Thermal properties and residual strength after high temperature exposure of cement mortar using ferronickel slag aggregate

Abstract

This study evaluates the thermal properties of cement mortar using by-product ferronickel slag (FNS) fine aggregate and its residual strength after high temperature exposure. Compressive strength of mortar increased when FNS was used up to 50% replacement of sand and then reduced with further increase of FNS. Volume of permeable voids (VPV) increased by 4% and 7% respectively for using 50% and 100% FNS fine aggregate. Thermal conductivity of mortar decreased from 2.34 W/m.K for using 100% sand to 1.65 W/m.K and 1.16 W/m.K for 50% and 100% FNS, respectively. Similarly, specific heat increased from 2.18 MJ/m 3 .K to 2.43 MJ/m 3 .K for 100% replacement of sand by FNS. These changes of VPV and thermal properties are attributed to the cavity of FNS particles, and their larger size and angular shape. Residual strengths of mortar after exposure to 800 o C were found marginally less for using FNS aggregate. This is attributed to the decrease of thermal conductivity of mortar by FNS. Overall, FNS aggregate showed improved thermal insulating properties and thermal mass of mortar without compromising compressive strength. Therefore, FNS can be considered for use as an energy efficient sustainable building material.

Influence of calcined diatomite content and elevated temperatures on the properties of high strength mortars produced with basalt sand

“…Only the reduction in the HSMs produced with 5% CDT is higher than that of the control HSMs at this temperature. The decrease in the U w values of the HSMs from 400 to 600°C can be explained by the decomposition of Ca(OH) 2 to its components 50–52 . At 800°C, the U w value of the control HSM decreases at a rate of 11.5% with respect to their unheated condition.…”

“…At 600°C, while the reduction in the f c value of the control HSM is about 16.5% with respect to their initial strength at 25°C, the reductions in the f c values of the HSMs including CDT are between 12.5 and 14.9%. The decline in the f c values of mortar/concrete between 400 and 600°C temperatures is basically because of the decomposition of Ca(OH) 2 50–52 . At temperatures above 600°C, the rapid reduction in the f c is usually caused by the increase of crack formation and pore size, 33,48 decomposition of CSH, 48 dehydration of the hydrated cement paste 54 and decarbonation of CaCO 3 55 .…”

“…The intensities of all the XRD peaks of the HSM samples decrease gradually with the increasing of temperature. The dehydration of Ca(OH) 2 at temperatures above 400°C 50–52 and decomposition of CSH gel at temperatures above 600°C 48,57 are mainly caused by the decrease of the XRD peaks in the HSMs. Generally, the XRD peaks of the control HSMs at 800 and 1,000°C are again actually coincident with those of the HSMs produced with 10 and 20% CDT.…”

Performance of Sustainable Green Concrete Incorporated With Fly Ash, Rice Husk Ash, and Stone Dust

“…Because of the siliceous type, it reacts aggressively with calcium hydroxide and forms cementitious compound, thereby the strength of the concrete with an addition of the FA gets improved. The addition of the FA lowers the water demand in concrete mix, and thus results in less bleeding and little heat progression [3,18,19]. The FA has a high silica content and is highly amorphous in nature.…”

Thermal Action on Normal and High Strength Cement Mortars

“…Many researches have already been performed with focus on the thermo-hygro-mechanical properties of cementitious composite materials affected by high temperature at several scales of applications. Recent works investigated the effect of using by-products for modifying the residual strength after high temperature exposure [8][9][10]. Some works also highlight how the addition of (nano- [11], micro- [12] and macro- [13,14]) fibers can improve the residual strength of components and structures after high temperatures exposures.…”