The Effects of Pine (Pinus Canariensis) Tree Bark Extract on the Properties of Fresh and Hardened Concrete

Abstract

In this research, pine tree bark extract was prepared in a digester by using water, heat, and pressure. In the digester, the ratio of the mass of the bark to that of the water was 1:2, respectively. The temperature in the digester was raised from the ambient level to 121 ^o C in 15 minutes. At the temperature of 121^o C, the pressure inside the digester was 0.1 N/mm². These conditions of heat and pressure were maintained for a period one hour, resulting in the liquid phase of the mixture turning opaque brown (black liquor). Without further processing, the black liquor was used as a concrete admixture and tests carried out to determine its effects on workability of fresh concrete and strength of hardened concrete. Dosages of the black liquor used, expressed as a mass percentage of the cement content were 10 %, 20 %, 30 %, 40 %, and 47.5 %. In each case, the mixing water was reduced by an amount equal to the mass of the dosage. For each dosage, compressive strength tests were carried out at the ages of 3,7,28, and 61 days. Compared with control concrete, increases of workability were observed for all the dosages. However, consistent improvement in compressive strength only occurred when the dosage of pine bark extract was 20 %.

Keywords: Concrete admixture, lignin, pine, strength, workability.