Abstract
Drying could change the microstructure of cement-based materials and inevitably affect their mechanical properties. The isothermal drying process of concrete at three scales and its effect on compressive behavior and microstructure were investigated. The deformations of cement paste, mortar, and concrete in the drying process all exhibit the characteristics of expansion first and then shrinkage. The porosity and average pore diameter increase after drying, which is mainly attributed to the increase of pores less than 100 nm diameter for paste and to the pores within 100~1000 nm for mortar. Drying makes paste denser, while the bonding between paste and aggregate is weakened. Microstructural studies indicate that the increase in compressive strength of concrete caused by isothermal drying is the competition result between the strengthening effect and the weakening effect, and is related to the paste content.
Highlights
Concrete, a most widely used building material at present, is a typical heterogeneous and porous material
The water-losing rate of cement paste, mortar, and concrete during the drying process, defined as the water mass escaped from unit surface area of specimen per unit time (Unit: kg/(m2 ·h)), was plotted in
As the increase of porosity and average pore diameter is harmful to results, with the experimental results of strength increases (Figure 4) caused by isothermal drying at strength, there seem to be contradictory results, with the experimental results of strength increases three scales
Summary
A most widely used building material at present, is a typical heterogeneous and porous material. For concrete structures exposed to water environments, or those in an environment where humidity varies considerably, the effect of moisture content is significant and should be considered in structural design. Investigators have achieved many satisfactory results in which strength, elastic modulus, creep, and shrinkage of concrete are generally recognized as functions of moisture content [5,6,7]. As a basic and most important engineering indicator of concrete, compressive strength under different moisture content has been extensively studied. Isothermal drying is generally used as an effective method to control water content of concrete in the laboratory [1,8,9,10]. When the drying temperature is not too high, a positive effect on strength termed as “drying-strengthening”
Sign-in/Register to view highlights & summary 
Published Version (
Free)
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call