Lightweight Geopolymer Concrete Research Articles

Analysis of Blended Concrete using Aerating Agent with Geopolymer

Geo polymer is considered as the third-generation cement after lime and ordinary Portland cement. Light weight geo polymer concrete is produced when for foaming agent is added to slurry, the function of foam is to create an air voids in fly ash–based geo polymer slurry. In this investigation of Light weight geo polymer concrete mixtures are produced foaming agent like aluminum powder with 0.5%,1.0%, 1.5% and 2.0% with Geo Polymer concrete and 15 Cube specimens are prepared and tested for mixtures of M30 mix as used in conventional concrete for Geo Polymer concrete ,then their physical (Density and workability) as well as specific structural (Compressive Strength) properties were investigated, Specific Strength and Percentage Strength gain for aerated concrete is compared with normal weight concrete and the results are reported. Key words- Light-weight concrete, Geo polymer concrete mass, Geo Polymer, strength –properties, foaming agent, density, target strength, fly ash.

Producing Sustainable Lightweight Geopolymer Concrete Using Waste Materials

Abstract A research has been undertaken to investigate the possibility of producing sustainable lightweight geopolymer material by using waste zeolite (zeolite molecular sieve) as aluminates and silicates source and at the same time as lightweight medium. This was done by totally or partially replacement of fly ash by waste zeolite particles. Six geopolymer mixes were designed and produced using different source materials (fly ash F, fly ash C and zeolite) and alkaline solution of sodium silicate and sodium hydroxide. From the results, it was found that using fly ash C resulted in producing geopolymer mix with higher density than those made with fly ash F (Gf mix). However, replacing the fly ash totally with the zeolite particles helped in producing lightweight geopolymer concrete (1600 kg/m3) by achieving about 27% weight reduction and gaining about 5.1 MPa compressive strength. Not only reducing CO2 emissions by adopting zeolite- based geopolymer binder (instead of cement paste) but also achieving operational energy saving by producing lightweight concrete was obtained from producing lightweight geopolymer concrete as constructional material.

Development of a high-strength lightweight geopolymer concrete for structural and thermal insulation applications

Investigating the thermal insulation properties of lightweight geopolymer concrete is essential. This paper aims to develop a lightweight aggregate geopolymer concrete (LWAGC) with good density, compressive mechanical and thermal insulation properties. The dry density of LWAGC was adjusted by incorporating expanded perlite (EP). The variation in physical and mechanical properties of LWAGC with different EP content was discussed, including dry density, P-wave velocity, ultimate compression strength and elastic modulus. Based on infrared thermal imaging technology, a rapid measurement method was proposed to simulate the indoor temperature change of buildings at high ambient temperatures. The thermal insulation performance of the LWAGC with different EP contents was further evaluated. The findings show that as the EP content in LWAGC increases, there is a corresponding decrease in P-wave velocity, dry density, ultimate compressive stress, and elastic modulus. The lowest dry density of LWAGC reaches 1209kg/m3 while the ultimate compressive stress is still larger than 25.0MPa, which can used as LC25 building materials in load-bearing structures. The results also show that the addition of EP can improve the thermal insulation properties of LWAGC. The LWAGC with 50% EP content has the highest reduction rate of temperature and can maintain the indoor temperature lower than 35 °C under high ambient temperature, which have potential application prospects in the load-bearing structures and thermal insulation of tall buildings.

INFLUENCE AND PREDICTION OF SINTERED AGGREGATE SIZE DISTRIBUTION ON THE PERFORMANCE OF LIGHTWEIGHT ALKALI-ACTIVATED CONCRETE

The most effective method for mitigating the adverse environmental impacts of traditional concrete involves substituting cement and natural aggregate with waste and byproduct resources. Utilizing sintered lightweight aggregate (fly ash) in geopolymer concrete emerges as an efficient solution for managing and disposing of significant amounts of fly ash. The influence of sintered aggregate size distribution on the performance of alkali-activated concrete, focusing on compressive strength improvement. The study employs sintered fly ash aggregate (SFA) as coarse aggregate, aiming to optimize packing density through proper particle distribution. The highest compressive strength is achieved with a mix featuring 75% 4-8mm and 25% 8-12mm SFA. Regression-based strength models are developed, exhibiting good alignment with conventional concrete models. Thin section techniques reveal enhanced aggregate-matrix interaction due to the porous structure of SFA. The study emphasizes the potential of SFA in geopolymer concrete for sustainable construction. Lightweight geopolymer concrete, owing to its lower density, significantly reduces the overall structural load.

The effect of artificial metakaolin coarse aggregate on the mechanical and durability properties of lightweight geopolymer concrete

<p style="text-align:justify; margin-bottom:11px"><span style="font-size:11pt"><span style="line-height:150%"><span style="font-family:Calibri,"sans-serif""><span lang="PT-BR" style="font-size:12.0pt"><span style="line-height:150%"><span style="font-family:"Times New Roman","serif""><span style="color:#131413">This study presents a unique methodology for investigating the properties of  Metakaolin Coarse Aggregates (MCA). The NaOH ratios were varied as 8M, 10M, 12M, and 14M, while the NaOH to Na<sub>2</sub>SiO<sub>3</sub> ratio was maintained at 0.5 entire study. The liquid-to-binder (L/B) ratios set at 0.3, 0.35, and 0.4. Testing was conducted on the MCA to determine its physical and mechanical properties, comparing them with those of Natural Coarse Aggregate (NCA). Notably, the 8M mix with a 0.4 L/B ratio was found to be economical for producing MCA and was selected for further research. This chosen mix was then employed to prepare geopolymer concrete with 50% MK and 50% PA, with L/B ratios set at 0.4, 0.45, and 0.5. The NaOH ratio and Na<sub>2</sub>SiO<sub>3</sub> to NaOH ratio were maintained at a constant 8M and 2, respectively. Mechanical and durability properties were compared between Geopolymer concrete with NCA and Geopolymer concrete with MCA. The test results demonstrate that MCA in geopolymer concrete can effectively replace NCA in geopolymer concrete, making it a viable option for structural members. Additionally, microstructural characterization was performed on Geopolymer concrete with MCA mixes with varying L/B ratios of 0.4, 0.45, and 0.5, at 28 days. The study specifically focuses on the Interfacial Transition Zone (ITZ) between MCA and geopolymer paste, revealing an improvement in ITZ and microstructure in the GMCA sample with a 0.4 L/B ratio compared to other mixes.</span></span></span></span></span></span></span></p>

Mixture Design for Lightweight Geopolymer Concrete

Mixture Design for Lightweight Geopolymer Concrete

Optimisation of mechanical properties and pore structure of lightweight geopolymer concrete

Lightweight geopolymer has good physical and mechanical properties, thermal and chemical stability and low carbon dioxide emissions. The development of high-strength lightweight geopolymer concrete (LGC) for load-bearing structures can expand geopolymer applications. The use of ground granulated blast-furnace slag (GGBFS) to improve the mechanical properties and pore structure of LGC was investigated. The ultimate compressive stress of LGC containing GGBFS were analysed, as well as the variation in microscopic pore structure. Specimens of LGCs with different strengths (LC20, LC30 and LC40) were investigated. As the GGBFS content increases, the ultimate compressive stress and specific strength of LGC increases, while the strain corresponding to the peak stress decreases, indicating that the mechanical properties and deformation resistance of LGC are improved. The carbon dioxide emissions of LGC are less than those of cement-based lightweight concrete, indicating that LGC has good sustainability. Moreover, the addition of GGBFS can produce more gel and reduce the volume proportion of capillary pores and air pores, resulting in LGC densification. Recommended GGBFS contents for strength grades LC20, LC30 and LC40 are 0–12.7%, 12.7–24.6% and 24.6–30%, respectively. The LGC is lightweight and has high strength, and has potential for application in civil engineering.

Investigating the mechanical and physical properties of lightweight geopolymer concrete

Using waste materials and by-products from various building sectors is gaining popularity because natural resources are quickly depleting. Geopolymer concrete is made from by-product material and is a relatively new environmental material that does not require the presence of ordinary Portland cement as a binder. This study involves producing lightweight geopolymer concretes using a slag binder and replacing the conventional fine and coarse aggregates with two types of locally available lightweight aggregate (thermostone and montmorillonite). Several sequential steps were used to process the aggregates, along with a series of tests conducted to evaluate the concrete properties in different states. The fresh state test includes the slump test, while the hardened concrete tests involve compressive strength, flexural strength, density, thermal conductivity, and water absorption. This study reveals the suitability of lightweight concrete mixtures for various constructional applications. The most reliable mixture was the GMM, which consisted of coarse montmorillonite (5–25 mm) and fine montmorillonite aggregates. This mixture exhibited the highest compressive strength of 23.3 MPa, a flexural strength of 3.25 MPa compared to other LWGC mixtures, and a low density of 1785 kg/m3. The GMM density was 23.97% lower than the reference mixture, whereas the thermal insulation significantly improved by 65.58%. Consequently, this improvement was evident in the thermal conductivity coefficient, which measured as approximately 0.349 W/m.K. In addition, the GTT mixture containing thermostone aggregate (5-25 mm) yielded the most optimal thermal insulation and lowest density of 0.267 W/m.K and 1552 kg/m3, respectively. In general, the strength and density of the LWGC mixtures in this study meet the requirements of lightweight structural applications.

The effect of lightweight geopolymer concrete containing air agent on building envelope performance and internal thermal comfort

Innovative building materials are the primary focus for researchers seeking to reduce energy consumption and advance global sustainability initiatives. This target could accomplished by addressing environmental issues and confronting the adverse impact of climate change. In this regard, this paper used a combined experimental and simulation approach to evaluate the effectiveness of lightweight geopolymer concrete (LWGC) incorporating industrial waste of aluminum powder (AP) and ferrosilicon waste powder (FWP) for reducing the energy consumption in the building envelop. Seven concrete mixes for LWGC were prepared using an air operator. Three mixtures contain 0.1 %, 0.2 %, and 0.3 % AP (FA), and three mixtures contain 0.1 %, 0.2 %, and 0.3 % FWP by weight of fly ash. The workability, unit volume weight, compressive strength, thermal conductivity, and microstructure analysis of the LWGC were examined. In addition, energy simulations were performed to evaluate their ability to reduce energy use in residential buildings. The inclusion of AP and FWP in LWGC resulted in a significant decrease in the density of the material, which amounts to 55 % for AP0.3 and 35 % for FWP0.3. The diameter of the LWGC pore structure increased as the Ca/Si ratio was reduced. The AP and FWP materials reduced energy consumption for building envelope elements such as external walls and roof insulation by 14.5 %, resulting in a 9.2 % overall reduction compared to the traditional concrete mix as a control sample.

Mix design of FA-GGBS based lightweight geopolymer concrete incorporating sintered fly ash aggregate as coarse aggregate

Geopolymer concrete (GPC) is emerging as a sustainable alternative to conventional Portland cement-based concrete due to its significantly reduced carbon footprint and enhanced durability. To mitigate the environmental hazard posed by the disposal of fly ash (FA) and ground granulated blast furnace slag (GGBS) waste and reduce cement consumption, effective promotion of the geopolymerization technique is necessary. Incorporating sintered fly ash coarse aggregate (SFA) in GPC makes the concrete light in weight. This study involves the synthesis of geopolymer technology using FA and GGBS, as the primary source material. Due to the lack of an appropriate mix design method for using SFA in GPC, their application as a structural concrete is scanty. By using FA and GGBS with 100% SFA, a novel mix design methodology that offers greater simplicity and consistency is established in the present study. The proposed method is further verified by developing different concretes with alkali content to binder (AC/B) ratios ranging from 0.3 to 0.8. Fresh densities range between 1860 and 1930 kg/m3 and maximum compressive strength of nearly 50 MPa was attained after 28 days of ambient curing. The binder penetration and internal curing in SFA indicate that GGBS and FA have a superior synergistic effect on the efficacy of lightweight GPC using SFA.

Use of Alkaline-Activated Energy Waste Raw Materials in Geopolymer Concrete.

Silica fly ash, Certyd aggregate, and an alkaline solution were used to produce lightweight geopolymer concretes. The compressive strength, water absorption, and bulk density results, along with SEM photos showing the structure of the obtained composite, were obtained. Tests conducted on the specifications of lightweight geopolymer concretes have revealed significant chemical interactions between the ash aggregate and the geopolymer mortar, particularly when the coarse aggregate surface has been pre-treated with an alkaline solution. A statistical analysis of the experimental data, which investigated the influence of three key variables on the compressive strength, water absorption, and bulk density of lightweight geopolymer concrete (LBG), identified the following factors as having the most substantial impact: the quantity of alkali used, the curing temperature, and the concentration of alkali in the mixture. The optimal test series exhibited a commendable compressive strength of 20.14 megapascals (MPa), accompanied by a water absorption rate of 14.72%, and a bulk density of 1486.6 kg per cubic meter (kg/m³). These findings underscore the importance of alkali content, curing temperature, and alkali concentration in tailoring the properties of lightweight geopolymer concrete to meet specific performance requirements.

Renewable Energy for Carbon Footprint Reduction of Production of Lightweight Geopolymer Concrete

In the present world, researchers have been keenly interested in developing special concrete like Geo polymer concrete in recent years due to its lower global warming impact, better serviceability, higher durability, and overall economy compared to conventional concrete. Geo polymer is a comparatively new substitute binder for making concrete. The geopolymer binders are produced using industrial by-products such as fly ash and blast furnace slag instead of ordinary Portland cement. Using Geo polymer can reduce CO2 emissions and lower the global warming impact. The major issue before the present community is to minimize the CO2 emission, which is also the lead source of global warming. In the present research, an attempt has been made to predict that the CO2 emission rate has either increased or declined in preparing the concrete by using Hand-mixing concrete. The calculations of CO2 emission during manufacturing have been devised based on the collected data. It has also been proposed that how CO2 emission can be reduced by varying the concrete mix proportions or by replacing the ingredients of concrete.

Behaviour of sewage sludge based lightweight aggregate in geopolymer concrete

The global challenge of sewage sludge disposal has encouraged innovative solutions aimed at reducing environmental impact while simultaneously addressing the growing demand for sustainable construction materials. This study aimed to develop treated raw sewage sludge-based lightweight aggregates with strength comparable to commercially available aggregates. Two methods, namely cold bonding and sintering, were employed for the formation of aggregates. The sintering method produced well-formed and hard aggregates, while the cold bonded aggregates exhibited weakness and disintegrated under the slightest pressure. The optimal mix for quality aggregates was found to be 10%–20% sewage sludge, 70%–80% fly ash, and 10% lime using the sintering method. In the sintering method, an increase in sewage sludge content resulted in the reduction of bulk density and specific gravity by 13% and 4% respectively due to the high organic content in sewage sludge, volatile gas release, and porous structure formation. When 10% to 20% sewage sludge content was added, water absorption of the aggregates also increased by approximately 2%. Physical properties such as individual pellet strength. aggregate crushing value reduced by 18%, 20% respectively and the aggregate impact value increased by about 9%. These aggregates were then used to produce lightweight geopolymer concrete, which exceeded the design strength by 7% for the aggregate containing 20% sewage sludge and demonstrated excellent physical properties. The use of waste-based aggregates offers advantages including savings in cost, sustainability, resource conservation, waste reduction, and reduced environmental impact, making them a valuable alternative to natural crushed stone aggregates in specific applications.

Development of low carbon concrete and prospective of geopolymer concrete using lightweight coarse aggregate and cement replacement materials

The use of Ground Granulated Blast-furnace Slag (GGBS) as an alternative cement replacement material in combination with conventional coarse aggregate have been successful in the production of near green concrete. Undoubtedly, GGBS has exhibited good cementitious attributes, however, there are concerns with slow strength development and workability owing to its non-pozzolanic activities as well as some degree of porosity notwithstanding the sustainability potential. Therefore, this study presents a lytag based geopolymer lightweight concrete with high strength development, improved mechanical properties and reduced embodied carbon. To further improve and enhance the potential production of green concrete, complete replacement of conventional coarse aggregate with a recycled lightweight aggregate from industrial waste was carried out. The geopolymer precursors consisted of sodium hydroxide, sodium silicate, GGBS and silica fume to optimize the performance of the concrete at 60–80% cement replacement for a target design mix of 20, 30, 40, and 50 MPa. The performance of lytag based geopolymer concrete was compared with that of non-geopolymer lytag based concrete (control samples). The results show a 42% increase in compressive strength for the geopolymer lightweight concrete and a 22% increase in ultimate compressive strain which is an indication of improved moment of resistance in structural design. The results also show a 46–61% reduction in embodied carbon for the use of non-geopolymer lytag based concrete and 69–77% reduction for lytag based geopolymer concrete. The geopolymer concrete between 7 and 63 days of loading increases by 0.55% in creep strain compared with increases of 2.81% for non-geopolymer lytag based concrete and reduction to 27.96% for the normal weight concrete. Modulus of Elasticity reduces with age of loading for the geopolymer concrete during creep at 0.39% compared to reduction of 1.93% for non-geopolymer lytag based concrete and increase of 12% for the normal weight concrete.

Assessment of mechanical and durability properties of FA-GGBS based lightweight geopolymer concrete

The relentless consumption of natural aggregates and cement in concrete due to rapid construction has resulted in the exhaustion of natural resources; consequently, it's vital to create environment friendly building materials and implement sustainable construction methods. The development of geopolymer concrete (GPC) is a step towards the utilization of by-products. This study aims to prepare and assess the durability and mechanical characteristics of fly ash (FA) and ground-granulated blast furnace slag (GGBS)-based lightweight geopolymer concrete (LWGC). Utilizing sintered fly ash aggregate (SFA) in GPC is one such approach that can lower the usage of regular cement and natural aggregates. In the present investigation a total of six GPC mixes were prepared with varying alkaline activator to binder (AA/B) ratios of 0.3–0.8. The results shows that the AA/B ratio and the mechanical characteristics of LWGC samples are inversely related. The mechanical properties exhibits maximum strength at the lowest AA/B ratio. The LWGC achieved the highest compressive strength (CS) of 48.9 MPa, modulus of elasticity (EM) of 27.3 GPa, split tensile strength (STS) of 3.9 MPa, and direct shear strength of 5.4 MPa after 28 days of ambient curing. The oven dry density (OD) ranged from 1722–1805 kg/m3, satisfying the various codal provisions to be considered a lightweight concrete (LWC). The durability study indicates that for structural applications, the performance is satisfactory, especially in acidic conditions. SEM and EDS analyses also infer strong mechanical and durability characteristics. The obtained results suggests that LWGC is a possible material for structural concrete applications.

Impact of coconut husk microcrystalline cellulose on the properties of geopolymer lightweight concrete

Geopolymer composite is an alternative to ordinary Portland cement. It has potential to avoid CO2 emissions to the atmosphere and to save raw materials during its manufacture. Flyash-based geopolymer concrete is altered by adding ground granulated bast-furnace slag (GGBS) to improve its fresh and hardened properties. Thermal ash aggregate is used as coarse aggregate to reduce geopolymer concrete density, improve strength, and conserve natural aggregate. Along with this matrix, coconut husk microcrystalline cellulose (MCC) is added to enhance its performance. In a M40 grade flyash and GGBS-based geopolymer concrete, MCC was used to replace fly ash at 1% to 5% levels. The geopolymer composites were tested for slump, compression, split tensile, water absorption, and acid resistance to determine the way coconut husk MCC interacts with lightweight concrete. An inclusion of 3% MCC with geopolymer composites improved 2% slump, 6% of compressive and split tensile strength. About 1.6% of water absorption was reduced in GPC matrix with 3% of MCC. Meanwhile 3% of MCC in geopolymer concrete improved, 4% of weight and 7% of strength under acid exposure. The research strongly supported utilizing MCC in geopolymer concrete to render it more sustainable and eco-friendlier.

A Review of Lightweight Geopolymer Concrete Based on Slag

Abstract: The studies on Lightweight Geopolymer concrete (LGC) are leading-edge in the development of sustainable and ecofriendly concrete. Attempts were being made to develop LGC by various methods of production. This paper reviews about previously published research work on lightweight geopolymer concrete and the observations to the material binders - an alternate to the Ordinary Portland Cement (OPC) by the utilization of industrial by-products, alkaline activator solution, foaming agents, chemical expansive agents, lightweight aggregate, production methods, and their physical and mechanical properties. The main focus is to investigate pore size formation, density, compressive strength and curing conditions. From the review it is found that the stabilization of foam and the control of efflorescence are the two challenging problems faced by the industry for the mass production of lightweight geopolymer foam concrete. Furthermore, topics for future work in this field were suggested.

Investigating the fracture parameters of lightweight geopolymer concrete reinforced with steel and polypropylene fibers

In this current paper, the effects of different percentages of scoria (70, 80, and 90) replacing coarse aggregates, steel fiber volume fractions (Vsf = 0.5 %, 1 %, and 1.5 %) merely and in combination with polypropylene fiber volume fractions (Vppf = 0.1 %) on fracture parameters of lightweight geopolymer concrete(LWGC) have been studied using WFM(Work of Fracture Method) and SIZEM(Size Effect Method). The results indicate that: (a) increasing the content of Vsf and Vppf increases the fracture energy and fracture toughness. (b) The content of polypropylene and steel fibers has remarkable effects on fracture parameters in compositions containing 70 % scoria. (c)The composition of 70 % scoria instead of coarse aggregates, containing (Vsf = 1.5 %) and (Vppf = 0.1 %) is more significant in the analysis of fracture parameters than other samples in this research. In general, it can be said that the increase of fracture parameters like Gf, GF, KIC, and Cf is more noticeable in samples containing 70 % scoria. Also, in the samples containing 70 % scoria, containing (Vsf = 1.5 %) and (Vppf = 0.1 %), the Gf, KIC, and GF are almost 1.84, 1.44, and 2.08 times the control samples, respectively. It is also to see an increase in parameters such as Gf, GF, and KIC in samples containing (Vsf + Vppf) compared to (Vsf). This shows the positive effect of adding polypropylene fibers (Vppf = 0.1 %) to the samples. When the content of steel fibers increases by 0.5 %, 1 %, and 1.5 %, the increase in the mentioned parameters can also be observed. The positive effect of increasing the content of steel fibers in increasing the fracture energy obtained from the results is determined.

Thermal and mechanical performance of lightweight geopolymer concrete with pumice aggregate

AbstractThis study aims to prepare and assess the mechanical characteristics of fly ash (FA)‐based lightweight geopolymer concrete (LWGPC) utilizing pumice as a coarse aggregate. A comprehensive set of 16 LWGPC mixtures were synthesized. The first twelve mixtures produced with varying alkaline to FA ratio and varying proportions of coarse aggregates. The mixture proportion that has given the highest compressive strength (CS), was selected to create four other LWGPC mixes with water‐to‐solid ratios (w/s) ranging from 0.17 to 0.23. Fresh and mechanical properties as well as thermal conductivity (TC) of the LWGPC samples were examined. The experimental findings indicate an inverse relationship between the w/s ratio and mechanical properties of LWGPC samples. Notably, the mechanical properties attain their highest values at the lowest w/s ratio, primarily attributed to reduced porosity and higher concentration of alkali solution in the mixtures with lesser water content. The LWGPC achieved highest CS of 13 MPa, modulus of elasticity (ME) of 8.8 GPa, flexural strength (FS) of 2.2 MPa, and tensile splitting strength (TSS) of 1.64 MPa. The oven dry density (ODD) and TC values ranged from 1746 to 1815 kg/m3 and 0.119 to 0.131 W/m K, respectively. A low‐cost and eco‐friendly novel lightweight concrete composition with low TC was developed.

Assessment of sustainable eco-processed pozzolan (EPP) from palm oil industry as a fly ash replacement in geopolymer concrete

This research focusses on the feasibility of using eco-processed pozzolan (EPP), a palm oil industrial by-product, as partial replacement for fly ash (FA) in the geopolymer concrete (GPC); in addition, the effect of another palm oil industrial by-product, palm oil clinker (POC) as the lightweight coarse aggregate in the EPP-based GPC was also investigated. The ratios of alkaline activator to binder and sodium silicate to sodium hydroxide were kept constant, and the specimens were cured at 60 °C for 24 h. The mechanical properties, namely compressive, splitting tensile and flexural strengths, and modulus of elasticity (MOE) were investigated; further, microstructural analyses such as SEM, XRD and EDX were conducted. The test results show that the utilisation of 10–30% of EPP as FA replacement produced the compressive strengths in the range of 28–39 MPa. The splitting tensile strength of both the lightweight (LW) and normal weight (NW) GPC, except for M6 containing 30% of EPP substitution, fulfilled the minimum requirement of 2.0 MPa. In addition, the flexural strength of GPC produced about 12% of the respective compressive strength. The lower MOE of LW GPC compared to the NW GPC is attributed to the lower stiffness and specific gravity of POC aggregates. The XRD analysis shows the evidence of geopolymerization products of quartz, sillimanite, magnetite, and almandine.