Concrete Technology Questions

• Legacy grade notation: For concrete graded as M 150, the specified 28-day compressive strength of a standard 15 cm cube is
• Fresh concrete testing: The slump test primarily measures which property of a concrete mix for site quality control and placement suitability?
• Units in materials management: Bulk density (unit weight) of aggregates at the stockyard or in batching is typically expressed in which unit?
• Concrete mixer planning: With an effective working time of 7 hours and a 150-litre mixer taking 3 minutes per batch, estimate the practical output (litres) for the day, allowing a reasonable efficiency factor for loading/unloading losses.
• Movement and cracking control: Why are joints (construction, contraction, and expansion joints) provided in concrete slabs and structures?
• Time window for handling OPC concrete: For mixes using Ordinary Portland Cement without set-retarding admixtures, the total time from mixing through transport, placement, and compaction should not exceed
• Quality control statistics: If the average compressive strength of specimens is 4000 kg/cm2 with a standard deviation of 500, what is the coefficient of variation (COV) expressed as a percentage?
• Raw materials for Ordinary Portland Cement (OPC): OPC clinker is primarily manufactured by burning a proportioned mix of which natural materials in the kiln, followed by inter-grinding with gypsum?
• Cement chemistry (C3S) — identify the incorrect statement For ordinary Portland cement, consider the following statements about tricalcium silicate (C3S). Which one is NOT correct?
• Fine aggregate grading — which IS sand zone typically demands a higher water–cement ratio? According to standard Indian grading zones for fine aggregates, sand that requires a relatively higher water–cement ratio for similar workability belongs to:
• Building services — features of an ideal warehouse (storage building) For an efficient and protective warehouse, which of the following features are typically provided to safeguard stored goods and maintain serviceability?
• Cement manufacturing — why is gypsum added to clinker during grinding? In Portland cement production, gypsum is interground with clinker primarily for:
• Nominal mixes — determine the corresponding legacy grade If the nominal volumetric proportion of concrete ingredients (cement : sand : coarse aggregate) is 1 : 3 : 6, the corresponding legacy grade designation is:
• Admixtures — identify the incorrect blanket statement about their effects Which of the following statements about concrete admixtures is NOT generally true?
• Compaction quality — effects of non-uniform compaction on concrete Non-uniform compaction during placement and vibration of concrete may result in which of the following problems?
• Air entrainment in concrete — primary effect on fresh and hardened properties The introduction of well-dispersed entrained air bubbles in concrete generally:
• Workability classification — what does a slump of about 6.5 cm indicate? A concrete mix measured by the slump test gives a slump of approximately 6.5 cm (65 mm). This mix is generally described as:
• Trial mixes — identify the incorrect practice for preliminary concrete tests While conducting preliminary (trial) mix tests to establish proportions, which of the following statements is NOT correct?
• Mix design practice — estimating mixing water for ordinary concrete In conventional civil engineering practice for ordinary (workable) concrete, an empirical rule of thumb is often used to estimate the quantity of mixing water as a percentage of constituent weights. Which of the following combinations best represents the approximate water required for preparing ordinary concrete?
• Portland cement manufacture — identify the raw material blend Cement used for normal concrete construction is produced by burning a carefully proportioned mixture of which categories of natural materials?