Cementitious binders, activators and methods for making concrete

Abstract

A cementitious binder comprises at least 90% by weight of a hydraulically-active material comprising ground granulated blast furnace slag (GGBS) and/or pulverised fuel ash (PFA), and at least 0.1% by weight of CaO in an activator composition for the hydraulically-active material. The cementitious binder does not comprise any Portland cement and is, therefore, more environmentally friendly. The binder further comprises a superplasticiser such as a polycarboxylate ether (PCE). A concrete, mortar, grout, screed or render may be formed from a mixture of the cementitious binder, aggregate particles, water and superplasticiser.

Claims

1. A cementitious binder consisting of at least 90% by weight of a non-Ordinary Portland Cement (non-OPC) pozzolanic hydraulically-active material comprising ground granulated blast furnace slag (GGBS), pulverised fuel ash (PFA) or a mixture of GGBS and PFA, at least 0.1% and less than 9.5% by weight of an activator, which is CaO or lime, and a superplasticiser.

2. A cementitious binder according to claim 1, in which the superplasticiser is a polycarboxylate-ether-based (PCE) superplasticiser.

3. A cementitious binder according to claim 1, which consists of GGBS, PFA or the mixture of GGBS and PFA, the CaO or lime and the superplasticiser.

4. A cementitious binder according to claim 1, comprising at least 1 wt % CaO or lime.

5. A cementitious binder according to claim 1, comprising greater than 93% by weight hydraulically-active material.

6. A cementitious binder according to claim 1, comprising between 0.2% and 2% by weight superplasticiser.

7. A cementitious binder according to claim 1, in which the superplasticiser is in powder form and the binder comprises more than 0.3% by weight and 1.2% by weight superplasticiser.

8. A cementitious binder according to claim 1, in which the superplasticiser is in liquid form and the binder comprises more than 0.2% by weight and less than 2% by weight superplasticiser.

9. A concrete, mortar, grout or render comprising a cementitious binder as defined in claim 1.

10. A concrete, mortar, grout, or render according to claim 9, in which the weight ratio of water to binder is between 0.2:1 and 0.4:1.

11. A concrete, mortar, grout or render according to claim 9, which has a compressive strength of greater than 15 MPa after 7 days, and greater than 20 MPa after 14 days, and greater than 30 MPa after 28 days.

12. A cementitious binder comprising; between 94 and 97% by weight of a hydraulically-active material comprising ground granulated blast furnace slag (GGBS), pulverised fuel ash (PFA), or a mixture of GGBS and PFA; between 1.5% and 3.5% by weight CaO or lime; and between 0.2% and 2% by weight superplasticiser.

13. A cementitious binder according to claim 12, comprising between 1-2.5 wt % microsilica and/or PFA.

14. A concrete, mortar, grout or render comprising a cementitious binder according to claim 12.

15. A cementitious binder according to claim 12, in which the superplasticiser is a polycarboxylate-ether-based (PCE) superplasticiser.

Description

DESCRIPTION OF SPECIFIC EMBODIMENTS OF THE INVENTION

(1) Specific embodiments according to one or more aspects of the invention will now be described by way of example.

EXPERIMENTAL METHODS

(2) Unless otherwise specified, in the following Examples a cementitious binder was prepared by mixing GGBS with activator compositions or components consisting of or comprising CaO. The cementitious binder was then mixed with aggregates. After a brief pre-mixing period, 80% of the mixing water was added, which was followed by the addition of a fluidifier (dispersant, or superplasticiser) together with the rest of the mixing water. The entire blend was thoroughly mixed for 10 minutes after which it was placed in appropriate moulds with the aid of vibration.

(3) Samples for strength testing were left to cure in air for 24 hours and then under water until tested. Samples for shrinkage testing were left in air for 24 hours and then de-moulded.

(4) Tests were performed in accordance with the following standards (BS=British Standard).

(5) SlumpBS EN 12350-2:2009

(6) Setting timeBS EN 13294:2002

(7) StrengthBS EN 12390-3:2009

(8) Drying shrinkage/wetting expansionBS EN 12617-4:2002

Example 1

(9) A cementitious binder was prepared having a composition defined by the following weight ratio: GGBS 95%, CaO 3%, Microsilica 2%. The specific weights of these components were: GGBS (2.57 kg), CaO (0.08 kg), Microsilica (0.05 kg).

(10) The GGBS was supplied by Hanson Ltd. This is a blastfurnace slag principally comprising the oxides of calcium, silicon, aluminium, and magnesium. This GGBS has been ground to a specific surface area of approximately 500 m.sup.2/kg, and the powder has a bulk density of 1000-1300 kg/m.sup.3. The mean particle size is 5-30 micrometers and the particle density is 2750-3000 kg/m.sup.3.

(11) The microsilica used has the trade name SILACEM, and is a silica fume having an average particle size of between 0.13 and 0.16 micrometers.

(12) To form a concrete, the following components were mixed;

(13) 2.69 kg of the cementitious binder described above;

(14) 27 ml Sika ViscoCrete10 (a liquid PCE superplasticiser added as a component of the binder);

(15) 1.5 kg Ardleigh stone;

(16) 5.6 kg Granite;

(17) 5.1 kg Sand;

(18) 0.81 l tap water.

(19) The components were mixed completely and cast.

(20) The resulting concrete had a strength of 41 MPa at 14 days, and 44 MPa at 28 days.

Example 2

(21) Mix design (per 15 kg batch of solids)

(22) Binder: GGBS 94.6%+CaO 2.6%+PFA super fine 1.8%+PCE 1%

(23) The weights used were GGBS (2.57 kg), CaO (0.07 kg), PFA super-fine (0.05 kg), 27 ml Sika ViscoCrete10 (a liquid PCE superplasticiser added as a component of the binder); the solid components of the binder were mixed and then the PCE mixed 1:100 with the remainder of the binder (i.e. 1 wt %)

(24) Aggregates: Ardleigh stone (1.5 kg), Granite (5.6 kg), Sand (5.1 kg)

(25) Water: tap water (0.81 L, water/binder ratio=0.3)

(26) Slump: 40 mm

(27) Setting time: 6 hrs initial, 9 hrs final

(28) 7 days compressive strength: 37 MPa

(29) 14 days compressive strength: 40 MPa

(30) 28 days compressive strength: 46 Mpa

Example 3

(31) Mix design (per 15 kg batch of solids)

(32) Binder: GGBS 96.4%+CaO 2.6%+superplasticiser 1%.

(33) The weights used were GGBS (2.63 kg), CaO (0.07 kg), 27 ml Sika ViscoCrete10 (a liquid PCE superplasticiser as a component of the binder). The PCE was mixed 1:100 with the remainder of the binder (i.e. 1 wt %)

(34) Aggregates: Ardleigh stone (1.5 kg), Granite (5.6 kg), Sand (5.1 kg)

(35) Water: tap water (0.81 L, water/binder ratio=0.3)

(36) Slump: 40 mm

(37) 14 days compressive strength: 38 MPa

(38) 28 days compressive strength: 42 MPa

(39) Drying shrinkage characteristics: 400-600 micro strains (OPC control 600 micro strains)

Example 4

(40) Mix design (per 15 kg batch of solids)

(41) Binder: GGBS 94.6%+CaO 2.6%+Undensified microsilica 1.8%+superplasticiser 1%.

(42) The weights used were GGBS (2.57 kg), CaO (0.07 kg), undensified microsilica (0.05 kg), 27 ml Sika ViscoCrete10 (a liquid PCE superplasticiser as a component of the binder). The solid components of the binder were mixed and then the PCE mixed 1:100 with the remainder of the binder (i.e. 1 wt %)

(43) Aggregates: Ardleigh stone (1.5 kg), Granite (5.6 kg), Sand (5.1 kg)

(44) Water: tap water (0.81 L, water/binder ratio=0.3)

(45) Slump: 40 mm

(46) 14 days compressive strength: 41 MPa

(47) 28 days compressive strength: 44 MPa

(48) Drying shrinkage characteristics: 400-600 micro strains (OPC control 600 micro strains)

Example 5

(49) GGBS 98.9%, CaO 0.1% PCE 1%

(50) Mix design (per 15 kg batch of solids)

(51) Binder: GGBS (2.697 kg), CaO (0.003 kg), 27 ml Sika ViscoCrete10 (a liquid PCE superplasticiser as a component of the binder). The PCE was mixed 1:100 with the remainder of the binder (i.e. 1 wt %)

(52) Aggregates: Ardleigh stone (1.5 kg), Granite (5.6 kg), Sand (5.1 kg)

(53) Water: tap water (0.81 L, water/binder ratio=0.3)

(54) Slump: 160 mm

(55) 7 days compressive strength: 3.1 MPa

(56) 28 days compressive strength: 23.8 MPa

Example 6

(57) GGBS 98.5%, CaO 0.5%, PCE 1%

(58) Mix design (per 15 kg batch of solids)

(59) Binder: GGBS (2.687 kg), CaO (0.013 kg), 27 ml Sika ViscoCrete10 (a liquid PCE superplasticiser as a component of the binder). The PCE was mixed 1:100 with the remainder of the binder (i.e. 1 wt %)

(60) Aggregates: Ardleigh stone (1.5 kg), Granite (5.6 kg), Sand (5.1 kg)

(61) Water: tap water (0.81 L, water/binder ratio=0.3)

(62) Slump: 175 mm

(63) 7 days compressive strength: 19.1 MPa

(64) 28 days compressive strength: 29 MPa

Example 7

(65) Mix design (per 15 kg batch of solids)

(66) Binder: GGBS 94.3%+CaO 2.9%+PFA super fine 1.8%+superplasticiser 1%.

(67) The weights used were GGBS (2.57 kg), CaO (0.08 kg), PFA super fine (0.05 kg), 27 ml Sika ViscoCrete10 (a liquid PCE superplasticiser as a component of the binder). The PCE was mixed 1:100 with the remainder of the binder (i.e. 1 wt %)

(68) Aggregates: Sand (4.8 kg), Gravel 10 mm (2.3 kg), Gravel 20 mm (5.3 kg)

(69) Water: tap water (1.13 L, water/binder ratio=0.4)

(70) Slump: 60 mm

(71) 7 days compressive strength: 25 MPa

(72) 28 days compressive strength: 35.4 MPa

Example 8

(73) Mix design (per 15 kg batch of solids)

(74) Binder: GGBS 94.3%+CaO 2.9%+PFA super fine 1.8%+superplasticiser 1%

(75) GGBS (2.57 kg), CaO (0.08 kg), PFA super fine (0.05 kg), superplasticiser: BASF RheoMatrix 23327 g mixed 1:100 with the remainder of the binder.

(76) Aggregates: Sand (4.8 kg), Gravel 10 mm (2.3 kg), Gravel 20 mm (5.3 kg)

(77) Water: tap water (0.89 L, water/binder ratio=0.33)

(78) Slump: 70 mm

(79) 7 days compressive strength: 33.1 MPa

(80) 28 days compressive strength: 42.2 MPa

Example 9

(81) Mix design (per 15 kg batch of solids)

(82) Binder: GGBS 94.8%+CaO 2.9%+PFA super fine 1.8%+superplasticiser 0.5%

(83) GGBS (2.57 kg), CaO (0.08 kg), PFA super fine (0.05 kg), superplasticiser: MELFLUX 2651Fpowder 13.5 g.

(84) The CaO, super-fine PFA and superplasticiser were mixed to form an activator composition, which was then mixed with the GGBS.

(85) Aggregates: Sand (4.8 kg), Gravel 10 mm (2.3 kg), Gravel 20 mm (5.3 kg)

(86) Water: tap water (0.89 L, water/binder ratio=0.33)

(87) Slump: 100 mm

(88) 7 days compressive strength: 28 MPa

(89) 28 days compressive strength: 44.7 MPa

Example 10

(90) Mix design (per 15 kg batch of solids)

(91) Binder: GGBS 94.8%+CaO 2.9%+PFA super fine 1.8%+superplasticiser 0.5%

(92) GGBS (2.57 kg), CaO (0.08 kg), PFA super fine (0.05 kg), superplasticiser: Sika VC225powder 13.5 g mixed 1:200 with the remainder of the binder (i.e. 0.5 wt %)

(93) The CaO, super-fine PFA and superplasticiser were mixed to form an activator composition, which was then mixed with the GGBS.

(94) Aggregates: Sand (4.8 kg), Gravel 10 mm (2.3 kg), Gravel 20 mm (5.3 kg)

(95) Water: tap water (0.89 L, water/binder ratio=0.33)

(96) Slump: 90 mm

(97) 7 days compressive strength: 29.5 MPa

(98) 28 days compressive strength: 44.5 MPa

Example 11

(99) Mix design (per 15 kg batch of solids)

(100) Binder: GGBS 84.4%+PFA (BS EN 450) 9.9%+CaO 2.9%+PFA super fine 1.8%+superplasticiser 1%

(101) GGBS (2.30 kg), PFA BS EN 450 (0.27)+CaO (0.08 kg), PFA super fine (0.05 kg), 27 ml Sika ViscoCrete10 (a liquid PCE superplasticiser as a component of the binder). The PCE was mixed 1:100 with the remainder of the binder (i.e. 1 wt %)

(102) Aggregates: Sand (4.8 kg), Gravel 10 mm (2.3 kg), Gravel 20 mm (5.3 kg)

(103) Water: tap water (1.13 L, water/binder ratio=0.4)

(104) Slump: 80 mm

(105) 7 days compressive strength: 13.2 MPa

(106) 28 days compressive strength: 23 MPa

Example 12

(107) Mix design (per 15 kg batch of solids)

(108) Binder: GGBS 54.7%+PFA (BS EN 450) 39.6%+CaO 2.9%+PFA super fine 1.8%+superplasticiser 1%

(109) GGBS (1.49 kg), PFA BS EN 450 (1.08 kg)+CaO (0.08 kg), PFA super fine (0.05 kg), 27 ml Sika ViscoCrete10 (a liquid PCE superplasticiser as a component of the binder). The PCE was mixed 1:100 with the remainder of the binder (i.e. 1 wt %)

(110) Aggregates: Sand (4.8 kg), Gravel 10 mm (2.3 kg), Gravel 20 mm (5.3 kg)

(111) Water: tap water (1.13 L, water/binder ratio=0.4)

(112) Slump: 90 mm

(113) 7 days compressive strength: 36.2 MPa

(114) 28 days compressive strength: 50.0 MPa

Example 13

(115) Mix design (per 15 kg batch of solids)

(116) Binder: GGBS 44.8%+PFA (BS EN 450) 49.5%+CaO 2.9%+PFA super fine 1.8%+superplasticiser 1%

(117) GGBS (1.22 kg), PFA BS EN 450 (1.35)+CaO (0.08 kg), PFA super fine (0.05 kg), 27 ml Sika ViscoCrete10 (a liquid PCE superplasticiser as a component of the binder). The PCE is mixed 1:100 with the remainder of the binder (i.e. 1 wt %)

(118) Aggregates: Sand (4.8 kg), Gravel 10 mm (2.3 kg), Gravel 20 mm (5.3 kg)

(119) Water: tap water (1.13 L, water/binder ratio=0.4)

(120) Slump: 80 mm

(121) 7 days compressive strength: 33.6 MPa

(122) 28 days compressive strength: 49.6 MPa

Example 14

(123) Mix design (per 15 kg batch of solids)

(124) Binder: GGBS 24.9%+PFA (BS EN 450) 69.4%+CaO 2.9%+PFA super fine 1.8%+superplasticiser 1%

(125) GGBS (0.68 kg), PFA BS EN 450 (1.89)+CaO (0.08 kg), PFA super fine (0.05 kg), 27 ml Sika ViscoCrete10 (a liquid PCE superplasticiser as a component of the binder). The PCE was mixed 1:100 with the remainder of the binder (i.e. 1 wt %)

(126) Aggregates: Sand (4.8 kg), Gravel 10 mm (2.3 kg), Gravel 20 mm (5.3 kg)

(127) Water: tap water (1.13 L, water/binder ratio=0.4)

(128) Slump: 110 mm

(129) 7 days compressive strength: 29.9 MPa

(130) 28 days compressive strength: 48.1 MPa

Example 15

(131) Mix design (per 15 kg batch of solids)

(132) Binder: Binder: PFA (BS EN 450) 94.3%+CaO 2.9%+PFA super fine 1.8%+superplasticiser 1%

(133) PFA BS EN 450 (2.57)+CaO (0.08 kg), PFA super fine (0.05 kg), 27 ml Sika ViscoCrete10 (a liquid PCE superplasticiser as a component of the binder). The PCE was mixed 1:100 with the remainder of the binder (i.e. 1 wt %)

(134) Aggregates: Sand (4.8 kg), Gravel 10 mm (2.3 kg), Gravel 20 mm (5.3 kg)

(135) Water: tap water (1.13 L, water/binder ratio=0.4)

(136) Slump: 90 mm

(137) 7 days compressive strength: 16.9 MPa

(138) 28 days compressive strength: 29.9 MPa