Concrete Temperature Monitoring of Accelerated Curing in Cold Weather

Concrete temperature monitoring of accelerated curing in cold weather

Khishgee R, Gerelkhuu J, Duinkherjav Ya

School of Civil Engineering and Architecture

khishgee_radnaa@yahoo.com, daamts@must.edu.mn

ABSTRACT

Curing temperature is the critical factor to the hydration process of cement in concrete. For accelerated curing the possible cracking due to the thermal stress is important consideration thus the limiting values to the temperature rise and temperature gradient in the member section is studied. Electric heating methods as accelerated curing are studied and temperature and strength data are given as a result of experiments carried out in such a low temperature of -35C.

Keywords: electric heating, electrode heating, heating cable, surface modulus,

INTRODUCTION

The theories of frost action such as hydraulic pressure theory (Powers, 1949), osmotic pressure theory (Helmuth and Powers, 1953) that explain the mechanism of frost action on concrete hardening all agree on that internal pressure is generated because of the freezing and it leads to destruction of the microstructure [9]. To prevent the frost damage it is necessary to cure at least a compressive strength of 3.5MPa is achieved so that the concrete can withstand tensile stress without structural damage [1].

The Mongolian Building Code BNbD 52-02-05 requires must be taken cold weather curing measures when average ambient daily temperature drops below 5C or a temperature of day time drops below zero. The curing period should be continued until concrete reaches critical strength which is given based on the specified concrete class [2]. For the concrete of class B7.5 (M100) to B10 (M150) critical strength is 50 percent of the specified design strength, for B12.5 (M179) to B25(M350) it is 40 percent, and 30 percent over B30 (M400). If the structure has special requirements like hydraulic structure or pre-stressed concrete then it goes up to 70 to 80 percent of the design strength....