Unit Weight Of Concrete Research Articles

Sustainable use of recycled fine aggregates in steel fiber-reinforced concrete: Fresh, flexural, mechanical and durability characteristics

Recycling construction waste is a viable tactic for advancing environmentally friendly building methods. With regard to concrete applications, the purpose of this research is to determine whether it is feasible to use recycled fine concrete aggregates (RFA) in lieu of natural fine aggregates (NFA) and to lessen the environmental impact of natural resource depletion and landfill space. A sustainable steel fiber-reinforced concrete was created by replacing NFA with RFA at the replacement ratio of 0 %, 50 %, and 100 %. Steel fibers (SF) were also included to mixes at three different contents of 0, 25 and 50 kg/m3 in order to further improve the qualities of the concretes. Thus, the aim of this paper is to appraise how the addition of FRA affects the mechanical, freeze-thaw, fresh, and non-destructive qualities of concrete. Nine concrete mixtures were cast, and tests were made to evaluate the following properties: flowability, fresh concrete unit weight, tensile and compressive strengths, elastic modulus, surface hardness, crack mouth opening displacement (CMOD), freeze and thaw performance, sulfate resistance and abrasion. Moreover, microstructure properties of concrete were also analyzed. The outcomes revealed that the mechanical, flexural, and durability performances of the concrete mixtures were enhanced by substituting RFA for NFA. The mixture with 50%RFA and 50 kg/m3 SF gained maximum compressive strength of 44.82 MPa which was 20.7 % greater than the reference mixture (RFA0F0). The mixture containing 100 % RFA and 25 kg/m3 SF had the highest elastic modulus and showed an approximately 33 % augmentation in elastic modulus as per the reference mixture. The mixture with 100%RFA and 50 kg/m3 SF exhibited the largest tensile strength indicating 60 % tensile strength enhancement as per the reference mixture. Combined use of RFA and 50 kg/m3 SF in concrete mixtures had the best abrasion and freeze-thaw resistance. SF incorporated concrete mixtures with RFA exhibited worse sulfate resistance. This study contributed significantly to global resource efficiency and environmental preservation by shedding light on the sustainable use of RFA and SF in the making of concrete. The results made important contributions to global research and promote environmentally friendly building methods all throughout the world.

Evaluation of the Properties of High Strength Lightweight Concrete with High Temperature History

In this study, we evaluated the compressive strength and ultrasonic velocity based on the temperature and age of ordinary aggregate and lightweight aggregate concrete (30 and 60 MPa) and examined their correlation. The unit weight and compressive strength of ordinary aggregate and lightweight aggregate concrete were measured to evaluate the mechanical properties and examine the correlation between ultrasonic velocity and compressive strength. The W/B ratio was set at 0.41 and 0.28, and measurements were made at 1, 3, 7, 28, 56, and 91 days. The physical properties were evaluated at 23, 100, 200, 300, 500, and 700 ℃. In all test specimens, compressive strength and ultrasonic speed increased with age; and the higher the temperature, the lower the compressive strength and ultrasonic speed. By analyzing the correlation between ultrasonic velocity and compressive strength, a strength prediction equation in the form of an exponential function was found. Moreover, from the error rate test, we confirmed that the strength prediction equation generally had an error rate of 15% or less.

Prediction of mechanical properties of concrete blended with marble stone powder by artificial neural network

The current research work is mainly concentrated on the mechanical properties concrete blended with marble stone power resulted from waste sludge marble processing it has a high specific area. M25 grade concrete mix design was considered for this research work. The mechanical properties of concrete i.e. compressive strength, unit weight, splitting tensile strength, modulus of elasticity and flexural strength were considered for the study. The compressive strength of these mixes was measured on 150mm ×150mm × 150mm cubes and tension test split tensile test 150 mm dia × 300 mm height cylinders. The concrete unit weight was considered for calculating the elastic modulus of concrete. The investigational values were matched with ACI, CEB-FIP, BIS and AASHTO LRFD empirical equation and regression analysis was done. The empirical equation result was compared with regression analysis of Artificial Neural Network, and conclusion was brough down that regression analysis of artificial neural network had better prediction than that of above-mentioned empirical equations. The study concluded that 15% replacement of marble power attained highest strength and optimum replacement, 25% replacement was concluded as economical replacement to attain designed strength.

Experimental study on static and impact properties of concrete incorporating nano-SiO2, nano-Al2O3 and Fe2O3 in single and combined forms

This paper presents a comparative evaluation of the single and combined effect of nanoparticles on the static and impact properties of concrete. Nano-SiO2, nano-Al2O3 and nano-Fe2O3 were used separately and in combined forms as partial replacements of cement by 1% and 2% by weight. The impact of nanoparticles on the unit weight, compressive strength, split tensile strength, flexural strength, toughness, fracture energy, impact performance of concrete was experimentally examined. In addition, the effect of these nanoparticles on the microstructure of concrete was investigated using SEM analysis. Moreover, to evaluate the commercial production of such concretes, the cost effectiveness of use of nanoparticles in concrete was also discussed. Desirability function analysis was also conducted to compare the overall performance of the tested concretes. The results revealed that use of nano materials in concrete had a positive effect on improving their mechanical performance. Nanoparticles increased the compressive strength, split tensile strength, flexural strength, and energy absorption capacity of concrete. Use of nanoparticles didn't show any significant influence on the unit weight of concrete. Moreover, the results also showed that nano materials didn't have a good influence on the impact performance of concrete. SEM analysis showed that use of nanoparticles improved the microstructure of concrete.

Shrinkage and thermo-mechanical properties of concretes incorporated with different substitutions of natural aggregates by cold bonded calcined attapulgite lightweight aggregates

Calcined attapulgite (CAT), a fibrous calcined clay represents a promising option for advancement as a relatively new cementitious material with strong pozzolanic activity. This study investigates the impact and potential use of CAT in producing cold-bonded lightweight aggregates and their utilization in microsilica (MS) and fly ash (FA) blended concretes by analyzing the shrinkage and thermo-mechanical behavior. Initially, attapulgite rocks were processed including crushing, grinding and calcination to produce pozzolanic material. Following this, a dry powder mix of 80% calcined attapulgite (CAT) and 20% Portland cement (PC) was pelletized into calcined attapulgite lightweight aggregates (CATLWAs) using cold bonding with moisture and cured for 28 days. Subsequently, twelve concrete mixtures were formulated considering different substitutions of normal aggregate with CATLWAs and various proportions of PC, MS and FA. Mechanical properties such as compressive, splitting, and flexural strengths as well as elastic moduli and impact resistance were evaluated. Drying shrinkage, weight loss and thermal conductivity were assessed for all mixtures. Likewise, scanning electron microscopy was employed to analyze microstructural changes. Experimental results indicated that the incorporation of fine and coarse CATLWAs reduced the concrete unit weight by approximately 22% compared to the control mixture. However, there was a declining trend in mechanical properties, especially for impact resistance with increasing CATLWA content. However, the use of binary and ternary blends of cementitious materials improved overall mechanical behavior. Regardless of CATLWA content, the utilization of CATLWA enhanced thermal conductivity up to 46.9%. These findings hold significance for using CATLWAs in sustainable lightweight concrete production, thus advancing lightweight concrete technology and offering valuable insights into their advantages and constraints.

Identifikasi Karakteristik Fisik Berbagai Jenis Agregat Halus dan Korelasinya pada Sifat Beton Segar dan Beton Padat

One of the main constituents of concrete is fine aggregate or sand. As a filler, the characteristics of sand affect the properties of both fresh and hardened concrete. The aim of this research is to identify the characteristics of various types of sand and to correlate them with the properties of the concrete. The type of sand used in the experiment is common type of sand used in construction; for instance, silt sand, river sand, and beach sand, as well as recycled sand from concrete waste. The examination on physical characteristics includes visualization with a digital microscope, specific gravity, water absorption, fine modulus, and impurities content. This characteristic is compared with the value of slump, concrete unit weight, and concrete compressive strength. Quarry sand has denser particles and a fairly coarse texture, while recycled sand has the finest, hollowest, lightest particles and a lighter color than other sands. According to the properties of fresh concrete, silt sand produces the lowest slump value while recycled sand has the highest slump value. A positive correlation in the form of y = 1,55x + C is obtained from the relationship of the specific gravity of sand (x) to the compressive strength of concrete (y) and constants (C). the same correlation but in a negative relationship is obtained from the influence of water absorption characteristics

Modeling and experimental studies on energy consumption and properties of concrete containing waste brick powder and waste tire rubber for sustainable construction

The advantages of utilising waste materials in concrete have led to the use of waste brick powder (WBP) and waste tire rubber (WTR) in concrete production. The awareness of factors influencing energy required during concrete production and the capability to optimise energy consumption and modified concrete properties could pave way for adoption of modified concrete in construction industry. This paper is aimed at generating models via response surface methodology (RSM) which are suitable at establishing best compromises amongst responses of energy consumption, unit weight and compressive strength of concrete. The generated models facilitated the understanding of effect of parameters of WTR (0–20%) substituting coarse aggregates and WBP (0–5%) substituting cement on energy consumption, unit weight and compressive strength responses. The reliability of the constructed models was verified using analysis of variance (ANOVA). The models using RSM illustrated increased R2 values of larger than 0.84 for all responses which proved that the established models were reliable in the prediction of all the responses. The energy consumption response was established with the linear regression model while the unit weight and compressive strength responses were established with quadratic regression models. The desirability analysis produced 5% WBP and 0.614% WTR as values illustrating higher concrete unit weight at decreased energy consumption for concrete production. Optimisation procedure of energy consumption and compressive strength of concrete by desirability analysis provided 5% WBP and 0% WTR as optimum parameters establishing higher compressive strength at lower energy consumption. Moreover, no significant relationship was noticed between energy consumption of concrete and 28-days compressive strength of concrete as the compressive strength increased. The findings in this research motivate the reduction of energy consumption during concrete production without significantly influencing concrete properties.

Using serpentine in concrete: A literature review

Concrete is the most important and extensively used building material. It is used for various functions, including shielding materials from radiation sources such as nuclear power plants. Nuclear technology is applied in numerous research institutes, enterprises, and healthcare facilities, in addition to the exposure to radiation from power plants. Concrete has been considered as a potential shielding material by a number of researchers due to its low cost, durability, and strength, as well as the fact that it can be made using readily available materials. Numerous concrete technologists have turned to materials such as Serpentine to make heavy-weight concrete for radiation shielding against different levels of gamma rays and neutron shielding. This review investigates the radiation shielding materials of Serpentine and materials containing Serpentine mineral, such as Green Marble, in the building industry. This review study is divided into two primary areas: serpentine concrete and the use of serpentine aggregates as a radiation shielding material in concrete. Concrete mixtures using Serpentine alone and in combination with other efficient materials like boric acid and other minerals were used to create radiation-shielding concrete (RSC). On the basis of experimental data, the indicator of radiation shielding performance and the unit weight of concrete was found to have a correlation with a high degree of fitting. The objective of this study is to review the use of Serpentine with concrete and to provide direction on the difficulties encountered in the research process so far regarding the use of the mining waste from serpentine rock in concrete.

Case study on performance of pumping concrete with super-fine river-sand and manufactured-sand

Natural ecological protection changes the traditional practice for concrete production which faces a situation of the source exhaustion of natural materials, and the sufficient utilization of waste local materials becomes a strategy to reduce the carbon emission in infrastructure construction. This promotes a possible economic production of concrete with mixed-sand composited by coarse manufactured-sand and super-fine river-sand. Due to lack of study on the mixed-sand used for pumping concrete, an experimental study was carried out in this paper. The proportion of super-fine river-sand and manufactured-sand was determined at a target fineness modulus with a gradation in zone-II, the sand ratio of concrete was determined by the closed packing test of aggregates. Twelve mix proportions of mixed-sand concrete were designed by the absolute volume method, considering the content of super-fine river-sand and the sand ratio. The target cubic compressive strength of mixed-sand concrete was 48.2 MPa, while the target pumpability aimed at pumping height of 300 m. The pumpability of fresh mixed-sand concrete was evaluated by multi-indices including slump, slump flow, static segregation rate, pressure bleeding rate and air content, and explained by the rheological property including the indices of yield stress and plastic viscosity. The mechanical property was evaluated by the cubic and axial compressive strengths, the modulus of elasticity and the splitting tensile strength at curing age from 7 days to 56 days. Based on the test results, the absolute volume method for mix proportion design of mixed-sand concrete is rational to keep a consistent unit weight of fresh concrete, the optimal content of super-fine river-sand in mixed-sand is 25%− 35% with a rational sand ratio of 45%− 51%. The developments of compressive strength and tensile strength of mixed-sand concrete are identical to those of conventional concrete. The mixed-sand concrete presents the same relationships to the conventional concrete for the axial compressive strength, the splitting tensile strength and the modulus of elasticity with the cubic compressive strength. However, the splitting tensile strength of mixed-sand concrete is about 90% that of conventional concrete at the same strength grade. Further studies can be conducted to improve the flowability by adjusting superplasticizer and to enhance the tensile strength of mixed-sand concrete.

Effect of steam‒curing on the glass fiber reinforced concrete

Due to the increased need to use precast concrete to reduce construction duration and to accelerate the cement reaction process to achieve the required concrete resistance that enables the elements to gain the required strength to handle the loads generated by the transportation process, many companies use steam curing methods to expedite the hydration process. The steam curing process negatively affects the concrete strength, especially in the long term. Fibers of different types are used to improve the interior composition of concrete and increase its crack resistance. The purpose of the current study was to determine the effect of the glass fiber on the behavior of steam-cured concrete. In this study 90 concrete cubes were used with 15cm dimensions, three different weight ratios of glass fibers (0%, 0.12%, and 0.24%) with two curing methods standard curing in the water tank (water curing - WC) for 3, 7, and 28 days, and steam curing (SC) for 4 and 8 hours. Nine specimens of each mix were cast in 12 mm, and 24 mm fibers length and tested for each curing duration and method. The results of this study indicate that fiber glass addition to the steam-cured concrete has a positive effect on the concrete unit weight and the ultrasonic pulse velocity. Moreover, the result showed that the tensile and compressive strength of the concrete has been positively affected by the length of the fiber more than the fiber weight percentage.

Increasing the Compressive Strength of Concrete Using PPC

Cement factories in Indonesia rarely produce OPC due to the high cost of production and less environmentally friendly, so they prefer to produce PPC or PCC. Cement factories located in areas that are rich in natural pozzolan will prefer producing PPC. In general, there is an assumption that increasing the compressive strength of concrete using PPC is slow at the early age. Based on these assumptions, it is necessary to conduct research on increasing the compressive strength of concrete using PPC at an early age. The specimen used was a concrete cylinder, with 3 specimens for each variation. The compressive strength test of concrete is carried out at the ages of: 3, 7, 14, 21, and 28 days. From the research results obtained, compressive strength of concrete has increased with increasing age of the concrete. The increasing the compressive strength of concrete using PPC is comparable with concrete using OPC. The unit weight of concrete is almost the same for all ages of concrete.

Employment of cisco metal slag in fly ash bricks for a progressive sustainable solution for reusing waste from manufacture of creation materials

The metal-production industry creates a wide exhibit of strong waste, fluid effluents, and vaporous squanders. The stable wastes include slag, powdery materials, sludge, and scrap. So feasibility have a look at of metal slag recycling in fly ash bricks applied laboratory assessments and commercial trials on three exceptional styles of wastes and clay bodies. Crucial necessities consist of slag grinding at 90micron in size, in addition to magnetic separation. In an effort to replace everyday conventional bricks with Cisco metallic ash CSA) and Fly Ash (FA), lime is used as a binder cloth and whereas gypsum as a stabilizer. A huge variety of houses became examined, which includes unit weight and workability of fresh concrete, compressive strength, dihydrogen monoxide (water absorption), efflorescence of hardened concrete. In keeping with Indian codal provision three types were taken in account (Type1, Type2, Type3) with alternative of composition like [Type I - Fly ash: lime: M-sand: gypsum, Type II-Fly ash: cisco steel: M-sand: gypsum, Type III- - Fly ash: cisco steel: lime: M-sand: gypsum] to test the energy properties. While doing the test with metallic ash composition, it effects in higher electricity in lieu of metallic performs a tension position at some stage in loading. Although this addition of metal slag consequences in the discount of shrinkage which ends up in financial and better nice bricks.

Flow simulation of self-consolidating concrete through V-funnel for sustainable buildings

Self-consolidating concrete (SCC) is one of the trending low-yield stress material innovations of the new age building industry due to its ability to flow through heavily reinforced structural members without segregation and without losing its moderate viscosity. In this research paper, a V-funnel simulation has been developed for the flow time to establish its validity with allowable design conditions according to the European standard. The Bernoulli’s equation and the continuity flow state conditions were adopted for the V-funnel of 515 mm upper width, 75 mm thick, and vertical dimensions (depth) of 450 mm and 150 mm for the V-section and funnel duct (75 mm × 65 mm) respectively. Concrete shear stress with the funnel wall was considered as a factor of concrete unit weight (ρ) and frictional force under downward velocity with respect to variational height (dh). The result of the V-funnel simulation for the flow time shows that the kinematic viscosity (η) of the concrete is bound within the limits of 0 and 1/64. This implies that ηmin ≈ 0 (no friction with walls), and the minimum flow time (Tmin) becomes 8.7 sec while minimum shear stress is zero (τmin ≈ 0 N/m2). However, for ηmax ≈ 1/64 (maximum friction with walls of τmax τ ρ/64 N/m2 is attained) and Tmax becomes 18.9 sec. These values fall within the flow time after 10 seconds of mixing, ranging between 8 and 10 seconds, and the flow time after 5 minutes of mixing of 11 to 25 seconds, according to the European Guidelines for self-consolidating concrete. These results for the flow simulation of the concrete placement during construction, are also consistent with the United Nations sustainable development goals (SDGs) for technological innovation, infrastructure, and sustainable cities.

Sustainable usage and the positive environmental impact of wastewater dry sludge-based concrete

The paper examined the application of dry sludge in lightweight concrete and the associated environmental risk. Population growth has led to an increase in residential and commercial wastewater sludge production. The sludge is deposited to a designated landfill, rendering the area useless and posing a significant environmental concern. The need for lightweight materials in the construction sector has resulted in the replacement of dry sludge for the basic components of concrete. The dry sludge came from the WWTPs in Polokwane, Limpopo Province, was used as a partial replacement for sand (0, 2.5, 5, 7.5, 10, and 12.5%) in concrete. The samples prepared were cured in wastewater and potable water. The results showed that the partial substitution of sand with 7.5% dry sludge in the concrete mixture reached the desired strength of 25 MPa and can be employed in lightweight structural applications. Concrete cube unit weight reduced by 0.8, 2.3, 2.6, 3.9, and 4.6% compared to the control sample when 2.5, 5.0, 7.5, 10, and 12.5% of the sand was substituted with sludge. Concrete samples were submerged in iodine water for 28, 90, and 140 days to test the leaching of soluble metals. The levels of heavy metals in leachate were far lower than what the US Environmental Protection Agency (EPA) considers to be safe, under their Toxicity Characteristics Leaching Procedure (TCLP) standards. EDX examination of sludge-based concrete showed a considerable reduction in metal weight percentage, the concentration of calcium increased by 69% due to the cement content; and the blending aggregates lowered silicon, aluminium, iron, and potassium by 33.3, 66.9, 34.2, and 77.8%. Therefore, wastewater may be utilized as a concrete curing medium, and sludge-based concrete can be used for simple structural repairs at WWTPs.

Compressive Behavior and Durability Performance of High-Volume Fly-Ash Concrete with Plastic Waste and Graphene Nanoplatelets by Using Response-Surface Methodology

Plastic waste (PW) generation continuously increases every year due to the growing population and demand for plastic materials. This situation poses a challenge to many countries, including developed ones, on how to dispose of PW. Accordingly, PW was utilized in this study to replace coarse aggregates partially in high-volume fly-ash (HVFA) concrete. However, PW decreased the strength and durability of concrete. To address this issue, graphene nanoplatelets (GNPs) were added to mitigate the negative consequences of PW and HVFA on concrete’s properties. The objective of this study is to investigate the influences of PW and GNP contents on the durability and deformation of HVFA concrete. Response-surface methodology (RSM) was used to design and optimize a series of cement mixes to achieve the most desirable properties. Independent variables included PW content as partial replacement for coarse aggregates (0%, 15%, 30%, 45%, and 60% by volume), fly ash as partial substitute for cement (0%, 20%, 40%, 60%, and 80% by volume), and GNPs as additives (0%, 0.075%, 0.15%, 0.225%, and 0.3%). The considered responses were concrete unit weight, modulus of elasticity (MoE), and Cantabro abrasion loss at 300 revolutions. Results showed that PW and HVFA decreased concrete unit weight and MoE but increased Cantabro abrasion loss. By contrast, GNPs increased concrete unit weight and MoE but decreased Cantabro abrasion loss. PW and HVFA also increased the compressive toughness and porosity of concrete, while GNPs increased its stiffness but decreased its compressive toughness and porosity. The mathematical models developed to predict the unit weight, MoE, and abrasion resistance of concrete were significant, with errors of less than 6%. An optimized mix was achieved by partially replacing 12.44% of coarse aggregates with PW and 24.57% of cement with fly ash and adding 0.279% GNPs with a desirability of 100%.

Usage of ready-mixed concrete plant wastewater in concrete with superplasticizer: Effect on physico-mechanical properties

• As the WW content increased, the temperature of the concrete mixtures increased. • The workability of the mixtures is improved at the maximum usage dosage of SP (at 2%). • The air content of fresh concrete is between 2.1% and 2.5%. • The 28-day compressive strength of concrete mixes varies between 37.1 and 41.3 MPa. • The use of washing water on all test days decreased the compressive strength. The rapid growth of population and industrialization increases the demand for concrete day by day. In concrete production, a high amount of waste washing water is released. This waste washing water that is released causes soil and water pollution. This study investigated the fresh and physico-mechanical properties of the concretes prepared with the washing water released in the ready-mixed concrete plants. Wastewater (WW) was used at the rate of 25, 50, 75 and 100 % instead of potable water (PW). In addition, the mixtures used a naphthalene-sulfonate-based superplasticizer (1, 1.5 and 2 %). The effectiveness of SP in concrete produced with WW was also investigated. WW workability was relatively improved in mixtures without SP. However, to increase the workability in mixtures using 100 % WW, the SP dosage should be 2 %. The unit weight of fresh concrete is more than 2300 kg/m 3 . WW ratio and SP dosage did not greatly affect the unit weight of fresh concretes. Increasing the SP dosage decreased the air content of the fresh concrete, while the air content increased as the WW ratio increased. In mixtures with WW, the air content decreased by 20 % when the SP dosage was 2 %. The 28-day compressive strength of concrete varies between 36.9 and 49.00 MPa. It has been determined that C30/37 class concrete can be produced with 100 % WW mixtures. The 28-day compressive strength of the mixtures using 100 % WW decreased by 10 % compared to the reference mixture. As a result, the demand for water or SP increases in concretes using WW. Therefore, approximately 40 MPa compressive strength was obtained in WW concrete produced using SP. By producing concrete using WW, environmental pollution will be greatly reduced.

Metal-Nails Waste and Steel Slag Aggregate as Alternative and Eco-Friendly Radiation Shielding Composites

Metal waste recycling has become a global requirement owing to its environmental benefits and powerful economic activity. Metal nail waste (MNW) is a byproduct of metal nail manufacture. MNW has an equal size, contains a high ratio of iron, and has a high specific gravity comparable to normal aggregate. We present MNW recycling as a partial replacement for fine aggregates and electric arc furnace steel slag (EAFSS) as coarse aggregates to produce sustainable heavyweight concrete (HWC). Our main research aim was to study the radiation shielding and mechanical properties of sustainable HWC by partially replacing MNW with 10, 20, 30, and 40% sand. EAFSS is a coarse aggregate for 60% of the total volume. Fresh and hardened properties of HWC are presented. Furthermore, we analysed the internal structure of HWC mixes using a scanning electron microscope. Our results showed the positive effects of MNW on the unit weight of concrete. The density of HWC mixes ranges between 2650 and 3170 kg/m3. In addition, MNW contributes to increasing the compressive strength of concrete mixes with their use of up to 30%. Therefore, the MNW ratios improved the failure behaviour of HWC mixes. The improved linear attenuation coefficient of HWC mixes was due to using MNW ratios and higher densities than the reference mix.

Punching Shear Capacity of Lightweight Aggregate Concrete Flat Slabs without Shear Reinforcements

This study examined the effect of the unit weight and compressive strength of concrete on the punching shear capacity of flat slabs without shear reinforcements. The slabs were prepared using all-lightweight aggregate concrete (ALWAC), sand-lightweight aggregate concrete (SLWAC), and normal-weight concrete (NWC) at the different compressive strengths of concrete of 24 and 45 MPa. Based on the upper-bound theorem of concrete plasticity, the failure surface generatrix is generalized to account for the increased horizontal extension with a decrease in the unit weight of concrete. Thus, the punching shear capacity of concrete flat slabs is mathematically driven considering the reduced effective strengths of LWAC under tension and compression. Test results showed that the radius of the punching shear tended to increase with a decrease in the unit weight of concrete. This yielded a lower normalized punching shear capacity observed for ALWAC or SLWAC flat slabs than NWC flat slabs. The proposed model accurately estimated the punching shear capacity, indicating that the mean and standard deviation of the ratios between the experiments and predictions were 1.10 and 0.05, respectively. This indicated that the proposed model reasonably reflects the reduced aggregate interlock action of lightweight aggregates.

The effect of using polyolefin fiber on some properties of slurry-infiltrated fibrous concrete

Abstract Slurry-infiltrated fibrous concrete (SIFCON) is a special type of concrete that has great strength, as well as high ductility. However, the unit weight is high, which exceeds the unit weight of fiber-reinforced concrete, because of the high fiber content. This research aims to verify the compressive and flexural strength, as well as the density of SIFCON when using two different fibers (steel and polyolefin). Sometimes mono type of fiber steel or polyolefin, sometimes by hybridizing two types of fiber steel + polyplefin. Volume fraction (6% for all species) was used. Hook-end steel fiber and polyolefin fiber are used. With hybridization, a total volume fraction of 6% was used, which is 2/3 steel fibers with 1/3 polyolefin and vice versa. In addition, silica fume replaced 10% of the weight of cement. After checking all the results, the highest compressive strength was achieved in the SNS (symbol of mix SIFCON with 6% steel fiber) series by 81 MPa, as well as the highest flexural strength by 23 MPa, but it was the highest density of 2,490 kg/m3. The series contained 2/3 polyolefin and 1/3 steel fibers, which are ideal as they significantly reduced the density of the steel fiber series 2,490–2,210 kg/m3, as well as there was no significant reduction in strength as it achieved 67 MPa in the compressive strength and 19 MPa in the flexural strength, which are values suitable for high SIFCON applications.

Unit Weight of Foam Concrete Containing Blended Cement and Fly Ash

Abstract. The rapid development of construction and infrastructure results in increasing demands for natural resources continue. One of the many natural elements required for construction and infrastructure activities was cement, which is the basic ingredient in concrete. This study aims to analyze the unit weight of foam concrete containing blended cement and fly ash. The research approach used in this study was a laboratory experiment. Foam concrete was produced using 4 variations of cement (OPC, PCC-T, PCC-B and OPC+FA), fine aggregate, water and foam. The shape of the test object used was cube with a size of 15 cm × 15 cm × 15 cm. Unit weight test was used to evaluate the foam concrete mixture produced at the age of 3, 7, 28 and 730 days. The results showed that the unit weight of foam concrete in all variations of the specimens: OPC, PCC-T, PCC-B and OPC+FA, met the requirements for the unit weight of lightweight structural concrete based on SNI 03-3449-2002 and ACI 213R3 which was between 800 to 1400 kg/m3.