Shunbo Zhao

Experimental Study on Autogenous and Drying Shrinkage of Steel Fiber Reinforced Lightweight-Aggregate Concrete

Steel fiber reinforced lightweight-aggregate concrete (SFRLAC) has many advantages applied in structural engineering. In this paper, the autogenous shrinkage and drying shrinkage of SFRLAC for up to 270 days were measured, considering the effects of types of coarse and fine aggregates with the changes of water-to-binder ratio and volume fraction of steel fiber, respectively. The properties of mix workability, apparent density, and compressive strength of SFRLAC were also reported and discussed in relation to above factors. Test results show that the development of autogenous and drying shrinkage of SFRLAC was fast within 28 days and tended to be steady after 90 days. The development of autogenous shrinkage of SFRLAC reduced with the increasing water-to-binder ratio and by using the expanded shale with higher soundness and good water absorption, especially at early age within 28 days; the later drying shrinkage was reduced and the development of drying shrinkage was slowed down with the increasing volume fraction of steel fiber obviously; manufactured sand led to less autogenous shrinkage but greater drying shrinkage than fine lightweight aggregate in SFRLAC. The regularities of autogenous shrinkage and drying shrinkage of SFRLAC expressed as the series of hyperbola are analyzed.

Dataset of tensile strength development of concrete with manufactured sand

This article presents 755 groups splitting tensile strength tests data of concrete with manufactured sand (MSC) in different curing age ranged from 1 day to 388 days related to the research article “Experimental study on tensile strength development of concrete with manufactured sand” (Zhao et al., 2017) [1]. These data were used to evaluate the precision of the prediction formulas of tensile strength of MSC, and can be applied as dataset for further studies.

A salt-assisted combustion method to prepare well-dispersed octahedral MnCr 2 O 4 spinel nanocrystals

Well-dispersed nanocrystalline MnCr2O4 was prepared by a salt-assisted combustion process using low-toxic glycine as fuel and Mn(NO3)2 and Cr(NO3)3ċ9H2O as raw materials. The obtained products were characterized by X-ray Diffraction (XRD), Fourier Transform Infrared (FT-IR) spectroscopy, Raman spectroscopy, Transmission Electron Microscopy (TEM), and Scanning Electron Microscopy (SEM). The fabrication process was monitored by thermogravimetric and differential thermal analysis (TG-DTA). The phase formation process was detected by XRD, and MnCr2O4 single phase with high crystallinity was formed at 700°C. TEM and SEM images revealed that the products were composed of well-dispersed octahedral nanocrystals with an average size of 80 nm. Inert salt-LiCl played an important role in breaking the network structure of agglomerated nanocrystallites.

Development of Steel Fiber-Reinforced Expanded-Shale Lightweight Concrete with High Freeze-Thaw Resistance

For the popularized structural application, steel fiber-reinforced expanded-shale lightweight concrete (SFRELC) with high freeze-thaw resistance was developed. The experimental study of this paper figured out the effects of air-entraining content, volume fraction of steel fibers, and fine aggregate type. Results showed that while the less change of mass loss rate was taken place for SFRELC after 300 freeze-thaw cycles, the relative dynamic modulus of elasticity and the relative flexural strength presented clear trends of freeze-thaw resistance of SFRELC. The compound effect of the air-entraining agent and the steel fibers was found to support the SFRELC with high freeze-thaw resistance, and the mechanisms were explored with the aid of the test results of water penetration of SFRELC. The beneficial effect was appeared from the replacement of lightweight sand with manufactured sand. Based on the test results, suggestions are given out for the optimal mix proportion of SFRELC to satisfy the durability requirement of freeze-thaw resistance.

Cracking Resistance of Reinforced SFRFLC Superposed Beams with Partial Ordinary Concrete in Compression Zone

Abstract: A new reinforced SFRFLC (abbr. steel fiber reinforced full-lightweight concrete) superposed beam was proposed to sufficiently utilize the good peculiarities of ordinary concrete in compression and SFRFLC in tension, and reduce its self-weight. Experimental study was carried out on the flexural behaviors of reinforced SFRFLC superposed beams compared with reinforced concrete beams and reinforced SFRFLC beams, the effects of such factors as sectional depth of SFRFLC, volume fraction of steel fiber, longitudinal tensile reinforcement ratio and strength of ordinary concrete were analyzed. Based on the composite principle, formulas are proposed for calculating the cracking resistance of reinforced SFRFLC superposed beam and the reasonable sectional depth of SFRFLC. The results showed that there was the optimal sectional depth of SFRFLC, steel fiber was the main factor while high-strength ordinary concrete and proper reinforcement ratio were beneficial to enhance the cracking resistance of reinforced SFRFLC superposed beam.