Thermal properties of cement mortar with different mix proportions

Abstract

The energy required for the heating and cooling of buildings is strongly dependant on the thermal properties of the construction material. Cement mortar is a common construction material that is widely used in buildings. The main aim of this study is to assess the thermal properties of cement mortar in terms of its ther­mal conductivity, heat capacity and thermal diffusivity in a wide range of grades (cement: sand ratio between 1:2 and 1:8). As there is insufficient information to predict the thermal conductivity and diffusivity of a cement mortar from its physical and mechanical properties, the relationships between thermal conductivity and diffu­sivity and density, compressive strength, water absorption and porosity are also discussed. Our results indicate that, for a cement mortar with a 28-day compressive strength in the range of 6–60 MPa, thermal conductivity, specific heat and thermal diffusivity are in the range of 1.5–2.7 W/(m.K), 0.87–1.04 kJ/kg.K and 0.89–1.26 (x10-6 m2/s), respectively. The scanning electron microscope (SEM) images showed that pore size varied from 18 μm to 946 μm for samples with different cement-to-sand ratios. The porosity of cement mortar has a signifi­cant effect on its thermal and physical properties. For this reason, thermal conductivity and thermal diffusivity was greater in cement mortar samples with a higher density and compressive strength.

Recycled Cellulose Fiber Reinforced Plaster

“…Based on the values of the bulk densities of the mortar samples in the dried state, they belonged to the ordinary mortars [ 82 ] without thermal insulation properties. The measured thermal conductivities for 28-day hardened reference mortars R2 and R3 (2.519 and 2.699 W/m·K, respectively) were very close to the value (2.7 W/m·K) found for the cement mortar in [ 83 ]. Figure 11 illustrates the trend in the simple moving average of the thermal conductivity coefficient for hardened mortar samples with an increasing content of fiber sample C in the mixture.…”

A study on the effects of the fractal characteristics of aggregates on the mechanical behavior of cemented sand and gravel

“…The section of an aggregate is rough and complex with obvious fractal characteristics; this can be represented by the box dimension. One of the most widely used fractal dimensions, its mathematical expression is as follows: supposing that is any non-empty bounded subset on R and N δ is the minimum number of boxes of size δ that can cover the set F, the box dimension can be obtained through the following Equation [3] ( 14): [3] where δ represents the unit measurement scale in a continuous distribution, i.e., a unit square used in the two-dimensional plane; N δ represents the number of measurement scales, which is the number of small squares covering polygonal aggregates; and D x represents the box dimension of an aggregate shape.…”

“…In order to study the effect of the mix proportion of different shapes of sand gravel aggregates on the performance of CSG, the fractal characteristics of mixed aggregates were determined as listed in Table 5. Based on Equation [3], the mixing ratios (LC1, LC2, LC3, LC4, LC5) of the above-mentioned five different shapes of aggregates are calculated, and the fractal dimension regression calculation results are shown in Figure 4 and Table 6. Since there were no polygonal aggregates in LC6, it was not required to calculate its fractal dimension.…”

“…The presence of unscreened aggregates in CSG complexifies its aggregate characteristics; moreover, CSG properties are different from those of ordinary concrete. Aggregate type, shape, and grading are all important factors influencing the mechanical behavior of concrete materials (3,4). Therefore, in order to provide a theoretical basis for CSG use in engineering design, it is necessary to systematically study the relationship between aggregate characteristics and CSG properties.…”

Design and Application of Cellular Concrete on a Mexican Residential Building and Its Influence on Energy Savings in Hot Climates: Projections to 2050

“…Measurements of mortar and concrete mixtures' mechanical properties, both fresh and hardened, are common in construction materials laboratories. However, measures related to thermal performance are different, such as the case of thermal conductivity [28], since it requires specialized equipment if measurements are to be carried out with a low error. This work presents the resulting thermophysical values of the designed materials with high certainty levels, which allows estimating the building's thermal performance through dynamic simulations with a closer approach to reality.…”