Preparation Of Lightweight Reactive Powder Concrete Using Super-Absorbent Polymer

A newly engineered concrete in the construction industry with remarkable mechanical properties as well as high durability in terms of application has been developed and termed as Reactive Powder Concrete(RPC).However,due to the large bulk density of RPC,certain difficulties emerge with transportation and construction during it’s engineering application.The ultimate strength to density ratio for a material is one of the key indications of it’s economical characterization to reduce the dead load of a concrete structure.In order to make the engineering application of RPC components lighter,various types of lightweight aggregates are applied to RPC to prepare lightweight RPC.Super-absorbent Polymer(SAP),as a special lightweight aggregate can make holes in concrete to effectively reduce the bulk weight of reactive powder concrete to obtain lightweight concrete.Therefore,the incorporation of certain amount of pre-soaked SAP(0%,0.1%,0.3%,0.5%,0.7%and 0.9%)into RPC to prepare lightweight will go a long way to promote it’s effective and wide utilization.This paper studied the influence of pre-soaked super-absorbent polymer dosage on RPC bulk density,dry-density,fluidity,strength,total shrinkage,water absorption and explored the effect of different conservation regimes[Ambient Temperature curing(ATC),Water Curing(WC),High Temperature Steam Curing(HTSC)and Hot Air Curing(HAC)]on lightweight reactive powder concrete.Two separate samples were prepared;thus,samples with fibre and samples without fibre addition.The results show that by increasing pre-soaked SAP doping in RPC effectively reduces the bulk density of RPC and improves the fluidity.But a sharp decline in strength was witnessed.Pre-soaked SAP enhanced the flexural strength of lightweight RPC under water curing regime due to the presence of high humidity.The highest compressive strength was obtained with Hot air curing regime.High temperature steam curing provides both high humidity and high temperature which was conducive for both compressive and flexural strength of lightweight RPC.As far as ambient temperature curing is concerned,the maximum compressive strength was obtained at 28 d rather than 56 d due to humidity gradient variation in the sample.By increasing the SAP doping,the total shrinkage is increased due to an increase in the total water-binder ratio which in turn increases the free water content of the concrete.Water absorption rate increases as the SAP doping increase in the concrete.In view of this,SAP can be used to prepare high-strength lightweight RPC with a dry-density ranging between(2325–1726 kg/m~3)for samples without fibre and compressive strength not less than 40 MPa.A density of(2481–1924 kg/m~3)for samples with fibres can be obtained with a compressive strength not less than 60MPa.