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[Display omitted] • A novel expanded vermiculite/xonotlite insulation composite was prepared via the hydrothermal method. • Vermiculite thermal expansion and nano xonotlite fiber synthesis were comprehensively studied. • The effect of intercalation on thermal insulating performance was systematically investigated. Natural disasters caused by global warming are threatening the survival of mankind. Reducing carbon emissions is an effective way to prevent global warming. In recent years, the construction industry is playing a dominant role in global energy consumption. Aimed to solve the problem of high energy consumption in the construction industry, a novel expanded vermiculite/xonotlite thermal insulation composite was successfully prepared via the hydrothermal method. The microstructure and thermal performance of the composite were systematically analyzed using field emission scanning electron microscopy (FESEM), energy dispersive spectroscopy (EDS), X-ray diffraction (XRD), thermogravimetric analysis (TGA), laser flash analysis (LFA), and infrared thermal imaging. The test results indicated that xonotlite fibers could be inserted well into the interlayers of expanded vermiculite. And the intercalation of xonotlite greatly improved the thermal insulation performance of expanded vermiculite at high temperature. The thermal conductivity of this composite decreased with intercalation rate increasing. The composite with intercalation rate of 51.43 % had the lowest thermal conductivity of 0.2116 W/mK at 800 °C which was 55.36 % lower than the expanded vermiculite sample. Meanwhile, this composite had good thermal stability and high temperature resistance. In addition, the thermal expansion of vermiculite and the synthesis of nano-xonotlite fibers were comprehensively studied and discussed. This study will provide a new perspective and ideas for developing vermiculite-based thermal insulating materials. [ABSTRACT FROM AUTHOR]

• This study proposed the surrogate model to predict recycled aggregate concrete (RAC) creep behavior utilizing machine learning (ML). • Both grid search algorithm and k-fold cross-validation were utilized to find the optimal hyperparameters. • The XGBoost, was shown to have a higher efficiency and accuracy for predicting RAC creep over other methods. • The results are helpful to comprehend the performance of RAC structures and promote the application of RAC in buildings. This paper comprehensively investigated the surrogate model of recycled aggregate concrete (RAC) creep behavior prediction for the first time utilizing five typical machine learning (ML) algorithms trained with the RAC_Creep_v1 database. The grid search algorithm and k -fold cross-validation are performed to find the optimal hyperparameters. Then, attribute importance analysis and correlation analysis were conducted to evaluate the effect of various input variables on the results. By retraining the XGBoost model after feature selection, the results revealed that loading age has the greatest impact on RAC creep performance. The XGBoost, the optimal model via evaluation and comparison, was shown to have a higher efficiency and accuracy for predicting RAC creep subjected to different variables. Furthermore, the result of this paper can assist designers in comprehending the performance of RAC structures, promoting the application of RAC in buildings and the study for reducing carbon emissions. [ABSTRACT FROM AUTHOR]

[Display omitted] • A novel humidity self-regulating interior wall coating composite based on red mud was prepared. • The hygroscopicity of HRCRM were systematically investigated and analyzed. • Various properties of HRCRM were tested and the moisture absorption mechanism was analyzed. Aimed to resolve the problem of excessively high indoor humidity in subtropical areas and develop a new resource disposal technique for red mud, a novel humidity self-regulating interior wall coating composite based on red mud (HRCRM) was successfully prepared using red mud as a matrix material and vermiculite as a humidity regulator. The effects of component proportion, ambient humidity, exposure time on hygroscopicity of this composite were systematically investigated. This composite exhibited good humidity regulating ability with the largest water absorption rate of 16.38% under experimental conditions. Moreover, various properties were tested including surface drying time, hardness, adhesion, coating appearance, water resistance and reusability, meeting the national standard requirements well. The mechanism was comprehensively analyzed by XRD, TG-DTG, FESEM, and FTIR, indicating that the humidity self-adjusting function of HRCRM was realized by regulating the interlayer water storage of vermiculite. This study can provide theoretical and technical guidance for residential environment improvement in subtropical areas and comprehensive utilization of red mud. [ABSTRACT FROM AUTHOR]

The present study aimed to increase the utilization of phosphogypsum and reduce cement consumption. Single-factor experiments were designed to the effects of water-cement ratio (0.45–0.30), silica fume (1 %∼7 %), cement dosage (0 %∼20 %), and the RPG/HPG (20/80–0/100) on mechanical properties of phosphogypsum-based concretes (PGBCs). A new phosphogypsum-based concrete was prepared to meet the compressive strength requirement of C30 grade. The maximum 28d compressive strength of this PGBC reached 45.1 MPa. Simultaneously, the effect mechanisms of above four factors on the mechanical properties of PGBCs were discussed by combining XRD and SEM results. Moreover, the volume stability, elastic parameters, and compressive constitutive model of this PGBC with compressive strength above 30 MPa were investigated. This PGBC used more than 80 % phosphogypsum and 10∼20 % cement, exhibiting well economy and environmental friendliness. Moreover, the constitutive model was established to well predict the compressive behavior of PGBC with different RPG/HPG relative ratios. This PGBC had better volume stability and weaker deformation resistance than cement-based concrete. The present results can provide more theoretical and technical supports for the large utilization of PG. • PGBC is prepared with a large amount of PG as a cementing material. • The effects of four facters on the strength of PGBC were discussed. • The strength formation mechanism of PGBC were discussed by XRD&SEM. • A damage constitutive model with good correlation coefficient was established. • Providing theoretical and technical supports for the efficient utilization of PG. [ABSTRACT FROM AUTHOR]