Three materials were studied as internal curing agents: artificial fly ash and slag aggregates, drinking water treatment waste, and porous ceramic waste aggregates. Artificial fly ash and slag aggregates were made from fly ash or slag bonded with cement and cured to act as reservoirs for hydration water. Drinking water treatment waste and porous ceramic waste provided hydration water for cement. All three materials improved concrete properties like strength and reduced shrinkage when used to internally cure concrete, making them potential alternatives for field use depending on availability and exposure conditions.

1. INTERNAL CURING USING
DIFFERENT
ADMIXTURES
Guided by
Dr. B. Kondraivendhan
Assistant prof.
Presented by –
AMRATA YADAV
(U13CE068)

2. Introduction
oCuring?
• maintaining moisture inside concrete during early ages
and beyond.
• controlling rate and extent of moisture loss.
• to ensure uninterrupted hydration of cement.
o Reasons to Cure Concrete
•Concrete strength gain
•Improved durability of concrete
•Enhanced serviceability
•Improved microstructure

3. o Right Time to Cure Concrete
• during initial set - if rate of evaporation of bleed water is greater
than rising water –Plastic Shrinkage occurs- Mist curing
• between initial set and final set- to prevent loss of moisture-
curing in the form of barriers - covering with plastic sheets,
waterproof paper.
• after final set – Precise curing -Ponding, wet coverings with
cloth etc
o Duration of Curing
• depends on grade & type of cement, mix proportion, desired
strength, shape and size and environmental & exposure
conditions.
• vary from few days to a month.
• at least 7 days - Ordinary Portland Cement.
• at least 10 days- mineral admixtures used.

4. o Methods to Cure Concrete
• Water curing-Ponding ,Sprinkling, fogging & mist curing, Wet
coverings.
• Membrane curing-Formwork , Plastic Sheetings, Membrane
curing compounds –wax, acrylic.
• Steam curing-Exposure to steam and humidity.-raising the
temperature of concrete to accelerate rate of strength gain.

5. o Internal Curing?
• process by which hydration of cement continues because of
availability of internal water that is not part of mixing water
o Need for Internal Curing??
 High-Strength concretes (HSCs)
• Uses -> High Rise Structures, Highway Bridges
-> Components like columns, shear walls and foundations.
• Properties -> higher paste volume, denser, high cement content
low water-cement ratio (w/c)
• Problem with high-strength concretes -> discontinuous
capillary pores , low porosity, inadequate water for hydration, no
water entry.
 Difficult terrain where access is impossible & structure are inaccessible.
 If water contains high chemical content such as chlorides, fluorides and
other salts , areas where scarcity of water.

6. INTERNAL CURING USING ARTIFICIAL
AGGREGATES AS WATER RESERVOIR
oArtificial Aggregates
• aggregates produced through cold bonding pelletization of
90% fly ash or slag with 10% Portland cement.
oWhy Artificial Aggregates ?
• to preserve the natural resources like ..Water
• effective way to increase recycling of byproducts
• autogenous shrinkage performance of HSCs can be
improved
• reduction of cost of project to a great extent

7. o Making of Artificial Fly Ash(AFA) & Slag
Aggregates(ASA)
• dry mixture of 90% FA+10% PC or 90% GGBFS+10% PC
was pelletized through moisturizing in a rotating inclined
pan at ambient temperature.
• For hardening, kept in sealed plastic bags & stored at
20°C and a relative humidity of 70% for 28 days

8. Concrete design mix (kg/m3 )

9. o Performance of Artificial Aggregates as Internal
Curing Agent
• Readily available water within pre-wetted AAs maintained
saturation of the cement paste and thereby reduced autogenous
shrinkage.
• AFA was much more effective than ASA in mitigating the
autogenous shrinkage.
• Concrete with ASA aggregates had comparable compressive
strengths to that of normal concrete. But reduction in compressive
strength of concretes with increasing AFA was observed.
• In case of ASA, compressive strength was 7.6% higher at a 20%
replacement level.
• ASA, may be considered a novel option for internal curing.

11. USING DRINKING WATER TREATMENT
WASTE
oIntroduction
 water treatment processes result in approximately
4% sludge generation of the total of water treated.
 The water in sludge is : bulk water and bond water.
 Bond water includes interstitial water, vicinal water,
and water of hydration.
 bond water is easily accessible and can be beneficial
for internal curing.

12. • Mortar mixture designs
PC- Portland cement control mortar
SP- Portland cement mortar with superabsorbent polymer
LW- Portland cement mortar with pre-wetted lightweight aggregate
substituted for a portion of the standard sand
WT- Portland cement mortar with DWTW substituted for a portion
of the standard sand.

13. Mortar mixture proportion, lb/yd3
(kg/m3)

14. o Performance of DWTW as Internal Curing Agent
• DWTW provided an increased degree of hydration
over the control mortar.
• DWTW used as an internal curing agent in cement
mortar mixture resulted in increased compressive
strength at 7 and 28 days.
• Mortar containing DWTW showed a 25% reduction in
autogenous shrinkage versus the control group at 28
days.
• Drinking water treatment waste is an effective internal
curing agent and has similar performance to both the
investigated superabsorbent polymer and pre-wetted
lightweight fine aggregate.

16. USING CERAMIC ROOF MATERIAL
oIntroduction
 waste aggregate produced from roof material,
designated as porous ceramic waste aggregate (PCA)
is effective in internal curing.
 water from presaturated porous aggregate can be
supplied for the hydration of the cement when
porous aggregates are replaced by natural course
aggregates.

17. oPerformance of PCA as Internal Curing Agent
 Internal curing using PCA replacing coarse aggregate
by 10 and 20% in volume was effective in improving the
compressive strength of Portland blast furnace cement
by 9% compared with ordinary Portland cement
concrete at the age of 28 days.
 A 10% replacement of coarse aggregate by PCA was
more effective in improving compressive strength than
a 20% replacement by PCA at the early ages of 3 and 7
days.
 Internal curing using PCA was not effective in reducing
autogenous shrinkage.

18. CHALLENGES TO INTERNAL CURING
1. properties of AA change with the production
process. performance of concretes having AA
should be investigated independently for each
type of AA.
2. Drinking Water Treatment Waste may contain
some other chemicals which can affect the
mechanical properties of Concrete.

19. SUMMARY
• Three materials used as an internal curing agents were
studied. That are
• Artificial Fly Ash and Slag Aggregates
• Drinking water treatment waste
• Porous Ceramic waste aggregates
• All the three materials were effective as an internal
curing agents. Therefore they can be used in the field
depending on the factors like availability of these
materials, exposure conditions etc.

20. References
• [1] 2013S.B.Kulkarni AVP, Technical Services, and Clinton Pereira Dy.Manager Technical-
UltraTech Cement Ltd, Mumbai, “Significance of Curing of Concrete for Durability of
Structure” NBM&CW Technical article
• [2] Indian Standard-Plain & Reinforced concrete-Code of Practice, 4th revision, page 27)
• [3] Mehmet Gesog˘ lu, Erhan Güneyisi, Ali Nooruldeen Ismael Ismael, and Hatice Öznur
Öz, “Internal Curing of High-Strength Concretes Using Artificial Aggregates as Water
Reservoirs,” ACI Materials Journal, V. 112, No. 6, November-December 2015.
• [4] Qiwei Cao Nowasell and John T. Kevern, “Using Drinking Water Treatment Waste as
Low-Cost Internal Curing Agent for Concrete,” ACI Materials Journal 112(1) · January 2014
• [5] Sato, R., Shigematsu, A., Nukushina, T., and Kimura, M. (2011). "Improvement of
Properties of Portland Blast Furnace Cement Type B Concrete by Internal Curing Using
Ceramic Roof Material Waste." J. Material. Civ. Eng., 10.1061/(ASCE)MT.1943-
5533.0000232, 777-782.
• [6] Espinoza-Hijazin, G., Paul, Á., and Lopez, M. (2012). "Concrete Containing Natural
Pozzolans: New Challenges for Internal Curing." J. Material. Civ. Eng.,
10.1061/(ASCE)MT.1943-5533.0000421, 981-988.
• [7] ACI Concrete Terminology-2013.