Construction Waste Dust Activation And Preparing A Lightweight Building Materials Pilot Study

This research has analyzed and researched the dus which was collected by dust collector when construction waste in pretreatment(short title construction waste dust).From the main methods of thermal activation and thermal- grind activation, activated the construction waste dust. And use activated powder to preparae the cement-based composite materials-activated powder foam concrete(lightweight materials).(1) The best effection of construction waste dust was thermal activation temperature 600℃activation time 150min. Compared to the construction waste dust without activation:①The physical properties had changed, dehydration had appeared after activation thermal.②As cementitious materials and admixtures had improved the compressive strength.③Particle shape was round,the surface attachment significantly reduced the hydration products and improved the separation effect.④The construction waste dust with thermal activation increased the effect of grinding activation:thermal activation temperature 400℃, 600℃,800℃,activation time 150min in the same milling time,at the same ratio of ball and materials,0.075mm sieve were less than construction waste dust without thermal activation, the thermal activation temperature increased,0.075mm sieve decreased.(2)The physical properties of construction waste dust with thermal-grind activation had improved. The separation of cement paste and cement clinker had effectively achieved. The dus with thermal activation temperature 600℃activation time 150min grind activation 4h had improved the compressive strength as cementitious materials and admixtures.(3) Thermal-grind activated powder/alkali activation process had improved the compressive strength when activated powder as cementitious materials and admixtures. The best effection was:NaOH was 1.5% of construction waste dust.(4) This research determined the activation method of construction waste dust was: heating treatment at 600℃for 150min,3MZ-30A three cylindrical vibration ball mill at ratio of ball and materials 2:1, grinding 4h (0.075mm sieve27.6%), incorporation of activators NaOH is 1.5% of the quality of construction waste dust.(5) The production process of activated powder foam concrete is simple,eliminated the need for autoclave steam curing and sintering processes, reducing of secondary pollution and cost;Activated powder utilization is 24% of the total feeding amount, the construction wasted recycling has achieved.(6)From analysising the technological factors and experimental ratio.The experimental ratio of this research is:30% cement,10% lime, fly ash36%, construction waste dust24%, SBS concentration of 0.4% addition is 2ml/kg, water-cement ratio is 0.42, water reducing agent FDN-2 addition is 1% of the amount of cement, Na2SO4 addition is 1% of the amount of cement.(7) The performance of activated powder foam concrete is:compressive strength is 4.1MPa, bulk density is 843 kg/m3.Compressive strength reached and surpassed the requirements of "new wall material".which required the 28d compressive strength at 2.5～3.5MPa; according to JC/T 1062-2007 "foam concrete block" industry standard, this research 28d compressive strength reached A3.5 level (average≥3.5MPa, one group minimum≥2.8MPa), bulk density reached B09 level (830 kg/m3≤dry apparent density≤930 kg/m3).