Development of lightweight portland-limestone cement mortar : towards thermally resistive, solar reflective and fire protective renders

الملخص EN

Energy saving and environment protection are the key rules of sustainable development that driving global efforts to decrease the thermal conductivity(TC) of building materials in order to minimize energy consumption for heating and cooling in buildings.

In this study we aimed to extend our previous research for the production of ecofriendly lightweight (LW) one-coat rendering mortar with reduced thermal conductivity, enhanced solar reflectivity and improved fire resistance (Fr) and mechanical strength for energy efficient buildings.

green and economical binder has been prepared by replacing 60 wt% of the white portland cement by a blend of limestone(LS) powder and metakaolin (MK) with LS : MK of 1:2 (wt%).

the binder has been mixed with expanded perlite (EP) aggregate with various aggregate volume contents of 25, 50 and 75%.

Polypropylene (PP) microfibers were added at a constant ratio of 0.5% by weight of binder.

compressive strength, indirect tensile strength, capillary water absorption, bulk density, thermal conductivity, solar reflectivity, fire resistance and microstructure of the hardened mortars were studied at 7 and 28 days of curing.

the results revealed that the newly developed mortars fulfill the standard technical requirements for thermal insulating renders.

the mortar incorporating 75 vol.

% EP is the most promising render.

It achieved 28 days-compressive strength of 12.45 MPa, TC as low as 0.19 W/m.K, solar reflectivity of 91%; furthermore, it reduces thermal loads into buildings by 38% and provides fr of about 50 minutes.

the simultaneous improvement of thermal and mechanical properties in addition to the enhanced solar reflectivity and fire resistance with the potential to reduce carbon footprint summarize the major innovation presented in this study.