Quantitative Measurement of Water Absorption of Coarse Lightweight Aggregates in Freshly-Mixed Concrete

Yong-Hyok Kim,Byoung Il Choi,Jae Hong Kim,Yubin Jun,Cho-Bum Park,Tae Yong Shin

doi:10.1186/s40069-020-00408-x

Abstract

The high water-absorption of lightweight aggregate causes a high slump loss and poor workability of concrete. A prewetting process is usually recommended to compensate for the workability problem, but its application needs more delicate consideration in field. A method is proposed to measure the additional water absorption of lightweight aggregate, and its application in cement paste and concrete mixes confirms the absorption amount remaining unaffected by the mix proportion. The additional water absorption in cement-based materials can be considered as a material property, and its value is smaller than the water absorption measured by a standard test method (water-soaking). Compensating the additional water absorption finally allows to use dry lightweight aggregates for concrete, which is more robust and stabler than taking a saturated surface-dry lightweight aggregates.

Highlights

Lightweight aggregate concrete (LWAC) is beneficial to the design of structures and foundations
The porous microstructure of Lightweight aggregates (LWA) is good for the low-density LWAC, but it increases the water absorption
The additional water absorption of dry LWA in a cement paste was different from the conventional measurement of water absorption by 24 h water-soaking

Summary

Introduction

Lightweight aggregate concrete (LWAC) is beneficial to the design of structures and foundations. Workability control of LWAC requires more attention to the details than ordinary concrete when it is applied in the field (Videla and López 2000). The water absorption of normal aggregates is generally restricted by less than 3% while the specific limit varies according to the standard in a specific region. The high water absorption causes poor workability, significant slump loss and blockage of concrete pumping when the LWA is not adequately prewetted. The prewetting needs to be carefully accomplished until the LWA reaches a saturated surface-dry (SSD) condition (the water absorption after 24 h water-soaking). Water-soaking LWAs, prepared by immersing them in water longer than 24 h, may be an ideal method to obtain fully water-filled pores of

Methods

Results

Conclusion