Common use of Batching and Mixing Clause in Contracts

Batching and Mixing. The location and preparation of the sites for the stock pilling of aggregates the maximum size of stock piles and the method adopted to prevent segregation of coarse and fine material shall be subject to the approval of the Superintending Engineer. Each separate size of coarse aggregates shall be stock piled separately. The aggregate shall be handled from the stock piles to the batching plant in such a manner as to secure a typical grading of the material. Aggregates that have become mixed with earth of foreign material shall be used only after washing and cleaning. All washed aggregates shall be stocked for draining atleast 12 hours before being batched. After determining the proportions of ingredients for the field mix, the fine aggregate and each separated size of coarse aggregate shall be proportioned and placed into the xxxxxx of the mixer along with necessary quantity of ceme[1t. Ct'ment shall be measured by the bag per by weight. At batching or mixing of materials as far as possible shall be on the basis of one or more whole bags of cement. rhe Superintending Engineer may permit the use of fractional bags of cement in a manner meeting with the approval. Water may be measured either by volume or by weight. The contents of the xxxxxx shall then be emptied into the drum of the approved mixer taking care to prevent possible loss of c.ement by being blown away in high wing. The aggregate and the cement shall be thoroughly mixed in the mixer for a period of not less than one minute during which time the drum shall make not less than 16, not more than 20 revolutions per minute. The water shall be introduced in a uniform manner during the first 15 seconds of the mixing period. The mixing time may be extended if necessary to obtain thorough mixing and uniform consistency. Any concrete mixed less than the specified mixing time shall be rejected and disposed off by the contractor at his expense. The entire contents of the drum shall be discharged before any materials are placed therein for the succeeding batch. The skip and throat of the drum shall be kept free of accumulation. The volume of material mixed per batch shall not exceed the manufacture's rated capacity of the drum. The mixer shall be placed as close to the part of the structure being concreted as possible. The concrete shall be mixed only in the quantity required for immediate use. In volume batching suitable allowance shall be made for the bulking of fine aggregate due to the presence of water. For this purpose the bulking shall be determined as directed by the Superintending Engineer. When hand mixing is authorised it shall be done with 10% increase in cement content on a watertight platform and in such a manner as to ensure a uniform distribution of the materials throughout the mass. Mixing shall be continued untill all the stone particles are thoroughly covered and a homogenous mixture of the required consistency is obtained. Hand mixed batches shall be of volume to take in one bag of cement only. No extra cost will be paid for this 10% cement.

Batching and Mixing. The location and preparation of the sites for the stock pilling of aggregates the maximum size of stock piles and the method adopted to prevent segregation of coarse and fine material shall be subject to the approval of the Superintending Engineer. Each separate size of coarse aggregates shall be stock piled separately. The aggregate shall be handled from the stock piles to the batching plant in such a manner as to secure a typical grading of the material. Aggregates that have become mixed with earth of foreign material shall be used only after washing and cleaning. All washed aggregates shall be stocked for draining atleast 12 hours before being batched. After determining the proportions of ingredients for the field mix, the fine aggregate and each separated size of coarse aggregate shall be proportioned and placed into the xxxxxx of the mixer along with necessary quantity of ceme[1t. Ct'ment cement. Cement shall be measured by the bag per by weight. At batching or mixing of materials as far as possible shall be on the basis of one or more whole bags of cement. rhe The Superintending Engineer may permit the use of fractional bags of cement in a manner meeting with the approval. Water may be measured either by volume or by weight. The contents of the xxxxxx shall then be emptied into the drum of the approved mixer taking care to prevent possible loss of c.ement cement by being blown away in high wing. The aggregate and the cement shall be thoroughly mixed in the mixer for a period of not less than one minute during which time the drum shall make not less than 16, not more than 20 revolutions per minute. The water shall be introduced in a uniform manner during the first 15 seconds of the mixing period. The mixing time may be extended if necessary to obtain thorough mixing and uniform consistency. Any concrete mixed less than the specified mixing time shall be rejected and disposed off by the contractor at his expense. The entire contents of the drum shall be discharged before any materials are placed therein for the succeeding batch. The skip and throat of the drum shall be kept free of accumulation. The volume of material mixed per batch shall not exceed the manufacture's rated capacity of the drum. The mixer shall be placed as close to the part of the structure being concreted as possible. The concrete shall be mixed only in the quantity required for immediate use. In volume batching suitable allowance shall be made for the bulking of fine aggregate due to the presence of water. For this purpose the bulking shall be determined as directed by the Superintending Engineer. When hand mixing is authorised it shall be done with 10% increase in cement content on a watertight platform and in such a manner as to ensure a uniform distribution of the materials throughout the mass. Mixing shall be continued untill all the stone particles are thoroughly covered and a homogenous mixture of the required consistency is obtained. Hand mixed batches shall be of volume to take in one bag of cement only. No extra cost will be paid for this 10% cement.