expansions remain lower than the limits fixed in the standard test method, even at older ages.

Properties of Pervious Concrete Made with Ferrochrome Slag as a Coarse Aggregate

Ferrochrome slag (FCS) is produced during the production of ferrochrome alloy, which is an essential component of stainless steel. FCS has favorable physical and chemical properties for use as an aggregate in place of natural aggregate in the production of conventional and pervious concrete. Previous studies reported that the mechanical properties of concrete are enhanced when FCS is used in place of natural aggregates. This study evaluated the performance of pervious concrete containing FCS aggregates to replace the natural aggregates (NA) in various percentages (0%, 25%, 50%, 75% and 100% by weight). The effect of FCS replacement ratios on the mechanical properties (compressive strength, flexural strength, and split tensile strength), water permeability in terms of infiltration rate and density of the pervious concrete were determined. The results showed that the coefficient of water permeability increases with the increase of ferrochrome slag content. However, the compressive strength and density are reduced due to the increase of the porosity of the concrete. The optimum replacement percentage of natural aggregate with FCS aggregate was found to be 75%. The study concluded that it is possible to produce sustainable pervious concrete by using waste ferrochrome slag.

Mortar intended for the production of cementitious slabs: use of waste green foundry sand and polymeric fibers

The development of cementitious cover slabs with replacement of natural sand (NS) by waste green foundry sand (WGFS) and with addition of polyester fibers was the main objective of this work. Different percentages of replacement of NS by WGFS (0, 25, 50, 75 and 100%), different cements (CP-V ARI and CP-II Z 32) and addition of polyester fibers (0% and 0.6%) were employed as factors in the experimental design. The results showed that the apparent specific mass decreased when the percentage of aggregate replacement was increased, however, the air void and water absorption of the composite increased with replacement. The highest compressive strengths were obtained for the mortars made entirely with NS, which reached 20.4 MPa and 12.9 MPa for cements CP-V ARI and CP-II Z, respectively. The addition of fibers showed no evidence of significant influence on the properties of prismatic specimens, but the fibers were significantly influential on the properties of cementitious plates. Evaluating the results, it is observed that the total replacement of NS by WGFS, in cementitious cover slabs, is not recommended, because the mechanical strengths reduce around 60% when compared to the reference material

BENDING AND BUCKLING STRENGTH CONCRETE WITH COARSE AGGREGATE REPLACEMENT WASTE PLASTIC BAGS

<p>Mix concrete practical 1pc: 2 ps: 3split, people used to build houses, has a specific <br />gravity of 22-24 kN/m3. Density large concrete impact severity construction was, <br />blend ingredients lightweight aggregates to produce lightweight concrete. One is <br />used for lightweight aggregate material is waste plastic bags. Because the amount <br />of waste plastic bags or piled carelessly discarded in landfills (TPA) impact of <br />environmental pollution. This paper presents the study of the flexural strength and <br />buckling the use of waste plastic bags as a partial replacement of coarse aggregate <br />mix. The percentage of coarse aggregate replacement with waste plastic bag of <br />approximately 30% is expected to produce flexural strength and buckling optimum <br />reinforcement variation different. Bending beam size 10/15 cm length of 70 cm, <br />variations in the tested reinforcement bending strength. While buckling strength <br />using the dimensions of length 70 cm 10/10 with a variety of symmetrical and non <br />symmetrical reinforcement. Effective capacity reinforcement ratio press the tensile <br />reinforcement that generates maximum torque is 66.67%.</p>

Experimental investigation on mechanical properties of glass fiber reinforced recycled aggregate concrete under uniaxial cyclic compression

In this investigation, glass fiber (GF) was incorporated into recycled concrete to form a new sustainable material (glass fiber reinforced recycled concrete) to solve the shortcomings of easy cracking and high brittleness of recycled concrete. At present, there are few investigations and experiments on the mechanical properties of the material under uniaxial cyclic compression, and there is a lack of prediction of the behavior of the material in a specific mechanical environment. Thus, this investigation focuses on the stress–strain relationship and mechanical properties of glass fiber reinforced recycled concrete (GFRAC) under uniaxial cyclic compression. In order to achieve this goal, the stress and strain of the specimen under cyclic compression were discussed by designing three variables: recycled aggregate replacement rate, glass fiber content, and loading rate. The failure process of GFRAC under cyclic loading was observed and recorded, and the failure mechanism of GFRAC was analyzed in depth from macro to micro levels. The stress–strain curve law of GFRAC under cyclic action is summarized. The plastic strain and stiffness degradation law of recycled glass fiber reinforced concrete were revealed. The hysteretic energy consumption of each cycle is quantified and compared. The results show that, under the influence of GF content and recycled aggregate replacement percentage, GFRAC specimens appeared oblique shear failure, splitting failure and oblique shear & splitting failure under cyclic action. The stress–strain envelope curve of GFRAC under cyclic loading is similar to the monotonic one. Increasing the replacement ratio of aggregates can increase the peak strain of the specimen under cyclic action, and the maximum improvement value can reach 12.62 percent. The addition of GF can improve the ductility of recycled concrete, increase the hysteresis energy consumption, and finally affect the stiffness degradation rate of the specimen. Among them, under the same recycled aggregate replacement rate and the same cycle numbers, the stiffness degradation rate of the specimen with 0.05 % GF content is twice that of the specimen with 0.15 % GF content. This investigation provides a theoretical basis and reference for further research on GFRAC.

Nonlinear Numerical Analysis and Restoring force Model of Composite Joints with Steel Reinforced Recycled Concrete Columns and Steel Beams

Cyclic loading tests were conducted for eight composite joints (five interior joints and three exterior joints) with steel reinforced recycled concrete (SRRC) columns and steel beams under cyclic loading. The axial compression ratio and recycled coarse aggregate (RCA) replacement percentage were considered as the main design parameters for the above composite joints. The seismic behavior of the composite frame joints with (SRRC) columns and steel beams were studied by numerical simulation and the constitutive models of recycled aggregate concrete (RAC), steel and reinforcement were given to the corresponding elements. The experimental results were used to validate the finite element (FE) model. The results indicated that the FE model can accurately predict the deformation and stress load-strain curves of the composite joints. Then, a FE parameter analysis was carried out on the seismic behavior of the composite joints. The RAC strength, steel strength and column steel web thickness were considered as the main parameters. Results pinpointed that the increase in RAC strength and steel web thickness of the columns significantly affected the horizontal bearing capacity of the composite joints. However, with the increase in RAC and steel strength, the deformation ability and ductility of composite joints were almost unaffected. The reasonable increase in column steel web thickness can improve the seismic ductility of composite joints, evidently. On this basis, considering the stress characteristics of joint specimens, a four broken line restoring force model for steel reinforced recycled concrete column steel beam composite frame joints was established. This model includes the skeleton curve model, the stiffness degradation pattern and hysteresis rules. The calculation curve was in good agreement with experimental curves, which can well reflect the hysteretic behavior of joints subjected to low cyclic repeated loading. The above results can be used as a reference for the seismic design of composite frame joints.

The cyclic bond behavior between H-shaped steel and recycled concrete

To investigate the cyclic bond behavior between H-shaped steel and recycled concrete, ten specimens were adopted and tested under push-out load. The main parameters are recycled concrete aggregate (RCA) replacement percentage, loading scheme, bond position, and H-shaped steel dimension. Based on the test results, the effect of the main parameters on the cyclic bond behavior was analyzed. It is found that the damage first appears on both ends of the bond interface and then gradually extends to the middle area during the cyclic loading. At the same time, the cyclic bond strength exhibits a significant degradation compared to the static bond strength, and the cyclic bond strength decreases with the increased RCA replacement percentage and H-shaped steel dimension. In addition, the seismic damage of the bond interface is quantitatively analyzed based on the Park-Ang seismic damage model, and the influence of the main parameters on the seismic damage is analyzed. It suggests that the seismic damage of specimens with RCA develops more rapidly than those with natural aggregate (NA). As the H-shaped steel dimension increases, the seismic damage of specimens develops more and more rapidly.

Eccentric compression behavior of reinforced recycled aggregate concrete columns after exposure to elevated temperatures: Experimental and numerical study

As the thermal performance of recycled aggregate concrete (RAC) is different from that of natural aggregate concrete (NAC), the mechanical properties of reinforced recycled aggregate concrete (RRAC) members after exposure to elevated temperature have been attracted great interest. However, there are little literatures about the eccentric compression behavior of the RRAC column after exposure to elevated temperature. This paper presents experimental and numerical studies on the eccentric compression behavior of RRAC columns after exposure to elevated temperatures. In this research, nine specimens were tested to study the effects of the recycled coarse aggregate (RCA) replacement percentage, elevated temperature and eccentricity ratio on eccentric compression behavior. The results showed that the temperature was the primary factor influencing the eccentric compression behavior, followed by eccentricity ratio, while RCA replacement percentage had the least effect. As temperature increased or eccentricity ratio decreased, the failure mode of eccentric columns changed from tension-controlled to compression-controlled, while the RCA replacement percentage had a little influence on it. The eccentric load bearing capacity decreased as the temperature and eccentricity ratio increased or RCA replacement percentage decreased. The parametric analysis of finite element (FE) model indicated that there was a coupling effect between design parameters of slenderness ratio, eccentricity ratio and longitudinal reinforcement ratio with temperature on the eccentric load bearing capacity. Based on the ABAQUS, the cross-sectional thermal field of RRAC columns was simulated. An equivalent model for the residual bearing capacity of RRAC columns was presented and agreed well with the results of experiment and simulation.

Study some Mechanical and Thermal Properties of reinforced Perlite Concrete

Expanded perlite as an aggregate in concrete may make insulating concrete and fire-resistant suitable for roof decks and other purposes. Expanded perlite aggregate (EPA) may be used with gypsum plasters and Portland cement to protect columns, beams, and external applications. Other building uses are chimney linings, under-floor insulation, ceiling tiles, gypsum boards, and roof insulation boards. The primary goal of this research is to learn more about the effects of employing perlite aggregate (EPA) as a partial or complete substitute for sand on various characteristics of expanded perlite concrete (EPC) at 7 and 28 days. Air-dry density, compressive strength, water absorption, flexural strength, and thermal conductivity are all investigated in this research. EPA replacement by volume of sand was used to create five EPC mixes with 0%, 25 %, 50 %, %, and 100%. The effects of introducing 0.5% polypropylene fiber on the characteristics of EPC mixes were investigated. To increase the EPC workability, superplasticizer was utilized, particularly at the higher EPA replacement levels. The test outcomes reveal that the measured mechanical and physical properties of EPC decrease when increasing the EPA content. Thermal insulation of EPC increases with increasing the percentage of perlite aggregate replacement. In addition, using polypropylene fibers in the EPC specimens cause a slight reduction in density, compressive strength, and thermal conductivity compared to unreinforced specimens. Polypropylene fibers significantly increase in modulus of rupture reach 29% at 28 days, and increase in water absorption compared with unreinforced specimens.

Dynamic response of square recycled aggregate concrete-filled steel tube columns subjected to close-range blast loads

To study the dynamic response of square recycled aggregate concrete-filled steel tube (RACFST) columns under explosion loads, explosion examinations and numerical analyses were performed. Based on the measured longitudinal strain and residual displacement of the columns, the effects of recycled aggregate replacement percentage, steel tube thickness, explosive charge weight, blast center distance, and explosion height on the dynamic response of square RACFST columns are analyzed, and the failure modes are investigated. Then, the established numerical model was verified through test results, and further explore the dynamic response of square RACFST columns. It indicates that square RACFST columns suffer localized damage after detonation, and no obvious global deformation occurs. The localized failures, including blast pit, steel tube bulge or rupture, and weld fracture, could be observed on these columns. The square RACFST columns strain and displacement values are positively correlated with TNT equivalent and RA content, while negatively correlated with steel tube thickness and blast center distance. Furthermore, the concrete absorbs most of the total energy, implying the important role of core concrete in the explosion resistance of RACFST columns.

An experimentation made on plastic and demolished waste in concrete mix

In the current experimental investigation, plastic waste is used as a partial substitute for fine aggregate to the extent of 10%, and coarse aggregate is partially replaced by destroyed material to the extent of 0%, 10%, 20%, 30%, 40%, and 50% of the total amount of coarse aggregate in the experiment. The standard mix for M25 grade concrete has been developed, with a water-to-cement ratio of 0.45. This proportion is employed in the concrete manufacturing process. During the course of this experiment, sixteen distinct combinations are created. The impact moulds used are 150 mm × 75 mm and the cubes used are 150 mm × 150 mm. The specimens used include cubes with dimensions of 1550 mm × 150 mm and cubes with dimensions of 300 mm × 300 mm. The density of concrete may be varied between 2500 and 2100 kg/m3 by replacing plastic garbage with sand at a constant percentage and modifying the replacement percentage of coarse aggregate with damaged material at a variable percentage. It was found that adding more recycled aggregate to fresh concrete made it less workable. According to the results, replacing natural sand and coarse aggregate in normal concrete with plastic waste and recycled aggregate increases compressive strength (fck) and split tensile strength (ft) by up to 10%, but then decreases when the quantity of recycled waste is increased. According to the findings of the experiment, fine aggregate replaced with 10% plastic waste and coarse aggregate replaced with 10% recycled aggregate resulted in excellent quality for new concrete as well as attaining the conventional concrete's goal mean strength.

Residual mechanical properties and numerical analysis of recycled pebble aggregate concrete after high temperature exposure and cooled by fire hydrant

In urban fire, the structure will not only be subjected to high temperature, but also cooled by fire hydrant. This paper presents the experimental results of the residual mechanical performance and the complete compressive stress–strain relationship of recycled pebble aggregate concrete (RAC) after exposure to high temperature of 20 to 600 ℃ and cooled by fire hydrant. In the experiments, five different concrete compositions were designed by substituting natural coarse aggregates with recycled coarse aggregates at the replacement ratios of 0%, 30%, 50%, 70% and 100%. Results exhibit that with the increase of exposure temperature, the surface color of the specimens changes from light to dark, the mass of RAC first increases and then decreases, and the residual mass of RAC at 200 ℃ is higher than that at room temperature. The compressive strength and the strain at the peak point decrease rapidly with the increase of temperature. The compressive strength and the strain at the peak point fluctuate with the increase of aggregate replacement percentage, and the temperature and aggregate replacement percentage have little effect on the ductility of RAC. The residual bearing capacity calculation method and constitutive equation of RAC after high temperature exposure and cooled by fire hydrant are proposed and verified. The accuracy of the constitutive equation is verified by ABAQUS finite element analysis software.

Performance of Recycled Aggregate Concrete Made with Waste Refractory Brick

Concrete containing recycled aggregates have different properties from concrete containing natural aggregates. This work investigates, firstly, the possibility of using recycled refractory bricks (RBA) as coarse aggregate for concrete, and secondly, finds the ideal replacement percentage of natural coarse aggregate (NCA) by RBA. For this, an experimental study was carried out to assess the physical and mechanical properties of concrete produced with the partial and total replacement of NCA by RBA. Two types of RBA from two different sources were used, RBA-1 obtained from the grinding of new refractory bricks and RBA-2 obtained from refractory bricks used in the furnace recovered from the cement plant. For each type of RBA, two concretes with water/cement (w/c) ratios of 0.59 and 0.38 were tested. These concretes were evaluated by density, water porosity, ultrasonic pulse velocity (UPV) and compressive strength, and compared to those obtained on conventional concretes. The results obtained show that concrete can be manufactured using RBA. Concrete containing 20% ​​RBA shows good quality compared with conventional concrete.

Fire resistance of lightweight foam concrete by incorporating lightweight bio-based aggregate

Concrete is widely used in the industry due to its effectiveness in terms of cost and strength. In this study, the introduction of bio-based aggregate as coarse aggregate in lightweight foam concrete will be investigated to find a better solution for fire incidents that are commonly happened. As such, lightweight foam concrete (LWFC) has been applied in many buildings especially in non-load bearing wall to enhance thermal conductivity, sound insulation and fire resistance. The aim of this research is to investigate the effect of incorporating bio-based aggregate namely oil palm shell (OPS) into lightweight form concrete in terms of strength properties and fire resistance. Three different concrete mix was designed containing different percentage of OPS aggregate replacement (0, 5, 10 and 15%). From the result, the compressive strength of the LWFC-CTR mixture had achieved the highest compressive strength at 28-day, which is recorded at 3.82 MPa. The fire resistance of LWFC-OPS 15% had showed a positive outcome with improvement by almost 23.5% compared to control mix at 15 minutes. Therefore, the major finding of this research is the incorporation of eco-friendly OPS aggregate has improved the fire resistance of lightweight foam concrete, which can be used as an alternative solution for non-load bearing walls.

Influence of crack on the damping properties of recycled concrete

This paper investigates the damping property of a recycled concrete beam with prefabricated cracks through the lens of free vibration attenuation. The experiment is designed to evaluate the effects of various recycled aggregate replacement percentages and fracture depths. The frequency and damping characteristics of recycled concrete and cracking, as well as their evolution through time, were explored, as well as the influence of a variety of factors and their interactions. For various recycled aggregate replacement ratios, the testing results indicate that the frequency of free vibration is between 3000 and 4000 Hz. The damping ratio of unconstrained vibration varies between 0 and 0.04 and is typically about 0.015. The analysis demonstrates that as the replacement ratio of recycled aggregate increases, the average frequency decreases but the damping ratio increases overall; vibration frequency has a parabolic relationship with the replacement ratio of recycled aggregate but a linear relationship with the crack depth; and damping ratio has a parabolic relationship with the replacement ratio of recycled aggregate. The average frequency decreases as the recycled aggregate replacement ratio increases. The average frequency decreases as the recycled aggregate replacement ratio increases. The frequency of vibration is proportional to the recycled aggregate replacement ratio and is linear in relation to the crack depth. The damping ratio and the recycled aggregate replacement ratio are related to the crack depth in a parabolic fashion. In the test, no statistically significant relationship exists between the vibration amplitude and the damping ratio.