Curing Sensitivity of Mortars Containing Cement, Calcined Clay, Fly Ash, and Limestone Powder

The purpose of this study is to investigate the effect of multi-binder systems which consist of cement, calcined clay, fly ash, and limestone powder on the curing sensitivity of mortars. Three series of mortar with different water to binder ratios by weight (w/b) of 0.35 and 0.55 and different paste ratios of 1.2 and 1.4 were produced for testing compressive strength. The specimens of each binder system were put under two conditions of curing water curing (water-cured) and no curing (air-cured). The curing sensitivity index was calculated by considering compressive strength as an indicator. It was found that for the mixes with the same water to binder ratio and paste content, the use of fly ash increased curing sensitivity while limestone powder and calcined clay reduced curing sensitivity. Mixes with a higher water to binder ratio (w/b= 0.55) showed higher curing sensitivity compared to mixes with a lower water to binder ratio (w/b= 0.35).  Reducing paste content resulted in reduced curing sensitivity of the mortars

Effect of Addition of Free Lime in Fly Ash on Expansion and Weight Loss in Sulfate Solution of Mortar with Fly Ash and Limestone Powder

AbstractThis research was aimed to study the effect of free lime (Free CaO) content in fly ash on expansion and weight loss of cement mortars, fly ash and limestone powder submerged in sulfate solutions. Free lime was added to the original fly ash in order to vary free lime content of fly ash. Test results revealed that the expansion of type I cement mortar was higher than that of type V cement mortar in sodium sulfate solution. It was also found that the expansion of mixture with 10% replacement of limestonepowder was about the same as that of type V mixture. The expansion of binary mixtures with fly ash and ternary mixtures with cement, fly ash and limestone powder depended very much on the content and type of fly ash such that mixtures with low or higher replacement ratio of low CaO fly ash yielded low expansion. In case of high CaO fly ash, the expansion of mortar with higher fly ash content was lower than the mortar with high fly ash content. In magnesium sulfate solution, weight loss of type Icement mortar was higher than those of type V cement mortar and mortar with limestone powder. Weight loss of mortars with 20% and 40% fly ash were higher than those of type I and type V cement mortars. Ternary mixture incorporating cement, fly ash and limestone powder showed lower weight loss than type I cement mixture and was similar to type V cement mixture. Free limecontent of fly ash had no effect on the expansion and weight loss of mortar in sulfate solutions

Models for Predicting Hydration Degree and Adiabatic Temperature Rise of Mass Concrete containing Ground Granulated Blast Furnace Slag

Predicting adiabatic temperature rise is essentially useful for investigating thermal cracking potential especially in early stage of mass concrete.  Existing prediction methods and models have some problems such as constant thermal properties are mostly utilized for predicting temperature rise. This study is aimed to develop time-dependent models for predicting hydration degrees of cement and slag, free water amount, specific heat, and total heat generation of concrete incorporating slag.  These models are then composed to predict the adiabatic temperature rise of mass concrete incorporating slag.  The model is able to predict adiabatic temperature rise in mass concrete with different water to binder ratios, slag replacements, physical properties of slag, and initial temperature conditions.  The validity of the proposed model was evaluated by comparing the model predictions with test results for adiabatic temperature rise of slag concrete.  The model simulations can be used to predict the experimentally measured data from differentPredicting adiabatic temperature rise is essentially useful for investigating thermal cracking potential especially in early stage of mass concrete.  Existing prediction methods and models have some problems such as constant thermal properties are mostly utilized for predicting temperature rise. This study is aimed to develop time-dependent models for predicting hydration degrees of cement and slag, free water amount, specific heat, and total heat generation of concrete incorporating slag.  These models are then composed to predict the adiabatic temperature rise of mass concrete incorporating slag.  The model is able to predict adiabatic temperature rise in mass concrete with different water to binder ratios, slag replacements, physical properties of slag, and initial temperature conditions.  The validity of the proposed model was evaluated by comparing the model predictions with test results for adiabatic temperature rise of slag concrete.  The model simulations can be used to predict the experimentally measured data from differen