Sawdust waste material is a by-product of manufacturing furniture and other wood products. It poses a major problem for the environment if no action is considered to get rid of it. For this reason, this research presents a new modality for recycling sawdust west material as a partial replacement of a plaster of Paris (POP). Six composite mortars prepared from different sawdust ratios 0, 2, 4, 6, 8 and 10 % by wt. of POP were used to investigate the physical and mechanical properties of these mortars. The effect of different temperature levels (100, 200, 300, 400 and 500 Cₒ) on the properties of these composite mortars was also investigated. The results show that the optimal proportion of sawdust in the mortar was 10 %, where the compressive strength increased by about 51.47 % compared to the reference mix (without sawdust) at 50 Cₒ. Additionally, there was a development in the modulus of rupture (MOR) for composite mixtures. The 6% sawdust content exhibited a 28.33 % increase in MOR. It was also found that sawdust reduced the density of the samples. Raising the temperature to 200 Cₒ and beyond affects the mechanical properties negatively.

The effect of retarding admixture on the fresh and hardened behaviour of different types of cement mortars and pastes when using a retarding admixture was investigated in this study. The types of cement used are; White cement (WhC), Ordinary Portland cement (OPC) and Sulphate Resistant Portland cement (SRC). Different cement mortar and paste mixes were cast, for this purpose, with and without the admixture. Initial and final setting times, compressive strength, length change, absorption and density for these mixes were examined at the curing ages of 3,7,28,45 days. The results showed that the addition of retarding admixture delayed the setting time significantly of WhC paste. The retarding admixture has a positive effect on the compressive strength of the mortar specimens for all types of cement used. regarding the length change test, the admixture was found to reduce the initial expansion for all types of cement at all ages. The results also showed an increase in the density and decrease in water absorption, especially at the later ages for all types of cement.  Among all cement types used, WhC was noticeably the most affected type by using the retarding admixture compared to other types of cement used.