The effects of expanded perlite aggregate, silica fume and fly ash on the thermal conductivity of lightweight concrete

Effects of expanded polystyrene (EPS) particles on fire resistance, thermal conductivity and compressive strength of foamed concrete

The effects of different cement dosages, slumps, and pumice aggregate ratios on the thermal conductivity and density of concrete

Influence of mineral admixtures on thermal conductivity and compressive strength of mortar

Effect of Pumice and Fly Ash Incorporation on High Temperature Resistance of Cement Based Mortars

The bond between concrete and steel reinforcing bars was evaluated by electromechanical pullout testing that involved measuring the shear bond strength and contact electrical resistivity of each sample. The bond strength was increased by steel reinforcing bar surface treatment (acetone, water, ozone, or sandblasting, with ozone treatment being the most effective and acetone treatment being the least effective), adding silica fume and polymer to the concrete, an increase in the water-cement ratio of concrete (particularly from 0.45 to 0.50), and a decrease in the curing age (particularly from 14 days to 7 days). The origins of these effects are reinforcing bar cleansing for acetone treatment (accompanied by a decrease in contact resistivity), reinforcing bar surface oxide film formation for water and ozone treatments (accompanied by increases in contact resistivity), reinforcing bar surface roughening for sandblasting, polymer interface layer formation for the addition of polymer (accompanied by an increase in contact resistivity for the addition of latex, but not for the addition of methyl-cellulose), a decreased interfacial void content (accompanied by a decrease in contact resistivity) for an increase in the water-cement ratio (because of an increase in fluidity) and for a decrease in the curing age (because of a decrease in shrinkage), and an increase in the matrix modulus for the addition of silica fume. Corrosion initially caused the bond strength to increase while the contact resistivity increased, but further corrosion caused the bond strength to decrease while the contact resistivity continued to increase.

Effects of Water-Cement Ratio, Curing Age, Silica Fume, Polymer Admixtures, Steel Surface Treatments and Corrosion on the Bond between Concrete and Steel Reinforcing Bar

A comparative study was conducted on the thermal and thermomechanical behavior of cement pastes containing various additives (silica fume, latex, methylcellulose, and short carbon fibers). The thermal conductivity was decreased by silica fume, methylcellulose, or latex by up to 46%. It was not increased by carbon fibers. The specific heat was increased by silica fume, latex, methylcellulose, or carbon fibers by up to 9%. The flexural storage modulus decreased reversibly with increasing temperature from 30 deg C to 150 deg C, whereas the weight loss upon heating was irreversible. Silica fume gave higher modulus than methylcellulose or latex, which in turn gave higher modulus than the absence of any additive. The creep rate was lower for silica fume than methylcellulose or latex, for which the creep rate was lower than the absence of any additive. The apparent coefficient of thermal expansion was reduced by silica fume (but was still positive), but was negative for methylcellulose or latex.

Ddl Chung

Papers

Effects of Water-Cement Ratio, Curing Age, Silica Fume, Polymer Admixtures, Steel Surface Treatments and Corrosion on the Bond between Concrete and Steel Reinforcing Bar

Effect of Admixtures on Thermal and Termo-mechanical Behavior of Cement Paste