Elastomeric Effect of Natural Rubber Latex on Compressive Strength of Concrete at High Temperatures

The inclusion of elastomeric substances into concrete aimed at improving performance properties may pose a serious threat, particularly at high temperatures. This paper presents experimental findings regarding the elastomeric influence of natural rubber latex on compressive strength of concrete at elevated temperatures. Normal and modified concrete specimens were prepared, heated, and subsequently tested for compressive strength. Five temperatures-ambient temperature (27 degrees C), 150, 300, 500, and 800 degrees C-were applied. Microstructural samples were observed through scanning electron microscopy (SEM), and the role of poly(1,4-isoprene) particles in the modified system was evaluated using thermogravimetric analysis (TGA) conducted on hardened cement paste, latex film, and cement-latex blend. Finally, compressive strength of the modified concrete was observed to depreciate at the softening point temperature of the latex films in the comatrix, eventually with more strength loss. At 800 degrees C, the strength loss was 50.5% in the modified concrete versus 37.8% in the normal concrete. Thus, special precautionary design measures may be necessary for latex-modified concrete, particularly in situations where the concrete is likely to face temperatures above the softening point temperature of the modifier. DOI: 10.1061/(ASCE)MT.1943-5533.0000338. (C) 2011 American Society of Civil Engineers.