Research On Chemical Shrinkage And Dry Shrinkage Behavior Of Alkali Activated Slag Cement And Concrete

Alkali activated slag cement and concrete(AASC&C) with better physical mechanics and durability property is a kind of environmentally friendly materials in accord with making use of substantial amounts of by-product and waste materials, thereby consuming less energy and generating less waste. There have been 50 years from invention of AASC&C to this day. The correlation theory of AASC&C is more and more mature day after day. The setting time controlling difficult problem was shoved and probability of happen alkaline-aggregate reaction was proved to be very small in 19th 80 to 90 years. The research shows that shrinkage deformation of AASC&C is a little great. Hereinto the study report of chemical shrinkage of AASC can't find up to present, and the research of dry shrinkage of alkali activated slag cement concrete(AASCC) used in building engineering is practical problem and cried for studying. So in this paper the chemical shrinkage deformation of AASC and dry shrinkage defamation of AASCC are studied. The purpose is to do some base work for extending the apply of alkali activated slag cement and concrete. The result shows that:â‘ The kind and special surface of slag, alkaline kind and alkaline concentration (count as Na2O equal dosage ) all affect the chemical shrinkage of AASC. When the alkali is NaOH, the chemical shrinkage value of AASC (about 6~10 ml/100g) is equivalent with the the value of ordinary portland cement(about 7~10 ml/100g), while the water glass(about 3~6 ml/100g) is smaller than the value of ordinary portland cement.â‘¡The water loss of AASCC is less than that of Ordinary Portland Cement concrete(OPCC) when in the some environment condition, but the dry shrinkage value is about 1.2 to 1.9 times of OPCC. The dry shrinkage character of AASCC is correlation with its excessive small pore structure. The dry shrinkage character of AASCC is different when alkali constitute is different. When activated with water glass, the behavior of dry shrinkage of AACC is similar with that of OPCC, the dry shrinkage develop slowly after 120 days, while NaOH the dry shrinkage is continuous grow with the day within the test day.â‘¢When the other condition is the same, when solution to aggregate ratio is from 0.40 to 0.50, the ratio increases with the decrease of dry shrinkage of AASCC; when sand percentage is from 32% to 40%, its influence on dry shrinkage is very little; when alkali content is from 3% to 6%, as the content increase the dry shrinkage increase too, according to economy and the comprehensive influence on the AASCC, the alkali content(count as Na2O equal dosage) is better controlling about 4% of slag quantity; when modulus of water glass is from 1.0 to 2.0, with the increase of modulus the dry shrinkage grow.â‘£The influence of fly ash on the AASCC dry shrinkage is connected with the activator. When alkali constituent is water glass with replace dosage increase the dry shrinkage increase, While NaOH reduce. The influence of naphthalene water reduce on dry shrinkage of AASCC is relative with alkaline kind, when activated with NaOH the dry shrinkage reduce, but water glass increase.