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Recycling of concrete: Dehydration and reactivation of cement

Susana Gil SayasRecycling of concrete: Dehydration and reactivation of cement,ULB-VUB2018 (June).

The main objective is to compare different recycled mortars to conclude which one maintains
better mechanical and thermal properties after the recycling process. The compared mortars
are formed by a combination of different cement pastes (with Ordinary Portland Cement and
blast furnace slag), different activation solutions (water and alkaline solutions) with different
proportions of the water-to-cement ratio (water or other solution) and molarities.
The methodology followed starts with the preparation of cement pastes with fresh cement and
water, which are heat up (dehydrated) and reactivated with other solutions (water and alkaline
solutions, blast furnace slag and fresh cement, to analyse the influence of each product. The
reactivated cement pastes are mixed with sand to prepare recycled mortars. These mortars are
compared using mechanical test (compressive strength test) and doing a thermal study with a
calorimeter and thermogravimetric analyser.
The results show that mortars after the recycling process do not achieve the same properties as
fresh or new mortars. But it is seen that the addition of slags and alkalis increases the reactivity
of recycled cement, but the compressive strength obtained with alkalis is very low. That is why
the main conclusion is that the addition of alkalis gives less strength due to the low workability
of the mortars. Also, cement without slags mixed with alkaline solutions does not react as much
as mixed with water. In addition, a decrease of water (or other solution) content increases the
compressive strength but decreases the reactivity of the mixture. And lower molarity increases
the compressive strength, but no difference is seen in the reactivity when comparing it with
higher molarity (comparison between 0.5 and 1M).


    author      = "Susana Gil Sayas",
    title       = "Recycling of concrete: Dehydration and reactivation of cement",
    institution = "ULB-VUB",
    year        = "2018",
    address     = "",
    month       = "June",
    doi         = "",
    note        = "",