A. general: this specification refers to the execution of supply operations; material storage; dosage; elaboration of forms; preparation; transport; placement; forge; vibration; cured; finishing and repair of concrete or concrete; according to the resistances; alignment; dimensions and details as indicated in the drawings. cement: cement must be portland type or other type; previously approved by the controller; as long as it meets the standards i. the cement must be of the same type and brand as that used for mix designs. any change in the characteristics or origin of the cement will make it necessary to redesign the mixtures in accordance with the order of the controller. it will not be accepted for any reason to mix cement from different factories. it will be the contractor's obligation to present; along with the mix designs; certified copies of the results of the physical and chemical tests of the cement that will be used in the production of the concrete throughout the work (131). the contractor must provide adequate spaces to store the cement and protect it from moisture. cement should be stored in covered locations and on wooden platforms. the cement bags must be placed on their sides; in piles whose height is not more than five bags and must be turned every fourteen days. the storage of the bags must allow free access for the inspection and identification of each lot. the different types of cement that are required for the work must be stored in separate sections in the tanks; each type of cement must be clearly identified by means approved by the financial controller.