Prediction of Geopolymer Concrete Compressive Strength Using Convolutional Neural Networks

Geopolymer concrete emerges as a promising avenue for sustainable development and offers an effective solution to environmental problems.Its attributes as a non-toxic,low-carbon,and economical substitute for conventional cement concrete,coupled with its elevated compressive strength and reduced shrinkage properties,position it as a pivotal material for diverse applications spanning from architectural structures to transportation infrastructure.In this context,this study sets out the task of using machine learning(ML)algorithms to increase the accuracy and interpretability of predicting the compressive strength of geopolymer concrete in the civil engineering field.To achieve this goal,a new approach using convolutional neural networks(CNNs)has been adopted.This study focuses on creating a comprehensive dataset consisting of compositional and strength parameters of 162 geopolymer concrete mixes,all containing Class F fly ash.The selection of optimal input parameters is guided by two distinct criteria.The first criterion leverages insights garnered from previous research on the influence of individual features on compressive strength.The second criterion scrutinizes the impact of these features within the model’s predictive framework.Key to enhancing the CNN model’s performance is the meticulous determination of the optimal hyperparameters.Through a systematic trial-and-error process,the study ascertains the ideal number of epochs for data division and the optimal value of k for k-fold cross-validation—a technique vital to the model’s robustness.The model’s predictive prowess is rigorously assessed via a suite of performance metrics and comprehensive score analyses.Furthermore,the model’s adaptability is gauged by integrating a secondary dataset into its predictive framework,facilitating a comparative evaluation against conventional prediction methods.To unravel the intricacies of the CNN model’s learning trajectory,a loss plot is deployed to elucidate its learning rate.The study culminates in compelling findings that underscore the CNN model’s accurate prediction of geopolymer concrete compressive strength.To maximize the dataset’s potential,the application of bivariate plots unveils nuanced trends and interactions among variables,fortifying the consistency with earlier research.Evidenced by promising prediction accuracy,the study’s outcomes hold significant promise in guiding the development of innovative geopolymer concrete formulations,thereby reinforcing its role as an eco-conscious and robust construction material.The findings prove that the CNN model accurately estimated geopolymer concrete’s compressive strength.The results show that the prediction accuracy is promising and can be used for the development of new geopolymer concrete mixes.The outcomes not only underscore the significance of leveraging technology for sustainable construction practices but also pave the way for innovation and efficiency in the field of civil engineering.

A Study on the Effect of Low Calcium Ultra-fine Fly Ash as a Partial Sustainable Supplementary Material to Cement in Self-compacting Concrete

The aim and scope of the present study were to determine the efficacy of UFFA in evaluating the workability,static and dynamic stabilization properties,retention period,and slump loss of SCC systems in their fresh state,as well as their compressive strength at various ages.Microstructure(SEM and XRD)of blended SCC systems were studied.Also,the thermogravimetry behavior of blended SCC specimens were researched.According to the evaluated results,incorporating up to 20%UFFA into fresh concrete improved its performance due to its engineered fine particle size and spherical geometry,both of which contribute to the enhancement of characteristics.Blends of 25%and 30%of UFFA show effect on the water-binder ratio and chemical enhancer dosage,resulting in a loss of homogeneity in fresh SCC systems.The reduced particle size,increased amorphous content,and increased surface area all contribute to the pozzolanic reactivity of the early and later ages,resulting in denser packing and thus an increase in compressive strength.The experimental results indicate that UFFA enhances the properties of SCC in both its fresh and hardened states,which can be attributed to the particles’fineness and their relative effect on SCC.

Prediction Model of Compressive Strength of Fly Ash-Slag Concrete Based on Multiple Adaptive Regression Splines

Accurate prediction of compressive strength of concrete is one of the key issues in the concrete industry. In this paper, a prediction method of fly ash-slag concrete compressive strength based on multiple adaptive regression splines (MARS) is proposed, and the model analysis process is determined by analyzing the principle of this algorithm. Based on the Concrete Compressive Strength dataset of UCI, the MARS model for compressive strength prediction was constructed with cement content, blast furnace slag powder content, fly ash content, water content, reducing agent content, coarse aggregate content, fine aggregate content and age as independent variables. The prediction results of artificial neural network (BP), random forest (RF), support vector machine (SVM), extreme learning machine (ELM), and multiple nonlinear regression (MnLR) were compared and analyzed, and the prediction accuracy and model stability of MARS and RF models had obvious advantages, and the comprehensive performance of MARS model was slightly better than that of RF model. Finally, the explicit expression of the MARS model for compressive strength is given, which provides an effective method to achieve the prediction of compressive strength of fly ash-slag concrete.

Surface Modification of Fly Ashes with Carbide Slag and Its Effect on Compressive Strength and Autogenous Shrinkage of Blended Cement Pastes

Surfaces of grade III fly ashes were modified through mixing with carbide slag and calcining at 850 ℃ for 1 h. Mineralogical compositions and surface morphology of fly ashes before and after modification were characterized by X-ray diffraction （XRD） and scanning electron microscopy （SEM）, respectively. Effect of surface-modified fly ashes on compressive strength and autogenous shrinkage of blended cement pastes was investigated. Microstructures of cement pastes were examined by backscattered electron （BSE） imaging and mercury intrusion porosimetry （MIP）. The experimental results showed that β-C2S was formed on the surfaces of fly ashes after modification. Hydration ofβ-C2S on the surface-modified fly ashes densified interface zone and enhanced bond strength between particles of fly ashes and hydrated clinkers. In addition, surface modification of fly ashes tended to decrease total porosity and 10-50 nm pores of cement pastes. Surface modification of fly ashes increased compressive strength and reduced autogenous shrinkage of cement pastes.

Preparation of Reactive Powder Concrete Using Fly Ash and Steel Slag Powder

To decrease the cement and SF content of RPC by using ultra-fine fly ash （UFFA） and steel slag powder （SS）, the effect of these mineral admixtures on compressive strength of RPC were investigated. The experimental results indicate that the utilization of UFFA and SS in RPC is feasible and has prominent mechanical performance. The microstructure analysis （SEM and TG-DTG-DSC） demonstrated that the excellent mechanical properties of RPC containing SS and UFFA were mainly attributed to the sequential hydration filling effect of the compound system.

Shrinkage, Strength of High and Ordinary Concrete Incorporating Kosovo and Japanese Fly-ash

Ordinary and high performance concrete （OC-C 25/30 and HPC C-50/60） made with fly ash has found numerous applications all over the world since 1970. In Kosovo, fly ash as cement substitution in concrete has not been utilized yet despite the large amount that is produced annually and the positive economical-environment aspects of such technique. This hesitance is due to the laek of experience in the concrete engineering field and because of the chemical composition of Kosovo fly ash, which is classified as non-standard high calcium fly ash （KF）. In light of this fact, this study intended to develop further. So, this paper reports the consistency, workability, shrinkage, high and ordinary compressive strength of concrete containing different percentage of non-class high calcium fly ash as Portland cement substitution （first case-Kosovo fly ash KF） comparing results with F class-low caleium fly ash content （second ease-Japanese fly ash JF） which is common used as cement replacement.

Modeling Wood and Fly Ash Behaviour as Partial Replacement for Cement on Compressive Strength of Self Compacting Concrete

Wood and fly ash were observed to have significant qualities that could improve the strength of self compacting concrete.The material was applied to increase the compressive strength of concrete strength.This material could be the demanding material for partial replacement for ce­ment.The study observed the behaviour of the material from experts that applied these material through experimental investigation,but the study monitored the behaviour of this material by applied modeling and simula­tion to determine other effect that could influence the behaviour of these materials in compressive strength.This was to determine the significant effect on the addictive applied as partial replacement for cement.Lots of experts have done works on fly ash through experiment concept,but the application of predictive concept has not been carried out.The adoption of this concept has expressed other parameters that contributed to the effi­ciency of wood and fly ash as partial replacement for cement on self com­pacting concrete.The study adopting modeling and simulation observed 10 and 20%by weight of cement as it is reflected on its performance in the simulation,from the simulation wood recorded 10%as it was ob­served from the growth rate of this self compacting concrete reflected from the trend.The simulation for model validation was compared with the works of the studies carried out[20].And both values developed best fits correlation.

Assessment of Curing Efficiency and Effect of Moist Curing on Performance of Fly Ash Concrete

This study was conducted to evaluate the sensitivity of compressive strength,water permeability and electrical resistance of near-surface layer concrete with different fly ash contents to curing conditions.It is shown that the sensitivity to curing condition and fly ash content descends in the following order：difference between internal and surface resistivity （ρ） at 28 days,water permeability and compressive strength;both of longer duration of moist curing and use of fly ash in concrete enhanced the water penetration resistance.It is indicated that the resistivity difference ρ at 28 days can reflect accurately the curing history of fly ash concrete regardless of mix proportions;and use of fly ash in concrete requires longer moist curing duration.

Cellular lightweight concrete containing high-calcium fly ash and natural zeolite

Cellular lightweight concrete （CLC） with the controlled density of approximately 800 kg/m3 was made from a preformed foam, Type-I Portland cement （OPC）, fly ash （FA）, or natural zeolite （NZ）, and its compressive strength, setting time, water absorption, and microstructure of were tested. High-calcium FA and NZ with the median particle sizes of 14.52 and 7.72 μm, respectively, were used to partially replace OPC at 0, 10wt%, 20wt%, and 30wt% of the binder （OPC and pozzolan admixture）. A water-to-binder mass ratio （W/B） of 0.5 was used for all mixes. The testing results indicated that CLC containing 10wt% NZ had the highest compressive strength. The replacement of OPC with NZ decreased the total porosity and air void size but increased the capillary porosity of the CLC. The incorporation of a suitable amount of NZ decreased the setting time, total porosity, and pore size of the paste compared with the findings with the same amount of FA. The total porosity and cumulative pore volume decreased, whereas the gel and capillary pores increased as a result of adding both pozzolans at all replacement levels. The water absorption increased as the capillary porosity increased; this effect depended on the volume of air entrained and the type or amount of pozzolan.

Comparison of High Performance Fly Ash Concrete Using Nano Silica Fume on Different Mixes

This paper investigates the experimental results on the effect of nano silica fume on compressive strength development of concretes containing high volume fly ash (HVFA). The effect of various silica fumes contents such as 1%, 2% & 3% (wt. %) as partial replacement of cement on the compressive strength of cements is evaluated in the first part. The nano silica fume content which exhibits the highest compressive strength above is used in high volume fly ash concretes containing 30% and 50% class F fly ash. The results show that among three different silica fumes contents, the addition of 1% increases the compressive strength of concretes. The addition of 1% silica fume also increases the early age and 28 days compressive strengths of HVFA concretes.

Effective Utilization of Coal Fly Ash in Building Material Production

This paper is aimed at verifying utilization possibilities of alkaline modified coal fly ash as cement replacement in the concrete. The influence of alkaline activated coal fly ash originating from Slovakian power plant in Novsky （Si/Al = 3,1） as a partial cement replacement in concrete on compressive strength of hardened composites after 28 and 90 days was investigated. Alkaline activation of coal fly ash was realized in an autoclave at 130 ℃ and pressure of 160 kPa during 5 hours and in a reactor under normal conditions （equal temperature during 36 hours） at solid/liquid ratio of 0.5. Coal fly ash/cement mixtures were prepared with 25 % cement replacement by starting and modified coal fly ash and given in forms. Compressive strengths of composites after 28 and 90 days of hardening were compared to referential composite without coal fly ash and evaluated according to the standard of STN EN 450 by the value of relative strength KR （compressive strength of coal fly ash/cement composite to compressive strength of comparative concrete）. The final compressive strengths of hardened composites based on alkaline activated coal fly ash reached values in the range of 6 up to 50 MPa. In the set of experimental composites based on alkaline activated coal fly ashes, the highest value of relative strength after 28- and 90- days of hardening reached composite with cement replacement by coal fly ash zeolitized in autoclave （105% of compressive strength of referential sample）, what is connected with formation of zeolitic phases on surface of coal fly ash particles. The achieved results confirm that alkaline activation of coal fly ash in an autoclave under observed conditions can be successfully used as a partial cement replacement in concrete of C20/25 and C25/30 in accordance with requirements of standards （STN EN 450 and STN EN 206）.

地聚物混凝土干燥收缩性能及活性氧化镁补偿收缩研究

制备粉煤灰-矿渣基地聚物混凝土,并进行地聚物混凝土28 d抗压强度和干燥收缩测试,探究分析活性氧化镁含量、水玻璃模数、碱当量和矿渣含量对其抗压强度和干燥收缩的影响机理。结果表明:随着活性氧化镁掺量增大,地聚物混凝土28 d抗压强度下降,干燥收缩变形显著减小;与0%(质量分数,下同)活性氧化镁混凝土相比,掺量为3%、6%和9%时混凝土28 d抗压强度分别下降8.0%、8.2%和18.2%,干燥收缩分别减小21.5%、26.4%和38.2%,此外,当活性氧化镁掺量为3%和6%时,不仅有效补偿了干燥收缩,且抗压强度损失较小;随着水玻璃模数升高,地聚物混凝土28 d抗压强度和干燥收缩变形增大;随着碱当量升高,地聚物混凝土28 d抗压强度下降、干燥收缩变形增大;随着矿渣含量增加,地聚物混凝土28 d抗压强度增大、干燥收缩变形减小。综合考虑抗压强度及收缩的要求,建议实际应用中选择高活性、大掺量氧化镁,掺量宜控制在3%~6%。

废水泥浆对陶粒加气混凝土砌块性能的影响研究

在废水泥浆中的水取代全部拌合水的条件下,探究废水泥浆中的粉体以等量取代或系数为0.65~1.05折算取代部分粉煤灰时,对陶粒加气混凝土和易性及陶粒加气混凝土砌块抗压强度、干密度、干燥收缩、导热系数的影响。研究表明,水胶比为0.45,当废水泥浆浓度为0~18%时,按等量取代后,砌块28 d平均抗压强度为5.51~5.54 MPa,干密度为728~730 kg/m~3,干燥收缩值为0.28~0.41 mm/m,导热系数为0.137~0.145 W/(m·K);当废水泥浆浓度为20%时,按系数为0.75~0.95折算取代后,砌块28 d平均抗压强度为5.18~5.43MPa,干密度为732~743 kg/m~3,干燥收缩值为0.35~0.42 mm/m,导热系数为0.146~0.178 W/(m·K),此时,砌块符合JG/T 504—2016对CA5.0B07砌块要求。

铁尾矿基多固废混凝土抗压性能及微观结构分析

针对铁尾矿堆存困难、综合利用率低和活性低的问题,以铁尾矿钢渣脱硫灰为复合掺合料制备多固废混凝土。通过抗压性能测试,研究复合掺合料掺量、铁尾矿细度对混凝土抗压强度的影响,并利用压汞法(MIP)和背散射电子成像技术(BSE)探究混凝土的微观结构。结果表明:复合掺合料的掺入对混凝土早期抗压强度影响较大,掺量小于20%的混凝土28 d抗压强度与无掺合料组抗压强度基本持平,30%掺量的混凝土抗压强度随铁尾矿比表面积的增大而先增大后减小;掺入复合掺合料和减小铁尾矿细度能够改善混凝土孔结构和提高界面过渡区的密实度。

高温蒸汽养护复掺混凝土力学性能时变特性与模型研究

为研究高温蒸汽养护下粉煤灰-矿粉机制砂混凝土(简称复掺混凝土)力学性能时变特性与模型,本文结合某高速公路高温蒸汽养护复掺混凝土预制梁项目,设计了蒸汽-标准养护、蒸汽-自然养护和标准养护三种养护方式,测试了不同阶段复掺混凝土的抗压强度、劈裂抗拉强度和弹性模量,探究了抗压强度与劈裂抗拉强度、弹性模量的关系。结果表明:合适的蒸汽养护方式能促进复掺混凝土抗压强度、劈裂抗拉强度和弹性模量更快增长,其中对抗压强度形成作用最显著,后期的力学性能不倒缩;蒸汽养护恒温阶段复掺混凝土的力学性能具有最大的增长率,其次是升温阶段,降温阶段力学性能增长率最小;蒸汽-标准养护方式下复掺混凝土的抗压强度时变模型可取对数或对数与幂函数复合函数,劈裂抗拉强度、弹性模量时变模型可取幂函数。

粉煤灰-矿渣再生混凝土抗压强度及尺寸效应研究

以粉煤灰和矿渣掺入方式和掺量为变量,设计24组C30再生粗骨料混凝土,对再生混凝土的抗压强度进行了研究。试验结果表明,粉煤灰或矿渣单掺时,再生混凝土的抗压强度随矿物掺料的掺量增加呈现先上升后下降趋势,同等掺量下矿渣单掺优于粉煤灰单掺;双掺时保持粉煤灰或矿渣掺量20%不变,再生混凝土立方体和轴心抗压强度随另一种微细矿物掺量的增加同样呈现先上升后下降趋势,双掺较单掺方式对再生混凝土抗压强度的提升效果更佳,且再生混凝土的抗压强度存在明显的尺寸效应。单掺粉煤灰或矿渣时再生混凝土轴心抗压强度和立方体抗压强度换算系数随其掺量增加而增大,双掺则稳定保持在0.85±0.02。此外,论文还建立了不同微细矿物掺料条件下再生混凝土抗压强度换算系数的修正公式,验证结果表明公式预测误差较小。建议实际工程再生混凝土配制采用粉煤灰和矿渣双掺方式,且掺量控制在25%以内。

钢渣-粉煤灰-脱硫石膏胶凝协同作用研究

以抗压强度作为主要指标研究了粉煤灰、钢渣和脱硫石膏三种工业固废的协同胶凝效应,并采用XRD和SEM分析手段对复合胶凝试块的矿物组成和微观形貌进行分析以明确其协同作用机理。研究表明:不同胶凝体系的协同效应依次为三元体系、二元体系和一元体系。XRD分析发现,三元体系胶凝试块具有更明显的硅铝酸盐水化产物衍射峰,并且多出了钙矾石的衍射峰。SEM分析表明,三元体系胶凝试块呈现针杆状的钙矾石晶体与水化硅酸钙凝胶交错生长,形成致密网络状结构的微观形貌。

再生混凝土砌块抗压强度试验研究

文中主要针对不同掺量粉煤灰、钢纤维及再生骨料取代率对再生混凝土砌块抗压强度影响展开研究。结果表明,不同掺量的粉煤灰对混凝土强度产生明显负面影响,且粉煤灰掺量越大,抗压强度下降幅度越大,推荐粉煤灰掺量控制在15%~30%,能够在保持抗压强度达标的同时,降低材料造价;再生骨料抗压强度水平随再生骨料取代率的提升而逐渐降低,混凝土承载力极限值也随之逐渐降低。

The Impact of Marine Water on Different Types of Coarse Aggregate of Geopolymer Concrete

This research studies the impact of different types of coarse aggregate on the behavior of geopolymer concrete based on both fly ash (FA) and ground granulated blast furnace slag (GGBFS) in different marine environments. Aiming to solve the problems caused by the construction and demolition waste and the depletion of natural aggregates, in the present study coarse recycled aggregates is used to produce new green concrete with a fly ash-slag based geopolymer. By this examination, the research seeks to improve the quality and productivity of concrete used in construction and hydraulic projects. For this research, four mixtures containing different types of coarse aggregate in two different water environments were used. The utilized mixtures contained natural aggregate concrete (NAC) such as basalt and crushed marble. Also, recycled coarse aggregate concrete (RAC), which totally replaced natural aggregate, was presented in this paper such as crushed concrete and crushed ceramic. For this study, in the sieve analysis;specific and unit weights, was recorded. Furthermore, the mechanical properties were determined, using a compressive test that was conducted on the 7th, 28th, 56th and 90th days at different water environments;potable water (PW) and sea water (SW). Durability test was also performed for total absorption measurement. Results indicated that geopolymer concrete exhibits better strength in marine environments than in those of potable water. Results also showed that crushed marble (CMA) exhibits higher compressive strength and durability.

复合矿物掺合料对高性能混凝土强度的研究

采用了单掺和复掺矿物掺合料的方法,研究了粉煤灰与矿渣对混凝土7 d和28 d抗压强度的影响,分析了两种矿物掺合料球磨前与球磨后分别提升混凝土性能的机理。结果表明,粉煤灰的加入对混凝土早期强度起负作用,矿渣的掺入对混凝土早期和后期的强度发展都能起到积极的作用,当复掺12%球磨15 min的粉煤灰和12%球磨15 min的矿渣时,混凝土抗压强度最高,与基准配合比相比提高了12%。