Concrete Test 2024 Questions and Answers with complete solution

Concrete Test 2024 Questions and Answers with complete solution What's the maximum time a concrete truck can wait after leaving the batch plant and still be poured? - Answer ️️ -90 minutes When should floor slabs be sawcut and how deep? - Answer ️️ -Sameday, 1/4 of the thickness of the slab The function of dowels at a construction joint is? - Answer ️️ -To prevent differential settlement of the slabs What is the maximum number of rotations of the drum of a ready mixed concrete truck between batching and placement? - Answer ️️ -300 What are the four components of concrete? - Answer ️️ -Water, cement, sand, aggregate On exterior slabs, we use air entrained concrete to? - Answer ️️ -Provide greater resistance to deicing salts At ARCO we will refuse any concrete that has a slump greater than? - Answer ️️ -5.5 inches In mix proportioning, what factor is most important in controlling strength? - Answer ️️ -The water to cement ratio (the amount of water in the mix in comparison with the amount of cement) governs the strength. Adding unneeded water to the mix dilutes the cement paste and weakens the concrete. To protect against wheel loads, what kind of Construciton joint is used? - Answer ️️ -Dowel baskets What joint spacing would you recommend for a 4" thick concrete slab? - Answer ️️ -The joints spacing in feet shall not exceed 2 to 3 times the slab thickness in inches. The joint spacing for the 4" thick slab should be between 8 feet and 12 feet. What is the best way to prevent surface drying? - Answer ️️ -Immediate application of a membrane cure prevents early drying after finishing. Which of the materials in the mix affects concrete temperature the most? - Answer ️️ -The aggregate has the greatest effect on concrete temperature, water is next, and cement has the least the effect. How many tons does an 8.5" thick tilt wall panel weigh that is 28' tall and 15' wide? - Answer ️️ -(8.5/12)(28')(15')(150lbs/CF) all divided by 2,000 = 22.3 A sack of cement weighs? - Answer ️️ -94 LBS. The maximum number of gallons per sack of cement that we specify is? - Answer ️️ -6 gallons Adding one gallon of water to a cubic yard of concrete will? - Answer ️️ -Increase the slump approximately 1", increases the shrinkage potential about 10%, increase the possibility of seepage through the concrete by 50%. What percentage of concrete's ultimate strength does it achieve in seven days? - Answer ️️ - 70% We have the testing laboratory inspect the sub grade prior to pouring to confirm? - Answer ️️ - The proper compaction of the sub grade, the sub grade is graded to the proper grade, the mesh is properly overlapped When should we sawcut a floor slab? - Answer ️️ -As soon as the slab will support the saw and the edges won't spall. How can settlement cracks in the slabs on grade be prevented? - Answer ️️ -Settlement cracks in concrete slabs are caused by subgrade settlement. Carefully compacting the sub grade prior to concrete placement At what depth should the reinforcement be placed in a slab on grade? - Answer ️️ - Reinforcement should be placed in the upper part of the slab but 2" below the top of the concrete surface. It is always a good idea to use fiber mesh in the floor slab when used to cast tilt up panels for extra strength? (True or False) - Answer ️️ -Fals