Building Materials and Concrete Technology MCQs 2026

Alkali-aggregate reaction (AAR) involves

1. Aonly sulphate in soil✓
2. Bonly carbonation✓
3. Creactive silica in aggregate with alkaline cement pore solution✓
4. Donly chloride attack✓

Air entrainment in concrete is achieved using

1. Aextra cement only✓
2. Bcoarse sand only✓
3. Chigh w/c only✓
4. Dair-entraining admixtures (e.g., Vinsol resins)✓

Water-reducing admixtures (plasticizers) allow

1. Ahigher w/c always✓
2. Bno cement✓
3. Cinstant set only✓
4. Dlower water content for same workability✓

Retarding admixtures are used to

1. Adelay setting time in hot weather or long haul✓
2. Baccelerate strength always✓
3. Cincrease bleeding only✓
4. Dreplace cement✓

Accelerating admixtures such as calcium chloride promote

1. Apermanent retardation✓
2. Bfaster setting and early strength (use restricted in reinforced concrete)✓
3. Conly colour change✓
4. Dsulphate immunity✓

Fly ash as supplementary cementitious material exhibits

1. Ahydraulic set without water✓
2. Bonly filler with no reaction✓
3. Cpozzolanic activity consuming Ca(OH)2✓
4. Dnegative strength always✓

Ground granulated blast furnace slag (GGBS) in concrete typically

1. Aincreases early heat greatly✓
2. Bimproves sulphate resistance and reduces permeability✓
3. Celiminates need for curing✓
4. Dprevents all shrinkage✓

Silica fume is used to produce

1. Aonly lean mixes✓
2. Bhigh-strength, low-permeability concrete✓
3. Czero cement mortar✓
4. Donly road sub-base✓

Maturity of concrete relates strength development to

1. Aonly calendar days regardless of temperature✓
2. Btime-temperature history✓
3. Caggregate colour✓
4. Dformwork type✓

Curing of concrete is essential to

1. Adry surface rapidly✓
2. Bprevent any hydration✓
3. Cmaintain moisture for continued hydration and strength gain✓
4. Dremove all cement paste✓

Minimum curing period for ordinary concrete is commonly

1. A2 hours only✓
2. B7 to 14 days depending on cement type and exposure✓
3. Cno curing if high w/c✓
4. Donly in winter✓

Steam curing is used in precast plants to

1. Areduce strength✓
2. Bincrease w/c✓
3. Cprevent hydration✓
4. Daccelerate strength gain by elevated temperature✓

Shrinkage in concrete includes

1. Aonly elastic deformation under load✓
2. Bonly aggregate crushing✓
3. Cplastic, drying and autogenous components✓
4. Dthermal expansion only✓

Creep in concrete is

1. Atime-dependent deformation under sustained load✓
2. Binstant elastic strain only✓
3. Creversible upon unloading immediately✓
4. Donly in steel✓

Modulus of elasticity of concrete is influenced by

1. Aonly bar diameter✓
2. Bonly wind✓
3. Cpaint colour✓
4. Daggregate stiffness, w/c and age✓

Standard cube compressive strength of concrete is tested at

1. A1 hour only✓
2. B28 days on 150 mm cubes (common practice)✓
3. Cafter carbonation only✓
4. Don wet cubes without caps✓

The compound C3S in Portland cement clinker is primarily responsible for

1. Aearly strength development✓
2. Bsulphate resistance only✓
3. Clong-term heat of hydration only✓
4. Dair entrainment✓

C2S in cement contributes mainly to

1. Aimmediate flash set✓
2. Blater-age strength gain✓
3. Chigh early heat only✓
4. Defflorescence✓

C3A reacts rapidly with water and is controlled by adding

1. Aextra sand✓
2. Bonly water reducers✓
3. Cgypsum during grinding✓
4. Dcoarse aggregate✓

Fineness of cement is commonly measured by

1. ABlaine air permeability test✓
2. Bslump test✓
3. Caggregate impact value✓
4. DProctor test✓

Initial setting time of OPC should not be less than

1. A10 minutes✓
2. B30 minutes✓
3. C60 minutes✓
4. D12 hours✓

Ordinary Portland Cement (OPC) is manufactured by grinding clinker with a small amount of

1. Asand✓
2. Blime only✓
3. Cfly ash only✓
4. Dgypsum✓

Final setting time of OPC should not exceed

1. A60 minutes✓
2. B600 minutes (10 hours)✓
3. C30 minutes✓
4. D24 hours always✓

Hydration of cement is

1. Aa chemical reaction between cement and water forming C-S-H gel✓
2. Bonly physical drying✓
3. Cevaporation of mixing water only✓
4. Dcarbonation only✓

Heat of hydration is highest for cement rich in

1. AC3A and C3S✓
2. BC2S only✓
3. Cgypsum only✓
4. Dinert fillers✓

Rapid Hardening Cement attains high early strength because it is

1. Acoarser than OPC✓
2. Bfree of gypsum✓
3. Cpure lime✓
4. Dfiner ground with higher C3S content✓

Sulphate Resistant Cement has low

1. AC2S content✓
2. Bgypsum✓
3. Csilica fume✓
4. DC3A content✓

Portland Pozzolana Cement uses pozzolana to improve

1. Aonly colour✓
2. Bworkability, durability and resistance to chemical attack✓
3. Conly aggregate grading✓
4. Dzero strength✓

White cement is produced using

1. Ahigh fly ash only✓
2. Bsea water curing only✓
3. Ciron-free or low-iron raw materials and cooler kiln conditions✓
4. Dextra C3A✓

Water-cement ratio primarily governs

1. Astrength and durability of hardened concrete✓
2. Bonly slump✓
3. Conly aggregate shape✓
4. Dformwork cost only✓

According to Abrams law, concrete strength is inversely related to

1. Acement content alone✓
2. Baggregate size only✓
3. Cair temperature only✓
4. Dwater-cement ratio✓

Workability of fresh concrete is commonly assessed by

1. Acompressive test on hardened cubes✓
2. BRebound hammer✓
3. Cslump test✓
4. Dcore cutting✓

A true slump indicates

1. Ashear failure of cone✓
2. Bconcrete subsides uniformly without disintegration✓
3. Ccollapse slump✓
4. Dzero movement✓

Segregation in concrete means

1. Auniform distribution✓
2. Bair entrainment✓
3. Cproper curing✓
4. Dseparation of coarse aggregate from mortar✓

Bleeding in fresh concrete is

1. Arise of free water to the surface✓
2. Bloss of cement✓
3. Cair loss only✓
4. Dinstant setting✓

Bulking of sand occurs due to

1. Asurface moisture films increasing apparent volume✓
2. Bcement hydration✓
3. Caggregate crushing✓
4. Dchemical reaction with cement✓

Fineness Modulus of sand indicates

1. Acement strength✓
2. Bslump in mm only✓
3. Cwater demand zero✓
4. Daverage particle size — higher FM means coarser sand✓

Coarse aggregate for RCC should generally be

1. Asoft shale only✓
2. Borganic clay lumps✓
3. Cwell graded, clean, hard and durable✓
4. Dhighly absorptive without limit✓

Maximum size of coarse aggregate is often limited by

1. Acolour of formwork✓
2. Bspacing of reinforcement and cover thickness✓
3. Ctype of cement only✓
4. Dwind speed✓

Grading of aggregate means

1. Aparticle size distribution across standard sieves✓
2. Bshape only✓
3. Cspecific gravity only✓
4. Dmoisture only✓

Specific gravity of aggregates is used to

1. Ameasure slump✓
2. Bconvert mass batching to volume batching and mix design✓
3. Ctest compressive strength✓
4. Ddetermine setting time✓

Water absorption of aggregate affects

1. Aeffective water-cement ratio in mix✓
2. Bonly colour✓
3. Conly formwork pressure✓
4. Dgypsum content✓

Deleterious materials in aggregate include

1. Aclean crushed granite only✓
2. Bwell-graded quartz✓
3. CSSD moisture✓
4. Dclay lumps, organic impurities and excessive fines✓