Effects of modifiers on magnesium oxychloride cement doped with paper mill sludge

Abstract

To apply the composite material of magnesium oxychloride ce

ment (MOC) doped with paper mill sludge (PMS) to engineering,

the four modifiers such as phenylacrylic emulsion (PE), sodium

methyl silicate (SMS), sodium phosphate monobasic (SPM), and

citric acid (CA) were used to explore their effects on the compo

site material. The effects of these modifiers on the setting time,

flowability, mechanical strength, softening coefficient, and stren

gth loss coefficient of the composites were analyzed by physical

properties, mechanical strength, water resistance, and resistance

to sulfate attack, as well as by XRD. Results show that all four

different modifiers can delay the setting time of the slurry and

increase the fluidity of the mortar. With the increase of modifier

dosage, the strength of mortar modified by different modifiers is

lower than that of the control group, and the softening coefficient

and sulfate erosion resistance coefficient of the modified mortar

are significantly improved. At 2% and 1.5%, respectively, SPM and

CA have the best modification effects, but PE integration decrea

ses the softening coefficient of the mortar and only increases it by

47.30% at 0.5%. The obtained conclusions can provide a reference

for the engineering application of PMS-MOC.