Changyong Li

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.

Method of mix proportion design for concrete with machine-made sand

As many differences with natural sand in particle shape, surface characteristics and grading, especially in larger content of stone powder, machine-made sand has the important effects on the workability of fresh concrete and the strength of hardened concrete. By reviewing the formerly experimental results of concrete with machine-made sand, this paper gives out the comprehensively table including the effective test data for statistical analysis. The unified formula is proposed to calculate the water to cement ratio of the plastic, pasty and flowing concrete. The design procedure for mix proportion of concrete with machine-made sand is suggested considering the reasonable content of water, sand ratio and stone powder in machine-made sand.

Study on workability of plastic fresh concrete with machine-made sand

As many differences of machine-made sand from natural sand in particle shape, surface characteristics and particle size distribution (i.e. grading), especially in larger content of stone powder, it is important to realize what influences should be considered of machine-made sand on workability of fresh concrete. This paper firstly reviews the formerly experimental results of workability of plastic fresh concrete affected by fineness modulus and grading of sand, sand ratio, content of stone powder and water to cement ratio. After that, the new experimental results are introduced and analyzed, in which the effects of the content of stone powder in machine-made sand, the water to cement ratio and the content of water reducer were considered. It is concluded that the influence of the content of stone powder on the workability of plastic fresh concrete is inherent in the changes of density, void ratio and water absorption of machine-made sand. The optimum content of stone powder in machine-made sand is 9% in this study of concretes in strength grades of C30, C40 and C50. The reasonable content of water-reducer has not obvious influence on the workability of plastic fresh concrete.

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.

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.

Dataset of long-term compressive strength of concrete with manufactured sand

This paper presents 186 groups compressive strength tests data of concrete with manufactured sand (MSC) in different curing age and 262 groups compressive strength tests data of MSC at 28 days collected from authors’ experiments and other researches in China. Further interpretation and discussion were described in this issues.

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.

Bond Properties of Plain Steel Bar with Machine-made Sand Concrete (MSC)

To meet the requirement of machine-made sand application in concrete structures, it is necessary to understand the bond properties of steel bar with machine-made sand concrete (MSC). Therefore, the experimental studies were carried out on the bond of plain steel bar with MSC by the central pull-out test method. Three specimens were cast as one group, 6 groups were tested considering the changes of strength grade of MSC and ordinary concrete. The bond-slip curves were measured and analyzed. The results show that the bond slip begins at the tensile side and transfers gradually to the free end before the entire slip turns up along the interface of plain steel bar and surrounded concrete, the largest average bond stress, i. e. the bond strength of plain steel bar corresponds to the initial entire slip of plain steel bar. With the increasing strength grade of MSC and ordinary concrete, the difference of slip at tensile side and free end becomes greater. Comparing that only appears in ordinary concrete with higher strength, the larger slips turn up while the bond stress reaches the largest for the plain steel bar in MSC. Larger scatter of bond strength is between specimens in the same group. Some plain steel bars yields with the beginning of entire slip along the interface.