Indian Journal of Engineering & Materials Sciences Vol. 23, October 2016, pp. 301-311 Factors influencing the mechanical properties of lightweight aggregate concrete Tao Wu, Hui Wei, Xi Liu & Guohua Xing* School of Civil Engineering, Chang’an University, Xi’an 710061, China Received 15 February 2016; accepted 22 September 2016 This paper presents an experimental study evaluating the mechanical properties, particularly the compressive strength, tensile strength, bulk density and elastic modulus, of lightweight concrete with three types of aggregates, i.e., expanded clay, sintered fly ash and expanded shale. The effects of aggregate types, volumetric fly ash content and water-cement ratio on the mechanical properties of lightweight aggregate concrete (LWAC) are discussed in this paper. The fly ash content ranged from 18% to 22% by cement volume, and the water-cement ratios are set to 0.3, 0.33 and 0.36 for each type of LWA. By utilizing the critical influencing parameters, including the water-cement ratio, cement strength, fly ash-cement content ratio, cylinder compressive strength and volume content of LWA, a generalized model for predicting the 28-day LWAC compressive strength was also proposed and compared with four other existing models. The test results showed that a higher strength of LWA and a decreased water-cement ratio resulted in improved mechanical performance, especially in terms of LWAC compressive strength. LWAC crack patterns are quite different from those of normal-weight concrete (NWC). However, for the high-strength lightweight aggregate concrete (HSLAC) proposed in this paper, the crack patterns based on the strength of LWAs is similar to that of mortar matrix, which indicates that each concrete phase is functioning adequately. The proposed 28-day compressive strength predicting model for LWAC is verified, resulting in good agreement with test results, and can be accurately used in design of building or bridge structures. Keywords: Lightweight aggregate concrete, Mechanical properties, Mixture proportions, Influence factors, Compressive strength Lightweight aggregate concrete (LWAC) has been used extensively for structural applications for many years 1-6 . Low unit weight, low permeability, high absorption, better thermo-insulating capacity and excellent durability of LWAC are its prominent characteristics. These characteristics have been sufficiently observed and used in long-span bridges, high-rise buildings and floating structures exposed to a marine environment 7-11 . LWAC is produced by replacing normal-weight aggregates with lightweight aggregates (LWA) to reduce the structures’ dead loads and to limit buildings’ energy consumption. This makes LWAC relatively ‘green’ material 12-15 . In addition, LWAC mechanical properties are to a large extent controlled by the properties of LWA, such as cylinder compressive strength, porosity and elastic modulus. Before the 19 th century, the applicable raw materials of LWA were rare and had low crushing resistance. As a result of the rapid development of manufacturing technology, various LWAs with higher crushing resistance, lower density, and greater porosity gradually appeared and have been used in structural engineering. In the last few decades, a large number of experimental tests had been conducted to investigate the properties of LWA as well as the associated mechanical properties of LWAC, even for high- strength LWAC. Zhang 16 noted that the properties of the resulting concrete are primarily controlled by LWA rather than by the mortar matrix due to the lower strength and elastic modulus of LWA. Lydon 17 investigated the compressive strength of LWAC using different aggregates and found that it mainly depends on the aggregate types and increases with an increase in density. Yang and Huang 18 indicated that the volume fraction of LWA has a remarkable effect on the compressive strength and elastic modulus of LWAC. Ke et al. 19 reported that the experimental results on mechanical properties of concrete using expanded clay and shale aggregates are affected by the volume fraction and characteristics of LWA. In addition, shell thickness, as well as the percentage of large pores and broken grains also showed a certain influence on the compressive strength of LWAC. He et al. 20 also investigated the effect of particle sizes, gradation and shape properties through grey correlation analysis methods, and stated that the particle specific surface area and particle aspect ratio —————— *Corresponding author (E-mail: [email protected])
Factors influencing the mechanical properties of lightweight aggregate concrete
Apr 22, 2023
Welcome message from author
This document is posted to help you gain knowledge. Please leave a comment to let me know what you think about it! Share it to your friends and learn new things together.
Related Documents
