High Performance Lightweight Concrete Research Articles

Enhancing the performance of lightweight high-performance concrete through an alternative pre-wetting method for lightweight aggregates using simulated cement pore solution

Lightweight aggregates (LWAs) are typically pre-wetted to prepare lightweight concrete. However, the incorporation of pre-wetted LWAs by water, may dilute the pore solutions of the cement matrix surrounding the LWAs during the process of internal curing. To this end, this paper proposes an alternative pre-wetting method for LWAs using simulated cement pore solutions (saturated Ca(OH)2 or real cement solution) instead of water. The effects of LWAs pre-wetted by various agents on the performance of lightweight high-performance concrete (LW-HPC) were investigated and compared. Experimental results confirmed that water released from LWAs diluted the pore solutions of cement in LW-HPCs. By using cement solution and Ca(OH)2 solution, the compressive strengths of LW-HPCs were respectively increased by 41.7% and 28.2% at 3d, and 11.6% and 3.2% at 28d compared with LWAs pre-wetted by water only. Among the three pre-wetting agents, the saturated cement solution was found to be the optimal one for promoting the hydration of cement, elastic modulus of the interfacial transition zone, and compressive strength.

Applied development of sustainable-durable high-performance lightweight concrete: Toward low carbon footprint, durability, and energy saving

Over the past few decades, the utilization of Lightweight Concrete (LWC) has emerged as a promising solution for reducing the dead load of structures. However, a key concern associated with the reduction of concrete density, is the potential decrease in mechanical and durability properties. This paradox necessitates a precise mix design that fulfills the requirements of high-strength concrete. This article investigates the influence of Lightweight Expanded Clay Aggregate (LECA) on the strength and durability, and thermal conductivity of Lightweight High-Performance Concrete (LWHPC). The LWHPC mixes explored in this study include sustainable cement solutions such as Portland limestone cement, varying water/binder ratios of 0.3 and 0.35, Leca contents ranging from 5 % to 20 % by volume, and two different pozzolanic supplements, namely silica fume and fly ash, which can be reducing porosity and enhancing durability and mechanical strength. The durability properties of the concrete were assessed through water absorption, electrical resistivity, and chloride migration profiles. Additionally, thermal conductivity measurements were conducted on all specimens. The results indicate that LWHPC, with a lower water/binder ratio, exhibits higher compressive strength and lower absorption, indicating good concrete quality. Generally, after a curing period of 90 days, mixtures with a density exceeding 1700 kg/m3 demonstrated superior durability characteristics. Furthermore, LWHPC mixes in both water/binder ratio groups displayed significantly low thermal conductivity with increasing lightweight aggregate content.

Influence of spatial dislocation of water on the properties of lightweight high-performance concrete

To prepare high-performance concrete, the mixing water was normally blended with the dry constituents directly, whereas in this study part of water was pre-located in the lightweight aggregates (LWA) for producing a high-performance lightweight concrete (HPLC). With the pre-location of water in the LWA, an extremely low w/b ratio paste (ultra high-performance composite) was resulted for producing HPLC. High-performance cement mortar (HPCM) was prepared with similar volumes of natural aggregates for comparison. Based on the initial spatial dislocation of mixing water in two systems, the physical, thermal and durability properties of high-performance cementitious composites were evaluated and compared. The results showed that the HPLC experienced delayed heat evolution when compared with that of the HPCM, while the cumulative heat output and degree of cement hydration of the two systems were similar. With the use of an increasing amount of LWA, the density of HPLC decreased significantly while the water penetration and ion permeability of HPLC were comparable to those of HPCM. More importantly, the HPLC exhibited a higher structural efficiency and much lower thermal conductivity than the HPCM. In addition to the pozzolanic reactivity and internal curing provided by the water-entrained LWA, the dislocation of mixing water method also enhanced the microhardness of the paste matrix, which contributed to the excellent performance of HPLC.

A novel high-performance lightweight concrete prepared with glass-UHPC and lightweight microspheres: Towards energy conservation in buildings

Improving energy conservation of buildings and promoting wastes recycling contribute to reducing CO2 emissions. This work developed a green high-performance lightweight concrete (HPLC) with good thermal insulation for energy-saving purposes. The HPLC was comprised of lightweight microspheres and sustainable ultra high-performance concrete (UHPC), which was prepared with a large volume of waste glass. For the glass-based UHPC, the use of glass cullet led to mechanical decrement, while the workability and mechanical properties were improved with the replacement of 50% cement by glass powder. Combining glass aggregates and powder in UHPC significantly enhanced its thermal insulation properties. Meanwhile, incorporating two kinds of lightweight microspheres in the glass-based UHPC further lowered the density and thermal conductivity of HPLC. The performance of HPLC was dependent on the physical characteristics of lightweight microspheres rather than their chemical reaction based on molecular dynamics simulation. The developed HPLC exhibited a low density (<2000 kg/m3) and excellent mechanical properties (compressive strength >100 MPa and flexural strength >35 MPa). The superior performance of HPLC was ascribed to the high pozzolanic reactivity of glass powder and its promotion on cement hydration, the low thermal conductivity of glass, the chemical reactivity of microspheres as well as their hollow nature for impeding heat transfer. The good flexure and thermal insulation performance would make this eco-HPLC a promising material for applications in energy efficient buildings and long-span lightweight structures.

Multiaxial Damage Ratio Strength Criteria for Fiber-Reinforced Concrete

Based on the damage ratio strength theory, a dimensionless damage ratio strength criterion for fiber-reinforced concrete (FRC) under true triaxial stress states was established under the assumption of small strains. Based on the experimental data of steel fiber–reinforced concrete (SFRC), polypropylene fiber–reinforced concrete (PFRC), hybrid fiber–reinforced concrete (HFRC), and steel fiber–reinforced high-performance lightweight concrete (SFRHLC), parameters for the damage ratio criterion were recommended. The damage ratio values were verified by SFRC experimental results under uniaxial, biaxial, and triaxial loading conditions, and the damage ratio values of SFRC under uniaxial tension, uniaxial compression, and biaxial equal compression stress conditions were compared with those of plain concrete. The true triaxial damage ratio strength criterion can be reduced to the conventional triaxial criterion and biaxial criterion, and the corresponding simplified strength criteria were proposed. The proposed dimensionless six-parameter criterion agrees well with the experimental results of the aforementioned materials for true triaxial, conventional triaxial, and biaxial loading conditions. Compared with the strength criteria in other studies, the proposed criterion can accurately represent the strength characteristics of FRC.

Fusion-Learning-Based Optimization: A Modified Metaheuristic Method for Lightweight High-Performance Concrete Design

In order to build high-quality concrete, it is imperative to know the raw materials in advance. It is possible to accurately predict the quality of concrete and the amount of raw materials used using machine learning-enhanced methods. An automated process based on machine learning strategies is proposed in this paper for predicting the compressive strength of concrete. Fusion-learning-based optimization is used in the proposed approach to generate a strong learner by pooling support vector regression models. The SVR technique proposes an optimization method for finding the kernel radial basis function (RBF) parameters based on improving the innovative gunner algorithm (AIG). As a result of AIG's diverse solutions, local optima are effectively avoided. Therefore, the novelty of our research is that, in solving the uncertainty of predicted outputs based on integrated models, we use fusion-learning-based optimization to improve regression discrimination. We also collected a standard dataset to analyze the proposed algorithm, and subsequently, the dataset was designed from concrete laboratory tests on 244 samples, seven features, and three outputs. Different regression intensities are determined by correlation analysis of responses. Regression fusion is sufficiently accurate to estimate the number of desired outcomes examined based on the appropriate input data sample. The best quality concrete can be achieved with an error rate of less than 5%.

Review of materials used in Low density concrete as Eco-friendly

Lightweight concrete is the most popular type in constructional activities to get low density for the concrete just as to diminish the extra weight of the structure. There are different types of lightweight concrete based on the type of lightweight material used. As considering eco-friendly materials like waste tires, waste steel fibres, plastic waste, agricultural waste, waste glass can be utilized in concrete by replacing coarse aggregate and fine aggregate. Lightweight concrete is preferable in constructional activities because of its low warm conductivity and improves fire resistance. In general, lightweight concrete ranges from 1440 to 1840 kg/m3. The main aim is to conclude the high-performance lightweight concrete by using a different type of materials in the same way to achieve low density for the concrete. By this study, we understand that high performance can be achieved by adding steel fibres to improve ductility and for low-density waste tire rubber by partial replacement in coarse aggregate and to improve durability by adding bacillus subtilis JC3 crack formation can be reduced.

Development of high performance lightweight concrete using ultra high performance cementitious composite and different lightweight aggregates

To reduce the dead load of concrete structures, this study developed a high performance lightweight aggregate concrete (HPLAC) by combining the use of ultra high performance cementitious composite (UHPC) and different types of aluminosilicate lightweight aggregates (LWAs). The physicochemical properties of two types of LWAs (i.e. expanded clay and expanded shale) influencing the HPLAC were elaborated and compared. The composition distribution and micromechanical properties in the interfacial regions of paste and LWAs were revealed by elemental mapping and nanoindentation. The results showed that the incorporation of the clay LWAs or shale LWAs in the HPLAC led to similar density and thermal conductivity values, while the use of the shale LWAs induced a lower water absorption and higher strength of HPLAC as compared to the clay LWAs due to the fine pore structure and higher pozzolanic activity of the former. The internal curing effect provided by the pre-wetted shale LWAs was more efficient in enhancing the hydration of binder, and the Al dissolution from the shale LWAs further densified the interfacial bonding to form a dense rim surrounding LWAs, resulting in improved micromechanical properties at the interface. The X-ray CT results indicated that the adoption of UHPC was beneficial to preventing segregation of the LWAs and steel fibers in the HPLAC. By virtue of the physical-chemical interactions of LWAs, the synergetic use of UHPC and pre-wetted shale LWAs was able to produce an HPLAC with high structural efficiency, good thermal insulation, low autogenous shrinkage and permeability.

Study on Effects of Pumice in High Performance Light Weight Concrete by Replacing Coarse Aggregates

Pumice is a rock particle that was used in this experiment’s concrete, and light weight aggregate is a type of aggregate that is lighter than natural aggregate. The major purpose of the suggested methodology is to use optimization techniques to frame a mathematical model. Structural lightweight concrete is used extensively in the construction sector, particularly in high-rise buildings. Only lightweight aggregates can be used to make it. Pumice is a solid component and a highly porous rock light in nature that can be used as an alternative to coarse aggregate (CA) in concrete and Nano Silica an alternative for cement. This lightweight aggregate, on the other hand, has a higher density than other natural and artificial lightweight aggregates. As a result, the density of concrete made with this lightweight aggregate is relatively high, falling into the semi-lightweight concrete category. According to the latest analysis, to further at the density of an lightweight concrete with high strength, Pumice was partially replaced with a coarse aggregate. In this study, pumice was substituted for CA in percentages of 0%, 20% and 30% by quantity and Nano Silica replaced in 1-3% for different mixes to predict three output parameters such as compressive strength (Mpa), split tensile strength (Mpa), flexural strength (Mpa). The addition of pumice to CA concrete decreases density while also lowering all mechanical properties, according to test results. This is because pumice has a smooth surface texture and has a lower density than CA. On the other hand, lightweight concrete containing more than 20% pumice changes into structural lightweight concrete with excellent strength. Several studies demonstrated an overall gain in strength as well as weight loss. As a result, light-weight concrete is equal to heavy-weight concrete in terms of strength.

Yüksek Performanslı Hafif Betonlarda Donatı Çapı ile Aderans Gerilmesi Arasındaki İlişki

High performance lightweight concrete (HPLC) is a new and original research in structural engineering. Due to the high risk of earthquakes, which is one of the biggest disasters today, the need for HPLCs has increased. The purpose of this study is to experimentally research concrete-reinforcement bond for the change parameters such as different reinforcement diameters and different embedded lengths. For this purpose, HPLCs with different mix ratios and different concrete components were prepared by using pumice aggregates. Within this scope, HPLC beam specimens of 100×180×800 mm dimensions were prepared and produced specimens were subjected to the Standard Belgium Hinged Beam (SBHB) test. There are limited studies in the literature on the investigation of the bond properties of HPLC beams with this test. The mentioned study draws attention with this aspect. In the present study, ribbed steel reinforcement bars with different diameters were used. The beam specimens were produced considering the different embedded lengths for each reinforcement diameter. The bond tests were performed. Using the load applied vertically and read with the help of the load cell in the experiment, the bond stress occurring in the reinforcement was calculated with the help of the force in the reinforcement indirectly found. As a result of the experiments, it has been determined that there is a significant relationship between bond stress and reinforcement diameter and embedded length. It has been determined that the bond stress decreases with the increase of reinforcement diameter and embedded length.

Study of Light Weight High Performance Concrete Filled Steel Tube Columns

Study of Light Weight High Performance Concrete Filled Steel Tube Columns

Effect of Impact Hot- Dry Weather Conditions on the Properties of High Performance Lightweight Concrete

The aim of this investigation is to produce high performance lightweight aggregate concrete in actual hot- dry weather conditions, and then study the combined effect of hot-dry weather conditions on the fresh properties of high performance lightweight aggregate concrete such as workability, initial and final setting time, measuring concrete temperature, and hardened concrete properties (compressive strength, splitting tensile strength and flexural strength, modulus of elasticity). The experimental program including the use of fixed mix proportions and was carried out in a typical Iraqi summer days (under actual conditions) of different times during the day, where the mean maximum temperature in shadow in July and August usually is more than 44° C and relative humidity of about 24 %, the results were compared with the specimens prepared and casted in laboratory and others in shadow site. The results indicate that as temperature rises, and relative humidity falls, the initial and final setting time were reduced, beside that actual drop in slump. The results also show that rising placing temperatures more than allowable concrete temperature that recommended in ACI 305 does not, as a rule, lead to lower strengths. The strength performance of concrete can remain unaffected by higher placing temperatures, or it can even improve over that at lower temperatures. Using pre-soaked lightweight aggregates (pumice) as internal water reservoirs for producing this type of concrete under actual hot-dry weather condition played positive role in improvement of concrete properties by compensate the evaporation of water due to the rising temperature and decreasing relative humidity, and provide additional moisture in concrete for a more effective hydration of the cement.

Mechanical Properties of Fiberous High Performance Lightweight Aggregate Concrete

Structural lightweight aggregate concrete solves weight and durability problems in buildings and structures. Recent advanced in material technology have accelerated the development of high performance concrete using lightweight aggregate. The main objective of this research is to produce high performance lightweight aggregate concrete reinforced with polypropylene and to study the mechanical properties of this type. The effect of various factors such as type of fiber and volume fraction of fibers also has been investigated. The experimental work included the use of pumice as coarse and fine lightweight aggregate, superplasticizer and silica fume to produce high performance lightweight concrete. Several trial mixes were examined to determine the proper proportion of the concrete constituent. Three types of polypropylene with different volume fraction were used. The procedure also includes studying the compressive strength, splitting tensile strength, flexural strength and static modulus of elasticity. The test results shows that the addition of all types of polypropylene fiber results in significant improvement in most mechanical properties compared with reference concrete specimens at different ages except compressive strength it was improved at Vf =0.25% and decrease at Vf =0.75%.

Strength and durability characteristics of ternary blend and lightweight HPC

High performance concrete (HPC) in three different forms were used in the present research and they were made with mineral admixtures, air entraining agent (AEA) and light weight aggregate (LWA). This paper deals with compressive strength, sorptivity, porosity, corrosion resistance and load carrying capacity of HPC. Experimental results reveal that, HPC with ground granulated blast furnace slag (GGBFS) (20%) and Quartz powder (10%) gave 68.4MPa (for fck=70MPa) the maximum compressive strength among three different forms used. In terms of durability the same mix showed a reduction of 60% in voids compared to control concrete. The load carrying capacity of that mix was only 6% less than control concrete. Performance of HPC made with LWA and AEA was inferior to HPC with mineral admixture. Hence HPC with GGBFS (20%) and Quartz powder (10%) was an optimum mix among the various mixes used.

Effect of CNT on Microstructure and Minearological Composition of Lightweight Concrete with Granulated Foam Glass

Light weight concrete is more and more popular material in modern building construction. Foamed concrete (FC) is the most prospective kind of light weight concrete.The most effective solution for achieving low density, law water absorption and localization of shrinkage is application of light weight aggregate - foamed glass grains. However, due to high silica content in foam glass aggregate, using these one in a cement-based composites creates a risk of alkali-silica reactions.The aim of this study is to achieve high performance light weight concrete with granulated foamed glass, and to evaluate the possibilities to localize alkali silica reactions using different admixtures, including carbon nanotubes.

Experimental analysis of behaviour of light weight high performance concrete with crystallized slag

Purpose The aim of this paper is to make lightweight high-performance concrete (LWHPC) with high economic performance from existing materials on the Algerian market. Concrete with high values with regard to following properties: mechanical, physical, rheological and durability. Because of the implementation of some basic scientific principles on the technology of LWHPC, this study is part of the valuation of local materials to manufacture LWHPC with several enhanced features such as mechanical, physical chemical, rheological and durability in the first place and with regard to the economic aspect in the second place. Design/methodology/approach The experimental study focused on the compatibility of cement/superplasticizer, the effect of water/cement ratio (W/C 0.22, 0.25, 0.30), the effect of replacing a part of cement by silica fume (8 per cent), the effect of combined replacement of a part of cement by silica fume (8 per cent) and natural pozzolan (10 per cent, 15 per cent, 25 per cent) and the effect of fraction of aggregate on properties of fresh and hardened concrete using the mix design method of the University of Sherbrooke, which is easy to realize and gives good results. Findings The results obtained allow to conclude that it is possible to manufacture LWHPC with good mechanical and physical properties in the authors’ town with available materials on the Algerian market. The mix design and manufacture of concrete with a compressive strength at 28 days reaching 56 MPa or more than 72 MPa is now possible in Biskra (Algeria), and it must no longer be used only in the experimental field. The addition of silica fume in concrete showed good strength development between the ages of 7 and 28 days depending on the mix design; concrete containing 8 per cent silica fume with a W/B (water/binder) of 0.25 has a compressive strength higher than other concretes, and concrete with silica fume is stronger than concrete without silica fume, so we can have concrete with a compressive strength of 62 MPa for W/C of 0.25 without silica fume. Then, one can avoid the use of silica fume to a resistance of concrete to the compressive strength of 62 MPa and a slump of 21 cm, as silica fume is the most expensive ingredient in the composition of the concrete and is very important economically. A main factor in producing high-strength concrete above 72 MPa is to use less reactive natural pozzolan (such as silica fume) in combination with silica fume and a W/B low of 0.25 and 0.30. The combination of silica fume and natural pozzolan in mixtures resulted in a very dense microstructure and low porosity and produced an enhanced permeability of concrete of high strength, as with resistance to the penetration of aggressive agents; thus, an economical concrete was obtained using this combination. Research limitations/implications The study of the influence of cementitious materials on concrete strength gain was carried out. Other features of LWHPC such as creep, cracking, shrinkage, resistance to sulphate attack, corrosion resistance, fire resistance and durability should be also studied, because there are cases where another feature is most important for the designer or owner than the compressive strength at 28 days. Further studies should include a range of variables to change mixtures significantly and determine defined applications of LWHPC to produce more efficient and economical concretes. It is important to gather information on LWHPC to push forward the formulation of characteristics for pozzolan concrete for the building industry. Practical implications The LWHPC can be used to obtain high modules of elasticity and high durability in special structures such as marine structures, superstructures, parking, areas for aircraft/airplane runways, bridges, tunnels and industrial buildings (nuclear power stations). Originality/value The novel finding of the paper is the use of crystallized slag aggregates and natural pozzolan aggregates to obtain LWHPC.

Fire performance assessment of HPLWC hollow core slabs through full-scale furnace testing

High-Performance Light-Weight Concrete (HPLWC) is used for many structural applications when superior strength and low self-weight of the structural components are required. Among these applications there are thin floor structures, like hollow core slabs, that require characteristics of lightness, relatively high resistance and superior durability. Although the fire performance of normal strength concrete hollow core slabs has been extensively studied, the behavior of HPLWC hollow core slabs has not been suitably investigated.The paper reports the results of two full-scale furnace tests on HPLWC hollow core slabs. Each of them involved one panel with an applied load and one without load. The evolution of temperature inside the slabs was measured along with the load bearing capacity under fire conditions. During the first test severe spalling occurred in the loaded slab while during the second one, performed on slabs cured for some months under dry conditions, spalling did not occur. Finite elements simulations were also carried out in order to support the interpretation of the experimental results. Experimental and numerical investigations gave insight into the fire performance of HPLWC hollow core slabs and highlighted the influence of dry curing conditions in reducing the spalling and increasing the fire resistance.

Manufacture and performance of cold bonded lightweight aggregate using alkaline activators for high performance concrete

Cold bonded lightweight aggregate (LWA) was produced by adding 12–50% ground granulated blast furnace slag (GGBS) and/or rice husk ash (RHA) to fly ash (FA) by the pelletization process without cement additives. Alkaline activator solution (as a combination of sodium silicate and sodium hydroxide) was the wetting agent acting as coagulant. The selected LWA was used as coarse aggregate for producing high performance concrete. The addition of GGBS and RHA in both binary and ternary blends improved crushing strength of LWA. The crushing strength of the binary and ternary blends was in the range of 6.0–15.7MPa, while that of the only use of FA was 5.7MPa. The unit weight of LWA ranged from 769 to 1060kg/m3. Fresh high performance lightweight concrete (HPLWC) with unit weight in the range of 1836–2056kg/m3 showed excellent flow-ability without bleeding or segregation. The 28-day compressive strength of HPLWC in the 14.8–38.1MPa range was obtained. The electrical resistivity and ultrasonic pulse velocity results showed that the physical conditions of HPLWC with the binary use of FA and GGBS and the only use of FA was better than that of the others.

Characteristics of Cold-Bonded Lightweight Aggregate Produced with Different Mineral Admixtures

Cold bonded lightweight aggregate (LWA) was produced by adding 0%, 25% and 50% granulated blast furnace slag (GGBS) or rice husk ash (RHA) to fly ash (FA) by the pelletization process with cement additives. The results show that GGBS addition significantly improved the crushing strength of LWA, whereas there was no effective on crushing strength of LWA when RHA was used. GGBS addition significantly reduced the water absorption of LWA; on the contrary, effect of RHA was to increase the water absorption. Unit weight of LWA added RHA was in range of 719-903 kg/m3, while that of LWA added GGBS was in range of 918-1082 kg/m3. High performance lightweight concrete (LWC) made with the selected LWA (60% FA + 40% Cement and 30% FA + 40%Cement + 30%RHA) had unit weight lower than 2000 kg/m3. The 28-day compressive strength of the LWC was in range of 49 to 57 MPa. The results of the electrical resistivity and ultrasonic pulse velocity tests indicate that the LWCs might be considered to be durable concrete.

Thermal Analysis of High Performance Lightweight Concrete Sandwich Panels

Thermal Analysis of High Performance Lightweight Concrete Sandwich Panels