Self-compacting Geopolymer Concrete Research Articles

GGBFS-Based Self-Compacting Geopolymer Concrete with Optimized Mix Parameters Established on Fresh, Mechanical, and Durability Characteristics

GGBFS-Based Self-Compacting Geopolymer Concrete with Optimized Mix Parameters Established on Fresh, Mechanical, and Durability Characteristics

Effect of mineral admixtures on the performance of self-compacting geopolymer concrete

Self-Compacting Geopolymer Concrete (SCGC) emerges as a groundbreaking construction material in the domain of concrete technology. This method integrates supplementary cementitious materials (SCM), alkaline solutions like sodium hydroxide and sodium silicate, and a superplasticizer to form a binder for matrix development and strength enhancement, thereby eliminating the need for compaction.In the present study, fly ash-based Self- Compacting Geopolymer Concrete (SCGC) was substituted with varying proportions of Ground Granulated Blast Furnace Slag (GGBS). Concrete specimens were subjected to curing under both oven and ambient conditions to assess their performance.The investigation unveiled that incorporating GGBS into fly ash-based SCGC resulted in reduced workability alongside improved strength with increasing binder content. Notably, SCGC samples cured at 70°C for 24 hours with a 50% replacement of GGBS emerged as the optimal proportion, meeting the required workability standards. However, surpassing this threshold led to a further enhancement in mechanical properties albeit at the expense of reduced workability.

Effect of Molarity of Sodium Hydroxide Solution Over GGBS-based Self Compacting Geopolymer Concrete

Applications of geopolymer concrete are increasing at a faster rate globally and are actively replacing cement concrete in all its facets. Regarding this, the advancement of, self-compacting geopolymer concrete is inevitable. The present study deals with the investigation of the effect of the molarity of sodium hydroxide solution that is to be used as part of an alkaline solution, over self-compacting and hardened properties of geopolymer concrete. Ground granulated Blast Furnace Slag (GGBS) is used as precursor material; hence, ambient curing is adopted. The alkaline activator solution is a combination of silicate solution and hydroxide based on sodium. In this work, the hydroxide solution’s molarity is varied to 8, 10, 12, 14, 16, and 18. Self-compacting properties are investigated through spread flow, T-50, V-funnel test, and L-box. The compressive strength of the hardened concrete is investigated over 7 and 28 days. Further water absorption test was also assessed in this investigation to determine the basic durability. All the specimens with different molarities exhibited fair self-compacting properties. Further optimum molarity required for the synthesis of self-compacting geopolymer concrete with fair compressive strength and excellent reduced water absorption capability is determined. The findings of this work tend to augment significant contributions to the geopolymer concrete in the facets of self-compacting nature.

Development of Self-Compacting Geopolymer Concrete Using Fayalite Slag Aggregates

Because of its high cement consumption, which limits its use in concrete construction, self-compacting concrete requires a higher cement content and various admixtures. Therefore, it is prudent to explore alternative options to minimize environmental impacts while creating environmentally friendly self-compacting concrete. This study examines the use of fly ash (FA) and ultrafine slag (UFS) in self-compacting geopolymer concrete (SGC), supplemented with fayalite slag aggregates (FSA). These aggregates, in varying quantities up to 60%, were used instead of traditional sand. The rheological properties and compressive strength of SGC were investigated. The analysis revealed that the addition of FSA improved the flowability of SGC. Notably, using a combination comprising 60% FSA, the largest slump measurement of 683.5 mm was achieved. Substituting up to 20% of FSA generally improved the properties of SGC at all ages. After one year, the mixture containing 20% FSA outperformed other compositions, with a maximum compressive strength of 49.38 MPa.

UTILIZATION OF BLAST FURNACE SLAG IN CONCRETE - REVIEW

The impact of silica fume on the strength development rate and durability of binary concretes containing low reactivity slag. Results show that silica fume moderately improves strength gain but significantly enhances durability and water demand. The use of blast furnace slag and fine aggregate in construction materials for cold weather conditions. It found that GBFS aggregate increased compressive strength, frost resistance, and enhanced resistance against sulfuric acid attacks, demonstrating its potential for use in cold weather construction. The durability and strength of coal gangue-based geopolymer concrete, revealing that proper GBFS content and alkali activator modulus can improve freeze-thaw resistance. Alkali activated Self-Compacting Geopolymer Concrete (SCGC) using Ground Granulated Blast Furnace Slag (GGBS) incorporated with 2% nano silica. The mix design with 16M alkaline solution and 500 Kg/m3 binder content exhibited the highest compressive, flexural, and split tensile strength at 90 days. The corrosion performance of recycled aggregate concrete, focusing on water to binder ratios and the impact of 50% ground granulated blast furnace slag. Showed that the addition of ground granulated blast furnace slag increased surface resistivity to 88 kΩcm and decreased carbonation resistance. This increased potential and decreased corrosion rate, indicating that the inclusion of ground granulated blast furnace slag in recycled aggregate concrete mixes enhances corrosion resistance. The impact of waste beverage glass on the performance of ground granulated blast furnace slag concrete mixes. Results show that waste beverage glass reduces workability but improves mechanical properties, while increasing water absorption.

Interfacial bond behavior between normal OPC concrete and self-compacting geopolymer concrete enhanced by nano-SiO2

This study investigated the interfacial bond performances between ordinary Portland cement concrete (OPCC) and self-compacting geopolymer concrete (SCGC). The studied factors include nano-SiO2, repair material type, curing time, casting direction, and interface pretreatment method. The interfacial bond performances were assessed by Bi-surface shear and drying shrinkage tests. The evolutions in elemental compositions, hydration products, and microstructure in the matrix and interface were verified by BSE/EDS, XRD, and FTIR tests, respectively. ANOVA analysis was conducted to quantitatively analyze the influences of each factor from a statistical approach. The results demonstrated that the bond strength of SCGC increased by 24.5% to 31.7% compared to conventional OPCC. Meanwhile, geopolymers exhibited more compact microstructures but higher drying shrinkage (εsh,u=891 µε). While nanofillers significantly amplified the cracking potential of geopolymers, which was attributed to the higher early-stage autogenous shrinkage instead of drying shrinkage. The SCGC showed a high enrichment degree of calcium at the interface, indicating that more calcium-rich products were formed. In contrast, the use of nano-SiO2 in SCGC caused the enrichment of Na, Al, and Si at the interfacial regions, which provided extra nucleation sites for the polymerization of (C, N)-A-S-H gels. The nano-SiO2 enhanced the intensity of the hydroxide ion and Si-O-T band and promoted the formation of (C, N)-A-S-H gels. The ANOVA analysis proved that the repair material, nano-SiO2, and interface treatment were significant factors to affect the interfacial bond strength. In addition, geopolymer-based repair materials were less sensitive to the casting direction, which differed from the conventional self-compacting OPCC.

Assessing the engineering properties of massive self-compacting geopolymer concretes utilising the Taguchi method

In this article, the potential of employing self-compacting geopolymer concrete in massive elements has been investigated. The main binder consisted of 85% ground granulated blast furnace slag and 15% fly ash. An alkaline solution of sodium hydroxide and sodium silicate was utilised. The effects of four parameters (binder content, water-to-binder [W/B] ratio, Na2O% and coarse-to-fine aggregate [C/F] ratio) on the fresh, mechanical and thermal properties of Massive Self-Compacting Geopolymer Concrete (MSCGC) mixes were evaluated. Taguchi’s design of experiments was used to minimise the number of trial mixes. The heat of geopolymerisation of MSCGCs was monitored using a semi-adiabatic chamber and then applied to concrete samples using a temperature match curing system. The maximum compressive and splitting tensile strengths and modulus of elasticity were 62.7 MPa, 5.04 MPa and 33.26 GPa, respectively. Binder content was identified as the most significant parameter affecting the thermal and mechanical properties of the mixtures. The impact of the C/F ratio was greater than the W/B ratio on the thermal characteristics. The results of a numerical analysis reveal that although a higher binder content enhances the mechanical properties of the MSCGCs, it leads to an increased risk of cracking owing to greater heat production.

Developing a sustainable self-compacting geopolymer concrete with 100% geopolymer-coated recycled concrete aggregate replacement

PurposeConcrete, the second most used material in the world, surpassed only by water, relies on a vast amount of cement. The process of cement production emits substantial amounts of carbon dioxide (CO2). Consequently, it is crucial to search for cement alternatives. Geopolymer concrete (GC) uses industrial by-product material instead of traditional cement, which not only reduces CO2 emissions but also enhances concrete durability. On the other hand, the disposal of concrete waste in the landfills represents a significant environmental challenge, emphasising the urgent need for sustainable solutions. This study aimed to investigate waste concrete's best form and rate as the alternative aggregates in self-compacting and ambient-cured GC to preserve natural resources, reduce construction and demolition waste and decrease pertinent CO2 emissions. The binding material employed in this research encompasses fly ash, slag, micro fly ash and anhydrous sodium metasilicate as an alkali activator. It also introduces the best treatment method to improve the recycled concrete aggregate (RCA) quality.Design/methodology/approachA total of25%, 50% and 100% of coarse aggregates are replaced with RCAs to cast self-compacting geopolymer concrete (SCGC) and assess the impact of RCA on the fresh, hardened and water absorption properties of the ambient-cured GC. Geopolymer slurry was used for coating RCAs and the authors examined the effect of one-day and seven-day cured coated RCA. The mechanical properties (compressive strength, splitting tensile strength and modulus of elasticity), rheological properties (slump flow, T500 and J-ring) and total water absorption of RCA-based SCGC were studied. The microstructural and chemical compositions of the concrete mixes were studied by the methods of energy dispersive X-Ray and scanning electron microscopy.FindingsIt is evident from the test observations that 100% replacement of natural aggregate with coated RCA using geopolymer slurry containing fly ash, slag, micro fly ash and anhydrous sodium metasilicate cured for one day before mixing enhances the concrete's quality and complies with the flowability requirements. Assessment is based on the fresh and hardened properties of the SCGC with various RCA contents and coating periods. The fresh properties of the mix with a seven-day curing time for coated RCA did not meet the requirements for self-compacting concrete, while this mix demonstrated better compressive strength (31.61 MPa) and modulus of elasticity (15.39 GPa) compared to 29.36 MPa and 9.8 GPa, respectively, for the mix with one-day cured coated RCA. However, incorporating one-day-cured coated RCA in SCGC demonstrated better splitting tensile strength (2.32 MPa) and water absorption (15.16%).Research limitations/implicationsA potential limitation of this study on SCGC with coated RCAs is the focus on the short-term behaviour of this concrete. This limited time frame may not meet the long-term requirements for ensuring the sustained durability of the structures throughout their service life.Originality/valueThis paper highlights the treatment technique of coating RCA with geopolymer slurry for casting SCGC.

Production of durable high-strength self-compacting geopolymer concrete with GGBFS as a precursor

Production of durable high-strength self-compacting geopolymer concrete with GGBFS as a precursor

Mix design process for sustainable self-compacting geopolymer concrete

Faster growth of infrastructure emphasizes the utilization of eco-friendly construction materials with a low carbon footprint. The objective of this experimental study is to propose a mix design methodology for self-compacting geopolymer concrete (SCGC) considering various influencing parameters recommended for self-compacting concrete (SCC) and geopolymer concrete (GPC). The experimental test results depict that SCGC had similar flow deformability with comparatively lesser flow speed compared to SCC. The increase in a sodium hydroxide (NaOH) molarity from 8 M to 16 M negatively affected the flow deformability as well as the flow speed of SCGC. The optimum compressive strength of 37 MPa was attained for SCGC having silica sand as fine aggregate, NaOH concentration of 16 M, fly ash to sand ratio (FA/S) of 0.75, and cured for 48 H at 80 °C. A mathematical equation is proposed to calculate Young's modulus of SCGC which is around 15 GPa. Young's modulus of SCGC was lesser than OPC concrete recommended by the ACI 318, however, Poisson's ratio of SCGC was found in the recommended range of OPC concrete. A flow chart is proposed for the mix design of SCGC with consideration of experimental test results in fresh and hardened stages.

Axial compressive behaviour and physical characteristics of high strength self-compacting geopolymer concrete (HSGC) columns exposed to elevated temperature

The growing demand in the utilization of the cement has increased carbon emissions, necessitating the adoption of new technologies that are eco-friendly. Geopolymer concrete (GC) is a viable alternative to traditional cement-based concrete, with superior mechanical properties and sustainable performance. However, research on the elevated temperature exposure of geopolymer paste, mortar, and concrete is limited, particularly with respect to high-strength and self-compacting geopolymer concrete. This study aims to investigate the performance of high-strength self-compacting geopolymer concrete (HSGC) at room temperature and elevated temperatures up to 1029 ℃. The investigation is carried out consisting of two strength grades: normal strength GC and HSGC. Tests are conducted on both HSGC cube and column specimens to examine the residual compressive strength (CS) and axial compression performance of the concrete before and after exposure to elevated temperature. The fresh physical characteristics of HSGC are examined following EFNARC guidelines. Post-fire performance is analysed through physical observation, surface modification, crack pattern, weight loss (WL), and residual CS of HSGC samples. Load-Moment (P-M) interaction curves are developed to predict the ultimate load and ultimate moment capacity of the HSGC columns before and after exposure to elevated temperature. The ductility of heated and unheated HSGC columns is found to be almost same. Microstructural analysis, scanning electron microscopy (SEM), and energy dispersive X-ray spectroscopy (EDS) are performed to examine the internal morphology of the HSGC samples before and after exposure to elevated temperature. Furthermore, a life-cycle assessment (LCA) is conducted to compare the cost of HSGC production with conventional cement-based concrete. The analysis indicates that HSGC emits 6.15% less CO2-e than its counterpart cement-based concrete.

Mechanical and microstructural properties of MK-FA-GGBFS-based self-compacting geopolymer concrete composites

Self-compacting geopolymer concrete (SCGC) is an eco-efficient and sustainable concrete with a lower carbon footprint than conventional concrete. The combination and doping of composites present a challenge in investigating the mechanical and microstructural properties of SCGC. This experimental work investigated the effect of different dosing levels of metakaolin (MK), fly ash (FA), and ground granulated blast furnace slag (GGBFS) on the properties of SCGC composites from both macroscopic and microscopic aspects. The main objectives of this study are to determine the fresh properties of SCGC in the fresh state and its mechanical properties in the hardened state and to explain the reasons for the differentiation of macroscopic properties through mesoscopic and microscopic analyses. Results showed that both MK and GGBFS reduce the flowability of fresh geopolymer concrete, with MK having a greater negative effect than GGBFS, with maximum and minimum slump flows of 645 mm and 505 mm, respectively. With the increase of MK and GGBFS admixture, the compressive strength of SCGC continuously increased until reaching the maximum value of 51.76 MPa, which corresponded to maximum admixtures of 50% and 40% for MK and GGBFS, respectively. GGBFS had the greatest positive effect on the rapid development of the early mechanical properties of SCGC, with calcium oxide (CaO) playing a crucial role. The 3d/7d compressive strength of SCGC was 0.83/0.85 of 28d when the slag admixture reached 40%, respectively. Strength prediction models with excellent fit coefficients were developed, and the correlation coefficients for the three equations were 0.83, 0.98, and 0.99. A higher stress level of SCGC corresponds to a higher intensity and density of the acoustic emission signal. Thermal analysis results showed that the higher the CaO content in the SCGC specimen, the smaller the residual mass of the sample, i.e., the higher the number of gels and compressive strength. Scanning electron microscope images showed that a higher CaO content of SCGC corresponded to a denser matrix structure and better mechanical properties.

Behavioural studies on binary blended high strength self compacting geopolymer concrete exposed to standard fire temperature

The production of Ordinary Portland Cement Concrete (OPCC) results in high carbon emissions and energy demand, necessitating the search for eco-friendly alternatives. Geopolymers, which utilize waste materials, are identified as a suitable alternative. Industrial by-products such as Fly Ash (FA), Ground Granulated Blast Furnace Slag (GGBS), and Metakaolin (MK) are used as precursor materials for binary blended High Self-Compacting Geopolymer Concrete (HSGC) production. Two HSGC mixes and one normal strength self-compacting mix are developed for comparison. This study aims to look at the residual strength characteristics of NSGC and HSGC specimens. Binary blended NSGC, HSGC, and temperature exposure are the key factor examined in the present study. The current study aimed to evaluate the residual strength of NSGC and HSGC exposed to temperature exposure using the ISO 834 guidelines. HSGC specimens are divided into four groups based on curing and cooling type: ambient curing, oven curing, air cooling, and water cooling. Mechanical properties such as Compression Strength, Tensile Strength, and Flexural Strength before and after exposure to elevated temperature are evaluated. Microstructural investigations are conducted to examine the internal structure of the binary blended HSGC mixes. The experimental results are validated using Indian code (IS 456), American code (ACI 318), European code (EC2), and Australian code (AS 3600). Compressive strength of the HSGC specimens was severely reduced when subjected to 1029 ℃, resulting in the formation of wider cracks attributed to the degradation of the gel structure. The oven-cured specimens possess 72 to 80% loss in strength, whereas ambient-cured specimens possess 77 to 86% loss in strength. The findings reveal that the binary blended mix FA/MK = 1 exhibits higher strength loss (%) compared to FA/GGBS and FA. Ambient-cured HSGC specimens exhibit higher mass loss than oven-cured HSGC mixes, and water-cooled samples show higher strength loss and wider cracks compared to air-cooled specimens. The scientific value of this study lies in the the fire performance and residual mechanical properties of binary blended HSGC mixes developed under various curing and cooling methods. Also, the experimental results are validated with multiple international codes (American, Australian and Indian Standards). These findings contribute to the understanding on the behaviour of HSGC under elevated temperature conditions by providing valuable insights for the development of eco-friendly concrete alternatives with improved fire performance.

Workability and Compressive Strength of Self-Compacting Geopolymer Concrete Blended with Industrial and Agricultural Waste

Workability and Compressive Strength of Self-Compacting Geopolymer Concrete Blended with Industrial and Agricultural Waste

Structural assessment of Basalt FRP reinforced self-compacting geopolymer concrete using artificial neural network (ANN) modelling

Basalt FRP geopolymer composites are considered a sustainable solution to address the conventional OPC-Steel composite structures' structural and environmental concerns, especially the increased carbon emissions and structural deterioration due to corrosion attacks. Recent research on novel composites reports the superior performance of these FRP-geopolymer concrete structural applications reporting high strength and durability. However, the existing design guidelines do not accurately predict the flexural capacity and strength characteristics, which hinders the broader use of FRP-based geopolymer composites. This study aims to develop a prediction tool to help the researchers model the structural performance of the novel FRP-geopolymer composite based on modern machine learning algorithms. It shall address the lack of data on novel composites' structural and long-term performance in various exposure conditions. This paper thus reports the suitability of Artificial Neural Network (ANN) based models to accurately predict the flexural strength of Basalt FRP reinforced self-compacting geopolymer concrete beams under various exposure conditions. The ANN model is trained and validated against the experimental data from the long-term study conducted on the beam specimens subjected to one-year ambient and marine exposures. The ANN prediction model developed in this study reported close agreement with the experimental data showing better prediction accuracy than the existing empirical and numerical models.

Long-term performance of basalt fibre-reinforced marine geopolymer concrete in harsh environment

The current study reports on the long-term structural performance of novel reinforced marine geopolymer concrete beams under accelerated weathering conditions. The study covers the flexural performance of 40 geopolymer concrete beams reinforced with basalt fibre-reinforced polymer (BFRP) bars, including 12 beams under sustained loading when exposed to 3, 6 and 12 months of accelerated marine environment consisting of tidal cycles of seawater at a temperature of 50°C. The experimental results revealed that the novel marine geopolymer concrete reinforced with BFRP bars reported minimal micro- and macro-mechanical degradation compared to geopolymer concrete or ordinary concrete beams under the same exposure environment, with and without sustained loading. The BFRP-reinforced self-compacting geopolymer concrete (SCGC) beams reported 87% residual ultimate load after 12 months of exposure to marine environments, while the sustained loaded BFRP-SCGC beams reported a residual strength of 79%. In addition, microstructural assessment using scanning electron microscopy and energy dispersive X-ray spectroscopy analysis revealed that after 12 months of exposure there was a trace of chloride salts, indicating the chemical ingress over time; however, the impact on structural properties is not distinct.

Influence of GGBFS-based blended precursor on fresh properties of self-compacting geopolymer concrete under ambient temperature

Geopolymer concrete having self-compacting nature is known as self-compacting geopolymer concrete (SCGC) which does not need mechanical compaction to improve the concrete density. The geo-polymerization process primarily depends on aluminosilicate materials and alkaline activator solution (AAS). The type of precursor material greatly affects the hardened concrete properties i.e. both the short-term and long-term concrete characteristics. The present study aims to achieve an optimal blended precursor-based SCGC possing acceptable fresh property characteristics where ground granulated blast furnace slag (GGBFS), the precursor in the control GGBFS-based SCGC is partially replaced by silica fume (SF), and rice husk ash (RHA) with various proportions. Mix proportions with the replacement of GGBFS by SF (10%, 20%, 30%, 40%) and RHA (5%, 10%, 15%, 20%) are prepared along with one control GGBFS-based SCGC. The fresh property of the nine SCGC mixes are interpreted through the filling ability (slump flow, T50cm slump, V-funnel); passing ability (L-box, J-ring), and resistance to segregation (V-funnel at T5minutes) test. All the ambient temperature-cured SCGCs are made with the following mix parameters: 12 M sodium hydroxide molarity, AAS ratio of 2.5, superplasticizer dose of 7%, and extra water of 24%.

Effect of superplasticizer types and dosage on the flow characteristics of GGBFS based self-compacting geopolymer concrete

Self-compacting geopolymer concrete (SCGC) is produced from waste materials that act as binders or precursors promoting sustainable concrete. Among all components of the SCGC mix, the superplasticizer dosage primarily controls the workability of concrete along with mechanical strength. An attempt is made in this current study to find the best suitable type of superplasticizer and its dosage through given fresh property investigation. For the accomplishment of the project objective, four types of superplasticizers are considered in the SCGC mix preparation and are polycarboxylate ether-based, modified naphthalene-based, lignosulphonate-based, and mother liquor-type superplasticizers. The superplasticizer dosage considered in each is 4%, 6%, and 8%. In the absence of a suitable design standard SCGC mix designs are prepared and concrete is produced with characterized material components. Twelve M25 SCGC mix designs are prepared with some constant parameters like 12 M concentration of sodium hydroxide, the ratio of sodium silicate to sodium hydroxide as 2.5, and 24% extra water addition. The freshly prepared concrete has undergone various workability tests to examine the filling ability (FA) (slump flow, T50cm slump flow, V-funnel); passing ability (PA) (L-box, J-ring); and segregation resistance (SR) (V-funnel at T5minutes). The 6% naphtha (NP)-based superplasticizer is regarded as the superior superplasticizer from the fresh property consideration in the GGBFS-based SCGC.

Study of Self Compacting Geopolymer Concrete (SCGC) haunch beams at monotonic loading and loading-unloading scheme

Numerous reinforced concrete structures require strengthening due to mistakes in detail engineering design, incorrect execution during construction, or overloading. One method of structural strengthening is to use haunch beam casted near column. The development of infrastructure in Indonesia leads to an increase in cement use. This phenomenon causes a greenhouse effect due to higher CO2 emissions, so that an effort is performed in order to reduce the use of cement concrete by using geopolymer concrete. This study aims to experimentally analyze the behavior of haunch beams using both Self-Compacting Geopolymer Concrete (SCGC) and conventional Self-Compacting Concrete (SCC) in terms of load and deflection at first crack, yield, and ultimate conditions as well as crack pattern and plastic hinge of the beam. This study utilized four specimens consisting of SCGC and SCC haunch beams with a compressive strength fc’ of 31 MPa. All identical specimens were tested at monotonic loading and loading-unloading conditions. As a result, the haunch beams due to monotonic loading have larger load capacity and deflection compared to the haunch beams due to loading-unloading. The SCGC haunch beam has slightly lower load capacity and smaller deflection compared to the SCC haunch beam. This shows the SCGC performance is relatively similar to that of the SCC. The SCGC can substitute the SCC, especially for structural reinforcements. Due to monotonic loading and loading-unloading state, both the SCGC and the SCC haunch beams were plasticized at the same location at the haunch end. By implementing the haunch beams, plastic hinges move away from the column.

Influence of Discrete Basalt Fibres on Shrinkage Cracking of Self-Compacting Ambient-Cured Geopolymer Concrete

Short basalt fibres (BFs) have recently gained significant interest in the building materials sector due to their superior mechanical characteristics and cheaper manufacturing cost than other fibre types. Drying shrinkage and the early-age cracking of concrete are the root cause of many durability issues in the long run. Including small dosages of fibres within concrete composites has been shown as an effective technique to minimise drying shrinkage rates and reduce the crack widths developed due to plastic shrinkage cracking. Nevertheless, limited research studies have investigated the influence of short and long BFs with different dosages on the drying shrinkage rates and early-age cracking of geopolymer composites. In the present study, self-compacting geopolymer concrete (SCGC) using fly ash and slag as the binder is mixed with anhydrous sodium metasilicate powder as an alkali-activator. The study aims to investigate the influence of short (12 mm), long (30 mm) and hybrid-length (1:3 (short/long)) BFs with 1%, 1.5% and 2% dosages on the drying shrinkage properties and plastic shrinkage cracking of SCGC. The study results showed that adding BFs to SCGC reduces the drying shrinkage rates compared to plain SCGC, and SCGC reinforced with a 2% dosage of hybrid-length BFs recorded the lowest drying shrinkage rate. Two methods were used to measure crack widths: manual measurement (crack width gauge) and image analysis. No plastic shrinkage cracks were identified in mixes reinforced with 12 mm (1.5% and 2% dosages), 30 mm and hybrid-length BFs.