Chloride Penetration Control And Its Properties In Sea Sand Mortar

When sea sand is used in concrete,the release and penetration of chloride ions will increase the concentration of chloride ions in the vicinity of the rebar,which will cause its corrosion.It is therefore of importance to control the release of chloride from sea sand and its penetration in concrete.In this thesis,measures to pretreat sea sand to remove chloride ions from sea sand and its effect on the compressive strength of sea sand mortar were examined by through orthogonal test with the addition of glass powder,the dosage of TEA and sea sand pretreating methods.And then,the effects of triethnolamine and triisopropanolamine on the chloride binding capacity and compressive strength of blended cement paste with the composition of 3% glass powder,30% fly ash and 67% cement were investigated,along with their effect on the rebar corrosion of the tested mortar.The relevant mechanism was studied by SEM-EDS and XRD.Pretreatment of sea sand with saturated calcium hydroxide suspension was found to be more effective to remove chloride than that with water.Mortar prepared with untreated sea sand added with 6%GP and 0.05% TEA and that prepared with sea sand pretreated with fresh water added with 0.05%TIPA were determined to be the best in raising the compressive strength in the orthogonal tests containing TEA and TIPA respectively.Both co-addition of TEA with GP and that of TIPA and GP were found to delay the corrosion of rebars compared to the blank samples.Chloride binding capacity of blended cement paste with 3% glass powder,30% fly ash and 67% cement was found to increase rapidly when added 0.025% TEA or TIPA compared to the blank samples and marginally with the increase of either TEA or TIPA till 0.1%.Wrapping sea sand with GGBS or silica fume before preparation of sea sand mortar was tried to improve the compressive strength and tested to be effective in compressive strength enhancement by 20 MPa compared to the mortar prepared with unwrapped sea sand.Addition of TEA from 0.025% to 0.075% and that of TIPA from 0.050% to 0.100% was found to reduce the porosity and increase the compressive strength of motar,indicating that TEA or TIPA could improve the resistance of penetration of the mortar.