Types Of Lightweight Aggregates Research Articles

Study on the effect of lightweight aggregate types and steel fibers on the mechanical properties of lightweight engineered geopolymer composites (LW-EGC)

In this paper, the effects of the content of steel fiber and lightweight aggregate types on the mechanical properties of lightweight engineered geopolymer composites (LW-EGC) were investigated by uniaxial compression tests. The effect on compressive strength, stress-strain curves, elasticity modulus, peak strain, and energy absorption were discussed. The results showed that the type of lightweight aggregate had a significant effect on the mechanical properties of LW-EGC. LW-EGC-C had higher compressive strength, elasticity modulus, and energy absorption capacity. LW-EGC-S had a higher peak strain. Adding steel fibers could greatly increase the compressive strength, peak strain, and energy absorption. Meanwhile, there was an optimal range for the volume content of steel fiber, so the best improvement effect was achieved when the content of steel fiber was 1.0 %. Compared with LW-EGC-M, the above mechanical properties were improved by 39.28 %, 15.32 %, and 26.17 %, respectively. In addition, based on the existing constitutive models and test results, a stress-strain model for LW-EGC suitable for incorporating steel fibers is proposed. The constitutive model was divided into a rising phase and a falling phase, which could describe the falling curve more accurately than the existing constitutive models, indicating that it could reliably describe the compressive stress-strain response of LW-EGC.

Geopolymer-based insulated wall incorporating construction and demolition waste: Experimental assessment of thermo-physical behavior

The benefit of the application of geopolymers in the building sector is nowadays undisputed. In addition to good structural characteristics, these are characterized by interesting thermophysical properties, obtained through a production process, that reduces CO2 emissions and could incorporate recycled material, thus responding to environmental sustainability. However, it is noted the lack of studies regarding the in-field thermal performance. Thus, the aim of the present study is to investigate the thermal performance, under real conditions, of an innovative geopolymer-based insulated wall. It incorporates over 70% of net weight of Construction and Demolition Waste materials. The wall is conceived within the European project called “Green INSTRUCT” aimed to realize modular prefabricated building elements, for retrofitting and new construction of buildings. Two wall prototypes are analysed, which differ for the type of lightweight aggregate of geopolymer matrix, 3% by weight: expanded polystyrene or extruded polystyrene. The study refers to almost one year of continuous monitoring within a full-scale test room located in southern Italy. The method developed consists of 5 different phases and it involves also a normative-insulated reference wall. The results show higher insulation level of the proposed wall package, with a reduction of the heat flux of about 66% and more stable indoor thermal conditions, compared to the reference wall. Also the inertial properties are satisfactory, showing an experimental decrement factor equal to 0.05 and a time-shift of decrement factor higher than 6 h. All told, the experimental results can provide valuable insights into the real impact of innovative technology on energy efficiency and indoor thermal comfort.

“Advancements in Lightweight Concrete: A Comprehensive Review”

Abstract: Lightweight concrete (LWC) has garnered considerable attention in recent years due to its advantageous properties such as reduced density, improved thermal insulation, and enhanced sustainability. This review paper provides a comprehensive overview of the advancements, properties, production methods, applications, and future prospects of lightweight concrete. It covers various types of lightweight aggregates, admixtures, and innovative techniques employed in the production of lightweight concrete. Furthermore, it discusses the mechanical, thermal, and durability properties of LWC and compares them with conventional concrete. The review also explores the wide range of applications of lightweight concrete in construction projects and its contribution to sustainable development goals. Finally, it identifies current challenges and future research directions in the field of lightweight concrete.

Characteristics of Lightweight Concrete Fabricated with Different Types of Strengthened Lightweight Aggregates

The vast majority of different waste building units have negative environmental impacts around the world. Crushed building units can be recycled and utilized in the concrete industry to solve these problems and maintain natural resources. This study investigated the feasibility of employing crushed autoclaved aerated concrete (CAAC) and crushed clay brick (CCB) as a lightweight aggregate (LWA) to fabricate environmentally friendly recycled lightweight concrete (LWC). In addition, a lightweight expanded clay aggregate (LECA) was also used as an LWA, namely to study how the high porosity of an LWA can adversely affect the properties of LWC. Through the experimental program, all types of LWAs were pre-treated and strengthened with two cementitious grouts, and then the performance of the produced LWC was assessed by determining the slump of fresh concrete, the dry density, the unconfined compressive strength, and the splitting tensile strength at ages of 3, 7, 28, and 56 days. The laboratory results revealed that both CCB and CAAC can be reused as full substitutions for normal-weight coarse aggregate to manufacture LWC with appropriate properties. The obtained data show that the properties of an LECA, CCB, and CAAC were improved, and the porous structure can be strengthened by pre-treatment and coating with grouts. In the same way, the mechanical performance of produced LWC is also enhanced.

Impact of fine lightweight aggregates and coal waste on structural lightweight concrete: Experimental study and gene expression programming

Light Expanded Clay Aggregate (LECA) is one of the materials used to make lightweight concrete. In this study, two types of lightweight aggregates including LECA in both coarse and fine aggregate forms and pumice in fine aggregate form have been used to produce lightweight aggregate concrete. Coal waste is also used as partial replacement for cement. The results show that the usage of pumice as partial replacement for sand and LECA as coarse aggregate is applicable and can used for producing structural lightweight aggregate concrete. Furthermore, by using and increasing in the amount of LECA as fine aggregate, the slump of lightweight concrete in comparison to using sand, is also increased. The mixtures with LECA in both fine and coarse aggregate forms have the best results. Also, the results show that adding the coal waste improves the properties of lightweight concrete, and the optimal ratio is about 15% as partial replacement for cement by weight. In addition, gene expression programming is employed to establish empirical connections derived from experimental outcomes. In this regard, a relationship is proposed to determine the compressive strength of lightweight aggregate concrete based on the experimental data. The outcomes of gene expression programming demonstrate that the suggested formula exhibits good accuracy and efficiency in forecasting the specified parameter.

New strategy for closing the plastic loop: Lightweight concrete by the waste of recycled synthetic fibers

Environmental protection related to the mismanagement of plastic waste and rational consumption of natural raw materials is an essential goal of the building materials industry and the production of structural lightweight concrete. Plastic waste is not a degradable polymer and increases severe environmental burdens each moment due to its significant quantity. In addition, the recycling of plastic materials is lower than that of other materials. It is usually described as an inefficient and complex process. The textile industry offers an eco-green, effective part of the recycling loop of plastics. Therefore, many textile mills consider recycled plastics as synthetic fiber raw material, particularly for household applications. Unfortunately, such a process results again in another waste known as popcorn. This study aims to introduce an end-of-life management option for the waste of synthetic textile fibers manufactured from recycled plastic materials in construction. Furthermore, the study presents a novel approach to develop an eco-green lightweight structural concrete by incorporating a unique type of lightweight aggregate (popcorn aggregate) as a 100% environmentally friendly product. To achieve that, fourteen mixes of fine and coarse popcorn aggregate contents (25%, 50%, and 100%) are considered to replace the fine and coarse natural aggregate by volume. In addition, the workability, compressive, splitting tensile, flexural strength, microstructure analysis, and Energy Dispersive X-ray Spectrometry are assessed. The results revealed that the higher the substitution ratio of ordinary aggregates by popcorn aggregates, the higher the slump value. Meanwhile, the unit weight of hardened concrete exhibited a tangible decrease at a 100% replacement ratio of fine and coarse natural aggregates; a 56% reduction achieved a dry density of 1059 kg/m³. Moreover, the compressive strength results indicated a decrease of 32% for mixing 25% fine e popcorn aggregate with 100% coarse popcorn aggregate, resulting in a compressive strength of 45 MPa. Fine ally, no evidence of chemical interactions between the popcorn aggregate and the cementitious element during hydration is found.

Evaluation of the Effect of the Composition of the Foam Glass Concrete on Its Flammability and Moisture Characteristics

The purpose of this study was to evaluate the moisture and flammability characteristics of lightweight concrete with different aggregates and different amounts of cement according to different criteria. The moisture properties of the specimens were evaluated by the coefficient of water absorption due to capillary action, short-term water absorption, and water vapour permeability. Short-term water absorption correlated with the density of the specimens, and capillary absorption was evaluated depending on the soaking time, amount of cement, and type of lightweight aggregate. The values of the water vapour diffusion resistance factor were estimated based on the amount of cement, the type of lightweight aggregate, the density, and the porosity. The porosity correlated with the amount of cement and the type of lightweight aggregate. The flammability properties of concrete with lightweight aggregate were evaluated by several methods, such as the single flame source test, the single burning item test, and the non-combustibility test. After assessing the flammability characteristics, a structure analysis of the samples was specifically performed to assess the processes that occur during the combustion of lightweight concrete. It was found that short-term water absorption depended mainly on the density, capillary absorption on the amount of cement, and the water vapour diffusion resistance factor, flammability, and thermal stability of lightweight concrete on the type of granules.

Thermal and mechanical variations of cementitious composites with phase change materials using a contactless ultrasonic method

Recently, research on reducing building energy by applying phase change materials (PCMs), such as n-octadecane, to cementitious materials, is being actively conducted. PCMs were modified as a type of lightweight aggregate (LWA) to prevent leakage in concrete. In this study, a fully contactless ultrasonic system was applied to monitor thermal and mechanical variations of concrete plates including PCM-LWAs subjected to temperatures up to 48 °C. Because surface preparation and direct coupling processes were not required, this method collected reliable information without thermal interference. The measurements were conducted during the melting and free cooling process of PCM-LWAs, where the methods monitored the variation of leaky Rayleigh waves for dynamic modulus changes of the solid material. The experimental results illustrated that the contactless ultrasonic system enabled a 5.5 % reduction in dynamic modulus for a concrete plate mixed with 160 kg/m3 PCM-LWAs, and showed the time lag effect of heat transfer and surface temperature reduction through heat storage performance. Further comparison studies of the dynamic modulus variation among different mix proportions of PCM-LWA concrete plates were conducted using temperature cycles. Based on the experimental study, the unique thermal and mechanical behaviors of PCM-LWA mixed concrete plates were discussed.

Structural performance of fiber-reinforced SCC beams containing Stalite lightweight aggregates

This study intends to investigate the structural performance of large-scale fiber-reinforced lightweight self-consolidating concrete (LWSCC) as well as lightweight vibrated concrete (LWVC) beams made with Stalite aggregates under flexure loads. A total of fourteen reinforced concrete beam specimens were tested under a four-point bending configuration until failure. Two different binder contents (550–600 kg/m3), two types of lightweight aggregates (coarse and fine Stalite aggregates), two PVA fiber lengths (8–12 mm), and three fraction volumes of fibers (0.3%, 0.5%, and 1%) were considered in this study. The structural performance of the tested beam specimens was assessed in terms of load–deflection response, cracking behavior, energy absorption, displacement ductility, cracking moment, and ultimate flexural strength. This study also investigated the performance of design code provisions in predicting the cracking and ultimate moment capacities of all tested specimens. The results indicated that using shorter PVA fibers seemed to better improve the structural performance of LWSCC beams in terms of deformability, energy absorption, ductility, and ultimate flexural capacity than using longer PVA fibers. Using up to 1% PVA8 fibers in lightweight concrete beams made with Stalite aggregates proved to completely compensate for the drop in ultimate flexural strength that resulted from the use of low-density aggregates and further helped the beams to experience much higher rates of deformation. The results also showed that the model proposed by Henager and Doherty well predicted the ultimate moment capacity of LWSCC/LWVC beams reinforced with PVA fibers.

Constitutive model for plain and fiber‐reinforced lightweight concrete under compression

AbstractIn this research work, experimental investigations of the compressive behavior of plain and fiber‐reinforced lightweight‐aggregate concrete have been carried out (this formed part of a wider study, which also examined tensile and flexural behaviors). Compression mechanical properties were established in the studies and a generic constitutive compressive σ–ε model for both plain and fibrous lightweight concrete was derived and validated against experimental results from the present studies and previous research in the literature involving different types of lightweight aggregates, concrete strengths, and steel fibers. The reliability of predictions of the constitutive model was also checked against existing fibrous concrete models. A fiber‐reinforcing factor was also introduced taking into account the fiber volume fraction, fiber length and diameter, the number of fiber bends, and concrete compressive strength. As such, this was considered a better descriptor of the material than simply using the fiber volume fraction. The lightweight aggregates examined in the experimental study were recycled from fly ash waste and the fibers were hooked‐ended with single, double, and triple bends (corresponding to DRAMIX steel fibers 3D, 4D, and 5D types, respectively). The fibers were added at volume fractions Vf of 1% and 2% and the experimental studies were carried out using standard cube and cylinder uniaxial compression test specimens. It was concluded that the higher the number of bends and fiber content, the more pronounced the enhancement provided by the fibers to the compressive strength and ductility responses. All steel fibers used in the present studies were found to significantly improve the compressive toughness, while only 4D and 5D fibers (i.e., those with double and triple end bends) enhanced the compressive strength by up to 12% and 15%, respectively. It was also found that the elastic properties of plain lightweight concrete remained unaffected by the addition of fibers.

The Effect of Different Types of Aggregate and Additives on the Properties of Self-Compacting Lightweight Concrete

The major aim of this research is study the effect of the type of lightweight aggregate (Porcelinite and Thermostone), type and ratio of the pozzolanic material(SF and HRM) and the use of different ratios of w/cm ratio(0.32 and 0.35) on the properties of SCLWC in the fresh and hardened state. SF and HRM are used in three percentage 5%,10%, and 15% as a partial replacement by weight of cement for all types of SCLWC. The requirements of self-compatibility for SCC are fulfilled by using the high performance superplasticizer (G51) at 1.2liter per 100 kg of cement. The values of air dry density and compressive strength at age of 28 days within the limits of structural lightweight concrete. The air dry density and compressive strength at age of 28 days for w/cm ratio(0.32) for SCLWC of Porcelinit aggregate are 1964 kg/m3 and 29.57 MPa, respectively. The corresponding values for the SCLWC of Thermostone aggregate are 1820 kg/m3 and 25.75 MPa, respectively. The results show that the HRM performance which is locally available is better than SF in production of SCLWC.

Thermal Performance Assessment of Lightweight Aggregate Concrete by Different Test Methods

Structural lightweight aggregate concrete is currently an alternative to normal-weight concrete when thermal insulation properties are required to meet the objectives of energy efficiency and sustainability. The accurate evaluation of the thermal performance is thus essential for designing structural lightweight concrete elements. This paper aims to evaluate the thermal behavior of structural lightweight aggregate concrete, assessed through different tests methods. To this end, a vast experimental campaign was carried out involving specimens produced with several types of lightweight aggregate and different water/cement ratios. The thermal performance was established by thermal conductivity, which was determined according to a modified transient pulse method and a quasi-stationary method, and specific heat capacity, which was determined through a transient pulse method and a heat transfer method. Normal-weight concrete was also tested for comparison purposes. Experimental evidence showed that lightweight aggregate concretes with lower density are associated with up to about 50% lower thermal conductivity and higher specific heat capacity than normal-weight concrete. Moreover, the study demonstrated that the expeditious transient pulse method is suitable for assessing the thermal conductivity of this type of concrete, and that both the transient pulse method and the heat transfer method are adequate to determine the specific heat capacity.

Performance of Stalite lightweight SCC beam-column joints under reversed cyclic loading

This paper investigates the structural performance of Stalite lightweight self-consolidating concrete (LWSCC) beam-column joints under quasi-static reversed cyclic loading. Six beam-column joints made with different lightweight aggregate types (Stalite lightweight coarse [LC] and fine [LF] aggregates) and designed with/without joint shear reinforcement were cast and tested. The performance of tested specimens was assessed in terms of failure mode, hysteretic response, deformation, strength degradation, ductility, brittleness index, and energy dissipation capacity. The applicability and accuracy of design code provision in predicting the shear and flexural strengths of the tested joints were also investigated. The results indicated that it is possible to design Stalite LWSCC mixtures with a density ranging from 1888–1966 kg/m3, having a sufficient structural performance under cyclic loading. Properly designed LWSCC beam-column joints made with Stalite aggregates slightly reduced the load-carrying capacity by around 8.5% and ductility and dissipated energy by around 11.4% and 15.8%, respectively, compared to the normal-weight SCC (NWSCC) specimen. Despite the brittle nature of Stalite lightweight aggregates, LWSCC joints with sufficient hoops exhibited satisfactory cyclic performance and experienced ductile flexural beam failure. The results also indicated that LWSCC specimens containing Stalite fine aggregates showed better structural performance in terms of load-carrying capacity, strength degradation, ductility, brittleness index, and energy dissipation capacity compared to counterpart specimens made with Stalite coarse aggregates.

Mechanical and acoustic absorption properties of lightweight fly ash/slag-based geopolymer concrete with various aggregates

Acoustic absorption and thermal insulation play a key role in modern buildings to make living comfortable and energy-saving. This paper aims to study the workability, physical and mechanical properties, thermal conductivity, and acoustic absorption of modified geopolymer concrete (GPC) with various types of lightweight aggregates (LWA) such as extruded polystyrene foam beads waste (EPS), vermiculite, or lightweight expanded clay aggregate (LECA). The mixtures of geopolymer concrete have been modified by substituting for the ordinary aggregates (dolomite) by volume with various ratios of 0, 25, 50, 75, and 100% for each type of LWA. Besides, the mechanisms of specimens were examined by scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), and mapping. The results illustrated that the compressive strength values range between 8.5 and 47.50 MPa. The hardened density of concrete was between 1500 and 2450 kg/m3, and thermal conductivity was between 0.45 and 1.16 W/m.K. Geopolymer concrete was considered an acoustic absorption and thermally insulating material. Geopolymer concrete was considered an acoustic absorption and thermally insulating material. EPS, vermiculite, and LECA will be beneficial for applications in lightweight geopolymer concrete due to their capability to reduce weight and excellent thermal conductivity, and the property of improving acoustic absorption. The mechanical results indicated that 25% LECA was the best compared with the ratios of other LWA and gained 35.0, 2.7, and 4.3 MPa of compressive, splitting tensile and flexural strength, respectively. It had positive workability; the thermal conductivity was 1.1 W/m.K, and hardened density was decreased to 10% compared to the control. In addition, LECA is considered the superior and suitable material for acoustic absorption compared with other aggregates.

Effects of LED Lights and New Long-Term-Release Fertilizers on Lettuce Growth: A Contribution for Sustainable Horticulture

The horticulture sector has been directed by European guidelines to improve its practices related to environmental sustainability. Moreover, the practice of horticulture in urban areas is increasing since it provides fresh products that are locally produced. At the same time, horticulture needs to implement circular economy approaches and energy-efficient models. Therefore, to address these issues, this study investigated the effects of an integrated fertilizer-box-based cultivation system equipped with LED lights and coated porous inorganic materials (C-PIMs), which was applied as fertilizer, on Lactuca sativa L. growth. Two different types of lightweight aggregates were formulated considering agri-food and post-consumer waste, and they were enriched with potassium and phosphorus. Involving waste in the process was part of their valorization in the circular economy. Using PIMs as fertilizers enabled the controlled release of nutrients over time. The tests were carried out in controlled conditions using two LED lighting systems capable of changing their light spectrum according to the growth phases of the plants. The effects of two different lighting schemes on the growth of lettuce plants, in combination with different amounts of aggregates, were studied. The results showed that increasing the amount of C-PIMs statistically improved the lettuce growth in terms of dry biomass production (+60% and +34% for two different types of PIM application) when the plants were exposed to the first LED scheme (LED-1). Plant height and leaf areas significantly increased when exposed to the second LED scheme (LED-2), in combination with the presence of C-PIMs in the soil. The analysis of the heavy metal contents in the lettuce leaves and the soil at the end of the test revealed that these elements remained significantly below the legislated thresholds. The experimental achievements of this study identified a new approach to improve the environmental sustainability of horticulture, especially in an urban/domestic context.

A Machine Learning Approach to Prediction of the Compressive Strength of Segregated Lightweight Aggregate Concretes Using Ultrasonic Pulse Velocity

Lightweight aggregate concrete (LWAC) is an increasingly important material for modern construction. However, although it has several advantages compared with conventional concrete, it is susceptible to segregation due to the low density of the incorporated aggregate. The phenomenon of segregation can adversely affect the mechanical properties of LWAC, reducing its compressive strength and its durability. In this work, several machine learning techniques are used to study the influence of the segregation of LWAC on its compressive strength, including the K-nearest neighbours (KNN) algorithm, regression tree-based algorithms such as random forest (RF) and gradient boosting regressors (GBRs), artificial neural networks (ANNs) and support vector regression (SVR). In addition, a weighted average ensemble (WAE) method is proposed that combines RF, SVR and extreme GBR (or XGBoost). A dataset that was recently used for predicting the compressive strength of LWAC is employed in this experimental study. Two different types of lightweight aggregate (LWA), including expanded clay as a coarse aggregate and natural fine limestone aggregate, were mixed to produce LWAC. To quantify the segregation in LWAC, the ultrasonic pulse velocity method was adopted. Numerical experiments were carried out to analyse the behaviour of the obtained models, and a performance improvement was shown compared with the machine learning models reported in previous works. The best performance was obtained with GBR, XGBoost and the proposed weighted ensemble method. In addition, a good choice of weights in the WAE method allowed our approach to outperform all of the other models.

Study on axial compressive stress-strain relationship of alkali-activated slag lightweight aggregate concrete

Alkali slag lightweight aggregate concrete (AAS-LWAC) is a new type of green concrete prepared by alkali excited slag as cementing material and lightweight aggregate as coarse aggregate. It can effectively reduce the amount of Polandite cement and reduce carbon dioxide emission. However, there are no relevant studies on its axial compression constitutive properties. The effects of the type of lightweight aggregate, fiber type, and fiber content on the elastic modulus Ec, peak compressive strain εc, and axial compressive strength fcc of AAS-LWAC were studied in this paper. A suitable AAS-LWAC axial compression constitutive model is proposed. Scanning Electron Microscope (SEM) and Computed Tomography (CT) experiments were carried out to reveal the influence mechanism of the microstructure on the axial compressive properties of AAS-LWAC. The results show that AAS-LWAC with pulverized coal ash ceramsite as coarse aggregate has the highest axial compressive strength and peak compressive strain, and AAS-LWAC with shale ceramsite as coarse aggregate has the highest elastic modulus. Steel fiber can significantly enhance the axial compressive strength and peak compressive strain of AAS-LWAC, and the improvement effect is the best when the volume content of steel fiber is 0.6%. Three kinds of fibers can increase the elastic modulus of AAS-LWAC, and the effect of steel fiber is the most obvious.

Optimization of a structural lightweight fiber-reinforced concrete for best performance under impact loading

Compared to normal concrete, lightweight fiber-reinforced concrete (LFRC) offers several advantages, such as a high tensile strength-to-weight ratio and high energy dissipation under impact loading. However, LFRC has a lower compressive strength and modulus of elasticity than normal concrete; finding the appropriate mix design is also essential for structural engineering. This study aims to determine the best mix proportion of LFRC by evaluating the mechanical characteristics and energy dissipation capacity under impact loading. For this purpose, an experimental study is performed to optimize the mix proportion using three types of lightweight aggregates (Leca, expanded perlite, and expanded polystyrene). Moreover, the effects of two different steel and polyvinyl alcohol fibers on LFRC properties are investigated to improve the fracture energy and tensile strength. In both phases, two Drop Weight impact and Modified Charpy impact tests are utilized in addition to the quasi-static tests (compressive, splitting tensile, and flexural tests). A quality function is proposed to achieve the best mix proportion of lightweight concrete. The results demonstrate that the mixture containing 50% expanded perlite replacement with normal weight aggregates, 20% Slag as partial replacement of cement, 0.25% PVA fiber, and 0.25% steel fiber has the best performance in the mechanical properties and energy dissipation capacity as a structural lightweight fiber reinforced concrete.

Mechanical and durability performance of lightweight concrete (LWC) from colombian thermally expanded clay aggregates

Lightweight concrete (LWC) has become an outstanding material in the construction sector to conform non-structural and structural members into buildings. Expanded clay aggregate is a special type of lightweight aggregate formed by heating clay with little lime content, having low unit weight, high durability, and mechanical strength. Despite the massive use of the expanded clay lightweight aggregate worldwide, their use in the Colombian context is still limited. This research reports the characterization of the behavior of lightweight concrete from Colombian expanded clay aggregates. Experimental tests on fresh and hardened state (compressive strength, apparent density, and chloride migration) were carried out on lightweight concrete added Colombian expanded clay aggregate. It was found that the inclusion of up to 50% of the Colombian expanded clay aggregate causes a 15% workability decrease, 36% compressive strength decrease, 22% apparent density decrease as well as 34% decrease in the chloride migration coefficient of the lightweight concrete. In the same way, the lightweight concrete added with 50% of Colombian expanded clay aggregate meets the lightweight concrete requirements prescribed by the ACI 318 building code in terms of compressive strength, and unit weight. From the results, it is concluded that the use of Colombian expanded clay aggregate added up to 50% by weight of conventional aggregate is feasible to manufacture structural lightweight concrete.

Behavior of structural lightweight concrete produced with expanded clay aggregate and after exposure to high temperatures

The residual compressive strength of eight lightweight concrete mixtures containing three commercial grading (Liapor HD 5 N, Liapor HD 7 N, and Liapor 8F) of coarse lightweight aggregate (LWA) were determined after to expose at high temperatures. Eight mixes were produced, two by normal weight aggregate and the rest by different types of LWA. The produced concrete was analyzed after high temperature exposure and the effect of using LWA, the type of LWA, and compaction method was studied. To do so, visual inspection, residual compressive strength, crack pattern, spalling, and thermoanalytical analysis were conducted. Generally, it could be concluded that concrete formulations with LWA behave more advantageous up to 500 °C, compared to those with quartz gravel aggregates. Moreover, this study found that an ideal type of LWA to produce structural concrete was Liapor HD 5 N, which was used for producing the mixes L1 and L3.