Activator composition and method for making concrete

Abstract

An activator composition for a non-OPC hydraulically-active material comprises CaO or lime and a polycarboxylate-ether-based (PCE) superplasticiser, and is mixable with a hydraulically active material comprising ground granulated blast furnace slag (GGBS) and/or pulverized fuel ash (PFA) to form a cementitious binder. The cementitious binder does not comprise any Portland cement and is, therefore, more environmentally friendly.

Claims

1. An activator composition mixable with a non-OPC hydraulically-active material comprising ground granulated blast furnace slag (GGBS), the activator composition comprising an activator, which is CaO or lime, and a polycarboxylate-ether-based (PCE) superplasticizer, and a further component which is microsilica and/or pulverised fuel ash (PFA).

2. An activator composition according to claim 1, in which the activator and the PCE superplasticiser are mixed in a weight ratio of between 1:1 and 38:1.

3. An activator composition according to claim 1, in which the activator and the further component are mixed in a weight ratio of between 1.2:1 and 3:1.

4. An activator composition according to claim 1, in which the PCE superplasticiser is in powder form.

5. An activator composition according to claim 1, in which the activator and the PCE superplasticiser are mixed in a weight ratio of between 1:1 and 6:1.

6. An activator composition according to claim 1, in which the activator composition is in powdered form.

7. An activator composition according to claim 1, in which the activator composition is pre-blended.

8. An activator composition mixable with a non-OPC hydraulically-active material comprising ground granulated blast furnace slag (GGBS), pulverised fuel ash (PFA) or a mixture of GGBS and PFA, the activator composition comprising an activator, which is CaO or lime, and a polycarboxylate-ether-based (PCE) superplasticizer, and in which the activator composition is contained within one or more water-soluble packages and is releasable from the one or more water-soluble packages on contact with water.

9. An activator composition according to claim 1, An activator composition mixable with a non-OPC hydraulically-active material comprising ground granulated blast furnace slag (GGBS), pulverised fuel ash (PFA) or a mixture of GGBS and PFA, the activator composition comprising an activator, which is CaO or lime, and a polycarboxylate-ether-based (PCE) superplasticizer, and in which the activator composition is packaged in a package for use in mixing with a hydraulically-active material, the package releasing the activator composition on contact with water.

10. An activator composition for combining with a hydraulically-active material comprising ground granulated blast furnace slag (GGBS), the activator composition comprising a first component consisting of CaO or lime and a second component consisting of a PCE superplasticizer, and a third component consisting of microsilica, PFA, or a mixture of microsilica and PFA.

11. An activator composition according to claim 10, in which the activator and the superplasticiser are mixed in a weight ratio of between 1:1 and 38:1.

12. An activator composition according to claim 10, in which the superplasticiser is in powder form.

13. An activator composition according to claim 10, in which the activator and the further component are mixed in a weight ratio of between 1.2:1 and 3:1.

14. An activator composition according to claim 10, in which a quantity of the activator composition is packaged in a package for use in mixing with a hydraulically-active material, the package releasing the activator composition on contact with water.

15. An activator composition according to claim 10, in which the activator and the superplasticiser are mixed in a weight ratio of between 1:1 and 6:1.

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. The mean particle size is 5-30 micrometres 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 mil 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% GGBS (2.57 kg), CaO (0.08 kg), PFA super fine (0.05 kg), superplasticiser: BASF RheoMatrix 233-27 g mixed 1:100 with the remainder of the binder.

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

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

(77) Slump: 70 mm

(78) 7 days compressive strength: 33.1 MPa

(79) 28 days compressive strength: 42.2 MPa

Example 9

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

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

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

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

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

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

(86) Slump: 100 mm

(87) 7 days compressive strength: 28 MPa

(88) 28 days compressive strength: 44.7 MPa

Example 10

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

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

(91) 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 %)

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

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

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

(95) Slump: 90 mm

(96) 7 days compressive strength: 29.5 MPa

(97) 28 days compressive strength: 44.5 MPa

Example 11

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

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

(100) 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 %)

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

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

(103) Slump: 80 mm

(104) 7 days compressive strength: 13.2 MPa

(105) 28 days compressive strength: 23 MPa

Example 12

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

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

(108) 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 %)

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

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

(111) Slump: 90 mm

(112) 7 days compressive strength: 36.2 MPa

(113) 28 days compressive strength: 50.0 MPa

Example 13

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

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

(116) GGBS (1.22 kg), PFA BS EN 450 (1.35)+CaO (0.08 kg), PFA super fine (0.05 kg), 27 mil 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 %)

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

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

(119) Slump: 80 mm

(120) 7 days compressive strength: 33.6 MPa

(121) 28 days compressive strength: 49.6 MPa

Example 14

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

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

(124) 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 %)

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

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

(127) Slump: 110 mm

(128) 7 days compressive strength: 29.9 MPa

(129) 28 days compressive strength: 48.1 MPa

Example 15

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

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

(132) 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 %)

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

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

(135) Slump: 90 mm

(136) 7 days compressive strength: 16.9 MPa

(137) 28 days compressive strength: 29.9 MPa

(138) Preferred Aspects

(139) 1. A cementitious binder comprising at least 90% by weight of a non-OPC hydraulically-active material comprising ground granulated blastfurnace slag (GGBS), pulverized fuel ash (PFA) or a mixture of GGBS and PFA, at least 0.1% by weight of CaO, and a superplasticiser.

(140) 2. A cementitious binder according to aspect 1, in which the hydraulically-active material comprises at least 50% or 70% or 80% or 90% GGBS, PFA or the mixture of GGBS and PFA.

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

(142) 4. A cementitious binder according to aspect 1, 2 or 3, comprising at least 90% of the hydraulically-active material, with the remainder comprising the CaO and the superplasticiser.

(143) 5. A cementitious binder according to any preceding aspect, which consists of GGBS, PFA or the mixture of GGBS and PFA, the CaO and the superplasticiser.

(144) 6. A cementitious binder according to any preceding claim, comprising an activator composition which comprises the CaO, optionally comprising the superplasticiser, and optionally further comprising microsilica and/or super-fine pulverized fuel ash (PFA).

(145) 7. A cementitious binder according to any preceding aspect, comprising at least 0.1 wt % or 1 wt % or 2 wt % CaO, and preferably an amount equal to or greater than about 2.5 wt %, 3 wt %, 4 wt %, 5 wt %, 6 wt %, 7 wt % or 8 wt % CaO.

(146) 8. A cementitious binder according to any preceding aspect, comprising greater than 93%, 95%, 96%, 97% or 98% by weight hydraulically-active material.

(147) 9. A cementitious binder according to any preceding aspect, comprising between 0.2% and 2%, or between 0.3% and 1.2%, or between 0.4% and 0.7% superplasticiser.

(148) 10. A cementitious binder according to any preceding aspect, in which the superplasticiser is in powder form and the binder comprises more than 0.2%, 0.25%, 0.3%, 0.35% or 0.4% and/or less than 0.7%, 0.75%, 1% or 1.2% superplasticiser.

(149) 11. A cementitious binder according to any preceding aspect, in which the superplasticiser is in liquid form and the binder comprises more than 0.2% or 0.5% and less than 2% superplasticiser.

(150) 12. A method of making a concrete, mortar, grout or render, comprising the steps of mixing together in a predetermined proportion; a) a cementitious binder, b) aggregate particles; and c) water in which the cementitious binder is a binder as defined in any preceding aspect.

(151) 13. A method according to aspect 12, in which the weight ratio of water to the cementitious binder is between 0.15:1 and 0.45:1, preferably between 0.2:1 and 0.4:1, preferably between 0.25:1 and 0.35:1, for example about 0.3:1, where non-absorbent aggregates are used.

(152) 14. A method according to aspect 12 or 13, in which the volume ratio of the cementitious binder to the aggregate particles is between 1:3 and 1:15, preferably between 1:4 and 1:8.

(153) 15. A method of making a concrete, mortar, grout or render, comprising the steps of mixing together in a predetermined proportion; a) a hydraulically-active material comprising GGBS, PFA or a mixture of GGBS and PFA; b) an activator composition comprising or consisting of CaO; c) aggregate particles; d) water; and e) a superplasticiser, which optionally forms a component of the activator composition; in which the hydraulically-active material, the activator composition and the superplasticiser (which optionally forms a component of the activator composition) combine to form a cementitious binder as defined in any of aspects 1 to 11.

(154) 16. A method according to aspect 15, in which components a), b) and e) combine to form a binder component of the concrete, mortar, grout or render, and the volume ratio of the binder component to component c) is between 1:3 and 1:15 and preferably between 1:4 and 1:8.

(155) 17. A method according to aspect 15 or 16, in which components a), b) and e) combine to form a binder component of the concrete, mortar, grout or render, and the weight ratio of component d) to the binder component is between 0.15:1 and 0.45:1, preferably between 0.2:1 and 0.4:1, preferably between 0.25:1 and 0.35:1, for example about 0.3:1, where non-absorbent aggregates are used.

(156) 18. A method according to any of aspects 15 to 17, in which the activator composition is contained within one or more water-soluble packages and is released from the one or more water-soluble packages as they are dissolved by the water.

(157) 19. A concrete, mortar, grout or render comprising a cementitious binder as defined in any of aspects 1 to 11.

(158) 20. A concrete, mortar, grout or render formed by the method defined in any of aspects 12 to 18.

(159) 21. A concrete, mortar, grout, or render according to aspect 19 or 20, in which the weight ratio of water to binder is between 0.2:1 and 0.4:1, preferably between 0.25:1 and 0.35:1, for example about 0.3:1, where non-absorbent aggregates are used.

(160) 22. A concrete, mortar, grout or render according to any of aspects 19 to 21, which has a compressive strength of greater than 15 MPa after 7 days, greater than 20 MPa after 14 days, and greater than 30 MPa after 28 days.

(161) 23. Use of an activator composition in combination with a hydraulically-active material comprising ground granulated blastfurnace slag (GGBS), pulverized fuel ash (PFA), or a mixture of GGBS and PFA to form a cementitious binder, the activator composition comprising CaO, in which the proportion of hydraulically-active material by weight in the resulting binder is greater than 90%, and the proportion of activator composition by weight in the resulting binder is less than 10%, and in which the binder comprises a superplasticiser such as a PCE.

(162) 24. Use of an activator composition according to aspect 23, in which the activator composition comprises the superplasticiser.

(163) 25. Use of an activator composition as defined in aspect 23 or 24, comprising the step of adding to the hydraulically-active material a predetermined quantity of the activator composition contained in a package, preferably a water-soluble package.

(164) 26. An activator composition for combining with a hydraulically-active material comprising ground granulated blastfurnace slag (GGBS), pulverized fuel ash (PFA), or a mixture of GGBS and PFA in combination with a superplasticiser such as PCE to form a cementitious binder, the activator composition comprising a first component consisting of CaO, and a second component consisting of microsilica and/or pulverized fuel ash (PFA), preferably in a superfine form, in which the first component and the second component are mixed in a weight ratio of between 1.2:1 and 3:1.

(165) 27. An activator composition according to aspect 26, in which the superplasticiser is a component of the activator composition.

(166) 28. An activator composition according to aspect 26 or 27, in which the CaO comprises lime.

(167) 29. An activator composition for combining with a hydraulically-active material comprising GGBS, PFA or a mixture of GGBS and PFA, the activator composition comprising a first component consisting of CaO and a second component consisting of a superplasticiser such as PCE superplasticiser.

(168) 30. An activator composition according to aspect 29, in which the superplasticiser is in powder form.

(169) 31. An activator composition according to aspect 29 or 30, further comprising a third component consisting of microsilica, PFA, or a mixture of microsilica and PFA, the PFA preferably being super-fine PFA.

(170) 32. An activator composition according to any of aspects 26 to 31, in which a predetermined quantity of the activator composition is packaged in a package for use in mixing with a hydraulically-active material, the package preferably releasing the activator composition on contact with water.

(171) 33. A cementitious binder comprising; more than 90% of a hydraulically-active material comprising GGBS, PFA or a mixture of GGBS and PFA; between 0.1% and 9% CaO; and between 0.2% and 2% superplasticiser, such as a PCE superplasticiser.

(172) 34. A cementitious binder according to aspect 33, comprising, between 94-97 wt % of the hydraulically-active material; between 1.5-3.5 wt % CaO; and between 0.2-2 wt % superplasticiser.

(173) 35. A cementitious binder according to aspect 33 or 34, comprising between 1-2.5 wt % microsilica and/or pulverized fuel ash (PFA), preferably super-fine PFA.

(174) 36. A concrete, mortar, grout or render comprising a cementitious binder formed from a combination of 94-97 wt % of a hydraulically-active material comprising ground granulated blastfurnace slag (GGBS), pulverized fuel ash (PFA), or a mixture of GGBS and PFA, 3-6 wt % of an activator composition, and aggregate particles bound together by the binder, in which the activator composition comprises a first component consisting of CaO and a second component consisting of microsilica and/or pulverized fuel ash (PFA), preferably in super fine form, the ratio of the first component to the second component being between 1.2:1 and 3:1 by weight, and in which the binder comprises a superplasticiser such as a PCE, optionally forming part of the activator composition.

(175) 37. A concrete, mortar, grout or render according to aspect 35, in which the CaO is lime.

(176) 38. A concrete, mortar, grout or render comprising a cementitious binder according to any of aspects 33 to 37.

(177) 39. A concrete, mortar, grout, render or binder as defined in any preceding aspect that does not contain ordinary Portland cement (OPC).