An-Najah University Journal for Research - A (Natural Sciences)

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Forms made of wood and steel in its different types are considered one of the widely used techniques in construction of Portland Cement Concrete structures. The effect of such forms on the physical and chemical properties of hardened Portland Cement Concrete (PCC) are under consideration relative to the durability of the exposed outer surfaces. This can be of great importance in structures exposed to weathering caused by either water-exposed structures or sever weathering of natural temperature cycles. In such structures, protective measures are used to insulate the hardened concrete against weathering. Such techniques are of no benefit if the chemical reaction between wood form and fresh concrete is already taking place. In other instances, high quality non-reactive ingredients are used to improve durability of Portland Cement Concrete. This is expected to deter deterioration of hardened cement surfaces, but casting is of concern in this case as well as the need for such measure. The type of interaction between wood forms and fresh concrete is a chemical reaction between acids which exists in the different types of wood and the ingredients of Portland Cement Concrete as well as a physical one in terms of the size of surface area exposed caused by the wood surface roughness.

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Forms made of wood and steel in its different types are considered one of the widely used techniques in construction of Portland Cement Concrete structures. The effect of such forms on the physical and chemical properties of hardened Portland Cement Concrete (PCC) are under consideration relative to the durability of the exposed outer surfaces. This can be of great importance in structures exposed to weathering caused by either water-exposed structures or sever weathering of natural temperature cycles. In such structures, protective measures are used to insulate the hardened concrete against weathering. Such techniques are of no benefit if the chemical reaction between wood form and fresh concrete is already taking place. In other instances, high quality non-reactive ingredients are used to improve durability of Portland Cement Concrete. This is expected to deter deterioration of hardened cement surfaces, but casting is of concern in this case as well as the need for such measure. The type of interaction between wood forms and fresh concrete is a chemical reaction between acids which exists in the different types of wood and the ingredients of Portland Cement Concrete as well as a physical one in terms of the size of surface area exposed caused by the wood surface roughness.