The Preparation And Performance Research Of Construction Waste Recycled Aggregate Dry-mixed Mortar

With the acceleration of urbanization construction, every year a huge amount ofconstruction waste is engendered due to the construction engineering. The vast majority ofconstruction waste is buried simply or stacked in the open air directly, resulting in the seriousdestruction of environment and a huge amount of economic loss. The development ofdry-mixed mortar started late in China. Not only the theoretical support and systematic researchis lacking, but also some regularity problem is still not clear. In this thesis, construction wasterecycled aggregate is made use of the dry mortar production.The thesis mainly includes the following several research contents: the basic physicalproperties are compared the recycled aggregate to the natural river sand, such as apparentdensity, porosity and water absorption et al. The construction waste recycled aggregatedry-mixed mortar is modified by the compound excitation agent and the interfacestrengthening agent. The effects of the compound excitation agent and the interfacestrengthening agent on the mechanical properties and interface of mortar are studiedsystematically. The effects of the fly ash, carboxymethylcellulose water-retention agent,naphthalene-based superplasticizer et al, on the various performances and action mechanismsof the recycled aggregate dry-mixed masonry mortar are studied. The effects of steel slag,silica fume and water retention agent et al, on the various performances and action mechanismsof the recycled aggregate dry-mixed plastering mortar are studied. The effects of fly ash,silica fume and water retention agent et al, on the various performances and action mechanismsof the recycled aggregate dry-mixed screeding mortar are studied.Experimental studies have shown that the apparent density of recycled aggregate is muchless than it of natural river sand. The porosity and the water absorption of recycled aggregateare larger than it of the natural river sand. The mechanical property of recycled aggregatedry-mixed mortar is superior to it of natural river sand dry-mixed mortar. Compound excitationagent can stimulate the activity of potentially gelation composition of recycled aggregate andthe activity of fly ash. The mechanical property of dry-mixed mortar is improved. The28dcompressive strength increases by5.93%when adding compound excitation agent. The polargroups of interface strengthening agent can control the spread of free water, which optimizes the combination of interface layer and improves the mechanical property of dry-mixed mortar.The28d compressive strength increases by8.71%when adding the interface strengtheningagent. The best mix proportion of raw material of M10recycled aggregate dry-mixed masonrymortar: The proportion of cementing material and aggregate is1:5. The dosage of fly ash is25%. The dosage of compound excitation agent is0.9%. The dosage of interface strengtheningagent is1.2%. The dosage of water retention agent is0.24%. The dosage of water reducingagent is1.2%. The various performances of M10dry-mixed masonry mortar meet therequirements of GB/T25181-2010《Pre-m ixed mortar》.The contraction performance of recycled aggregate dry-mixed mortar when added thewater-retention agent is obviously improved. When the dosage of water retention agent was0.12%, the28d shrinkage rate is1.56‰. The best mix proportion of raw material of M15recycled aggregate dry-mixed plastering mortar: The proportion of cementing material andaggregate is1:4. The dosage of silica fume is4%. The dosage of steel slag is18%. Thedosage of steel slag excitation agent is0.5%.The dosage of compound excitation agent is0.9%. The dosage of interface strengthening agent is1.2%. The dosage of water retentionagent is0.15%. The dosage of water reducing agent is1.5%. The various performances ofM15dry-mixed plastering mortar meet the requirements of GB/T25181-2010《Pre-mixedmortar》.The anti-frost property of Recycled aggregate mortar powder ground when addedwith the water reducing agent is improved. The dosage of water reducing agent is1.2%, theantifreeze grade is D35. The quality loss is2.45%, and the strength loss is17.37%passing35times freeze-thaw cycles. The best mix proportion of raw material of M15recycled aggregatedry-mixed screeding mortar: The proportion of cementing material and aggregate is1:4.5. Thedosage of steel slag is25%. The dosage of silica fume is4%. The dosage of compoundexcitation agent is0.9%. The dosage of interface strengthening agent is1.2%. The dosage ofwater retention agent is0.12%. The dosage of water reducing agent is1.2%. The variousperformances of M20dry-mixed screeding mortar meet the requirements of GB/T25181-2010《Pre-mixed mortar》.